A protection circuit and power converter

Abstract

The utility model discloses an embodiment of protecting circuit and power converter, this protecting circuit includes: digital isolator has low voltage side power supply end and high voltage side power supply end for the electrical isolation of bridge arm switch tube's drive signal, voltage detection module is electrically connected with high voltage side power supply end for detecting whether the power supply voltage of high voltage side power supply end is in the preset voltage range and exports detection signal, logic control module is electrically connected with the output of digital isolator and voltage detection module's output respectively for the output signal of digital isolator is exported to bridge arm switch tube after the gate control processing of detection signal. Through above -mentioned mode, the utility model embodiment can solve the problem that the random output signal of digital isolator is produced because low voltage side and high voltage side power supply time sequence is not identical, make the drive signal that exports to bridge arm switch tube when power supply time sequence is not identical is the certain low level, thereby effectively prevents bridge arm straight -through.

Description

Technical Field

[0001] This utility model relates to the field of power conversion, and in particular to a protection circuit and a power converter. Background Technology

[0002] In the field of modern power electronics and motor drives, efficient, reliable, and controllable conversion of electrical energy is a core technological requirement. As the basic functional unit constituting the mainstream power converter topology, the design and control of the bridge arm has a decisive impact on the performance, efficiency, and safety of the entire system. The key lies in the high-speed and precise switching action of the power switching transistors.

[0003] Power switching transistors are typically connected to the high-voltage DC bus, known as the high-voltage side, while the logic signals controlling their on / off states originate from the low-voltage control circuitry of the digital signal processor, known as the low-voltage side. A significant potential difference exists between the high-voltage and low-voltage sides. If the drive signals lack reliable electrical isolation, high voltage can directly enter the low-voltage control circuitry, causing equipment damage. Therefore, a safe and reliable electrical isolation barrier must be introduced between the gate drive of the switching transistors and the controller.

[0004] Digital isolators (DIS) technology has become the mainstream choice for achieving the aforementioned electrical isolation due to its advantages such as fast response speed and strong anti-interference capability. However, DIS has a power supply timing problem in practical applications. Specifically, DIS has a low-voltage side power supply terminal and a high-voltage side power supply terminal. When the low-voltage side power supply terminal is powered on first and the high-voltage side power supply terminal is powered on later, the output of the DIS may generate a random PWM signal. This random signal may trigger the upper and lower transistors of the same bridge arm to conduct simultaneously, forming a shoot-through state, causing the switching transistors to be damaged due to overcurrent, and thus causing the entire power supply system to fail. Utility Model Content

[0005] The main technical problem solved by this utility model embodiment is to provide a protection circuit and a power converter that can solve at least some of the defects of existing drive circuits.

[0006] In a first aspect, this utility model provides a protection circuit, comprising: a digital isolator having a low-voltage side power supply terminal and a high-voltage side power supply terminal, used for electrical isolation of the drive signal of the bridge arm switch; a voltage detection module electrically connected to the high-voltage side power supply terminal, used for detecting whether the power supply voltage of the high-voltage side power supply terminal is within a preset voltage range, and outputting a corresponding detection signal; and a logic control module electrically connected to the output terminal of the digital isolator and the output terminal of the voltage detection module, respectively, used for gating the output signal of the digital isolator according to the detection signal and then outputting it to the bridge arm switch; wherein, when the power supply voltage is within the preset voltage range, the logic control module transmits the output signal of the digital isolator to the bridge arm switch; when the power supply voltage is outside the preset voltage range, the logic control module outputs a low level to the bridge arm switch.

[0007] Optionally, the voltage detection module includes: a first comparator for comparing the supply voltage with a first reference voltage, the output of the first comparator being connected to the logic control module; a second comparator for comparing the supply voltage with a second reference voltage, the output of the second comparator being connected to the logic control module; a first voltage divider unit connected to the reference power supply and the non-inverting input of the first comparator for generating the first reference voltage; and a second voltage divider unit connected to the reference power supply and the inverting input of the second comparator for generating the second reference voltage; wherein the first reference voltage is the upper limit of the preset voltage range, and the second reference voltage is the lower limit of the preset voltage range.

[0008] Optionally, the first voltage divider unit includes a first resistor, a third resistor, and a third capacitor; the first end of the first resistor is connected to the reference power supply, the second end of the first resistor is connected to the first end of the third resistor, the first end of the third capacitor, and the non-inverting input of the first comparator, and the second end of the third resistor and the second end of the third capacitor are connected to the reference ground.

[0009] Optionally, the second voltage divider unit includes a fourth resistor, a fifth resistor, and a fourth capacitor; the first end of the fourth resistor is connected to the reference power supply, the second end of the fourth resistor is connected to the first end of the fifth resistor, the first end of the fourth capacitor, and the inverting input of the second comparator, and the second end of the fifth resistor and the second end of the fourth capacitor are connected to the reference ground.

[0010] Optionally, the voltage detection module further includes a second resistor, a first capacitor, and a second capacitor; the first end of the second resistor is connected to the high-voltage side power supply terminal, the second end of the second resistor is connected to the first end of the second capacitor, the inverting input terminal of the first comparator, and the non-inverting input terminal of the second comparator, the second end of the second capacitor is connected to reference ground, the first end of the first capacitor is connected to the output terminal of the first comparator, and the second end of the first capacitor is connected to the reference ground.

[0011] Optionally, the logic control module includes a first diode, a second diode, a fourth AND gate, and a thirteenth capacitor; the first input terminal of the fourth AND gate is connected to the output terminal of the digital isolator, the second input terminal of the fourth AND gate is connected to the cathode of the first diode, the cathode of the second diode, and the first terminal of the thirteenth capacitor, the anode of the first diode is connected to the first output terminal of the voltage detection module, the anode of the second diode is connected to the second output terminal of the voltage detection module, the output terminal of the fourth AND gate is connected to the controlled terminal of the bridge arm switch, and the second terminal of the thirteenth capacitor is connected to reference ground.

[0012] Optionally, the logic control module includes a fourth AND gate and a fifth AND gate; the first input of the fourth AND gate is connected to the output of the digital isolator, the second input of the fourth AND gate is connected to the output of the fifth AND gate, the first input of the fifth AND gate is connected to the first output of the voltage detection module, the second input of the fifth AND gate is connected to the second output of the voltage detection module, and the output of the fourth AND gate is connected to the controlled terminal of the bridge arm switch.

[0013] Optionally, the protection circuit further includes: a complementary signal processing module, the input of which is connected to a digital signal processor, and the output of which is connected to the input of the digital isolator, for performing logical processing on the first drive signal and the second drive signal output by the digital signal processor, so that the first drive signal and the second drive signal are complementary.

[0014] Optionally, the complementary signal processing module includes: a second NOT gate, the input of which is connected to the first driving signal; and a second AND gate, the first input of which is connected to the second driving signal, and the second input of which is connected to the output of the second NOT gate; wherein the output signal of the second AND gate is input to the corresponding digital isolator as the upper or lower MOSFET driving signal of the same bridge arm.

[0015] Secondly, this utility model provides a power converter, including: a bridge power conversion circuit, including at least one bridge arm, each bridge arm including an upper transistor and a lower transistor connected in series; and a protection circuit as described in the first aspect, for protecting and controlling the drive signal of the bridge arm.

[0016] The beneficial effects of this utility model embodiment are as follows: Unlike the prior art, this utility model embodiment can solve the problem of random output signals generated by digital isolators due to inconsistent power supply timing between the low-voltage side and the high-voltage side, so that the drive signal output to the bridge arm switch tube when the power supply timing is inconsistent is a definite low level, thereby effectively preventing bridge arm shoot-through. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0018] Figure 1 This is a schematic diagram of the existing full-bridge inverter circuit; Figure 2 This is a schematic diagram of the structure of a protection circuit provided by an embodiment of this utility model; Figure 3 This is a circuit diagram of a protection circuit provided by an embodiment of the present invention; Figure 4 This is a circuit diagram of another protection circuit provided by an embodiment of the present invention; Figure 5 This is a schematic diagram of another protection circuit provided by an embodiment of the present invention; Figure 6 The circuit schematic of the complementary signal processing module and the digital isolator is shown. Detailed Implementation

[0019] To facilitate understanding of this utility model, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this specification are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0021] Please see Figure 1 , Figure 1 A schematic diagram of a full-bridge inverter circuit is shown.

[0022] Specifically, a full-bridge inverter circuit includes a digital signal processor, a digital isolator, and a bridge power converter circuit. The bridge power converter circuit includes two bridge arms, each including an upper transistor and a lower transistor connected in series. This is provided as an example, not a limitation. Figure 1 The bridge power converter circuit in the diagram is an H4 full-bridge inverter topology. The first bridge arm includes switches Q1 and Q2, and the second bridge arm includes switches Q3 and Q4. Switches Q1 and Q3 are the upper transistors, and switches Q2 and Q4 are the lower transistors. The input of the bridge power converter circuit is connected to the DC bus voltage Udc, and the output is connected to the capacitor C and the load resistor RL through an inductor L.

[0023] It's easy to understand that digital signal processors are used to output drive signals. Figure 1 In the full-bridge inverter circuit shown, the digital signal processor outputs four drive signals, namely PWM1, PWM2, PWM3 and PWM4.

[0024] In some embodiments of this application, switching transistors Q1, Q2, Q3, and Q4 do not share a common ground with the drive signals PWM1, PWM2, PWM3, and PWM4 output by the digital signal processor. Therefore, a digital isolator is required between the digital signal processor and the bridge arm switching transistors. The digital isolator has a low-voltage side power supply terminal and a high-voltage side power supply terminal, used to electrically isolate the drive signals of the bridge arm switching transistors. Specifically, the drive signals PWM1, PWM2, PWM3, and PWM4 output by the digital signal processor are converted into drive signals PWM1A, PWM2A, PWM3A, and PWM4A, respectively, after passing through the digital isolator, and then output to the corresponding switching transistors Q1, Q2, Q3, and Q4.

[0025] It's easy to understand that under normal operating conditions, the upper and lower tubes of the same bridge arm need to conduct alternately and are not allowed to conduct simultaneously. If the upper and lower tubes of the same bridge arm conduct simultaneously, a straight-through state will be formed, causing the switching transistor to be damaged due to overcurrent.

[0026] In some embodiments of this application, the switching transistor can be a power device with an internally integrated drive circuit. By way of example and not limitation, the switching transistor can be a gallium nitride power device. Using a power device with an internally integrated drive circuit is advantageous for applications requiring higher frequencies and smaller size.

[0027] Specifically, when the low-voltage side of a digital isolator is powered on first and the high-voltage side is powered on later, the output of the digital isolator may generate a random signal. In a full-bridge inverter circuit, if both digital isolators corresponding to the same bridge arm generate random high-level output signals, it may trigger the upper and lower transistors of that bridge arm to conduct simultaneously, forming a shoot-through state.

[0028] In some embodiments of this application, to address the aforementioned problems, a protection circuit is provided between the output terminal of the digital isolator and the bridge arm switch. The protection circuit detects the power supply voltage status of the high-voltage side of the digital isolator and performs gating processing on the output signal of the digital isolator based on the power supply voltage status. This ensures that, in the event of inconsistent power supply timing, the drive signal output to the bridge arm switch has a defined level, thereby preventing bridge arm shoot-through.

[0029] In some embodiments of this application, a structure for a protection circuit is provided. Please refer to... Figure 2 , Figure 2 A schematic diagram of a protection circuit is shown.

[0030] Specifically, the protection circuit 10 includes a digital isolator 110, a voltage detection module 120, and a logic control module 130. The protection circuit 10 works in conjunction with the bridge arm switch 210 to protect and control the drive signal of the bridge arm switch 210.

[0031] In some embodiments of this application, the digital isolator 110 has a low-voltage side power supply terminal and a high-voltage side power supply terminal. It is easy to understand that the low-voltage side power supply terminal is used to connect to the power supply of the low-voltage control circuit, and the high-voltage side power supply terminal is used to connect to the power supply of the high-voltage drive circuit. The digital isolator 110 is used to electrically isolate the drive signal of the bridge arm switch 210 to prevent voltage from the high-voltage side from entering the control circuit on the low-voltage side.

[0032] In some embodiments of this application, the voltage detection module 120 is electrically connected to the high-voltage side power supply terminal of the digital isolator 110. The voltage detection module 120 is used to detect whether the power supply voltage of the high-voltage side power supply terminal is within a preset voltage range and outputs a corresponding detection signal.

[0033] Specifically, when the supply voltage of the high-voltage side power supply terminal is within the preset voltage range, it indicates that the high-voltage side power supply terminal is in a normal power-on state, and the voltage detection module 120 outputs a first detection signal. When the supply voltage of the high-voltage side power supply terminal is outside the preset voltage range, it indicates that the high-voltage side power supply terminal is in a non-power-on state or an abnormal supply voltage state, and the voltage detection module 120 outputs a second detection signal.

[0034] By way of example and not limitation, the first detection signal can be a high-level signal and the second detection signal can be a low-level signal. The preset voltage range can be set according to the rated voltage of the high-voltage side power supply terminal of the digital isolator 110 and its allowable fluctuation range.

[0035] In some embodiments of this application, the logic control module 130 is electrically connected to the output terminal of the digital isolator 110 and the output terminal of the voltage detection module 120, respectively. The logic control module 130 is used to perform gating processing on the output signal of the digital isolator 110 based on the detection signal output by the voltage detection module 120, and then output the signal to the bridge arm switch 210.

[0036] Specifically, when the supply voltage at the high-voltage side is within a preset voltage range, the voltage detection module 120 outputs a first detection signal, and the logic control module 130 transmits the output signal of the digital isolator 110 to the bridge arm switch 210. It is easy to understand that when the high-voltage side is normally powered on, the digital isolator 110 can operate normally, and its output signal is at a defined level, which can be directly used to drive the bridge arm switch 210.

[0037] In some embodiments of this application, when the power supply voltage of the high-voltage side power supply terminal is outside the preset voltage range, the voltage detection module 120 outputs a second detection signal, and the logic control module 130 outputs a low level to the bridge arm switch 210.

[0038] It is easy to understand that when the low-voltage side power supply is powered on first and the high-voltage side power supply is powered on later, the output of the digital isolator 110 may generate random signals. By detecting the power supply voltage status of the high-voltage side power supply through the voltage detection module 120 and gating the output signal of the digital isolator 110 through the logic control module 130, a low level can be forcibly output to the bridge arm switch 210 when the high-voltage side power supply is not normally powered on, thereby ensuring that the bridge arm switch 210 is in the off state and avoiding bridge arm shoot-through triggered by random signals.

[0039] In some embodiments of this application, the protection circuit 10 may be located in the lower transistor drive branch of the same bridge arm. By way of example and not limitation, when the supply voltage of the high-voltage side power supply terminal is outside the preset voltage range, the logic control module 130 outputs a low level to the lower transistor to keep the lower transistor in the off state, thereby ensuring that there is no closed current loop in the bridge arm and preventing bridge arm shoot-through.

[0040] In some embodiments of this application, specific circuit structures for the voltage detection module 120 and the logic control module 130 are provided. Please refer to... Figure 3 , Figure 3 A circuit diagram of a protection circuit is shown.

[0041] Specifically, the voltage detection module 120 includes a first comparator U1A and a second comparator U1B. The first comparator U1A is used to compare the supply voltage at the high-voltage side power supply terminal with a first reference voltage, and the output terminal of the first comparator U1A is connected to the logic control module 130. The second comparator U1B is used to compare the supply voltage at the high-voltage side power supply terminal with a second reference voltage, and the output terminal of the second comparator U1B is connected to the logic control module 130.

[0042] In some embodiments of this application, the first reference voltage is the upper limit of a preset voltage range, and the second reference voltage is the lower limit of the preset voltage range. It is easy to understand that the first comparator U1A and the second comparator U1B together constitute a window comparator, used to determine whether the supply voltage at the high-voltage side power supply terminal falls within the voltage window defined by the first and second reference voltages.

[0043] In some embodiments of this application, the voltage detection module 120 further includes a first voltage divider unit and a second voltage divider unit. The first voltage divider unit is connected to a reference power supply and the non-inverting input of the first comparator U1A, and is used to generate a first reference voltage. The second voltage divider unit is connected to the reference power supply and the inverting input of the second comparator U1B, and is used to generate a second reference voltage.

[0044] As an example and not a limitation, the reference supply voltage is +12V1.

[0045] Specifically, the first voltage divider unit includes a first resistor R1, a third resistor R3, and a third capacitor C3. The first end of the first resistor R1 is connected to the reference power supply, the second end of the first resistor R1 is connected to the first end of the third resistor R3, the first end of the third capacitor C3, and the non-inverting input of the first comparator U1A, and the second end of the third resistor R3 and the second end of the third capacitor C3 are connected to the reference ground VSS.

[0046] It's easy to understand that the first resistor R1 and the third resistor R3 form a voltage divider circuit, used to divide the voltage of the reference power supply to generate the first reference voltage. The third capacitor C3 is used to filter the first reference voltage to improve its stability.

[0047] In some embodiments of this application, the second voltage divider unit includes a fourth resistor R4, a fifth resistor R5, and a fourth capacitor C4. The first terminal of the fourth resistor R4 is connected to a reference power supply, the second terminal of the fourth resistor R4 is connected to the first terminal of the fifth resistor R5, the first terminal of the fourth capacitor C4, and the inverting input terminal of the second comparator U1B, and the second terminal of the fifth resistor R5 and the second terminal of the fourth capacitor C4 are connected to the reference ground VSS.

[0048] It's easy to understand that the fourth resistor R4 and the fifth resistor R5 form a voltage divider circuit, used to divide the voltage of the reference power supply to generate the second reference voltage. The fourth capacitor C4 is used to filter the second reference voltage to improve its stability.

[0049] In some embodiments of this application, the voltage detection module 120 further includes a second resistor R2, a first capacitor C1, and a second capacitor C2.

[0050] Specifically, the first end of the second resistor R2 is connected to the high-voltage side power supply terminal +5V_INV_L, and the second end of the second resistor R2 is connected to the first end of the second capacitor C2, the inverting input terminal of the first comparator U1A, and the non-inverting input terminal of the second comparator U1B. The second end of the second capacitor C2 is connected to the reference ground VSS. The first end of the first capacitor C1 is connected to the output terminal of the first comparator U1A, and the second end of the first capacitor C1 is connected to the reference ground VSS.

[0051] It's easy to understand that the second resistor R2 is used to sample the supply voltage at the high-voltage side, and the second capacitor C2 is used to filter the sampled supply voltage. Both the inverting input of the first comparator U1A and the non-inverting input of the second comparator U1B receive the sampled and filtered supply voltage signal. The first capacitor C1 is used to filter the output signal of the first comparator U1A to improve the stability of the detection signal.

[0052] In some embodiments of this application, the logic control module 130 includes a first diode D1, a second diode D2, a fourth AND gate U4A, and a thirteenth capacitor C13.

[0053] Specifically, the first input terminal of the fourth AND gate U4A is connected to the output terminal of the digital isolator 110 to receive the drive signal PWM2A output by the digital isolator 110. The second input terminal of the fourth AND gate U4A is connected to the cathodes of the first diode D1 and the second diode D2, and the first terminal of the thirteenth capacitor C13, to receive the detection signal output by the voltage detection module 120. The anode of the first diode D1 is connected to the first output terminal of the voltage detection module 120, the anode of the second diode D2 is connected to the second output terminal of the voltage detection module 120, and the output terminal of the fourth AND gate U4A is connected to the controlled terminal of the bridge arm switch 210 to output the gated drive signal PWM2B. The second terminal of the thirteenth capacitor C13 is connected to the reference ground VSS.

[0054] It is easy to understand that the thirteenth capacitor C13 is used to filter the detection signal output by the voltage detection module 120 in order to improve the stability of the detection signal and avoid the logic control module 130 from malfunctioning due to signal interference.

[0055] In some embodiments of this application, the working principle of the protection circuit is described.

[0056] Specifically, when the supply voltage at the high-voltage side is within a preset voltage range, the supply voltage is greater than the second reference voltage and less than the first reference voltage. It's easy to understand that when the supply voltage is input to the inverting input of the first comparator U1A and the first reference voltage is input to the non-inverting input of the first comparator U1A, since the supply voltage is less than the first reference voltage, the first comparator U1A outputs a high level. When the supply voltage is input to the non-inverting input of the second comparator U1B and the second reference voltage is input to the inverting input of the second comparator U1B, since the supply voltage is greater than the second reference voltage, the second comparator U1B also outputs a high level. The outputs of the voltage detection module 120 all output high-level detection signals. After passing through the logic AND gate formed by the first diode D1 and the second diode D2, a high level is output to the second input of the fourth AND gate U4A. The fourth AND gate U4A transmits the drive signal PWM2A output by the digital isolator 110 to the bridge arm switch 210.

[0057] In some embodiments of this application, when the power supply voltage at the high-voltage side power supply terminal is outside the preset voltage range, the power supply voltage is less than the second reference voltage or greater than the first reference voltage.

[0058] Specifically, when the supply voltage is less than the second reference voltage, the second comparator U1B outputs a low level, the first comparator U1A outputs a high level, and the logic AND gate formed by the first diode D1 and the second diode D2 outputs a low level; when the supply voltage is greater than the first reference voltage, the first comparator U1A outputs a low level, the second comparator U1B outputs a high level, and the logic AND gate formed by the first diode D1 and the second diode D2 still outputs a low level. Therefore, the output terminal of the voltage detection module 120 always outputs a low-level detection signal.

[0059] It is easy to understand that when the voltage detection module 120 outputs a low-level detection signal to the second input terminal of the fourth AND gate U4A, regardless of whether the drive signal PWM2A output by the digital isolator 110 is high or low, the output terminal of the fourth AND gate U4A outputs a low level to the bridge arm switch 210, keeping the bridge arm switch 210 in the off state, thereby preventing the bridge arm from shoot-through.

[0060] As an example and not a limitation, the rated voltage of the high-voltage side power supply is 5V, and the allowable fluctuation range of the supply voltage is ±10%. The first reference voltage can be set to 5.5V, and the second reference voltage can be set to 4.5V. When the reference power supply voltage is 12V, the values ​​of the first resistor R1 and the third resistor R3 satisfy the following relationship: R3 / (R1+R3)=5.5V / 12V. The values ​​of the fourth resistor R4 and the fifth resistor R5 satisfy the following relationship: R5 / (R4+R5)=4.5V / 12V.

[0061] In some embodiments of this application, specific circuit structures for the voltage detection module 120 and the logic control module 130 are provided. Please refer to... Figure 4 , Figure 4 The circuit diagram of another protection circuit is shown.

[0062] In this embodiment, the specific circuit structure of the voltage detection module 120 is the same as that of the voltage detection module 120 provided in the previous embodiment, and will not be described again here.

[0063] In some embodiments of this application, the logic control module 130 includes a fourth AND gate U4A and a fifth AND gate U4B.

[0064] Specifically, the first input of the fourth AND gate U4A is connected to the output of the digital isolator 110 to receive the drive signal PWM2A output by the digital isolator 110. The second input of the fourth AND gate U4A is connected to the output of the fifth AND gate U4B to receive the detection signal output by the voltage detection module 120. The first input of the fifth AND gate U4B is connected to the first output of the voltage detection module 120, and the second input of the fifth AND gate U4B is connected to the second output of the voltage detection module 120. The output of the fourth AND gate U4A is connected to the controlled terminal of the bridge arm switch 210 to output the gated drive signal PWM2B.

[0065] In some embodiments of this application, the working principle of the protection circuit is described.

[0066] Specifically, when the supply voltage at the high-voltage side is within a preset voltage range, the supply voltage is greater than the second reference voltage and less than the first reference voltage. It's easy to understand that when the supply voltage is input to the inverting input of the first comparator U1A and the first reference voltage is input to the non-inverting input of the first comparator U1A, since the supply voltage is less than the first reference voltage, the first comparator U1A outputs a high level. When the supply voltage is input to the non-inverting input of the second comparator U1B and the second reference voltage is input to the inverting input of the second comparator U1B, since the supply voltage is greater than the second reference voltage, the second comparator U1B also outputs a high level. The outputs of the voltage detection module 120 all output high-level detection signals. After passing through the fifth AND gate U4B, a high level is output to the second input of the fourth AND gate U4A. The fourth AND gate U4A transmits the drive signal PWM2A output by the digital isolator 110 to the bridge arm switch 210.

[0067] In some embodiments of this application, when the power supply voltage at the high-voltage side power supply terminal is outside the preset voltage range, the power supply voltage is less than the second reference voltage or greater than the first reference voltage.

[0068] Specifically, when the supply voltage is less than the second reference voltage, the second comparator U1B outputs a low level, the first comparator U1A outputs a high level, and the fifth AND gate U4B outputs a low level; when the supply voltage is greater than the first reference voltage, the first comparator U1A outputs a low level, the second comparator U1B outputs a high level, and the fifth AND gate U4B still outputs a low level. Therefore, the output terminal of the voltage detection module 120 always outputs a low-level detection signal.

[0069] It is easy to understand that when the voltage detection module 120 outputs a low-level detection signal to the second input terminal of the fourth AND gate U4A, regardless of whether the drive signal PWM2A output by the digital isolator 110 is high or low, the output terminal of the fourth AND gate U4A outputs a low level to the bridge arm switch 210, keeping the bridge arm switch 210 in the off state, thereby preventing the bridge arm from shoot-through.

[0070] In some embodiments of this application, another protection circuit structure is provided. See also... Figure 5 , Figure 5 A schematic diagram of another protection circuit is shown.

[0071] Specifically, the protection circuit 10 includes a digital isolator 110, a voltage detection module 120, a logic control module 130, and a complementary signal processing module 140. The protection circuit 10 works in conjunction with the bridge arm switch 210 to protect and control the drive signal of the bridge arm switch 210.

[0072] It is easy to understand that the structure and function of the digital isolator 110, voltage detection module 120 and logic control module 130 can be referred to the description of the aforementioned embodiments, and will not be repeated here.

[0073] In some embodiments of this application, the protection circuit 10 further includes a complementary signal processing module 140. The input of the complementary signal processing module 140 is connected to a digital signal processor, and the output of the complementary signal processing module 140 is connected to the input of the digital isolator 110.

[0074] Specifically, the complementary signal processing module 140 is used to perform logical processing on the first drive signal and the second drive signal output by the digital signal processor so that the first drive signal and the second drive signal are complementary.

[0075] It's easy to understand that under normal operating conditions, the drive signals output by the digital signal processor (DSP) should ensure that the upper and lower transistors of the same bridge arm conduct alternately. However, when the DSP malfunctions, it may output abnormal drive signals, causing the drive signals of both the upper and lower transistors of the same bridge arm to be high simultaneously, thus triggering a shoot-through in the bridge arm.

[0076] In some embodiments of this application, the complementary signal processing module 140 uses logic circuits to force the upper and lower drive signals of the same bridge arm to be complementary. By way of example and not limitation, when the first drive signal is high, after processing by the complementary signal processing module 140, the second drive signal is forced to be low; when the first drive signal is low, the second drive signal can be set accordingly according to the output of the digital signal processor.

[0077] It is easy to understand that through the logic processing of the complementary signal processing module 140, the situation where the upper and lower transistors of the same bridge arm simultaneously receive high-level drive signals due to a digital signal processor failure can be avoided.

[0078] In some embodiments of this application, the protection circuit 10 includes a voltage detection module 120, a logic control module 130, and a complementary signal processing module 140, which can realize dual protection functions.

[0079] Specifically, the complementary signal processing module 140 is used to solve the problem of abnormal output drive signals caused by digital signal processor failure. It forces the upper and lower drive signals of the same bridge arm to be complementary through logic processing. The voltage detection module 120 and the logic control module 130 are used to solve the problem of random output signals caused by inconsistent power supply timing of the digital isolator 110. By detecting the power supply voltage status of the high-voltage side and performing gating processing, they ensure that a definite low level is output to the bridge arm switch 210 when the power supply timing is inconsistent.

[0080] It is easy to understand that the complementary signal processing module 140 is located on the input side of the digital isolator 110, while the voltage detection module 120 and the logic control module 130 are located on the output side of the digital isolator 110. This dual protection on both the input and output sides effectively prevents bridge arm shoot-through problems caused by digital signal processor failure or inconsistent power supply timing of the digital isolator 110.

[0081] In some embodiments of this application, a specific circuit structure for the complementary signal processing module 140 is provided. Please refer to... Figure 6 , Figure 6 The circuit schematic of the complementary signal processing module 140 and the digital isolator 110 is shown.

[0082] Specifically, the complementary signal processing module 140 includes a second NOT gate and a second AND gate. The input of the second NOT gate is connected to the first driving signal, the first input of the second AND gate is connected to the second driving signal, and the second input of the second AND gate is connected to the output of the second NOT gate. The output signal of the second AND gate is input to the corresponding digital isolator 110 as the upper or lower MOSFET driving signal of the same bridge arm.

[0083] In some embodiments of this application, the digital signal processor 30 outputs multiple drive signals. By way of example and not limitation, the digital signal processor 30 outputs a first drive signal PWM1 and a second drive signal PWM2, which are used to control the upper and lower transistors of the same bridge arm, respectively.

[0084] Specifically, the input of the second NOT gate is connected to the first drive signal PWM1, and the output of the second NOT gate is connected to the second input of the second AND gate. The first input of the second AND gate is connected to the second drive signal PWM2.

[0085] It's easy to understand that the second NOT gate is used to invert the first drive signal PWM1. When the first drive signal PWM1 is high, the output of the second NOT gate is low; when the first drive signal PWM1 is low, the output of the second NOT gate is high.

[0086] In some embodiments of this application, the second AND gate is used to perform AND logic operations on the second drive signal PWM2 and the output signal of the second NOT gate.

[0087] Specifically, when the first drive signal PWM1 is high, the second NOT gate outputs a low level, and the second input of the second AND gate receives a low-level signal. It's easy to understand that regardless of whether the second drive signal PWM2 is high or low, the output of the second AND gate will always be low.

[0088] In some embodiments of this application, when the first driving signal PWM1 is low, the second NOT gate outputs a high level, and the second input of the second AND gate receives a high-level signal. Specifically, when the second driving signal PWM2 is high, the output of the second AND gate outputs a high level; when the second driving signal PWM2 is low, the output of the second AND gate outputs a low level.

[0089] It is easy to understand that through the logic processing of the second NOT gate and the second AND gate, the following complementary relationship can be forced: when the first drive signal PWM1 is high, the output signal of the second AND gate must be low; when the first drive signal PWM1 is low, the output signal of the second AND gate depends on the level state of the second drive signal PWM2.

[0090] In some embodiments of this application, the output signal of the second AND gate is input to the corresponding digital isolator 110 as the lower MOSFET drive signal of the same bridge arm. By way of example and not limitation, the first drive signal PWM1 outputs drive signal PWM1A to the upper MOSFET after passing through the digital isolator 110, and the output signal of the second AND gate outputs drive signal PWM2A to the lower MOSFET after passing through the digital isolator 110.

[0091] It is easy to understand that when the digital signal processor 30 malfunctions and simultaneously outputs the first high-level drive signal PWM1 and the second high-level drive signal PWM2, after the logic processing of the complementary signal processing module 140, the upper transistor receives the high-level drive signal and the lower transistor receives the low-level drive signal, thereby preventing the upper and lower transistors of the same bridge arm from being turned on at the same time.

[0092] Please refer to some embodiments of this application. Figure 5 , Figure 5 The circuit structure of the digital isolator 110 is also shown.

[0093] Specifically, the digital isolator 110 includes a first digital isolation chip U1 and a second digital isolation chip U2. Both the first digital isolation chip U1 and the second digital isolation chip U2 have a low-voltage side power supply terminal VDD1 and a high-voltage side power supply terminal VDD2.

[0094] In some embodiments of this application, the low-voltage side power supply terminal VDD1 of the first digital isolation chip U1 is connected to the low-voltage side power supply +5V, and the high-voltage side power supply terminal VDD2 of the first digital isolation chip U1 is connected to the high-voltage side power supply +5V_INV_H. The low-voltage side power supply terminal VDD1 of the second digital isolation chip U2 is connected to the low-voltage side power supply +5V, and the high-voltage side power supply terminal VDD2 of the second digital isolation chip U2 is connected to the high-voltage side power supply +5V_INV_L.

[0095] Specifically, the input terminal INB of the first digital isolation chip U1 is connected to the first drive signal PWM1, and the output terminal OUTB of the first digital isolation chip U1 outputs the drive signal PWM1A. The input terminal INB of the second digital isolation chip U2 is connected to the output signal of the second AND gate, and the output terminal OUTB of the second digital isolation chip U2 outputs the drive signal PWM2A.

[0096] The low-voltage side grounding terminal GND1 of the first digital isolation chip U1 and the second digital isolation chip U2 is connected to the low-voltage side reference ground GND, and the high-voltage side grounding terminal GND2 is connected to the high-voltage side reference ground VSS.

[0097] In some embodiments of this application, the digital isolator 110 further includes an external filtering circuit. By way of example and not limitation, the external filtering circuit of the first digital isolation chip U1 includes capacitors C5, C6, C7, and C8, and resistors R10, R11, R12, and R13. The external filtering circuit of the second digital isolation chip U2 includes capacitors C9, C10, C11, and C12, and resistors R14, R15, R16, and R17. The external filtering circuit is used to filter the power supply and signals to improve the stability of the digital isolator 110.

[0098] In some embodiments of this application, a power converter is provided.

[0099] Specifically, the power converter includes a bridge power conversion circuit and a protection circuit 10 as described in the foregoing embodiments.

[0100] In some embodiments of this application, the bridge power conversion circuit includes at least one bridge arm, each bridge arm including an upper transistor and a lower transistor connected in series. By way of example and not limitation, the bridge power conversion circuit can be a full-bridge inverter circuit or a half-bridge converter circuit.

[0101] Specifically, when the bridge power converter circuit is a full-bridge inverter circuit, it includes two bridge arms, each including an upper and lower transistor connected in series, for a total of four switching transistors. When the bridge power converter circuit is a half-bridge converter circuit, it includes one bridge arm, which includes an upper and lower transistor connected in series, for a total of two switching transistors.

[0102] In some embodiments of this application, the protection circuit 10 is used to protect and control the drive signal of the bridge arm. It is easy to understand that the protection circuit 10 can be set in the drive branch of at least one bridge arm to ensure that the drive signal output to the bridge arm switch 210 is a defined low level when the power supply timing of the digital isolator 110 is inconsistent, thereby preventing bridge arm shoot-through.

[0103] It should be noted that while the preferred embodiments of this utility model are provided in the specification and accompanying drawings, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of this utility model; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of this utility model. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of this utility model specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A protection circuit, characterized in that, include: A digital isolator, having a low-voltage side power supply terminal and a high-voltage side power supply terminal, is used to electrically isolate the drive signals of the bridge arm switching transistors; The voltage detection module is electrically connected to the high-voltage side power supply terminal and is used to detect whether the power supply voltage of the high-voltage side power supply terminal is within a preset voltage range and output a corresponding detection signal. The logic control module is electrically connected to the output terminal of the digital isolator and the output terminal of the voltage detection module, respectively, and is used to perform gating processing on the output signal of the digital isolator according to the detection signal and then output it to the bridge arm switch. When the power supply voltage is within the preset voltage range, the logic control module transmits the output signal of the digital isolator to the bridge arm switch. When the supply voltage is outside the preset voltage range, the logic control module outputs a low level to the bridge arm switch.

2. The circuit according to claim 1, characterized in that, The voltage detection module includes: A first comparator is used to compare the supply voltage with a first reference voltage, and the output of the first comparator is connected to the logic control module. A second comparator is used to compare the supply voltage with a second reference voltage, and the output of the second comparator is connected to the logic control module. The first voltage divider unit is connected to the reference power supply and the non-inverting input terminal of the first comparator, and is used to generate the first reference voltage. The second voltage divider unit is connected to the reference power supply and the inverting input of the second comparator, and is used to generate the second reference voltage. Wherein, the first reference voltage is the upper limit of the preset voltage range, and the second reference voltage is the lower limit of the preset voltage range.

3. The circuit according to claim 2, characterized in that, The first voltage divider unit includes a first resistor, a third resistor, and a third capacitor; The first end of the first resistor is connected to the reference power supply, the second end of the first resistor is connected to the first end of the third resistor, the first end of the third capacitor and the non-inverting input of the first comparator, and the second end of the third resistor and the second end of the third capacitor are connected to the reference ground.

4. The circuit according to claim 2, characterized in that, The second voltage divider unit includes a fourth resistor, a fifth resistor, and a fourth capacitor; The first end of the fourth resistor is connected to the reference power supply, the second end of the fourth resistor is connected to the first end of the fifth resistor, the first end of the fourth capacitor and the inverting input of the second comparator, and the second end of the fifth resistor and the second end of the fourth capacitor are connected to the reference ground.

5. The circuit according to claim 2, characterized in that, The voltage detection module also includes a second resistor, a first capacitor, and a second capacitor; The first end of the second resistor is connected to the high-voltage side power supply terminal, the second end of the second resistor is connected to the first end of the second capacitor, the inverting input terminal of the first comparator, and the non-inverting input terminal of the second comparator, the second end of the second capacitor is connected to the reference ground, the first end of the first capacitor is connected to the output terminal of the first comparator, and the second end of the first capacitor is connected to the reference ground.

6. The circuit according to claim 1, characterized in that, The logic control module includes a first diode, a second diode, a fourth AND gate, and a thirteenth capacitor; The first input terminal of the fourth AND gate is connected to the output terminal of the digital isolator. The second input terminal of the fourth AND gate is connected to the cathode of the first diode, the cathode of the second diode, and the first terminal of the thirteenth capacitor. The anode of the first diode is connected to the first output terminal of the voltage detection module. The anode of the second diode is connected to the second output terminal of the voltage detection module. The output terminal of the fourth AND gate is connected to the controlled terminal of the bridge arm switch. The second terminal of the thirteenth capacitor is connected to reference ground.

7. The circuit according to claim 1, characterized in that, The logic control module includes a fourth AND gate and a fifth AND gate; The first input terminal of the fourth AND gate is connected to the output terminal of the digital isolator, the second input terminal of the fourth AND gate is connected to the output terminal of the fifth AND gate, the first input terminal of the fifth AND gate is connected to the first output terminal of the voltage detection module, the second input terminal of the fifth AND gate is connected to the second output terminal of the voltage detection module, and the output terminal of the fourth AND gate is connected to the controlled terminal of the bridge arm switch.

8. The circuit according to claim 1, characterized in that, It also includes a complementary signal processing module, the input of which is connected to a digital signal processor, and the output of which is connected to the input of the digital isolator, for performing logical processing on the first drive signal and the second drive signal output by the digital signal processor, so that the first drive signal and the second drive signal are complementary.

9. The circuit according to claim 8, characterized in that, The complementary signal processing module includes: The second NOT gate, the input of which is connected to the first drive signal; The second AND gate has its first input connected to the second driving signal and its second input connected to the output of the second NOT gate. The output signal of the second AND gate is input to the corresponding digital isolator as the upper or lower drive signal of the same bridge arm.

10. A power converter, characterized in that, include: A bridge power conversion circuit includes at least one bridge arm, each of the bridge arms including an upper transistor and a lower transistor connected in series; The protection circuit as described in any one of claims 1 to 9 is used for protective control of the drive signal of the bridge arm.

Images