Voltage conversion protection circuit and power conversion equipment

Abstract

The utility model relates to the technical field of power supply control, in particular to a voltage conversion protection circuit and power supply conversion equipment. According to the voltage conversion protection circuit provided by the invention, the undervoltage protection circuit and the overvoltage protection circuit are arranged in the voltage conversion protection circuit, and the rectified external power supply is respectively input to the non-inverting input end of the first hysteresis comparator and the inverting input end of the second hysteresis comparator; when the external power supply is in an overvoltage state, a voltage protection control signal is output to the controller through the first hysteresis comparator, when the external power supply is in an overvoltage state, the voltage protection control signal is output to the controller through the second hysteresis comparator, and the controller protects the voltage conversion circuit according to the voltage protection control signal.

Description

Technical Field

[0001] This application relates to the field of power control technology, specifically to a voltage conversion protection circuit and a power conversion device. Background Technology

[0002] In recent years, the aerospace field has developed rapidly. In order to protect the safety of aircraft operation, the protection requirements for aircraft input power supply are becoming increasingly stringent. It is necessary to meet the power input requirements of "RTCA / DO-160G Airborne Equipment Environmental Conditions and Test Procedures".

[0003] The inventors of this application discovered in their research that airborne AC-DC conversion circuits often use dedicated conversion power modules. These power modules generally lack input overvoltage and undervoltage protection functions, and their own protection circuits cannot solve the overvoltage problem below the clamping voltage. This leads to lower safety of subsequent circuits and may even result in the risk of circuit damage or burnout. Utility Model Content

[0004] In view of the above problems, embodiments of this application provide a voltage conversion protection circuit and a power conversion device to solve the above-mentioned technical problems existing in the prior art.

[0005] In one embodiment of this application, a voltage conversion protection circuit is proposed, including a rectifier unit, a voltage protection unit, and a control unit;

[0006] The input terminal of the rectifier unit is electrically connected to an external power supply for rectifying the input power of the external power supply. The output terminal of the rectifier unit is electrically connected to the voltage protection unit for inputting the rectified power to the voltage protection unit.

[0007] The voltage protection unit includes a first voltage divider circuit, a first hysteresis comparator, a second voltage divider circuit, and a second hysteresis comparator.

[0008] The non-inverting input of the first hysteresis comparator is electrically connected to the output of the rectifier unit through a first voltage divider circuit, the inverting input is used to input a reference voltage, and the output is electrically connected to the control unit.

[0009] The inverting input of the second hysteresis comparator is electrically connected to the output of the rectifier unit through the second voltage divider circuit. The inverting input is used to input the reference voltage, and the output is electrically connected to the control unit.

[0010] The control unit is electrically connected to the voltage protection unit and the external voltage conversion unit respectively, and is used to control the voltage conversion unit;

[0011] When the rectified power supply voltage output from the output terminal of the rectifier unit is less than the reference voltage after being divided by the first voltage divider circuit, the output terminal of the first hysteresis comparator outputs a voltage protection control signal to the control unit; when the rectified power supply voltage output from the output terminal of the rectifier unit is greater than the reference voltage after being divided by the second voltage divider circuit, the output terminal of the second hysteresis comparator outputs a voltage protection control signal to the control unit; the control unit protects the external voltage conversion unit according to the voltage protection control signal.

[0012] Preferably, in some embodiments, the voltage protection unit further includes a first switching diode, a second switching diode, and an isolation circuit;

[0013] The cathode of the first switching diode is electrically connected to the output terminal of the first hysteresis comparator, and the anode of the first switching diode is electrically connected to the isolation circuit.

[0014] The cathode of the second switching diode is electrically connected to the output terminal of the second hysteresis comparator, and the anode of the second switching diode is electrically connected to the isolation circuit.

[0015] The isolation circuit is electrically connected to the control unit and is used to isolate the control unit from the voltage protection unit. When the first switching diode or the second switching diode is turned on, the isolation circuit is turned on and sends a voltage protection control signal to the control unit.

[0016] Preferably, in some embodiments, the isolation circuit includes a light-emitting diode and a photodetector;

[0017] The positive terminal of the light-emitting diode is connected to an external power source, and the negative terminal of the light-emitting diode is connected to the positive terminals of the first switching diode and the second switching diode, respectively.

[0018] The output terminals of the photoelectric sensor are electrically connected to the control unit.

[0019] When the first or second switching diode is turned on, the light-emitting diode is in the on state, and the output terminal of the photoelectric sensor sends a voltage protection control signal to the control unit.

[0020] Preferably, in some embodiments, a reference voltage output unit is also included;

[0021] The input terminal of the reference voltage output unit is electrically connected to the output terminal of the rectifier unit, and is used to step down the rectified power supply output from the output terminal of the rectifier unit to output a reference voltage.

[0022] Preferably, in some embodiments, the reference voltage output unit includes a power transistor and a Zener diode;

[0023] The collector of the power transistor is electrically connected to the output terminal of the rectifier unit, the base of the power transistor is electrically connected to the Zener diode, and the emitter of the power transistor outputs a reference voltage.

[0024] Preferably, in some embodiments, a grounding unit is further included; the grounding unit includes a first resistor and a first capacitor, the first resistor and the first capacitor being connected in parallel;

[0025] The ground terminals of the first hysteresis comparator and the second hysteresis comparator are respectively electrically connected to one end of the first resistor and the first capacitor; the other ends of the first resistor and the first capacitor are connected to the ground.

[0026] Preferably, in some embodiments, the rectifier unit includes a rectifier bridge circuit, a filter capacitor, and a transient voltage suppression diode;

[0027] The input terminal of the rectifier bridge circuit is electrically connected to the external power supply;

[0028] The filter capacitor and the transient voltage suppression diode are connected in parallel to form a parallel circuit. One end of the parallel circuit is electrically connected to the output terminal of the rectifier bridge circuit, and the other end of the parallel circuit is electrically connected to the grounding unit.

[0029] Preferably, in some embodiments, the rectifier unit further includes a fuse; one end of the fuse is electrically connected to the external power supply, and the other end is electrically connected to the input terminal of the rectifier bridge circuit.

[0030] Preferably, in some embodiments, the control unit is further configured to count the number of overvoltages or undervoltages of the external power supply according to the voltage protection control signal, and to protect the external voltage conversion unit according to the number of overvoltages or undervoltages.

[0031] In another aspect of this application, a power conversion device is also proposed, including a power input circuit, the voltage conversion protection circuit and the voltage conversion circuit described in the above embodiments; the power input circuit is electrically connected to the voltage conversion circuit through the voltage conversion protection circuit.

[0032] The voltage conversion protection circuit and power conversion device proposed in this application, by setting up an undervoltage protection circuit and an overvoltage protection circuit in the voltage conversion protection circuit, respectively inputs the rectified external power supply to the non-inverting input terminal of the first hysteresis comparator and the inverting input terminal of the second hysteresis comparator. When the external power supply is in an undervoltage state, the first hysteresis comparator outputs a voltage protection control signal to the controller. When the external power supply is in an overvoltage state, the second hysteresis comparator outputs a voltage protection control signal to the controller. The controller protects the AC-DC voltage conversion circuit according to the voltage protection control signal.

[0033] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0034] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0035] Figure 1 A schematic diagram of the power conversion device and voltage conversion protection circuit provided in the embodiments of this application is shown;

[0036] Figure 2 A circuit diagram of the rectifier unit provided in an embodiment of this application is shown;

[0037] Figure 3 A circuit diagram of the voltage protection unit provided in an embodiment of this application is shown;

[0038] Figure 4 A circuit diagram of a reference voltage output unit provided in an embodiment of this application is shown;

[0039] Figure 5 A circuit diagram of a grounding unit provided in an embodiment of this application is shown. Detailed Implementation

[0040] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0042] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0043] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0044] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0045] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0046] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0047] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0048] In the aerospace field, in order to protect the safety of aircraft operation, the protection requirements for aircraft input voltage are becoming increasingly stringent, and the safety requirements for airborne AC-DC conversion circuits are also becoming increasingly stringent. In order to prevent AC-DC voltage conversion circuits from malfunctioning, it is necessary to protect the AC-DC voltage conversion circuits.

[0049] Current protection methods for AC-DC voltage conversion circuits include using a fuse at the AC input terminal to protect downstream circuits by blowing the fuse. However, when using fuse protection, it's crucial to ensure that the upstream and downstream circuits are not damaged after the fuse blows. Power modules used in aerospace applications typically operate at voltages of 95–140VA, while AC power supplies with an input voltage of 180V only support millisecond-level operation; exceeding this time poses a risk of damage. Fuse protection is unlikely to meet the requirement of such close operating and protection voltages. Furthermore, the working principle of a fuse is to melt itself by increasing its thermal power; the determining factor is thermal power, not the input voltage. Therefore, fuse protection has significant inaccuracies.

[0050] In some protection methods for AC-DC voltage conversion circuits, varistors or TVS diodes are used for overvoltage protection. The protection mechanism of varistors and TVS diodes is to clamp the input voltage when the voltage exceeds the protection voltage. It is difficult for such devices to provide effective protection when the operating voltage and the protection voltage are close. In addition, varistors and TVS diodes are mainly devices for dealing with surge impacts in the microsecond range and are not suitable for overvoltage and undervoltage protection functions.

[0051] Therefore, addressing the problem that existing methods for protecting AC-DC voltage conversion circuits cannot effectively provide overvoltage and undervoltage protection, the inventors of this application propose a voltage conversion protection circuit and power conversion device. By incorporating undervoltage and overvoltage protection circuits into the voltage conversion protection circuit, the rectified external power supply is input to the non-inverting input of a first hysteresis comparator and the inverting input of a second hysteresis comparator. When the external power supply is undervoltage, the first hysteresis comparator outputs a voltage protection control signal to the controller; when the external power supply is overvoltage, the second hysteresis comparator outputs a voltage protection control signal to the controller. The controller then protects the AC-DC voltage conversion circuit based on these voltage protection control signals. This method achieves protection of the AC-DC voltage conversion circuit under undervoltage and overvoltage conditions, while simultaneously meeting the RTCA / DO-160G requirements for sensitivity to normal surge voltage (AC), abnormal surge voltage (AC), and induced signals.

[0052] The voltage conversion protection circuit and power conversion device proposed in this application can be applied to various scenarios that require AC-DC voltage conversion circuits, including but not limited to aircraft airborne equipment, high-speed rail airborne equipment, and other scenarios with such requirements.

[0053] like Figure 1 The diagram shows a schematic representation of a power conversion device according to an embodiment of this application. The device includes a power input circuit 100, a voltage conversion protection circuit 200, and a voltage conversion circuit 300. The power input circuit 100 is an interface circuit for an external power source, used to connect to an external power source and introduce external AC power. The voltage conversion protection circuit 200 is mainly used to detect the AC power introduced by the power input circuit 100. Since voltage changes in the external power source can affect the voltage conversion circuit 300, the voltage conversion protection circuit 200 controls the voltage conversion circuit 300 in a timely manner when the external power source is in an overvoltage or undervoltage state. For example, when the external power source is in an overvoltage or undervoltage state, the voltage conversion circuit 300 can be shut down in a timely manner to protect it. The voltage conversion circuit 300 is used to perform AC-DC voltage conversion under the control of the voltage conversion protection circuit 200.

[0054] In the above embodiments, in order to solve the problem that the voltage conversion circuit cannot be protected against overvoltage and undervoltage in the prior art, the power conversion device adopts a novel voltage conversion protection circuit 200, the structural schematic diagram of which is shown below. Figure 1 As shown, the voltage conversion protection circuit 200 includes a rectifier unit 210, a voltage protection unit 220, and a control unit 230.

[0055] The input terminal of the rectifier unit 210 is electrically connected to an external power supply and is used to rectify the input power introduced by the power input circuit 100. The output terminal of the rectifier unit 210 is electrically connected to the voltage protection unit 220 and is used to input the rectified power to the voltage protection unit 220.

[0056] The voltage protection unit 220 includes a first voltage divider circuit, a first hysteresis comparator, a second voltage divider circuit, and a second hysteresis comparator. The non-inverting input terminal of the first hysteresis comparator is electrically connected to the output terminal of the rectifier unit 210 through the first voltage divider circuit, the inverting input terminal is used to input a reference voltage, and the output terminal is electrically connected to the control unit 230. The inverting input terminal of the second hysteresis comparator is electrically connected to the output terminal of the rectifier unit 210 through the second voltage divider circuit, the inverting input terminal is used to input a reference voltage, and the output terminal is electrically connected to the control unit 230.

[0057] The control unit 230 is electrically connected to the voltage protection unit 220 and the voltage conversion circuit 300, respectively, and is used to control the voltage conversion circuit 300. When the rectified power supply voltage output from the output terminal of the rectifier unit 210 is less than the reference voltage after being divided by the first voltage divider circuit, the output terminal of the first hysteresis comparator outputs a voltage protection control signal to the control unit 230. When the rectified power supply voltage output from the output terminal of the rectifier unit is greater than the reference voltage after being divided by the second voltage divider circuit, the output terminal of the second hysteresis comparator outputs a voltage protection control signal to the control unit 230. The control unit 230 protects the voltage conversion circuit 300 according to the voltage protection control signal.

[0058] To facilitate the detection of the input AC power, this embodiment of the application performs full-wave rectification on the AC input to obtain a stable and easily detectable DC voltage. The input terminal of the rectifier unit 210 is electrically connected to the power input circuit 100, rectifying the AC power introduced into the power input circuit 100, converting the AC input into a corresponding DC voltage, and inputting the rectified DC power to the voltage protection unit 220. The voltage protection unit 220 protects the voltage conversion circuit 300 based on the DC power output from the rectifier unit 210.

[0059] Figure 2A circuit diagram of a rectifier unit 210 is shown. The rectifier unit 210 includes a rectifier bridge circuit U11, a filter capacitor CE31, and a transient voltage suppression diode D12. The rectifier bridge circuit U11 consists of four diodes configured in a "bridge" shape. In this embodiment, the rectifier bridge circuit U11 is a full-wave rectifier bridge, where both the positive and negative half-cycles of the AC input voltage are used to generate a DC output. When the positive half-cycle of the input voltage arrives, two diodes in the bridge circuit conduct, allowing current to flow through the load resistor. When the negative half-cycle of the input voltage arrives, the other two diodes conduct, and current still flows through the load resistor, but in the opposite direction. Thus, regardless of whether the AC input voltage is in a positive or negative half-cycle, the rectifier bridge can output a current in a single direction, i.e., direct current. Figure 2 In this circuit, input pins ACN and ACL represent the live and neutral input terminals of the AC power supply, respectively. The live wire is connected to pin 3 of the rectifier bridge circuit U11 via pin ACN, and the neutral wire is connected to pin 2 of the rectifier bridge circuit U11 via pin ACL. The filter capacitor CE31 and the transient voltage suppression diode D12 are connected in parallel to form a parallel circuit. One end of the parallel circuit is electrically connected to the output terminal OUT of the rectifier bridge circuit U11, i.e., pin 4, and the other end of the parallel circuit is electrically connected to the grounding pin 1 of the rectifier bridge and connected to the ground wire. The transient voltage suppression diode D12 can conduct transient high voltage to the ground when the input terminal encounters a high voltage spike or a transient high voltage introduced by lightning, effectively preventing damage to downstream devices caused by high voltage. After rectifying the input power supply, the rectifier unit 210 outputs a PWR_AC_DC_ABS210 voltage signal to the voltage protection unit.

[0060] Continue to refer Figure 3 , Figure 3 A schematic diagram of the voltage protection unit 220 is shown. This circuit includes an undervoltage protection branch and an overvoltage protection branch, each composed of a voltage divider circuit and a hysteresis comparator. The hysteresis comparator is based on a combination of an inverter and a non-inverter; the output of the inverter is opposite to the input signal, while the output of the non-inverter is the same as the input signal. The hysteresis comparator functions by comparing the outputs of the inverter and the non-inverter. When the input signal rises from a low level to a high level, the comparator output flips only when a higher threshold voltage Vh is reached; conversely, when the input signal falls from a high level to a low level, the comparator output flips only when a lower threshold voltage Vl is reached. The difference between the high-level and low-level threshold voltages, Vh-Vl, represents the hysteresis width. This hysteresis characteristic effectively eliminates noise and improves circuit stability.

[0061] The undervoltage protection branch consists of a first voltage divider circuit and a first hysteresis comparator. The first voltage divider circuit includes voltage divider resistors R120 and R117. The first hysteresis comparator includes a first amplifier U13A and a feedback resistor R130. The non-inverting input terminal 3 of the first amplifier U13A is electrically connected to the output terminal of the rectifier unit 210 through the voltage divider resistors R120 and R117. That is, the non-inverting input terminal 3 of the first amplifier receives the voltage signal PWR_AC_DC_ABS210, which is then divided by the voltage divider resistors R120 and R117 to adjust the voltage input to the non-inverting input terminal 3. Figure 3 As shown, R120 has a resistance of 110KΩ, and R117 has a resistance of 8.06KΩ, forming DC undervoltage protection points of Vh = 87.39V and Vl = 78.27V, and AC undervoltage protection points of Vh = 61.8V and Vl = 55.35V, respectively. Simultaneously, the voltage divider resistor R120 is connected in parallel with the filter capacitor C117, and the voltage divider resistor R117 is connected in parallel with the filter capacitor C116 to filter the current. The inverting input terminal 2 of the first amplifier U13A is electrically connected to the reference voltage VCC12_REF through the current-limiting resistor R128, and grounded through resistor R129. The output pin 1 of the first amplifier U13A is connected to the non-inverting input terminal 3 through the feedback resistor R130, forming a hysteresis comparator circuit. Furthermore, the output pin 1 of the first amplifier U13A is also grounded through the pull-up resistor R137 and connected to the control unit 230 to send voltage protection control signals to the control unit 230. The positive power input pin 8 of the first amplifier U13A is electrically connected to the reference voltage VCC12_REF, and the negative power input pin 4 is connected to the ground GND_PB_Signal. Since the non-inverting input terminal 3 of the first amplifier U13A is electrically connected to the output terminal of the rectifier unit 210, and the inverting input terminal 2 of the first amplifier U13A is electrically connected to the reference voltage VCC12_REF, when the voltage value of the voltage signal PWR_AC_DC_ABS210 after being divided by the first voltage divider circuit and input to the non-inverting input terminal 3 of the first amplifier U13A is less than the reference voltage VCC12_REF, it indicates that the external power supply is in an undervoltage state, and the output terminal of the first amplifier U13A outputs a low-level signal; when the voltage value of the voltage signal PWR_AC_DC_ABS210 after being divided by the first voltage divider circuit and input to the non-inverting input terminal 3 of the first amplifier U13A is greater than or equal to the reference voltage VCC12_REF, it indicates that the external power supply is in a normal state, and the output terminal of the first amplifier U13A outputs a high-level signal.

[0062] Continue to refer Figure 3The overvoltage protection branch consists of a second voltage divider circuit and a second hysteresis comparator. The second voltage divider circuit includes voltage divider resistors R135 and R134, and the second hysteresis comparator includes a second amplifier U13B and a feedback resistor R133. The inverting input terminal 6 of the second amplifier U13B is electrically connected to the output terminal of the rectifier unit 210 through the voltage divider resistors R135 and R134. That is, the inverting input terminal 6 of the second amplifier U13B receives the voltage signal PWR_AC_DC_ABS210, which is then divided by the voltage divider resistors R134 and R135 to adjust the voltage input to the inverting input terminal 6. Figure 3 As shown, R135 has a resistance of 243KΩ and R134 has a resistance of 6.04KΩ, forming overvoltage protection points for DC current of Vh = 250.06V and Vl = 233.48V, and undervoltage protection points for AC current of Vh = 176.85V and Vl = 165.12V, respectively. The voltage divider resistor R135 is connected in parallel with the filter capacitor C120, and the voltage divider resistor R134 is connected in parallel with the filter capacitor C121 to filter the current. The non-inverting input terminal 5 of the second amplifier U13B is electrically connected to the reference voltage VCC12_REF through the current limiting resistor R131 and grounded through the resistor R132. The output terminal pin 7 of the second amplifier U13B is connected to the non-inverting input terminal 5 through the feedback resistor R133 to form a hysteresis comparator circuit. Furthermore, the output pin 7 is also grounded through the pull-up resistor R136 and connected to the control unit 230 to send a voltage protection control signal to the control unit 230. The positive power input pin 8 of the second amplifier U13B is electrically connected to the reference voltage VCC12_REF, and the negative power input pin is connected to the ground GND_PB_Signal. Since the inverting input pin 6 of the second amplifier U13B is electrically connected to the output of the rectifier unit 210, and the non-inverting input pin 5 of the second amplifier U13B is electrically connected to the reference voltage VCC12_REF, when the voltage value of the voltage signal PWR_AC_DC_ABS210 after being divided by the second voltage divider circuit and input to the inverting input pin 6 of the second amplifier U13B is greater than the reference voltage VCC12_REF, it indicates that the external power supply is in an overvoltage state, and the output of the second amplifier U13B outputs a low-level signal. When the voltage value of the voltage signal PWR_AC_DC_ABS210 after being divided by the second voltage divider circuit and input to the inverting input pin 4 of the second amplifier U13B is less than or equal to the reference voltage VCC12_REF, it indicates that the external power supply is in a normal state, and the output of the second amplifier U13B outputs a high-level signal.

[0063] It should be noted that in practical applications, the first and second hysteresis comparators can be configured as two separate chips, i.e., using two independent amplifiers, or they can share a single chip, i.e., using a chip with two amplifiers, such as the dual-channel operational amplifier LM2904D. This reduces the size of the voltage conversion protection unit. Therefore, in the above embodiments, the description of the first and second hysteresis comparators is from a functional perspective and does not constitute a limitation on the protection scope. It should not be simply understood that the first and second hysteresis comparators are separate circuit structures.

[0064] Continue to refer Figure 3 After receiving the voltage protection control signal HGMS_ON sent by the voltage protection unit 220, the control unit 230 controls the voltage conversion circuit 300, for example, by shutting down the voltage conversion circuit 300 to protect it and prevent circuit damage or burnout. The control unit 230 can use an STM32F103C8T6 microcontroller, a 32-bit microcontroller based on the ARM Cortex-M core SMT32 series, with 64KB of program memory, a digital-to-analog converter with a maximum sampling frequency of 14MHz, and abundant I / O ports.

[0065] In summary, the embodiments proposed in this application, by setting up two hysteresis comparison circuits respectively, one for detecting overvoltage and the other for detecting undervoltage, allow the controller to protect the voltage conversion circuit according to the voltage protection control signal when overvoltage or undervoltage occurs, thus preventing damage or burnout of the voltage conversion circuit. This also meets the requirements of RTCA / DO-160G for sensitivity to normal surge voltage (AC), abnormal surge voltage (AC), and induced signals.

[0066] Furthermore, in practical applications, when performing AC-DC voltage conversion, the input voltage is typically 220V AC, while the controller is generally a low-voltage circuit. To avoid interference from the high-voltage circuit to the low-voltage circuit, in this embodiment of the application, such as... Figure 3As shown, the voltage protection unit 220 further includes a first switching diode D12, a second switching diode D11, and an isolation circuit; the cathode of the first switching diode D12 is electrically connected to the output terminal of the first hysteresis comparator, and the anode of the first switching diode D12 is electrically connected to the isolation circuit; the cathode of the second switching diode D11 is electrically connected to the output terminal of the second hysteresis comparator, and the anode of the second switching diode D11 is electrically connected to the isolation circuit; the isolation circuit is electrically connected to the control unit 230 and is used to isolate the control unit 230 from the voltage protection unit 220. When the first switching diode D12 or the second switching diode D11 is turned on, the isolation circuit is turned on and sends a voltage protection control signal to the control unit.

[0067] The isolation circuit can employ various methods, including optical isolation, electromagnetic isolation, or capacitive isolation. One end of the isolation circuit is connected to the control unit 230, and the other end is electrically connected to the voltage protection unit 220. When the external power supply is in an undervoltage state, the first hysteresis comparator outputs a low-level signal, at which time the first switching diode D12 is in a conducting state, and the isolation circuit is turned on. When the external power supply is in an overvoltage state, the second hysteresis comparator outputs a low-level signal, at which time the second switching diode D11 is in a conducting state, and the isolation circuit is also turned on. When the isolation circuit is turned on, a voltage protection control signal is output to the control unit 230. Therefore, the isolation circuit can achieve isolation between the front-end high-voltage circuit and the back-end low-voltage circuit, ensuring signal stability.

[0068] In this embodiment, the isolation circuit is preferably configured as an optical isolation circuit. Optical isolation circuits have high isolation voltage, stable signal transmission, are contactless, have a long lifespan, and are suitable for high-speed signal transmission. Figure 3 As shown, the isolation circuit can use a PO357N2J000F optocoupler, including a light-emitting diode (LED) and a photodetector. The positive terminal of the LED, i.e., pin 1, is connected to the power supply VCC12_REF through voltage divider resistors R115 and R114. The negative terminal of the LED, i.e., pin 2, is connected to the positive terminals of the first switching diode D12 and the second switching diode D11, respectively. The output terminals of the photodetector, i.e., pins 3 and 4, are electrically connected to the control unit, respectively.

[0069] When either the first switching diode D12 or the second switching diode D11 is turned on, the EN_HGMS signal is low, and the LED is in the on state under the action of the power supply VCC12_REF. The output of the photodetector sends a voltage protection control signal HGMS_ON to the control unit. When either the first switching diode D12 or the second switching diode D11 is turned off, the EN_HGMS signal is high, and the LED is in the off state. The isolation circuit is in the isolated state, isolating the front-end high-voltage circuit and the control unit. Therefore, by setting the isolation unit to optical isolation, the above embodiment greatly improves the isolation voltage and enhances the stability of signal transmission.

[0070] In some application scenarios, such as in airborne equipment, this embodiment of the application uses a separate floating ground method for grounding protection of the voltage protection unit 220 and the control unit 230. Therefore, the power supply of the voltage protection unit 220 and the control unit 230 cannot use the voltage output by the voltage conversion circuit 300, and an independent power supply needs to be designed. Therefore, this embodiment of the application also shows a reference voltage output unit 240. The input terminal of the reference voltage output unit 240 is electrically connected to the output terminal of the rectifier unit 210, and is used to step down the rectified power supply output by the output terminal of the rectifier unit 210 and output a reference voltage VCC12_REF.

[0071] like Figure 4 The diagram shows the circuit structure of a reference voltage output unit 240, which includes a power transistor Q27 and a Zener diode D10. The collector of the power transistor Q27 is electrically connected to the output terminal of the rectifier unit 210 and receives the voltage signal PWR_AC_DC_ABS210. Resistors R1004 and R110 are connected in parallel between the base and collector of the power transistor Q27. The base of the power transistor Q27 is electrically connected to the Zener diode D10. The emitter of the power transistor Q27 outputs a reference voltage VCC12_REF. A resistor R112 and filter capacitors C112 and C132 are provided at the emitter of the power transistor Q27.

[0072] When the voltage signal PWR_AC_DC_ABS210 is received, the transistor Q27 controls the collector-emitter path of the transistor through the base-emitter voltage, thereby controlling the current flowing through the circuit. When the current flows through the transistor Q27 and the Zener diode D10, the voltage on the Zener diode reaches its stable voltage. At this time, the Zener diode limits the voltage rise, and the Zener diode D10 limits the current flowing through the base, thereby controlling the conduction level of the transistor Q27. The collector current of the transistor Q27 is controlled by the base current, while the Zener diode D10 ensures the stability of the output voltage. By setting a reference voltage output unit, a stable reference voltage is ensured for the voltage protection unit 220 and the control unit 230, and interference is also avoided.

[0073] To achieve a floating grounding method for the voltage protection unit and the control unit, embodiments of this application further include a grounding unit 250, such as... Figure 5 As shown, the grounding unit 250 includes a first resistor R1003 and a first capacitor C139, which are connected in parallel with C139. The grounding terminals GND_PB_Signal of the first hysteresis comparator and the second hysteresis comparator are electrically connected to one end of the first resistor R1003 and the first capacitor C139, respectively. GND_PB_Signal is connected to the ground in parallel with a 10MΩ resistor and a 2200pF capacitor. This floating ground connection reduces mutual interference between circuits and prevents electromagnetic interference caused by common-impedance circuit coupling.

[0074] Furthermore, to protect the voltage conversion circuit 300, a fuse F1 can be installed in the rectifier unit 210, such as... Figure 2 As shown, one end of the fuse F1 is electrically connected to the external power supply, and the other end is electrically connected to the input terminal of the rectifier bridge circuit U11. The fuse can be selected with a maximum allowable current of 15A. When a short circuit occurs at the output terminal, the fuse will melt quickly.

[0075] Furthermore, in addition to the timely protection of the voltage conversion circuit 300 by the voltage conversion protection circuit 200 when the external power supply experiences overvoltage or undervoltage, to further improve the reliability and safety of the system, this embodiment of the application can also use the control unit 230 to count the number of overvoltage or undervoltage events of the external power supply based on the voltage protection control signal, and protect the external voltage conversion unit based on the number of overvoltage or undervoltage events. For example, the control unit 230 can count the number of times HGMS_ON is low to determine the number of times the external power supply experiences undervoltage or overvoltage. In this way, it is possible to record the number of times the input AC voltage exceeds specifications, detect the number of times the input level signal on the voltage conversion protection circuit is abnormal, and provide a serial port to transmit the recorded data to other control systems.

[0076] In summary, the voltage conversion protection circuit and power conversion device provided in this application embodiment greatly improve the protection capability of the voltage conversion circuit, enhance the safety of the subsequent circuits, and reduce the risk of the power supply being damaged or burned by the circuit.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A voltage conversion protection circuit, characterized in that, Includes a rectifier unit, a voltage protection unit, and a control unit; The input terminal of the rectifier unit is electrically connected to an external power supply for rectifying the input power of the external power supply. The output terminal of the rectifier unit is electrically connected to the voltage protection unit for inputting the rectified power to the voltage protection unit. The voltage protection unit includes a first voltage divider circuit, a first hysteresis comparator, a second voltage divider circuit, and a second hysteresis comparator. The non-inverting input of the first hysteresis comparator is electrically connected to the output of the rectifier unit through the first voltage divider circuit, the inverting input is used to input the reference voltage, and the output is electrically connected to the control unit. The inverting input of the second hysteresis comparator is electrically connected to the output of the rectifier unit through the second voltage divider circuit. The inverting input is used to input a reference voltage, and the output is electrically connected to the control unit. The control unit is electrically connected to the voltage protection unit and the external voltage conversion unit respectively, and is used to control the voltage conversion unit; When the rectified power supply voltage output from the output terminal of the rectifier unit is less than the reference voltage after being divided by the first voltage divider circuit, the output terminal of the first hysteresis comparator outputs a voltage protection control signal to the control unit; when the rectified power supply voltage output from the output terminal of the rectifier unit is greater than the reference voltage after being divided by the second voltage divider circuit, the output terminal of the second hysteresis comparator outputs a voltage protection control signal to the control unit; the control unit protects the external voltage conversion unit according to the voltage protection control signal.

2. The voltage conversion protection circuit according to claim 1, characterized in that, The voltage protection unit also includes a first switching diode, a second switching diode, and an isolation circuit; The cathode of the first switching diode is electrically connected to the output terminal of the first hysteresis comparator, and the anode of the first switching diode is electrically connected to the isolation circuit. The cathode of the second switching diode is electrically connected to the output terminal of the second hysteresis comparator, and the anode of the second switching diode is electrically connected to the isolation circuit. The isolation circuit is electrically connected to the control unit and is used to isolate the control unit from the voltage protection unit. When the first switching diode or the second switching diode is turned on, the isolation circuit is turned on and sends the voltage protection control signal to the control unit.

3. The voltage conversion protection circuit according to claim 2, characterized in that, The isolation circuit includes a light-emitting diode and a photoelectric sensor; The positive terminal of the light-emitting diode is connected to the external power supply, and the negative terminal of the light-emitting diode is connected to the positive terminals of the first switching diode and the second switching diode, respectively. The output terminals of the photoelectric sensor are electrically connected to the control unit. When the first switching diode or the second switching diode is turned on, the light-emitting diode is in the on state, and the output terminal of the photoelectric sensor sends the voltage protection control signal to the control unit.

4. The voltage conversion protection circuit according to claim 1, 2, or 3, characterized in that, It also includes a reference voltage output unit; The input terminal of the reference voltage output unit is electrically connected to the output terminal of the rectifier unit, and is used to step down the rectified power supply output from the output terminal of the rectifier unit to output a reference voltage.

5. The voltage conversion protection circuit according to claim 4, characterized in that, The reference voltage output unit includes a power transistor and a Zener diode; The collector of the power transistor is electrically connected to the output terminal of the rectifier unit, the base of the power transistor is electrically connected to the Zener diode, and the emitter of the power transistor outputs the reference voltage.

6. The voltage conversion protection circuit according to claim 1, 2 or 3, characterized in that, It also includes a grounding unit; The grounding unit includes a first resistor and a first capacitor, and the first resistor and the first capacitor are connected in parallel. The ground terminals of the first hysteresis comparator and the second hysteresis comparator are electrically connected to one end of the first resistor and the first capacitor, respectively; the other ends of the first resistor and the first capacitor are connected to the ground.

7. The voltage conversion protection circuit according to claim 6, characterized in that, The rectifier unit includes a rectifier bridge circuit, a filter capacitor, and a transient voltage suppression diode; The input terminal of the rectifier bridge circuit is electrically connected to the external power supply; The filter capacitor and the transient voltage suppression diode are connected in parallel to form a parallel circuit. One end of the parallel circuit is electrically connected to the output terminal of the rectifier bridge circuit, and the other end of the parallel circuit is electrically connected to the grounding unit.

8. The voltage conversion protection circuit according to claim 7, characterized in that, The rectifier unit also includes a fuse; One end of the fuse is electrically connected to the external power source, and the other end is electrically connected to the input terminal of the rectifier bridge circuit.

9. The voltage conversion protection circuit according to claim 1, characterized in that, The control unit is also used to count the number of overvoltage or undervoltage events of the external power supply according to the voltage protection control signal, and to protect the external voltage conversion unit according to the number of overvoltage or undervoltage events.

10. A power conversion device, characterized in that, Includes a power input circuit, a voltage conversion protection circuit as described in any one of claims 1-9, and a voltage conversion circuit; The power input circuit is electrically connected to the voltage conversion circuit through the voltage conversion protection circuit.

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