Overcurrent protection circuit of power module

Abstract

The utility model provides an overcurrent protection circuit of a power module. The overcurrent protection circuit comprises a voltage sensing unit, a comparator, an MOS tube, a driving chip, a reference power supply unit and a driving power supply end, the voltage sensing unit comprises a current sensing interface of the power module and a first resistor, a first end of the first resistor is respectively connected with the current sensing interface of the power module and a first input interface of the comparator, and a second end of the first resistor is grounded; a second input interface of the comparator is connected with the reference power supply unit, and an output interface of the comparator is connected with a control end of the MOS tube; and the comparator is used for controlling the MOS tube to be cut off when the voltage received by the first input interface is greater than the voltage received by the second input interface, so that the driving power supply end supplies power to the desaturation protection interface of the driving chip. After the technical scheme is adopted, the desaturation protection function of the driving chip can be quickly triggered through the current sensing interface of the power module.

Description

Technical Field

[0001] The utility model relates to the field of electronic technology, in particular to an overcurrent protection circuit of a power module. Background Art

[0002] When a short circuit occurs in a power module, the on-current will increase sharply, resulting in desaturation. It is necessary to return the on-current of the power module to a safe operating area. Most driver chips on the market have desaturation detection and protection functions, which shut down the power module when the voltage is detected to be too high. However, this protection function has the disadvantages of slow detection speed, blanking time, affecting the maximum voltage utilization of the module, low protection effectiveness, and false triggering.

[0003] At the same time, power modules with built-in current sensing interfaces are becoming more and more popular, and a method is needed to trigger the desaturation protection function of a driver chip through a signal from the built-in current sensing interface of the power module. Utility Model Content

[0004] In order to overcome the above technical defects, the purpose of the utility model is to provide an overcurrent protection circuit for a power module, so that a driver chip that cannot directly detect the overcurrent signal of the power module can also achieve rapid overcurrent protection for the power module.

[0005] The utility model discloses an overcurrent protection circuit of a power module, comprising a voltage sensing unit, a comparator, a MOS tube, a driving chip, a reference power supply unit, and a driving power supply terminal;

[0006] The voltage sensing unit comprises a current sensing interface of the power module and a first resistor, wherein a first end of the first resistor is respectively connected to the current sensing interface of the power module and a first input interface of the comparator, and a second end of the first resistor is grounded;

[0007] The second input interface of the comparator is connected to the reference power supply unit, and the output interface of the comparator is connected to the control end of the MOS tube;

[0008] The first end of the MOS tube is connected to the desaturation protection interface of the driving chip, and the second end of the MOS tube is grounded;

[0009] The driving power supply end is respectively connected to the desaturation protection interface of the driving chip and the first end of the MOS tube;

[0010] The comparator is used to control the MOS tube to be cut off when the voltage received by the first input interface is greater than the voltage received by the second input interface, so that the driving power supply end supplies power to the desaturation protection interface of the driving chip.

[0011] Preferably, the current sensing interface of the power module is a current mirror interface of the power module.

[0012] Preferably, a filter unit is further connected between the first input interface of the comparator and the voltage sensing unit, and the filter unit includes a second resistor and a first capacitor;

[0013] The first end of the second resistor is respectively connected to the current sensing interface of the power module and the first end of the first resistor, the second end of the second resistor is connected to the first input interface of the comparator, the first end of the first capacitor is connected to the second end of the second resistor, and the second end of the first capacitor is grounded.

[0014] Preferably, the MOS transistor is an N-channel MOS transistor, the first input interface of the comparator is a negative input interface, and the second input interface of the comparator is a positive input interface;

[0015] The drain of the MOS tube is connected to the desaturation protection interface of the driving chip, the source of the MOS tube is grounded, and the output interface of the comparator is connected to the gate of the MOS tube.

[0016] Preferably, the reference power supply unit comprises a reference power supply terminal, a third resistor, a fourth resistor and a second capacitor;

[0017] A first end of the third resistor is connected to the reference power supply end, and a second end of the third resistor is connected to the fourth resistor;

[0018] The first end of the fourth resistor is connected to the positive input interface of the comparator and the second end of the third resistor respectively, and the second end of the fourth resistor is grounded;

[0019] The first end of the second capacitor is connected to the positive input interface of the comparator and the first end of the fourth resistor respectively, and the second end of the second capacitor is grounded;

[0020] The external voltage interface of the comparator is connected to the reference power supply terminal, and the ground interface of the comparator is grounded.

[0021] Preferably, a fifth resistor is connected between the output interface of the comparator and the control end of the MOS tube, a first end of the fifth resistor is connected to the output interface of the comparator, and a second end of the fifth resistor is connected to the control end of the MOS tube.

[0022] Preferably, a sixth resistor is further connected between the driving power supply end and the first end of the MOS tube, the first end of the sixth resistor is connected to the driving power supply end, and the second end of the sixth resistor is connected to the first end of the MOS tube.

[0023] Preferably, a third capacitor is also connected between the driving power supply end and the desaturation protection interface of the driving chip, a first end of the third capacitor is respectively connected to the driving power supply end and the desaturation protection interface of the driving chip, and a second end of the third capacitor is grounded.

[0024] Compared with the prior art, the above technical solution has the following beneficial effects: by triggering the desaturation protection function of the driver chip through the signal of the current sensing interface of the power module, the overcurrent protection of the power module can be quickly realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a circuit schematic diagram of an overcurrent protection circuit for a power module. DETAILED DESCRIPTION

[0026] The advantages of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0028] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0029] It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0030] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0031] In the description of the present utility model, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection of two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0032] In the following description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention, and they themselves have no specific meaning. Therefore, "module" and "component" can be used interchangeably.

[0033] See also Figure 1 As shown, the utility model discloses an overcurrent protection circuit of a power module, including a voltage sensing unit, a comparator U1, a MOS tube Q1, a driving chip U2, a reference power supply unit, and a driving power supply terminal Vcc1.

[0034] The voltage sensing unit includes a current sensing interface of a power module and a first resistor R1, a first end of the first resistor R1 is respectively connected to the current sensing interface of the power module and a first input interface of the comparator U1, and a second end of the first resistor R1 is grounded.

[0035] The second input interface of the comparator U1 is connected to the reference power supply unit, and the output interface Out of the comparator U1 is connected to the control end of the MOS tube Q1.

[0036] A first end of the MOS transistor Q1 is connected to a desaturation protection interface Desat of the driving chip U2 , and a second end of the MOS transistor Q1 is grounded.

[0037] The driving power supply terminal Vcc1 is respectively connected to the desaturation protection interface Desat of the driving chip U2 and the first end of the MOS tube Q1.

[0038] The comparator U1 is used to control the MOS tube Q1 to be turned off when the voltage received by the first input interface thereof is greater than the voltage received by the second input interface thereof, so that the driving power supply terminal Vcc1 supplies power to the desaturation protection interface Desat of the driving chip U2.

[0039] In specific implementation, the detection current output by the power module at the current sensing interface has a certain internal attenuation ratio with the collector current of the power module. The detection current is converted into a detection voltage through the connection with the first resistor R1, and then the detection voltage is transmitted to the first input interface of the comparator U1. The reference power supply unit inputs the reference voltage to the second input interface of the comparator U1. According to the safety value of the collector current of the power module to be protected and the internal attenuation ratio, the safety value of the detection current of the power module can be obtained, thereby determining the reference voltage according to the safety value of the detection current of the power module and the resistance value of the first resistor R1. The comparator U1 preferably uses a high-speed comparator with a transmission delay of less than 100ns.

[0040] When the collector current of the power module is greater than the safety value, that is, an overcurrent state occurs, the detection voltage will be greater than the reference voltage. The voltage received by the first input interface of the comparator U1 is greater than the voltage received by the second input interface, and the MOS tube Q1 is controlled to be cut off. After the MOS tube Q1 enters the cut-off state, the voltage of the desaturation protection interface Desat of the driving chip U2 input by the driving power supply terminal Vcc1 will be rapidly raised. When the voltage of the desaturation protection interface Desat exceeds the desaturation protection voltage threshold built into the driving chip U2, the desaturation protection function of the driving chip U2 will be triggered, and the power module will be shut down through the protection path. Among them, the protection path connecting the driving chip U2 and the power module is a prior art, and therefore is not shown in the present utility model.

[0041] Furthermore, the current sensing interface of the power module is a current mirror interface of the power module.

[0042] In an optional implementation, a filter unit is further connected between the first input interface of the comparator U1 and the voltage sensing unit, and the filter unit includes a second resistor R2 and a first capacitor C1;

[0043] The first end of the second resistor R2 is respectively connected to the current sensing interface of the power module and the first end of the first resistor R1, the second end of the second resistor R2 is connected to the first input interface of the comparator U1, the first end of the first capacitor C1 is connected to the second end of the second resistor R2, and the second end of the first capacitor C1 is grounded.

[0044] It can be understood that, through the configuration of the above-mentioned filtering unit, the voltage output by the voltage sensing unit can be filtered to avoid false triggering.

[0045] Further, the MOS transistor Q1 is an N-channel MOS transistor, the first input interface of the comparator U1 is a negative input interface, and the second input interface of the comparator U1 is a positive input interface;

[0046] The drain D of the MOS transistor Q1 is connected to the desaturation protection interface Desat of the driving chip U2 , the source S of the MOS transistor Q1 is grounded, and the output interface Out of the comparator U1 is connected to the gate G of the MOS transistor Q1 .

[0047] Specifically, the MOS transistor Q1 can be an N-channel MOS transistor. For the N-channel MOS transistor, its gate G serves as a control terminal. When the gate G receives a high level, the MOS transistor will be turned on, and when the gate G receives a low level, the MOS transistor will be turned off. The first input interface of the comparator U1 is a negative input interface, and the second input interface is a positive input interface. When the voltage of the positive input interface is greater than the voltage of the negative input interface, the output interface Out of the comparator U1 will output a high level; when the voltage of the positive input interface is less than the voltage of the negative input interface, the output interface Out of the comparator U1 will output a low level. Therefore, when the detection voltage of the negative input interface of the comparator U1 is greater than the reference voltage of the positive input interface, the output interface Out of the comparator U1 outputs a low level to the gate G of the MOS transistor Q1, so that the MOS transistor Q1 is turned off.

[0048] Further, the reference power supply unit includes a reference power supply terminal Vin, a third resistor R3, a fourth resistor R4 and a second capacitor C2;

[0049] A first end of the third resistor R3 is connected to the reference power supply terminal Vin, and a second end of the third resistor R3 is connected to the fourth resistor R4;

[0050] The first end of the fourth resistor R4 is connected to the positive input interface of the comparator U1 and the second end of the third resistor R3 respectively, and the second end of the fourth resistor R4 is grounded;

[0051] The first end of the second capacitor C2 is connected to the positive input interface of the comparator U1 and the first end of the fourth resistor R4 respectively, and the second end of the second capacitor C2 is grounded;

[0052] The external voltage interface Vcc of the comparator U1 is connected to the reference power supply terminal Vin, and the ground interface Gnd of the comparator U1 is grounded.

[0053] In implementation, through the above connection mode, the third resistor R3 and the fourth resistor R4 divide the voltage of the reference power supply terminal Vin to form a reference voltage input to the positive input interface of the comparator U1, and the second capacitor C2 stabilizes the reference voltage. When the voltage of the positive input interface is greater than the voltage of the negative input interface, the output interface Out of the comparator U1 will output a high level that is the same as the voltage of the reference power supply terminal Vin; when the voltage of the positive input interface is less than the voltage of the negative input interface, the output interface Out of the comparator U1 will output a low level that is the same as the ground.

[0054] Preferably, a fifth resistor R5 is connected between the output interface Out of the comparator and the control end of the MOS tube Q1, a first end of the fifth resistor R4 is connected to the output interface Out of the comparator U1, and a second end of the fifth resistor R5 is connected to the control end of the MOS tube Q1.

[0055] Preferably, a sixth resistor R6 is connected between the driving power supply terminal Vcc1 and the first end of the MOS transistor Q1 , a first end of the sixth resistor R6 is connected to the driving power supply terminal Vcc1 , and a second end of the sixth resistor R6 is connected to the first end of the MOS transistor Q1 .

[0056] Preferably, a third capacitor C3 is also connected between the driving power supply terminal Vcc1 and the desaturation protection interface Desat of the driving chip U2, the first end of the third capacitor C3 is respectively connected to the driving power supply terminal Vcc1 and the desaturation protection interface Desat of the driving chip U2, and the second end of the third capacitor C3 is grounded.

[0057] Compared with the prior art, the above technical solution has the following beneficial effects: by triggering the desaturation protection function of the driver chip U2 through the signal of the current sensing interface of the power module, the overcurrent protection of the power module can be quickly realized.

[0058] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An overcurrent protection circuit for a power module, characterized in that: It includes a voltage sensing unit, a comparator, a MOS tube, a driver chip, a reference power supply unit, and a driver power supply terminal; The voltage sensing unit comprises a current sensing interface of the power module and a first resistor, wherein a first end of the first resistor is respectively connected to the current sensing interface of the power module and a first input interface of the comparator, and a second end of the first resistor is grounded; The second input interface of the comparator is connected to the reference power supply unit, and the output interface of the comparator is connected to the control end of the MOS tube; The first end of the MOS tube is connected to the desaturation protection interface of the driving chip, and the second end of the MOS tube is grounded; The driving power supply end is respectively connected to the desaturation protection interface of the driving chip and the first end of the MOS tube; the comparator is used to control the MOS tube to be cut off when the voltage received by its first input interface is greater than the voltage received by its second input interface, so that the driving power supply end supplies power to the desaturation protection interface of the driving chip.

2. The overcurrent protection circuit according to claim 1, characterized in that: The current sensing interface of the power module is a current mirror interface of the power module.

3. The overcurrent protection circuit according to claim 1, characterized in that: A filter unit is further connected between the first input interface of the comparator and the voltage sensing unit, and the filter unit includes a second resistor and a first capacitor; The first end of the second resistor is respectively connected to the current sensing interface of the power module and the first end of the first resistor, the second end of the second resistor is connected to the first input interface of the comparator, the first end of the first capacitor is connected to the second end of the second resistor, and the second end of the first capacitor is grounded.

4. The overcurrent protection circuit according to claim 1, characterized in that: The MOS tube is an N-channel MOS tube, the first input interface of the comparator is a negative input interface, and the second input interface of the comparator is a positive input interface; the drain of the MOS tube is connected to the desaturation protection interface of the driving chip, the source of the MOS tube is grounded, and the output interface of the comparator is connected to the gate of the MOS tube.

5. The overcurrent protection circuit according to claim 4, characterized in that: The reference power supply unit includes a reference power supply terminal, a third resistor, a fourth resistor and a second capacitor; A first end of the third resistor is connected to the reference power supply end, and a second end of the third resistor is connected to the fourth resistor; The first end of the fourth resistor is connected to the positive input interface of the comparator and the second end of the third resistor respectively, and the second end of the fourth resistor is grounded; The first end of the second capacitor is connected to the positive input interface of the comparator and the first end of the fourth resistor respectively, and the second end of the second capacitor is grounded; The external voltage interface of the comparator is connected to the reference power supply terminal, and the ground interface of the comparator is grounded.

6. The overcurrent protection circuit according to claim 1, characterized in that: A fifth resistor is also connected between the output interface of the comparator and the control end of the MOS tube, a first end of the fifth resistor is connected to the output interface of the comparator, and a second end of the fifth resistor is connected to the control end of the MOS tube.

7. The overcurrent protection circuit according to claim 1, characterized in that: A sixth resistor is also connected between the driving power supply end and the first end of the MOS tube, the first end of the sixth resistor is connected to the driving power supply end, and the second end of the sixth resistor is connected to the first end of the MOS tube.

8. The overcurrent protection circuit according to claim 1, characterized in that: A third capacitor is also connected between the driving power supply end and the desaturation protection interface of the driving chip, a first end of the third capacitor is respectively connected to the driving power supply end and the desaturation protection interface of the driving chip, and a second end of the third capacitor is grounded.

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