A DCDC converter input switch protection device and method

Abstract

The present invention provides an input switch protection device and method for a DCDC converter. The input switch protection device includes a power switch module, including a first switch Q1, a second switch Q2 and a third switch Q3, wherein the first switch Q1, the second switch Q2 and the third switch Q3 are voltage-type semiconductor switches; a current detection protection and alarm module, including an overcurrent comparison unit and a protection and alarm reset unit, wherein the protection and alarm reset unit includes a first triode Q4, a first diode D1 and a second diode D2; the collector of the first triode Q4 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the gates of the second switch Q2 and the third switch Q3 through a second resistor R2; the base of the first triode Q4 is connected to the overcurrent comparison unit through a third resistor R3 and a second diode D2 connected in series; the emitter of the first triode Q4 is connected to a negative power rail, and the emitter of the first triode Q4 is also connected to the base of the first triode Q4 through a fourth resistor R4.

Description

Technical Field

[0001] The present invention relates to the field of electronic power technology, and in particular to an input switch protection device and method for a DCDC converter. Background Art

[0002] As a key component in power electronic equipment, DCDC converters are widely used in power transmission and conversion systems. In order to ensure the operation of the DCDC converter, a switch protection device is usually set at the input end. Existing input switch protection devices mostly adopt a structure composed of a pre-charge relay, a pre-charge resistor and a main relay, in which the pre-charge relay and the pre-charge resistor pre-charge the input capacitor in the initial power-on stage, and the main relay carries the load current under normal working conditions and disconnects the main circuit when shut down or a fault occurs. However, since the relay is a mechanical switching component, it has a limited service life, usually only a few thousand times, and it is easy to have contact adhesion or disconnection failure when disconnecting large currents. At the same time, the relay has a slow response speed, and the disconnection time delay is usually tens of milliseconds. This characteristic makes it difficult to achieve fast and effective protection in the case of overcurrent faults such as load short circuits. Summary of the invention

[0003] To solve the above problems, some solutions in the prior art have attempted to introduce alternative components such as solid-state relays or fuses, but there are still problems such as high cost, large size or single function, which cannot fully meet the actual application needs. In addition, the current input switch protection devices usually lack the ability to protect bidirectional currents, and in some special application scenarios, they cannot effectively deal with the safety risks caused by reverse currents. Therefore, it is of great technical significance and application value to develop an input switch protection device and a control method that integrates pre-charging, current carrying, and fast disconnection functions and can achieve bidirectional current protection and alarm.

[0004] In a first aspect, the present invention provides an input switch protection device for a DCDC converter, comprising:

[0005] A power switch module, comprising a first switch Q1, a second switch Q2 and a third switch Q3, wherein the first switch Q1, the second switch Q2 and the third switch Q3 are voltage-type semiconductor switches;

[0006] A current detection protection and alarm module comprises an overcurrent comparison unit and a protection and alarm reset unit, wherein the protection and alarm reset unit comprises a first transistor Q4, a first diode D1 and a second diode D2; the collector of the first transistor Q4 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the gates of the second switch Q2 and the third switch Q3 through a second resistor R2; the base of the first transistor Q4 is connected to the overcurrent comparison unit through a third resistor R3 and the second diode D2 connected in series; the emitter of the first transistor Q4 is connected to a negative power rail, and the emitter of the first transistor Q4 is also connected to the base of the first transistor Q4 through a fourth resistor R4.

[0007] Optionally, the input switch protection device further includes a control module connected to the protection and alarm reset unit, and configured to receive an overcurrent signal when the input switch protection device fails, and the protection and alarm reset unit further includes:

[0008] a second transistor Q5, wherein the collector of the second transistor Q5 is connected between the second diode D2 and the third resistor R3 through a fifth resistor R5; and the emitter of the second transistor Q5 is connected to a power supply;

[0009] A first optocoupler OPT1, a first pin of the first optocoupler OPT1 is connected to the base of the second transistor Q5 through a sixth resistor R6, and is also connected to a power supply through a seventh resistor R7; a second pin of the first optocoupler OPT1 is connected to the collector of the first transistor Q4; a third pin of the first optocoupler OPT1 is grounded; a fourth pin of the first optocoupler OPT1 is connected to the control module, and is used to transmit the overcurrent signal generated by the overcurrent comparison unit to the control module; the fourth pin of the first optocoupler OPT1 is also connected to a power supply through an eighth resistor R8.

[0010] Optionally, the control module is further configured to send a fault reset signal to the protection and alarm reset unit when the fault of the input switch protection device is removed, and the protection and alarm reset unit further includes:

[0011] A second optocoupler OPT2, a fifth pin of the second optocoupler OPT2 is connected to the control module through a ninth resistor R9, and is used to receive a fault reset signal sent by the control module; a sixth pin of the second optocoupler OPT2 is grounded; a seventh pin of the second optocoupler OPT2 is connected between the second diode D2 and the third resistor R3; and an eighth pin of the second optocoupler OPT2 is connected to a negative power rail.

[0012] Optionally, the power switch module further includes a first capacitor C1, a second capacitor C2, a tenth resistor R10, an eleventh resistor R11 and a parallel relay TLY1;

[0013] The collector of the second switch Q2 is connected to a DC power supply, and the emitter is connected to the emitter of the third switch Q3 through the eleventh resistor R11; the collector of the third switch Q3 is connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is connected to the DC power supply;

[0014] The collector of the first switch Q1 is connected to the DC power supply through the tenth resistor R10, and the emitter is connected between the eleventh resistor R11 and the emitter of the second switch Q2;

[0015] One end of the first capacitor C1 is connected to a DC power supply, and the other end is connected between the collector of the third switch Q3 and the second capacitor C2;

[0016] One end of the parallel relay TLY1 is connected between the collector of the third switch Q3 and the second capacitor C2, and the other end is connected to the DC power supply.

[0017] Optionally, the current detection protection and alarm module further includes:

[0018] The current detection amplifier unit includes a first operational amplifier U1, wherein the positive input terminal of the first operational amplifier U1 is connected to one end of the eleventh resistor R11 through a twelfth resistor R12, and the negative input terminal of the first operational amplifier U1 is connected to the other end of the eleventh resistor R11 through a thirteenth resistor R13; and the output terminal of the first operational amplifier U1 is connected to the overcurrent comparison unit;

[0019] The positive input terminal of the first operational amplifier U1 is also grounded through a fourteenth resistor, and the negative input terminal of the first operational amplifier U1 is connected to the output terminal of the first operational amplifier U1 through a fifteenth resistor R15.

[0020] Optionally, the current detection protection and alarm module further includes:

[0021] A reference unit, comprising a second operational amplifier U2 and a reference voltage source U3, wherein the positive electrode of the reference voltage source U3 is connected to the power supply through a sixteenth resistor R16, and the negative electrode is grounded;

[0022] The positive input terminal of the second operational amplifier U2 is grounded through a seventeenth resistor R17, the negative input terminal is connected between the positive electrode of the reference voltage source U3 and the sixteenth resistor R16 through an eighteenth resistor R18, and the output terminal is connected to the overcurrent comparison unit;

[0023] The negative input terminal of the second operational amplifier U2 is also connected to the output terminal of the second operational amplifier U2 through a nineteenth resistor R19.

[0024] Optionally, the overcurrent comparison unit includes a third operational amplifier U4 and a fourth operational amplifier U5;

[0025] The negative input terminal of the third operational amplifier U4 is connected between the reference voltage source U3 and the eighteenth resistor R18, the positive input terminal is connected to the output terminal of the first operational amplifier U1, and the output terminal of the third operational amplifier U4 is connected to the second diode D2;

[0026] The negative input terminal of the fourth operational amplifier U5 is connected to the output terminal of the first operational amplifier U1, the positive input terminal is connected to the output terminal of the second operational amplifier U2, and the output terminal of the fourth operational amplifier U5 is connected to the second diode D2;

[0027] The output end of the third operational amplifier U4 and the output end of the fourth operational amplifier U5 are also connected in parallel and connected to a power supply via a twentieth resistor R20.

[0028] Optionally, the control module includes a microcontroller connected to the power switch module, and configured to control the closing and closing of the first switch Q1 , the second switch Q2 , and the third switch Q3 .

[0029] In a second aspect, the present invention further provides a protection method for an input switch protection device of a DCDC converter, the method comprising:

[0030] Detecting and amplifying the voltage across the eleventh resistor R11 to obtain an amplified voltage signal;

[0031] The amplified voltage signal is compared with a reference voltage signal by an overcurrent comparison unit, and when the amplified voltage signal exceeds a threshold value of the reference voltage signal, an overcurrent signal is generated and output to a protection and alarm reset unit;

[0032] The voltage of the control signal of the second switch Q2 and the third switch Q3 is pulled down by the protection and alarm reset unit, so that the second switch Q2 and the third switch Q3 are disconnected.

[0033] Optionally, the method further comprises:

[0034] Transmitting the overcurrent signal to the control module through the protection and alarm reset unit;

[0035] When the fault of the input switch protection device is removed, a fault reset signal is sent to the protection and alarm reset unit through the control module;

[0036] The voltages of the control signals of the second switch Q2 and the third switch Q3 return to normal, so that the second switch Q2 and the third switch Q3 are turned on again.

[0037] The input switch protection device for the DCDC converter provided by the present invention realizes accurate monitoring and efficient protection of the input current by setting a power switch module and a current detection protection and alarm module. The coordinated work of the first switch Q1, the second switch Q2 and the third switch Q3 of the power switch module can realize the rapid control and disconnection function of the input current. At the same time, the power switch module adopts a voltage-type semiconductor switch, which avoids the contact adhesion problem that may occur when the traditional mechanical relay disconnects a large current. When an overcurrent fault occurs, the overcurrent comparison unit in the current detection protection and alarm module is used to quickly judge the fault state, and the protection and alarm reset unit is triggered to drive the power switch to cut off the circuit, which significantly improves the operating reliability and safety of the DCDC converter.

[0038] Furthermore, by setting up a current detection amplifier unit and a reference module, the input current can be amplified and accurately compared to ensure the sensitivity and accuracy of overcurrent judgment. At the same time, the protection and alarm reset unit communicates with the control module through an optocoupler device, has good anti-interference ability and isolation characteristics, and realizes rapid alarm and fault reset of overcurrent status. In addition, through the combined design of capacitors and relays in the power switch module, it can not only complete the pre-charging function, but also undertake the tasks of current carrying and bidirectional current disconnection, which improves the protection capability of the input switch protection device under high current and short circuit conditions, and enhances the overall reliability and safety of the input switch protection device.

[0039] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A circuit diagram of a power switch module according to an embodiment of the present invention is shown;

[0041] Figure 2 A circuit diagram of a protection and alarm reset unit according to an embodiment of the present invention is shown;

[0042] Figure 3 A circuit diagram of a current detection amplifier unit according to an embodiment of the present invention is shown;

[0043] Figure 4 shows a circuit diagram of a reference unit according to an embodiment of the present invention;

[0044] Figure 5shows a circuit diagram of an overcurrent comparison unit according to an embodiment of the present invention;

[0045] Figure 6 A schematic flow chart of a method for protecting an input switch of a DCDC converter according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0046] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings. It is 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0047] The terms "including" and "having" and any variations thereof in the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0048] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0049] The input switch protection device for a DCDC converter of the present invention comprises a power switch module, Figure 1 FIG. 2 shows a circuit diagram of a power switch module according to an embodiment of the present invention. Figure 1 As shown, the power switch module includes:

[0050] The first switch Q1 , the second switch Q2 and the third switch Q3 are voltage-type semiconductor switches.

[0051] In some embodiments, the first switch Q1, the second switch Q2, and the third switch Q3 use IGBT (Insulated Gate Bipolar Transistor) as the core voltage-type semiconductor switch device. As a power semiconductor device with high input impedance and low on-resistance characteristics, IGBT provides key electrical performance support for the circuit operation of the present invention. Among them, the first switch Q1 is used as a pre-charge switch, which can accurately pre-charge the relevant circuit when the circuit is started; the second switch Q2 is used as a current on-off switch to control whether the current flows into the device; the third switch Q3 is used as a switch to control the current out of the device, which effectively controls the current out of the device. The three work together to ensure the stability and safety of the entire circuit system.

[0052] The present invention uses a voltage-type semiconductor switch, which has no mechanical contacts and no contact adhesion problem, and can reliably realize the on-off operation of the circuit. Secondly, the voltage-type semiconductor switch has an extremely fast disconnection speed, and can respond quickly when the input current is overcurrent, realizing rapid protection, and avoiding equipment damage and safety hazards caused by the long-term existence of fault current. In addition, these semiconductor switches can quickly protect bidirectional currents and give timely alarms while realizing the pre-charging, current-carrying, and disconnection functions, greatly improving the reliability and safety of the equipment.

[0053] The input switch protection device for the DCDC converter of the present invention also includes a current detection protection and alarm module. The current detection protection and alarm module includes an overcurrent detection comparison unit and a protection and alarm reset unit. Figure 2 FIG. 2 shows a circuit diagram of a protection and alarm reset unit according to an embodiment of the present invention. Figure 2 As shown, the protection and alarm reset unit includes:

[0054] A first transistor Q4, a first diode D1 and a second diode D2. The collector of the first transistor Q4 is connected to the cathode of the first diode D1, the anode of the first diode D1 is connected to the control module through the first resistor R1, and the anode of the first diode D1 is also connected to the gates of the second switch Q2 and the third switch Q3 through the second resistor R2. The base of the first transistor Q4 is connected to the overcurrent comparison unit through the third resistor R3 and the second diode D2 connected in series. The emitter of the first transistor Q4 is connected to the negative power rail, and the emitter of the first transistor Q4 is also connected to the base of the first transistor Q4 through the fourth resistor R4.

[0055] When an overcurrent occurs in the circuit, the overcurrent comparison unit will generate an OCP signal. The OCP signal is transmitted to the base of the first transistor Q4 through the second diode D2 and the third resistor R3 in sequence, thereby driving the first transistor Q4 to turn on. After the first transistor Q4 is turned on, the anode potential of the first diode D1 connected to its collector decreases accordingly. The anode of the first diode D1 is connected to the control module through the first resistor R1, and the anode of the first diode D1 is also connected to the gate of the second switch Q2 and the third switch Q3 through the second resistor R2, and the emitter of the first transistor Q4 is connected to the negative power rail. Therefore, when the first transistor Q4 is turned on, the control signals of the second switch Q2 and the third switch Q3 are pulled down to the -8V power rail through the second resistor R2, so that the gate-source voltage (Vgs) of the second switch Q2 and the third switch Q3 is lower than the threshold required for them to maintain conduction, thereby prompting the second switch Q2 and the third switch Q3 to be quickly turned off to achieve overcurrent protection of the circuit.

[0056] This circuit structure can respond quickly when an overcurrent occurs. Once the OCP signal is generated, the first transistor Q4 will be turned on immediately, quickly pulling down the control signals of the second switch Q2 and the third switch Q3, so that the second switch Q2 and the third switch Q3 are quickly turned off, thereby realizing rapid protection of the circuit and avoiding damage to the circuit components caused by overcurrent. At the same time, the first diode D1 and the second diode D2 act as anti-reverse diodes to prevent the current from flowing in the reverse direction. This helps to ensure the stability of the circuit during normal operation and overcurrent protection, and avoid circuit failures caused by reverse current flow. Through this precise overcurrent protection mechanism, the reliability of the circuit is significantly improved. It can cut off the overcurrent path in a timely and effective manner, reduce the probability of equipment damage and safety accidents caused by overcurrent, and ensure the safe and stable operation of the entire equipment.

[0057] According to the above embodiment, by setting a power switch module and a current detection protection and alarm module, accurate monitoring and efficient protection of the input current are achieved. The coordinated work of the first switch Q1, the second switch Q2 and the third switch Q3 of the power switch module can realize the rapid control and disconnection function of the input current. At the same time, the power switch module adopts a voltage-type semiconductor switch, which avoids the contact adhesion problem that may occur when the traditional mechanical relay disconnects a large current. In the event of an overcurrent fault, the overcurrent comparison unit in the current detection protection and alarm module is used to quickly judge the fault state, and the protection and alarm reset unit is triggered to drive the power switch to cut off the circuit, which significantly improves the operating reliability and safety of the DCDC converter.

[0058] The input switch protection device for a DCDC converter of the present invention further comprises a control module connected to the protection and alarm reset unit and used for receiving an overcurrent signal when the input switch protection device fails.

[0059] refer to Figure 2 The protection and alarm reset unit of the present invention further comprises:

[0060] The collector of the second transistor Q5 is connected between the second diode D2 and the third resistor R3 through the fifth resistor R5. The emitter of the second transistor Q5 is connected to the power supply.

[0061] The first optical coupler OPT1, the first pin is connected to the base of the second transistor Q5 through the sixth resistor R6, and is also connected to the power supply through the seventh resistor R7. The second pin of the first optical coupler OPT1 is connected to the collector of the first transistor Q4; the third pin of the first optical coupler OPT1 is grounded. The fourth pin of the first optical coupler OPT1 is connected to the control module, which is used to transmit the overcurrent signal generated by the overcurrent comparison unit to the control module; the fourth pin of the first optical coupler OPT1 is also connected to the power supply through the eighth resistor R8.

[0062] The first transistor Q4 and the second transistor Q5 form a latch. When the overcurrent signal appears and turns on the first transistor Q4, due to the connection relationship between the first transistor Q4 and the second transistor Q5, even if the overcurrent signal disappears, the first transistor Q4 will remain in the on state. Specifically, the collector of the second transistor Q5 is connected to the second diode D2 and the third resistor R3 through the fifth resistor R5, that is, connected to the base of the first transistor Q4. When the first transistor Q4 is turned on, its collector potential is pulled down, causing the primary (between the first pin and the second pin) current of the first optical coupler OPT1 to change. Because the first pin of the first optical coupler OPT1 is connected to the base of the second transistor Q5 through the sixth resistor R6, the current change will cause the voltage across the sixth resistor R6 to change, thereby causing the base potential of the second transistor Q5 to rise and fall accordingly. The state of the second transistor Q5 changes accordingly, and reacts to the state of the first transistor Q4 through its collector, eventually forming a latched state of the first transistor Q4 and the second transistor Q5 to keep the second switch Q2 and the third switch Q3 in the off state.

[0063] In addition, the second pin of the first optical coupler OPT1 is connected to the collector of the first transistor Q4. After the overcurrent signal turns on the first transistor Q4, the collector potential of the first transistor Q4 changes, causing the potential of the second pin of the first optical coupler OPT1 to change. The first optical coupler OPT1 is connected to the control module, so this level change transmits the overcurrent signal to the control module, and alarms the control module so that the control module can know the overcurrent situation. After receiving the overcurrent signal, the control module can take corresponding measures, such as recording fault information, sending alarm signals to external devices, etc. At the same time, it can temporarily stop the normal control operation of the power switch module to prevent the fault from further expanding.

[0064] According to the above configuration, the latch formed by the first transistor Q4 and the second transistor Q5 can maintain the off state of the second switch Q2 and the third switch Q3 after the overcurrent signal disappears, preventing the overcurrent fault from being erroneously restored when the overcurrent signal disappears due to instantaneous fluctuations or interference, thereby ensuring the safety of the circuit. The overcurrent signal is accurately transmitted to the control module through the first optical coupler OPT1, so that the control module can obtain the overcurrent information in time, which is convenient for subsequent fault processing and system monitoring.

[0065] In some embodiments, the control module for the input switch protection device of the DCDC converter is further used to send a fault reset signal to the protection and alarm reset unit when the fault of the input switch protection device is cleared.

[0066] refer to Figure 2 The protection and alarm reset unit of the present invention further comprises:

[0067] The second optocoupler OPT2, the fifth pin is connected to the control module through the ninth resistor R9, and is used to receive the fault reset signal sent by the control module; the sixth pin of the second optocoupler OPT2 is grounded; the seventh pin of the second optocoupler OPT2 is connected between the second diode D2 and the third resistor R3; the eighth pin of the second optocoupler OPT2 is connected to the negative power rail.

[0068] When the control system detects that the overcurrent fault is removed, a fault reset signal is sent. The signal is transmitted to the second optical coupler OPT2 through the ninth resistor R9, so that the second optical coupler OPT2 is turned on. When the second optical coupler OPT2 is turned on, the third resistor R3 provides a low impedance path for the base of the first transistor Q4, pulling its base to a low level, thereby turning off the first transistor Q4. The turning off of the first transistor Q4 causes the second transistor Q5 to lose the base drive, causing the second transistor Q5 to be turned off at the same time, breaking the latching condition of the first transistor Q4 and the second transistor Q5, causing the state of the first transistor Q4 and the second transistor Q5 to change, thereby releasing the turn-off control of the second switch Q2 and the third switch Q3. When the turn-off control of the second switch Q2 and the third switch Q3 is released, they can be turned on again according to the normal working requirements of the circuit, so that the circuit is restored to a normal working state, and the fault reset is realized, and the system can continue to operate normally. The transmission of the fault reset signal is realized through the second optical coupler OPT2, thereby ensuring the electrical isolation of the control signal, improving the reliability and stability of the system, and preventing the influence of external interference on the reset operation.

[0069] refer to Figure 1, the power switch module also includes a first capacitor C1, a second capacitor C2, a tenth resistor R10, an eleventh resistor R11 and a parallel relay TLY1. The collector of the second switch Q2 is connected to a DC power supply, and the emitter is connected to the emitter of the third switch Q3 through the eleventh resistor R11; the collector of the third switch Q3 is connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is connected to the DC power supply. The collector of the first switch Q1 is connected to the DC power supply through the tenth resistor R10, and the emitter is connected between the eleventh resistor R11 and the emitter of the second switch Q2. One end of the first capacitor C1 is connected to the DC power supply, and the other end is connected between the collector of the third switch Q3 and the second capacitor C2. One end of the parallel relay TLY1 is connected between the collector of the third switch Q3 and the second capacitor C2, and the other end is connected to the DC power supply.

[0070] In the circuit startup phase, the collector of the first switch Q1 (pre-charging switch) is connected to the DC power supply through the tenth resistor R10, and the emitter is connected to the eleventh resistor R11 and between the emitter of the second switch Q2. When pre-charging is required, the first switch Q1 is turned on, and the DC power supply slowly charges the capacitor in the circuit through the tenth resistor R10 and the first switch Q1 to avoid the large current shock caused by direct access to the DC power supply and protect the circuit components. In normal operation after the pre-charging is completed, the second switch Q2 is turned on, and the current flows out from its emitter, flows to the emitter of the third switch Q3 through the eleventh resistor R11, and the current flows out from the collector of the third switch Q3 to charge the second capacitor C2 or supply power to the subsequent load. At the same time, the first capacitor C1 is connected between the DC power supply and the collector of the third switch Q3 and the second capacitor C2 as an absorption capacitor to absorb possible voltage spikes to protect the first switch Q1, the second switch Q2 and the third switch Q3 from damage by high voltage pulses.

[0071] Under normal working conditions, the parallel relay TLY1 is in the off state and is closed only after the first switch Q1 is turned on and the pre-charging is completed to avoid the impact current caused by the excessive voltage difference from damaging the IGBT, the second switch Q2, the third switch Q3 and other devices. The function of the parallel relay TLY1 is to provide an auxiliary current path, reduce the current burden of the main switch during the pre-charging process, and improve the stability of the system. Once the second switch Q2 and the third switch Q3 are turned on, the relay will be disconnected, thereby cutting off the connection between the power supply and the load, protecting the system from overcurrent or short circuit faults.

[0072] The current detection protection and alarm module of the present invention further comprises a current detection amplification unit. Figure 3 FIG. 2 shows a circuit diagram of a current detection amplifier unit according to an embodiment of the present invention. Figure 3 As shown, the current detection amplifier unit includes:

[0073] A first operational amplifier U1, a positive input terminal of the first operational amplifier U1 is connected to one end of an eleventh resistor R11 through a twelfth resistor R12, a negative input terminal of the first operational amplifier U1 is connected to the other end of the eleventh resistor R11 through a thirteenth resistor R13; an output terminal of the first operational amplifier U1 is connected to an overcurrent comparison unit.

[0074] The positive input terminal of the first operational amplifier U1 is also grounded through a fourteenth resistor R14, and the negative input terminal of the first operational amplifier U1 is connected to the output terminal of the first operational amplifier U1 through a fifteenth resistor R15.

[0075] The twelfth resistor R12 is a current collection resistor, which is used to collect the current of the power switch module and convert the current signal of the power switch module into a voltage signal at both ends of the twelfth resistor R12. The positive input end of the first operational amplifier U1 is connected to one end of the eleventh resistor R11 through the twelfth resistor R12, and the negative input end is connected to the other end of the eleventh resistor R11 through the thirteenth resistor R13. The voltage signal at both ends of the eleventh resistor R11 is amplified by the first operational amplifier U1, and the amplified signal is output from the output end of the first operational amplifier U1, and then connected to the overcurrent comparison unit for subsequent overcurrent judgment. The positive input end of the first operational amplifier U1 is also grounded through the fourteenth resistor, and the negative input end is connected to the output end of the first operational amplifier U1 through the fifteenth resistor R15, forming a negative feedback loop.

[0076] By using an operational amplifier to amplify the voltage signal across the eleventh resistor R11, the current can be detected more accurately. Even if the voltage across the eleventh resistor R11 is very small, a sufficiently large signal can be obtained after amplification, which is convenient for subsequent circuits to process and judge, thereby improving the sensitivity and accuracy of current detection. The operational amplifier has a negative feedback loop, which makes the performance of the amplifier more stable. Negative feedback can reduce the amplifier's gain error, nonlinear distortion, and sensitivity to changes in component parameters, ensuring that stable and reliable amplification functions can be provided under different working conditions.

[0077] The current detection protection and alarm module of the present invention further comprises a reference unit. Figure 4 FIG. 4 shows a circuit diagram of a reference unit according to an embodiment of the present invention. Figure 4 As shown, the reference unit includes:

[0078] The second operational amplifier U2 and the reference voltage source U3, the positive electrode of the reference voltage source U3 is connected to the power supply through the sixteenth resistor R16, and the negative electrode is grounded.

[0079] The reference voltage source U3 and the sixteenth resistor R16 form a reference voltage generating circuit. The positive electrode of the reference voltage source U3 is connected to the +15V power supply through the sixteenth resistor R16, and the negative electrode is grounded. The sixteenth resistor R16 plays a current limiting role, ensuring that the current flowing from the power supply into the reference voltage source U3 is within a suitable range, and at the same time generating a stable reference voltage at both ends of the reference voltage source U3.

[0080] The positive input terminal of the second operational amplifier U2 is grounded through the seventeenth resistor R17, the negative input terminal is connected to the positive electrode of the reference voltage source U3 and the sixteenth resistor R16 through the eighteenth resistor R18, and the output terminal is connected to the overcurrent comparison unit. The negative input terminal of the second operational amplifier U2 is also connected to the output terminal of the second operational amplifier U2 through the nineteenth resistor R19.

[0081] The positive input terminal of the second operational amplifier U2 is grounded through the seventeenth resistor R17, and the negative input terminal is connected to the positive electrode of the reference voltage source U3 and the sixteenth resistor R16 through the eighteenth resistor R18. This allows the negative input terminal of the second operational amplifier U2 to receive the reference voltage generated by the reference voltage source U3 and the sixteenth resistor R16. The negative input terminal of the second operational amplifier U2 is also connected to its output terminal through the nineteenth resistor R19, forming a negative feedback loop. After being processed by the second operational amplifier U2, its output terminal outputs a stable voltage signal, which is connected to the overcurrent comparison unit. The overcurrent comparison unit can use this stable reference voltage signal to compare with the signal transmitted from the current detection amplifier unit to determine whether an overcurrent phenomenon occurs.

[0082] By using the reference voltage source U3 and the appropriate current-limiting sixteenth resistor R16, a stable reference voltage can be generated. This reference voltage is not affected by power supply fluctuations and other external interferences, and provides a reliable reference voltage for subsequent overcurrent comparison. The circuit composed of the second operational amplifier U2 and its negative feedback loop can follow and output the reference voltage with high precision. The negative feedback mechanism of the operational amplifier can effectively reduce the error of the output voltage and ensure that the voltage signal output to the overcurrent comparison unit has high precision and stability.

[0083] Figure 5 FIG. 2 shows a circuit diagram of an overcurrent comparison unit according to an embodiment of the present invention. Figure 5 As shown, the overcurrent comparison unit includes:

[0084] The third operational amplifier U4 and the fourth operational amplifier U5. The negative input terminal of the third operational amplifier U4 is connected between the reference voltage source U3 and the eighteenth resistor R18, the positive input terminal is connected to the output terminal of the first operational amplifier U1, and the output terminal of the third operational amplifier U4 is connected to the second diode D2. The negative input terminal of the fourth operational amplifier U5 is connected to the output terminal of the first operational amplifier U1, the positive input terminal is connected to the output terminal of the second operational amplifier U2, and the output terminal of the fourth operational amplifier U5 is connected to the second diode D2.

[0085] The output terminal of the third operational amplifier U4 and the output terminal of the fourth operational amplifier U5 are also connected in parallel and connected to the power supply through the twentieth resistor R20.

[0086] The positive input terminal of the third operational amplifier U4 and the negative input terminal of the fifth operational amplifier U5 are connected to the output terminal of the first operational amplifier U1, and the first operational amplifier U1 outputs the current detection signal amplified by the current detection amplifier unit. The negative input terminal of the third operational amplifier U4 is connected between the reference voltage source U3 and the eighteenth resistor R18, and the input voltage obtained is a positive reference voltage. The positive input terminal of the fourth operational amplifier U5 is connected to the output terminal of the second operational amplifier U2, and the second operational amplifier U2 outputs a negative reference voltage signal. The third operational amplifier U4 compares the current detection amplified signal with the reference voltage. When the current detection amplified signal is less than the negative reference voltage, the third operational amplifier U4 outputs a high level; otherwise, it outputs a low level. The fourth operational amplifier U5 also performs a comparison operation. When the current detection amplified signal is greater than the positive reference voltage, the fourth operational amplifier U5 outputs a high level; otherwise, it outputs a low level. The output terminal of the third operational amplifier U4 and the output terminal of the fourth operational amplifier U5 are connected in parallel, and are connected to the power supply through the twentieth resistor R20, and are also connected to the protection and alarm reset unit. When the third operational amplifier U4 or the fourth operational amplifier U5 outputs a high level, a high level signal is generated at the parallel output terminal and is transmitted to the protection and alarm reset unit through the second diode D2.

[0087] In some embodiments, the positive reference voltage is +2.5V and the negative reference voltage is -2.5V.

[0088] The overcurrent comparison unit uses the third operational amplifier U4 and the fourth operational amplifier U5 to compare with the positive and negative reference voltages respectively, which can achieve more accurate overcurrent judgment. This dual comparator structure can reduce the possibility of misjudgment and improve the accuracy of overcurrent detection. The overcurrent comparison unit can promptly transmit the overcurrent signal to the protection and alarm reset unit, so that the protection circuit can respond quickly (such as quickly turning off the second switch Q2 and the third switch Q3), realizing effective protection of the circuit and preventing overcurrent from damaging the circuit components.

[0089] In some embodiments, the control module of the input switch protection device for a DCDC converter of the present invention includes a microcontroller connected to a power switch module for controlling the closing and closing of a first switch Q1 , a second switch Q2 and a third switch Q3 .

[0090] The microcontroller in the control module is connected to the power switch module and can generate control signals according to the operating requirements of the system. These control signals are sent to the first switch Q1, the second switch Q2 and the third switch Q3. For example, when the circuit is started, the microcontroller will send a signal to turn on the first switch Q1 for pre-charging operation. When the pre-charging is completed and the circuit is ready for normal operation, the microcontroller will control the closing and closing of the second switch Q2 and the third switch Q3 according to the corresponding logic to achieve normal on and off of the power circuit and ensure that the current can flow into and out of the device according to the predetermined path.

[0091] Through the precise control of the power switch module by the microcontroller, the input current of the DCDC converter can be precisely adjusted. Whether in the pre-charging stage at startup or in the power circuit on-off control during normal operation, it can be operated according to the predetermined logic and parameters, which improves the working efficiency and performance of the entire converter. The control module can receive the overcurrent signal in time, which enables it to respond to the fault at the first time. For example, the power circuit can be cut off immediately to prevent the overcurrent from damaging the components in the circuit and protect the safety of the input switch protection device. At the same time, by recording the fault information and sending the alarm signal, it is convenient for the operator to understand the operating status of the input switch protection device in time and carry out subsequent troubleshooting and maintenance work. When the fault is removed, the control module sends a fault reset signal to enable the input switch protection device to quickly return to normal working state. This automatic fault recovery mechanism reduces the need for manual intervention, improves the availability and operating efficiency of the input switch protection device, and ensures that the DCDC converter can work continuously and stably.

[0092] According to the above embodiments, the technical solution of the present invention can amplify and accurately compare the input current by setting a current detection amplifier unit and a reference module, thereby ensuring the sensitivity and accuracy of overcurrent judgment. At the same time, the protection and alarm reset unit communicates with the control module through an optocoupler device, has good anti-interference ability and isolation characteristics, and realizes rapid alarm and fault reset of overcurrent status. In addition, through the combined design of capacitors and relays in the power switch module, not only can the pre-charging function be completed, but also the tasks of current carrying and bidirectional current disconnection can be undertaken, thereby improving the protection capability of the input switch protection device under high current and short circuit conditions, and enhancing the overall reliability and safety of the input switch protection device.

[0093] Figure 6FIG. 2 is a flow chart of a method for protecting an input switch of a DCDC converter according to an embodiment of the present invention. Figure 6 As shown, the input switch protection method for the DCDC converter includes:

[0094] Step S100 , detecting and amplifying the voltage across the eleventh resistor R11 to obtain an amplified voltage signal.

[0095] Step S200, the amplified voltage signal is compared with the reference voltage signal through the overcurrent comparison unit. When the amplified voltage signal exceeds the threshold of the reference voltage signal, an overcurrent signal is generated and output to the protection and alarm reset unit.

[0096] In step S300 , the voltage of the control signal of the second switch Q2 and the third switch Q3 is pulled down by the protection and alarm reset unit, so that the second switch Q2 and the third switch Q3 are disconnected.

[0097] Step S400: transmitting the overcurrent signal to the control module through the protection and alarm reset unit.

[0098] Step S500: When the fault of the input switch protection device is cleared, a fault reset signal is sent to the protection and alarm reset unit through the control module.

[0099] In step S600 , the voltages of the control signals of the second switch Q2 and the third switch Q3 return to normal, so that the second switch Q2 and the third switch Q3 are turned on again.

[0100] In the above-mentioned input switch protection method for a DCDC converter, the specific implementation of each module and unit refers to the relevant contents of the embodiment of the above-mentioned input switch protection device, and will not be described in detail here.

[0101] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An input switch protection device for a DCDC converter, characterized in that: include: A power switch module, comprising a first switch Q1, a second switch Q2, a third switch Q3, a first capacitor C1, a second capacitor C2, a tenth resistor R10, an eleventh resistor R11 and a parallel relay TLY1, wherein the first switch Q1, the second switch Q2 and the third switch Q3 are voltage-type semiconductor switches; the collector of the second switch Q2 is connected to a DC power supply, and the emitter is connected to the emitter of the third switch Q3 through the eleventh resistor R11; the collector of the third switch Q3 is connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is connected to the DC power supply; the The collector of the first switch Q1 is connected to the DC power supply through the tenth resistor R10, and the emitter is connected between the eleventh resistor R11 and the emitter of the second switch Q2; one end of the first capacitor C1 is connected to the DC power supply, and the other end is connected between the collector of the third switch Q3 and the second capacitor C2; one end of the parallel relay TLY1 is connected between the collector of the third switch Q3 and the second capacitor C2, and the other end is connected to the DC power supply; in normal working state, the parallel relay TLY1 is in the off state, and is closed only when the first switch Q1 is turned on and pre-charging is completed; A current detection protection and alarm module comprises an overcurrent comparison unit and a protection and alarm reset unit, wherein the protection and alarm reset unit comprises a first transistor Q4, a first diode D1 and a second diode D2; the collector of the first transistor Q4 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the gates of the second switch Q2 and the third switch Q3 through a second resistor R2; the base of the first transistor Q4 is connected to the overcurrent comparison unit through a third resistor R3 and the second diode D2 connected in series; the emitter of the first transistor Q4 is connected to a negative power rail, and the emitter of the first transistor Q4 is also connected to the base of the first transistor Q4 through a fourth resistor R4.

2. The input switch protection device for a DCDC converter according to claim 1, characterized in that: It also includes a control module, which is connected to the protection and alarm reset unit and is used to receive an overcurrent signal when the input switch protection device fails. The protection and alarm reset unit also includes: a second transistor Q5, wherein the collector of the second transistor Q5 is connected between the second diode D2 and the third resistor R3 through a fifth resistor R5; and the emitter of the second transistor Q5 is connected to a power supply; A first optocoupler OPT1, a first pin of the first optocoupler OPT1 is connected to the base of the second transistor Q5 through a sixth resistor R6, and is also connected to a power supply through a seventh resistor R7; a second pin of the first optocoupler OPT1 is connected to the collector of the first transistor Q4; a third pin of the first optocoupler OPT1 is grounded; a fourth pin of the first optocoupler OPT1 is connected to the control module, and is used to transmit the overcurrent signal generated by the overcurrent comparison unit to the control module; the fourth pin of the first optocoupler OPT1 is also connected to a power supply through an eighth resistor R8.

3. The input switch protection device for a DCDC converter according to claim 2, characterized in that: The control module is also used to send a fault reset signal to the protection and alarm reset unit when the fault of the input switch protection device is removed. The protection and alarm reset unit also includes: A second optocoupler OPT2, a fifth pin of the second optocoupler OPT2 is connected to the control module through a ninth resistor R9, and is used to receive a fault reset signal sent by the control module; a sixth pin of the second optocoupler OPT2 is grounded; a seventh pin of the second optocoupler OPT2 is connected between the second diode D2 and the third resistor R3; and an eighth pin of the second optocoupler OPT2 is connected to a negative power rail.

4. The input switch protection device for a DCDC converter according to claim 1, characterized in that: The current detection protection and alarm module also includes: The current detection amplifier unit includes a first operational amplifier U1, wherein the positive input terminal of the first operational amplifier U1 is connected to one end of the eleventh resistor R11 through a twelfth resistor R12, and the negative input terminal of the first operational amplifier U1 is connected to the other end of the eleventh resistor R11 through a thirteenth resistor R13; and the output terminal of the first operational amplifier U1 is connected to the overcurrent comparison unit; The positive input terminal of the first operational amplifier U1 is also grounded through a fourteenth resistor, and the negative input terminal of the first operational amplifier U1 is connected to the output terminal of the first operational amplifier U1 through a fifteenth resistor R15.

5. The input switch protection device for a DCDC converter according to claim 4, characterized in that: The current detection protection and alarm module also includes: A reference unit, comprising a second operational amplifier U2 and a reference voltage source U3, wherein the positive electrode of the reference voltage source U3 is connected to the power supply through a sixteenth resistor R16, and the negative electrode is grounded; The positive input terminal of the second operational amplifier U2 is grounded through a seventeenth resistor R17, the negative input terminal is connected between the positive electrode of the reference voltage source U3 and the sixteenth resistor R16 through an eighteenth resistor R18, and the output terminal is connected to the overcurrent comparison unit; The negative input terminal of the second operational amplifier U2 is also connected to the output terminal of the second operational amplifier U2 through a nineteenth resistor R19.

6. The input switch protection device for a DCDC converter according to claim 5, characterized in that: The overcurrent comparison unit includes a third operational amplifier U4 and a fourth operational amplifier U5; The negative input terminal of the third operational amplifier U4 is connected between the reference voltage source U3 and the eighteenth resistor R18, the positive input terminal is connected to the output terminal of the first operational amplifier U1, and the output terminal of the third operational amplifier U4 is connected to the second diode D2; The negative input terminal of the fourth operational amplifier U5 is connected to the output terminal of the first operational amplifier U1, the positive input terminal is connected to the output terminal of the second operational amplifier U2, and the output terminal of the fourth operational amplifier U5 is connected to the second diode D2; The output end of the third operational amplifier U4 and the output end of the fourth operational amplifier U5 are also connected in parallel and connected to a power supply via a twentieth resistor R20.

7. The input switch protection device for a DCDC converter according to claim 3, characterized in that: The control module includes a microcontroller connected to the power switch module and used to control the closing and closing of the first switch Q1, the second switch Q2 and the third switch Q3.

8. A protection method for an input switch protection device of a DCDC converter as claimed in claim 4, characterized in that: The method comprises: Detecting and amplifying the voltage across the eleventh resistor R11 to obtain an amplified voltage signal; The amplified voltage signal is compared with a reference voltage signal by an overcurrent comparison unit, and when the amplified voltage signal exceeds a threshold value of the reference voltage signal, an overcurrent signal is generated and output to a protection and alarm reset unit; The voltage of the control signal of the second switch Q2 and the third switch Q3 is pulled down by the protection and alarm reset unit, so that the second switch Q2 and the third switch Q3 are disconnected.

9. The protection method for the input switch protection device of the DCDC converter according to claim 8, characterized in that: The method further comprises: Transmitting the overcurrent signal to the control module through the protection and alarm reset unit; When the fault of the input switch protection device is removed, a fault reset signal is sent to the protection and alarm reset unit through the control module; The voltages of the control signals of the second switch Q2 and the third switch Q3 return to normal, so that the second switch Q2 and the third switch Q3 are turned on again.

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