Short circuit protection circuit and system using back-to-back logic control

Abstract

The application belongs to the technical field of short-circuit protection circuit, and discloses a short-circuit protection circuit and system using a back-saturation logic control, which comprises an upper and lower bridge back-saturation voltage sampling unit, an upper and lower bridge back-saturation voltage comparison unit, an upper and lower bridge back-saturation high and low voltage signal isolation integration unit, an upper and lower bridge back-saturation low voltage signal driving integration unit and a main power unit. The application increases an AND gate circuit at the output end of the back-saturation judgment circuit of each upper and lower bridge of the silicon carbide MOSFET, so that only when the upper and lower bridges both trigger back-saturation, the short-circuit protection is triggered. When only the upper or lower bridge single MOSFET tube triggers back-saturation, the short-circuit protection time still follows the existing protection parameters, that is, false positives caused by the fast opening of the silicon carbide and the interference of system noise are avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of short-circuit protection circuit, and particularly relates to a short-circuit protection circuit and system using a back-saturation logic control. BACKGROUND

[0002] With the rapid development of electric vehicle technology, consumers' pursuit of vehicle power performance is becoming more and more urgent, which is not only reflected in the extension of the cruising range, but also in the rapidity of acceleration response and the stability and efficiency of overall driving. Under such background, silicon carbide power modules have become the key technology to improve the efficiency of electric vehicle inverters and electric drive systems due to their excellent electrical performance, such as extremely low on-resistance, excellent high-temperature stability, ultra-fast switching speed and significantly reduced switching energy consumption. The application of silicon carbide material enables electric vehicles to maintain strong power output while effectively reducing energy consumption and prolonging battery life, which is of great significance to promote the development of electric vehicle industry towards more efficient and environmentally friendly direction.

[0003] However, one of the main challenges faced by current silicon carbide power modules in practical application is the lack of flexibility in short-circuit protection mechanism. Traditional short-circuit protection design often uses fixed time threshold setting. Although this method can protect the circuit from serious damage to some extent, its limitations are also obvious. If the protection time is set too long, it may not be able to cut off the circuit in time in the case of extreme short-circuit, resulting in damage to components and even causing more serious safety accidents. On the contrary, if the protection time is set too short, small fluctuations or electromagnetic interference in the system may be misjudged as short-circuit signals, triggering unnecessary protection actions, affecting the normal operation of the vehicle and increasing maintenance costs. SUMMARY

[0004] The purpose of the present application is to provide a short-circuit protection circuit using back-saturation logic control to solve the problem of non-adjustable short-circuit protection time in current silicon carbide power modules.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] The short circuit protection circuit controlled by desaturation logic includes an upper and lower bridge desaturation voltage sampling unit, an upper and lower bridge desaturation voltage comparison unit, an upper and lower bridge desaturation high and low voltage signal isolation integration unit, a lower bridge desaturation low voltage signal driving integration unit and a main power unit. The upper and lower bridge desaturation voltage sampling unit is used for collecting the source-drain voltage of a silicon carbide power module, and sending the collected source-drain voltage of the silicon carbide power module to the upper and lower bridge desaturation voltage comparison unit to determine whether the desaturation voltage is high or low. The upper and lower bridge desaturation high and low voltage signal isolation integration unit is used for integrating the output signal of the upper and lower bridge desaturation voltage comparison unit. The upper and lower bridge desaturation low voltage signal driving integration unit is used for receiving the signal input integrated by the upper and lower bridge desaturation high and low voltage signal isolation integration unit, and converting direct current into three-phase output.

[0007] Further, the upper and lower bridge desaturation voltage sampling unit includes a diode, a capacitor and a resistor, the diode and the resistor are connected in series, and the capacitor is connected in series between the diode and the resistor.

[0008] Further, one end of the diode is connected to the drain end of the Vd_UHS module, and one end of the resistor is connected to the Desat_UHS desaturation collection voltage end.

[0009] Further, the upper and lower bridge desaturation voltage comparison unit includes an operational amplifier follower and a comparator, the positive electrode of the operational amplifier follower is connected to the Desat_UHS desaturation collection voltage end, and the output end is connected to the comparator.

[0010] Further, if the desaturation voltage exceeds the threshold value, the output of the comparator is low, and if the desaturation voltage does not exceed the threshold value, the output of the comparator is high.

[0011] Further, the upper and lower bridge desaturation high and low voltage signal isolation integration unit includes an isolator and an AND gate; the output of the comparator is connected to the isolator, and the isolator is connected to the AND gate.

[0012] Further, the isolator converts the output of the comparator into a weak electric side signal and inputs the weak electric side signal into the AND gate, and when the upper bridge or the lower bridge appears short circuit, the output signal of the AND gate is low.

[0013] Further, the upper and lower bridge desaturation low voltage signal driving integration unit includes an AND gate and a driving chip; one end of the signal integrated by the upper and lower bridge desaturation high and low voltage signal isolation integration unit is connected to the AND gate, the AND gate is connected to the driving chip, and the other end of the AND gate is connected to the upper bridge and lower bridge driving signal.

[0014] Further, the main power unit is a direct current inverter, and the driving chip is connected to the direct current inverter to convert direct current into three-phase output to the motor.

[0015] Compared with the prior art, the present application has the following technical effects:

[0016] The application accurately collects the source-drain voltage of the silicon carbide power module through the upper and lower bridge desaturation voltage sampling unit, and utilizes the comparison unit to perform threshold judgment, so that the possible short circuit condition can be detected in a very short time (microsecond level). The fast response capability is crucial for protecting the circuit from serious damage.

[0017] The application adopts the combination of diodes, capacitors and resistors for voltage sampling, effectively filters the noise interference in the voltage signal, and improves the accuracy and reliability of sampling. At the same time, through the combination of operational amplifier follower and comparator, the stability and precision of signal processing are further enhanced. The application adds an AND gate circuit at the output end of the desaturation judgment circuit of the upper and lower bridges of each phase of the silicon carbide MOSFET, so that only when both the upper bridge and the lower bridge trigger desaturation, the short circuit protection will be truly triggered. When only the upper bridge or the lower bridge single MOSFET tube triggers desaturation, the short circuit protection time still follows the existing protection parameters, that is, to avoid false positives caused by the rapid opening of silicon carbide and the interference of system noise.

[0018] The design of the upper and lower bridge desaturation high and low voltage signal isolation integration unit enables the circuit to process the desaturation signals of the upper and lower bridges simultaneously, and realizes the integration and judgment of the signals through AND logic. This design not only improves the flexibility of the circuit, but also can adjust the protection logic according to actual needs to adapt to the short circuit protection requirements under different working conditions.

[0019] When the desaturation voltage exceeds the set threshold, the comparator quickly outputs a low-level signal to trigger the short circuit protection mechanism. This intelligent protection method can effectively prevent equipment damage or safety accidents caused by short circuit without sacrificing system stability.

[0020] The driving chip is connected to the direct current inverter to convert direct current into three-phase output to the motor. Through the optimization of control logic and circuit design, the energy consumption is reduced and the overall efficiency of the system is improved. At the same time, the fast response and accurate judgment of the short circuit protection mechanism also reduce the energy waste and system downtime caused by faults.

[0021] The technical scheme introduces the short circuit protection circuit with desaturation logic control to provide more perfect safety protection for the electric drive system of the electric vehicle. When abnormal conditions such as short circuit occur, the faulty circuit can be quickly cut off to prevent the situation from getting worse and protect the safety of the driver and the vehicle.

[0022] In summary, the technical scheme has significant technical effects in improving the safety, reliability, flexibility and efficiency of the electric drive system of the electric vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a whole circuit diagram.

[0024] Figure 2 The upper and lower bridge saturation voltage sampling circuit diagram.

[0025] Figure 3 The upper and lower bridge saturation voltage comparison circuit diagram.

[0026] Figure 4 The upper and lower bridge saturation high and low voltage signal isolation and integration circuit diagram.

[0027] Figure 5 The upper and lower bridge saturation low voltage signal and drive integration circuit diagram.

[0028] Figure 6 The main power circuit topology diagram. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0030] In the description of the present application, it should be understood that the terms "comprise" and "include" indicate the presence of described features, whole, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, whole, steps, operations, elements, components and / or sets thereof.

[0031] It should also be understood that the terms used in the present application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the present application specification and the appended claims, unless otherwise clear from the context, the singular forms "a", "an" and "the" are intended to include plural forms.

[0032] It should be further understood that the term "and / or" used in the present application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations, for example, A and / or B can represent three cases of A alone, A and B together, and B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0033] It should be understood that, although the terms first, second, third, etc. can be employed in describing the preset ranges, etc. in the embodiments of the present application, the preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from each other. For example, the first preset range can also be referred to as the second preset range, and similarly, the second preset range can also be referred to as the first preset range, without departing from the scope of the embodiments of the present application.

[0034] Depending on the context, the word "if" as used herein can be interpreted to mean "when" or "while" or "in response to determining" or "in response to detecting." Similarly, the phrase "if it is determined" or "if a detected (stated condition or event)" can be interpreted to mean "when it is determined" or "in response to determining" or "when a detected (stated condition or event)" or "in response to detecting (stated condition or event)".

[0035] Various structural diagrams according to the disclosed embodiments of the present application are shown in the accompanying drawings. These diagrams are not drawn to scale, in which certain details are exaggerated for the purpose of clarity, and certain details can be omitted. The shapes of various regions, layers, and the relative size and positional relationship therebetween shown in the drawings are only exemplary, and in actuality, they can be deviated due to manufacturing tolerances or technical limitations, and regions / layers with different shapes, sizes, and relative positions can be additionally designed according to actual needs by those skilled in the art.

[0036] Embodiment 1, please refer to Figure 1 A short circuit protection circuit using a desaturation logic control includes an upper and lower bridge desaturation voltage sampling unit, an upper and lower bridge desaturation voltage comparison unit, an upper and lower bridge desaturation high and low voltage signal isolation integration unit, and a lower bridge desaturation low voltage signal driving integration unit, and a main power unit. The upper and lower bridge desaturation voltage sampling unit is used to collect the source-drain voltage of the silicon carbide power module, and send the collected source-drain voltage of the silicon carbide power module to the upper and lower bridge desaturation voltage comparison unit to determine whether the desaturation voltage is high or low; the upper and lower bridge desaturation high and low voltage signal isolation integration unit is used to integrate the output signal of the upper and lower bridge desaturation voltage comparison unit; the upper and lower bridge desaturation low voltage signal driving integration unit is used to receive the signal input after integration of the upper and lower bridge desaturation high and low voltage signal isolation integration unit, and convert direct current into three-phase output.

[0037] The present application adds an AND gate circuit at the output end of the desaturation judgment circuit of the upper and lower bridge of each phase of the silicon carbide MOSFET, so that only when both the upper bridge and the lower bridge trigger desaturation, the short circuit protection is actually triggered. When only the upper bridge or the lower bridge single MOSFET tube triggers desaturation, the short circuit protection time still follows the existing protection parameters, that is, false positives caused by the fast turn-on of silicon carbide and the interference of system noise are avoided.

[0038] Example 2, please refer to Figures 1 to 6 This invention provides a short-circuit protection circuit using desaturation logic control, including an upper and lower bridge desaturation voltage sampling unit, an upper and lower bridge desaturation voltage comparison unit, an upper and lower bridge desaturation high and low voltage signal isolation and integration unit, an upper and lower bridge desaturation low voltage signal drive and integration unit, and a main power unit. The upper and lower bridge desaturation voltage sampling unit collects the source and drain voltages of the silicon carbide power module and sends the collected source and drain voltages to the upper and lower bridge desaturation voltage comparison unit to determine whether the desaturation voltage is high or low. The upper and lower bridge desaturation high and low voltage signal isolation and integration unit integrates the output signals of the upper and lower bridge desaturation voltage comparison unit. The upper and lower bridge desaturation low voltage signal drive and integration unit receives the integrated signal input from the upper and lower bridge desaturation high and low voltage signal isolation and integration unit, converting DC power into a three-phase output.

[0039] 1. Design the upper and lower bridge desaturation voltage sampling circuit: Vd_UHS is the module drain terminal, and Desat_UHS is the desaturation sampling voltage, such as... Figure 2 As shown: The upper and lower bridge desaturation voltage sampling unit includes a diode, a capacitor and a resistor. The diode and the resistor are connected in series, and the capacitor is connected in series between the diode and the resistor.

[0040] One end of the diode is connected to the drain terminal of the Vd_UHS module, and the other end of the resistor is connected to the desaturation acquisition voltage terminal of the Desat_UHS module.

[0041] 2. Design the upper and lower bridge desaturation voltage comparison circuit: The acquired upper and lower bridge desaturation voltages are first passed through an operational amplifier follower, and then input to comparators X5 and X7 respectively. If the desaturation voltage exceeds the threshold, Desat_UHS_out_HV is low; if the desaturation voltage does not exceed the threshold, Desat_UHS_out_HV is high. Figure 3 As shown: The upper and lower bridge desaturation voltage comparison unit includes an operational amplifier follower and a comparator. The positive terminal of the operational amplifier follower is connected to the Desat_UHS desaturation acquisition voltage terminal, and the output terminal is connected to the comparator.

[0042] If the desaturation voltage exceeds the threshold, the comparator output is low; if the desaturation voltage does not exceed the threshold, the comparator output is high.

[0043] 3. Design the high and low voltage signal isolation and integration circuit for the upper and lower bridges after desaturation: The high-voltage side Desat_UHS_out_HV / Desat_ULS_out_HV signals are input to isolators U5 and U6 respectively, converted into low-voltage side signals, and then passed through AND gate U2. When a short circuit occurs in either the upper or lower bridge, the AND gate output signal UHS_ULS_Desat will be low. Figure 4As shown: the upper and lower bridge desaturation high and low voltage signal isolation integration unit includes an isolator and an AND gate; the comparator output is connected to the isolator, and the isolator is connected to the AND gate.

[0044] The isolator converts the comparator output into a weak side signal and inputs it to the AND gate, and when the upper bridge or the lower bridge appears short circuit, the AND gate output signal is low.

[0045] 4. Design the upper and lower bridge desaturation low voltage signal and drive integrated circuit: input the integrated UHS_ULS_Desat signal to the AND gate U9 / U8, and the other end of U9 and U8 is connected to the upper bridge and lower bridge drive signal respectively, and then input to the drive chip U7 and U10 drive pin of the upper and lower bridge power module, such as Figure 5 As shown: the upper and lower bridge desaturation low voltage signal drive integration unit includes an AND gate and a drive chip; one end of the signal integrated by the upper and lower bridge desaturation high and low voltage signal isolation integration unit is connected to the AND gate, the AND gate is connected to the drive chip, and the other end of the AND gate is connected to the upper bridge and lower bridge drive signal.

[0046] The main power unit is a direct current inverter, and the drive chip is connected to the direct current inverter to convert direct current into three-phase output to the motor.

[0047] The application accurately collects the source-drain voltage of the silicon carbide power module through the upper and lower bridge desaturation voltage sampling unit, and judges the threshold value by using the comparison unit, so that the possible short circuit condition can be detected in a very short time (microsecond level). This fast response capability is crucial to protect the circuit from serious damage.

[0048] The application adopts the combination of diode, capacitor and resistor for voltage sampling, effectively filters the noise interference in the voltage signal, and improves the accuracy and reliability of sampling. At the same time, through the combination of operational amplifier follower and comparator, the stability and precision of signal processing are further enhanced. The application adds an AND gate circuit at the output end of the desaturation judgment circuit of each phase of the upper and lower bridge of the silicon carbide MOSFET, so that only when both the upper bridge and the lower bridge trigger desaturation, the short circuit protection will be triggered. When only the upper bridge or the lower bridge single MOSFET tube triggers desaturation, the short circuit protection time still follows the existing protection parameters, that is, to avoid false alarm caused by the rapid opening of silicon carbide and the interference of system noise.

[0049] Working process:

[0050] 1. The upper and lower bridge desaturation voltage sampling unit includes diode, capacitor and resistor, the diode and the resistor are connected in series, and the capacitor is connected in series between the diode and the resistor. One end of the diode is connected to the Vd_UHS module drain end, and one end of the resistor is connected to the Desat_UHS desaturation sampling voltage end.

[0051] 2. The collected Desat_UHS and Desat_UHS are first passed through an operational amplifier follower, then input to comparators X5 and X7 respectively. If the Desat_UHS voltage exceeds the threshold, Desat_UHS_out_HV is low, otherwise it is high.

[0052] 3. The Desat_UHS_out_HV and Desat_UHS_out_HV signals are input to isolators U5 and U6 respectively, and then converted to weak signal through AND gate U2. When the bridge or lower bridge is short-circuited, the UHS_ULS_Desat output signal is low.

[0053] 4. The integrated UHS_ULS_Desat signal is input to AND gates U9 / U8, and the other ends of U8 and U9 are connected to the upper bridge and lower bridge drive signals respectively, and then input to the drive chip U7 and U10 drive pins of the upper and lower bridge power modules.

[0054] 5. The DC power is converted into three-phase output to drive the motor.

[0055] Specifically:

[0056] 1. Working process of the upper and lower bridge desaturation voltage sampling unit

[0057] Connection and configuration: First, connect the anode (or cathode, depending on the specific circuit design) of the diode to the drain terminal of the silicon carbide power module (such as Vd_UHS). In this way, when the module is working, the voltage change between its source and drain will be captured by the diode.

[0058] Voltage sampling: When the silicon carbide power module is in normal working condition, the voltage between its source and drain is usually maintained within a certain range. When a short circuit or other abnormal situation causes the voltage to rise sharply (i.e. desaturation phenomenon), the diode conducts, allowing current to flow through the resistor to the capacitor, while the voltage drop across the resistor (i.e. Desat_UHS desaturation sampling voltage terminal) occurs.

[0059] Filtering and stabilization: The capacitor's role is to filter the sampled voltage to eliminate high-frequency noise and transient fluctuations, ensuring the stability and accuracy of the sampled voltage.

[0060] 2. Processing and comparison of voltage signals

[0061] Operational amplifier follower: The collected desaturation voltage is first passed through an operational amplifier follower for buffering and amplification (although in some cases it may mainly serve as a buffer to maintain signal integrity). The operational amplifier follower outputs a stable voltage signal to the comparator.

[0062] Comparator Decision: Comparators X5 and X7 (assuming for upper and lower bridges respectively) compare the received voltage signals against a pre-set threshold. If the voltage exceeds the threshold, indicating a possible short circuit, the comparators output a low level (Desat_UHS_out_HV / Desat_ULS_out_HV is low); otherwise, they output a high level.

[0063] 3. Signal Isolation and Integration

[0064] Signal Isolation: The Desat_UHS_out_HV / Desat_ULS_out_HV signals from the strong current side are converted to weak current side signals through isolators U5 and U6. This step is to protect the subsequent circuits from potential damage by high voltage signals and ensure the stability and safety of signals during transmission.

[0065] AND Gate Logic: The isolated signals are input to AND gate U2. The role of the AND gate is logical "AND" operation, that is, only when all input signals are high, the output is high. In this application, if either the upper or lower bridge has a short circuit (i.e., the corresponding signal is low), the UHS_ULS_Desat output is low.

[0066] 4. Control of Drive Signals

[0067] Role of AND Gates U9 / U8: The integrated UHS_ULS_Desat signal is further input to AND gates U9 and U8. The other end of these two AND gates receives the drive signals of the upper and lower bridges respectively. If UHS_ULS_Desat is low (indicating a short circuit), regardless of the original drive signal, the output of the AND gate will be forced to low, thereby cutting off the corresponding power module drive signal.

[0068] Drive Chip Control: The modified drive signal is input to the drive pins of the upper and lower bridge power module drive chips U7 and U10, controlling the switching state of the power module to prevent further damage caused by short circuits.

[0069] 5. DC Inversion and Motor Drive

[0070] Inversion Process: After confirming that there is no short circuit or other abnormal situation, the DC power supply is converted into three-phase AC power by the inverter for the motor. The specific working process of the inverter involves complex operations such as PWM control, filtering, phase adjustment, etc., but will not be detailed in this technical idea description.

[0071] Motor Drive: The three-phase AC power drives the motor to rotate, achieving the power output of the electric vehicle.

[0072] The above detailed process shows the complete flow from voltage sampling to motor driving, and how the short-circuit protection mechanism works in it. It should be noted that the actual circuit design may involve more details and elements, but the basic idea and technical framework are consistent.

[0073] The above is only to illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A short-circuit protection circuit using a back-to-back logic control, characterized by, The short circuit protection circuit controlled by the desaturation logic comprises an upper and lower bridge desaturation voltage sampling unit, an upper and lower bridge desaturation voltage comparison unit, an upper and lower bridge desaturation high and low voltage signal isolation integration unit, an upper and lower bridge desaturation low voltage signal driving integration unit and a main power unit; the upper and lower bridge desaturation voltage sampling unit is used for collecting source-drain voltages of silicon carbide power modules, and the collected source-drain voltages of the silicon carbide power modules are sent to the upper and lower bridge desaturation voltage comparison unit to determine whether the desaturation voltage is high or low; the upper and lower bridge desaturation high and low voltage signal isolation integration unit is used for integrating output signals of the upper and lower bridge desaturation voltage comparison unit; and the upper and lower bridge desaturation low voltage signal driving integration unit is used for receiving signals input after integration of the upper and lower bridge desaturation high and low voltage signal isolation integration unit and inverting direct current into three-phase output. The upper and lower bridge desaturation voltage comparison unit comprises an operational amplifier follower and a comparator, the positive electrode of the operational amplifier follower is connected to a Desat_UHS desaturation collector voltage end, and the output end is connected to the comparator; If the desaturation voltage exceeds a threshold value, the comparator outputs a low level, and if the desaturation voltage does not exceed the threshold value, the comparator outputs a high level; The upper and lower bridge desaturation high and low voltage signal isolation integration unit comprises an isolator and an AND gate; the output of the comparator is connected to the isolator, and the isolator is connected to the AND gate; The isolator converts the output of the comparator into a weak electric side signal and inputs the weak electric side signal into the AND gate; when short circuit occurs in the upper bridge or the lower bridge, the output signal of the AND gate is a low level.

2. A short circuit protection circuit using a de-saturation logic control according to claim 1, characterized in that, The upper and lower bridge desaturation voltage sampling unit comprises a diode, a capacitor and a resistor; the diode and the resistor are connected in series, and the capacitor is connected in series between the diode and the resistor.

3. A short circuit protection circuit using a de-saturation logic control according to claim 2, characterized in that, One end of the diode is connected to a Vd_UHS module drain end, and one end of the resistor is connected to a Desat_UHS desaturation collection voltage end.

4. The short circuit protection circuit using the de-saturation logic control according to claim 1, wherein, The upper and lower bridge desaturation low voltage signal driving integration unit comprises an AND gate and a driving chip; one end of the signal integrated by the upper and lower bridge desaturation high and low voltage signal isolation integration unit is connected to the AND gate, the AND gate is connected to the driving chip, and the other end of the AND gate is connected to upper bridge and lower bridge driving signals.

5. A short circuit protection circuit using a de-saturation logic control according to claim 4, characterized in that, The main power unit is a direct current inverter, the driving chip is connected to the direct current inverter, and direct current is inverted into three-phase output to a motor.

6. A short circuit protection system using back-to-back transistors with back-to-back diodes and control by back-to-back transistors with back-to-back diodes, characterized by, The short circuit protection circuit controlled by the desaturation logic comprises any one of claims 1 to 5.

Images