CN217903998U - Short-circuit protection circuit, inverter and motor assembly - Google Patents

Abstract

The utility model discloses a short-circuit protection circuit, dc-to-ac converter and motor element, this short-circuit protection circuit includes: the detection end of the short circuit trigger circuit is connected with the output end of the power switch tube, and the first charging end of the short circuit trigger circuit is connected with a charging current source; the short circuit trigger circuit is used for connecting a charging current source to charge when detecting that the power switch tube is short-circuited and outputting a short circuit trigger signal when the charging is saturated; the voltage lifting circuit is connected with the output end of the short circuit trigger circuit and is used for lifting the voltage value of the output end of the short circuit trigger circuit; and the input end of the short-circuit control circuit is connected with the output end of the short-circuit trigger circuit, and the short-circuit control circuit can output a switch control signal to control the turn-off of the power switch tube when receiving a short-circuit trigger signal. The utility model discloses can solve the lower problem of current protection point that current short-circuit protection circuit triggered.

Description

Short-circuit protection circuit, inverter and motor assembly

Technical Field

The utility model relates to a short-circuit protection technical field, in particular to short-circuit protection circuit, dc-to-ac converter and motor element.

Background

At present, power conversion equipment is widely applied to the field of electric automobiles, and the Sic Mosfet is used as a core device of the energy conversion equipment, so that the drive protection technology of the Sic Mosfet is very critical. In the prior art, a Desat circuit is commonly used for short-circuit protection of an IGBT (Insulated Gate Bipolar Transistor). However, the Desat protection circuit applied to the IGBT has defects in the aspect of compatibility with Sic mosfet protection, such as long trigger time, low triggered current protection point, and the like, so that the Sic mosfet short-circuit protection technology applied to the field of electric vehicles is a great difficulty.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a short-circuit protection circuit aims at solving the lower problem of current protection point that current short-circuit protection circuit triggered.

In order to achieve the above object, the present invention provides a short-circuit protection circuit, including:

the short circuit trigger circuit is provided with a detection end and a first charging end, the detection end of the short circuit trigger circuit is connected with the output end of the power switch tube, and the first charging end of the short circuit trigger circuit is connected with a charging current source;

the short circuit trigger circuit is used for connecting a power supply and a charging current source to charge when detecting that the power switch tube is short-circuited, and outputting a short circuit trigger signal when the charging is saturated;

the voltage lifting circuit is connected with the output end of the short circuit trigger circuit and is used for lifting the voltage value of the output end of the short circuit trigger circuit;

and the input end of the short-circuit control circuit is connected with the output end of the short-circuit trigger circuit, and the short-circuit control circuit can output a switch control signal to control the turn-off of the power switch tube when receiving the short-circuit trigger signal.

Optionally, the short circuit trigger circuit further has a second charging terminal;

the short-circuit protection circuit further comprises a pull-up charging circuit, wherein the input end of the pull-up charging circuit is used for being connected with a power supply, and the output end of the pull-up charging circuit is connected with the second charging end of the short-circuit trigger circuit;

the short circuit trigger circuit is also used for connecting a power supply and a charging current source to charge when detecting that the power switch tube is short-circuited, and outputting a short circuit trigger signal when the charging is saturated.

Optionally, the short circuit trigger circuit comprises:

the detection circuit is used for outputting a short-circuit detection signal when the short circuit of the power switching tube is detected;

the input end of the blanking circuit is connected with the output end of the detection circuit, the output end of the blanking circuit is connected with the input end of the short-circuit control circuit, the second charging end of the blanking circuit is connected with the output end of the pull-up charging circuit, and the first charging end of the blanking circuit is connected with a charging current source;

and the blanking circuit is used for blanking the short-circuit detection signal and outputting a short-circuit trigger signal to the short-circuit control circuit when receiving the short-circuit detection signal.

Optionally, the pull-up charging circuit includes a second resistor, a first end of the second resistor is connected to the power supply, and a second end of the second resistor is an output end of the pull-up charging circuit.

Optionally, the short-circuit protection circuit further comprises:

and the receiving end of the main controller is connected with the output end of the short-circuit control circuit, the control end of the main controller is connected with the power switch tube in a controlled manner, and the main controller is used for controlling the power switch tube to be switched off according to the switch control signal.

Optionally, the main controller and the comparator are integrated in the same integrated chip.

Optionally, the short circuit trigger circuit includes a first resistor, a first capacitor, and a diode, a cathode of the diode is a detection end of the short circuit trigger circuit, an anode of the diode is connected to a first end of the first resistor, a second end of the first resistor is connected to a first end of the first capacitor, a second end of the first capacitor is grounded, a common end of the first resistor and the first capacitor is an output end and a first charging end of the short circuit trigger circuit, and a common end of the first resistor and the diode is a second charging end of the short circuit trigger circuit.

Optionally, the short-circuit control circuit includes a comparator and a reference voltage source, a first input end of the comparator is connected to a positive terminal of the reference voltage source, a negative terminal of the reference voltage source is grounded, a second input end of the comparator is connected to an output end of the short-circuit trigger circuit, and an output end of the comparator is an output end of the short-circuit control circuit.

The utility model also provides an inverter, the inverter comprises a power switch tube and the short-circuit protection circuit; wherein the content of the first and second substances,

the detection end of the short-circuit protection circuit is connected with the output end of the power switch tube, and the output end of the short-circuit protection circuit is connected with the controlled end of the power switch tube.

The utility model discloses still provide a motor element, motor element includes motor and foretell dc-to-ac converter.

The utility model discloses technical scheme is through setting up short circuit trigger circuit, short circuit control circuit and pull-up charging circuit, and short circuit trigger circuit is used for detecting power switch tube's state to can insert charging current source and pull-up charging circuit when detecting power switch tube short circuit, in order to charge. And when the charging is saturated, a short circuit detection signal is output to the short circuit control circuit, so that the short circuit control circuit outputs a switch control signal when receiving the short circuit detection signal to control the power switch tube to be switched off, thereby realizing the short circuit protection of the power switch tube. The utility model discloses an extra configuration increases to pull up charging circuit and charges to short circuit trigger circuit in step to can increase the speed of charging to short circuit trigger circuit, reduce the time delay that charges, improve short-circuit protection's quick response ability, improve the reaction rate and the compatibility of insuring with detection circuitry, solve the longer problem of current short-circuit protection circuit triggering time.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic diagram of functional modules of an embodiment of the short-circuit protection circuit of the present invention;

FIG. 2 is a schematic diagram of a short-circuit protection circuit in the prior art;

fig. 3 is a schematic circuit diagram of an embodiment of the short-circuit protection circuit of the present invention.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				10	Pull-up charging circuit	I1	Charging current source
20	Short circuit trigger circuit	Vref	Reference voltage source
				30	Short circuit control circuit	D1	Diode with a high-voltage source
40	Voltage boosting circuit	C1	First capacitor
				50	Main controller	R1～R3	First to third resistors
U1	Comparator with a comparator circuit

The objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person skilled in the art without making creative efforts belong to the protection scope of the present invention.

It should be noted that, if directional indications (such as up, down, left, right, front, back, 8230; \8230;) are provided in the embodiments of the present invention, the directional indications are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the attached drawings), and if the specific posture is changed, the directional indications are correspondingly changed.

In addition, if there is a description relating to "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

The utility model provides a short-circuit protection circuit is applied to in the dc-to-ac converter, the dc-to-ac converter includes the power switch pipe.

At present, power conversion equipment is widely applied to the field of electric automobiles, and Sic mosfets are used as core devices of energy conversion equipment, and the driving protection technology of the Sic mosfets is very critical. In the prior art, a Desat circuit is commonly used for short-circuit protection of an IGBT (Insulated Gate Bipolar Transistor). However, the Desat protection circuit applied to the IGBT has defects in the aspect of compatibility with Sic mosfet protection, such as long trigger time, low trigger current protection point, and the like, so that the Sic mosfet short-circuit protection technology applied to the field of electric vehicles is a big difficulty.

As shown in fig. 2, fig. 2 is a schematic circuit structure diagram of a Desat short-circuit protection circuit in the prior art, where the Desat short-circuit protection circuit includes a high-voltage diode D1, a Desat blanking capacitor C1, a current-limiting resistor R1, a charging current source I1, a reference voltage source Vref, and a comparator U1. The high voltage diode D1, the Desat blanking capacitor C1, and the current limiting resistor R1 form a short circuit trigger circuit 20, and the comparator U1 and the reference voltage source Vref form a short circuit control circuit 30. Desat short-circuit protection circuit among the prior art mainly utilizes and withdraws from the saturation region when IGBT short-circuit fault, and IGBT's collection and emission pole voltage increases rapidly to lead to high voltage diode D1 to block, at this moment, charging current source I1 charges to comparator U1's detection threshold value to Desat blanking electric capacity C1, makes comparator U1 take place to overturn the back output low level to the controller, and by controller control IGBT turn-offs, realizes short-circuit protection. However, in the prior art, in order to implement express short-circuit protection, the threshold value Vref of the short-circuit protection Desat applied to Sic mosfet is usually low, so that the charging duration of the short-circuit trigger circuit 20 is shortened, and the quick response of short-circuit protection is implemented. When the class II short-circuit protection is triggered, the voltage at the two ends of the first capacitor C1 is close to Vref, the voltage on the resistor R1 and the conduction voltage drop on the diode D1 are considered to be removed, the voltage on the actual drain-source electrode can follow the Vref, the Vref value is low, the drain-source electrode voltage is low, and the current of the actual protection point can be low according to the linear characteristic of mosfet. When the motor is applied to the field of electric automobiles, when the motor executes ASC, the transient peak current is lower than the current of the protection point, so that Desat short-circuit protection is triggered during the ASC execution, the Sic mosfet is shut down to quit the ASC instruction, the ASC safety shut-off path is cut off, so that Desat protection is triggered during the ASC execution to shut down to quit the ASC instruction, and the ASC instruction cannot be completed or even the equipment is damaged.

To solve the above problem, referring to fig. 1 to 3, in an embodiment, the short-circuit protection circuit includes:

the short-circuit trigger circuit 20 is provided with a detection end and a first charging end, the detection end of the short-circuit trigger circuit 20 is connected with the output end of the power switch tube, and the first charging end of the short-circuit trigger circuit 20 is connected with a charging current source;

the short circuit trigger circuit 20 is configured to switch in a charging current source to charge when detecting that the power switching tube is short-circuited, and output a short circuit trigger signal when the charging is saturated;

and the voltage boost circuit 40, the voltage boost circuit 40 is connected with the output end of the short-circuit trigger circuit 20, and the voltage boost circuit 40 is used for boosting the voltage value of the output end of the short-circuit trigger circuit 20.

And the input end of the short-circuit control circuit 30 is connected with the output end of the short-circuit trigger circuit 20, and the short-circuit control circuit 30 can output a switch control signal to control the power switch tube to be switched off when receiving the short-circuit trigger signal.

In the present embodiment, the short protection circuit includes a short trigger circuit 20, a short control circuit 30 and a voltage boost circuit 40. The short circuit trigger circuit 20 and the short circuit control circuit 30 may be implemented by selecting the short circuit trigger circuit 20 and the short circuit control circuit 30 in the existing Desat short circuit protection circuit, or may be implemented by using other circuits having the same function. The voltage boost circuit 40 may be implemented by a voltage dividing resistor, a voltage stabilizing diode or other devices.

Specifically, the short circuit trigger circuit 20 and the short circuit control circuit 30 may be implemented by using the short circuit trigger circuit 20 and the short circuit control circuit 30 in the existing Desat short circuit protection circuit, when the power switch tube is out of the saturation region due to a short circuit fault, the voltage at the output end of the power switch tube is rapidly increased, when the voltage at the output end of the power switch tube is increased to the detection threshold of the short circuit trigger circuit 20, that is, when the short circuit trigger circuit 20 detects a short circuit of the power switch tube, the short circuit trigger circuit 20 connects the charging current source I1 for charging, and when the charging is saturated, outputs a short circuit trigger signal. The short circuit trigger circuit 20 may be configured to output the short circuit trigger signal when the charging reaches a preset threshold, and the short circuit trigger signal does not need to be output until the charging is saturated. When the short circuit control circuit 30 receives the short circuit trigger signal, the short circuit control circuit 30 outputs a switch control signal to control the power switch tube to be turned off. The switch control signal can be directly output to the power switch tube to realize direct control of the power switch tube, and also can be output to the drive controller of the power switch tube, so that the drive controller of the power switch tube controls the power switch tube to be switched off according to the switch control signal to realize short-circuit protection.

Further, on the basis of the short circuit trigger circuit 20 and the short circuit control circuit 30, a voltage boost circuit 40 is additionally arranged, so that a corresponding protection current point is raised. Preferably, the voltage boost circuit 40 can be implemented by selecting at least one voltage dividing resistor, as shown in fig. 3, fig. 3 is a schematic circuit structure diagram of an embodiment of the invention, wherein the third resistor R3 is the voltage boost circuit 40 in this embodiment. The utility model discloses in increased voltage lifting circuit 40, with short-circuit trigger circuit 20's detection threshold value through third resistance R3, first resistance R1 back that steps up, first resistance R1 right side electric potential is raised, considers diode D1 and switches on the voltage drop after, and the voltage of power switch tube output end is raised for the protection current point that corresponds is raised. Furthermore, the corresponding protection current point can be adjusted to be higher than the ASC transient current value by adjusting the resistance value of the voltage boost circuit 40, so that the situation that the power switch tube is turned off and withdrawn due to the fact that the short-circuit protection is triggered by mistake when the ASC is executed can be avoided, and the safety and the practicability of the short-circuit protection circuit are improved. In addition, the Vref value can be further reduced, and the voltage division is performed by the voltage lifting circuit 40, so that the corresponding protection current point is raised to be higher than the ASC transient current value, the Vref value is reduced, the ASC can be prevented from being executed, the short-circuit protection is triggered by mistake, the reaction speed of the short-circuit protection circuit can be further increased, the short-circuit protection is completed by quick response, and the reaction speed and the practicability of the short-circuit protection circuit are improved.

The utility model discloses a set up short circuit trigger circuit 20, short circuit control circuit 30 and voltage lifting circuit 40, short circuit trigger circuit 20 is used for detecting power switch tube's state to can insert charging current source I1 in order to charge when detecting power switch tube short circuit. And when the charging is saturated, a short circuit detection signal is output to the short circuit control circuit 30, so that the short circuit control circuit 30 outputs a switch control signal when receiving the short circuit detection signal, so as to control the power switch tube to be switched off, thereby realizing the short circuit protection of the power switch tube. The utility model discloses an extra configuration increases voltage lifting circuit 40 and carries out the partial pressure for corresponding protection current point is raised to being higher than ASC transient current value, reduces Vref value and can also prevent to carry out the short-circuit protection of mistake triggering when ASC, and can further improve short-circuit protection circuit's reaction rate, and short-circuit protection is accomplished to quick response, has improved short-circuit protection circuit's reaction rate and practicality.

Referring to fig. 1 to 3, in an embodiment, the short trigger circuit 20 further has a second charging terminal;

the short-circuit protection circuit further comprises a pull-up charging circuit 10, wherein an input end of the pull-up charging circuit 10 is used for accessing a power supply, and an output end of the pull-up charging circuit 10 is connected with a second charging end of the short-circuit trigger circuit 20;

the short circuit trigger circuit 20 is configured to switch in a power supply and a charging current source for charging when detecting that the power switch tube is short-circuited, and output a short circuit trigger signal when the charging is saturated.

Desat short-circuit protection circuit among the prior art mainly utilizes and withdraws from the saturation region when IGBT short-circuit fault, and IGBT's collection and emission pole voltage increases rapidly to lead to high voltage diode D1 to block, at this moment, charging current source I1 charges to comparator U1's detection threshold value to Desat blanking electric capacity C1, makes comparator U1 take place to overturn the back output low level to the controller, and by controller control IGBT turn-offs, realizes short-circuit protection. However, the existing Desat short-circuit protection circuit has a defect when applied to Sic mosfet protection, and the charging time of the Desat short-circuit protection circuit needs to be set to be shorter because the short-circuit tolerance time of Sic mosfet is shorter.

In order to solve the above problem, in this embodiment, a pull-up charging circuit 10 is added on the basis of the short-circuit trigger circuit 20 and the short-circuit control circuit 30, when the short-circuit trigger circuit 20 detects a short circuit of the power switch, the short-circuit trigger circuit 20 is connected to the charging current source I1 for charging, and meanwhile, the short-circuit trigger circuit 20 is also connected to the pull-up charging circuit 10, so that the power supply charges the short-circuit trigger circuit 20 through the pull-up charging circuit 10, so that the short-circuit trigger circuit 20 is charged quickly, the short-circuit trigger circuit 20 reaches charging saturation quickly, and a short-circuit trigger signal is output to the short-circuit control circuit 30, thereby implementing short-circuit protection. The utility model discloses an extra configuration increases to pull up charging circuit 10 and charges in step to short circuit trigger circuit 20 to can increase the speed of charging to short circuit trigger circuit 20, reduce the time delay of charging, improve short-circuit protection's quick response ability, thereby can realize the quick short-circuit protection to switching elements such as Sic mosfet, improve the reaction rate and the compatibility of withdrawing from the insurance and detection circuitry.

Referring to fig. 1 to 3, in an embodiment, the short circuit trigger circuit 20 includes:

the detection circuit is used for outputting a short-circuit detection signal when the short circuit of the power switching tube is detected;

a blanking circuit, an input end of which is connected with an output end of the detection circuit, an output end of which is connected with an input end of the short circuit control circuit 30, a second charging end of which is connected with an output end of the pull-up charging circuit 10, and a first charging end of which is connected with a charging current source;

the blanking circuit is configured to blank the short-circuit detection signal when receiving the short-circuit detection signal, and output a short-circuit trigger signal to the short-circuit control circuit 30.

It can be understood that, in practical applications, since a certain time is required for the power switch tube, for example, the SiC MOSFET to be turned on, a certain time is required for the drain-source voltage of the SiC MOSFET to drop, so as to prevent the short-circuit protection from being triggered by mistake in the turn-on stage of the SiC MOSFET. Therefore, in the present embodiment, the short-circuit trigger circuit 20 is provided with a detection circuit and a blanking circuit, and the blanking circuit can adjust the blanking time of the short-circuit protection, so that the protection is not performed within the blanking time, thereby effectively preventing the false protection. The detection circuit can be realized by a diode, when the power switch tube is in short circuit fault, the power switch tube exits from a saturation region, the voltage at the output end of the power switch tube is rapidly increased, when the voltage at the output end of the power switch tube is increased to the detection threshold value of the short circuit trigger circuit 20, the diode is blocked, and at the moment, a short circuit detection signal is output. The blanking circuit can be realized by a blanking capacitor, the blanking capacitor C1 is arranged at the output end of the detection circuit, the blanking time of short-circuit protection can be adjusted by adjusting the capacitance value of the blanking capacitor C1 under the energy storage effect of the blanking capacitor C1, and the protection is not carried out in the blanking time, so that the error protection is effectively prevented.

Referring to fig. 1 to 3, in an embodiment, the pull-up charging circuit 10 includes a second resistor R2, a first end of the second resistor R2 is connected to the power supply, and a second end of the second resistor R2 is an output end of the pull-up charging circuit 10.

In this embodiment, the pull-up charging circuit 10 is as shown in fig. 3, and fig. 3 is the circuit structure diagram of an embodiment of the disclosure, the pull-up charging circuit 10 is composed of a power supply and a second resistor R2, wherein the power supply may be a power supply in an inverter, or a power supply specially used for short-circuit protection. Quit the saturation region when power switch tube short circuit fault, the voltage of power switch tube output end increases rapidly, when the voltage of power switch tube output end increases to short circuit trigger circuit 20's detection threshold value, diode D1 blocks, when short circuit trigger circuit 20 detected the power switch tube short circuit promptly, power supply charges first electric capacity C1 simultaneously through second resistance R2 and charging current source I1 for the voltage value of first electric capacity C1 reaches preset threshold value fast, thereby output short circuit detection signal to short circuit control circuit 30. The resistance value of the second resistor R2 can be set according to implementation requirements, so that the charging speed of the power supply to the first capacitor C1 is adjusted, and the trigger value of the corresponding protection current point can be adjusted.

Referring to fig. 1 to 3, in an embodiment, the short-circuit protection circuit further includes:

and a receiving end of the main controller 50 is connected with an output end of the short circuit control circuit 30, a control end of the main controller 50 is connected with the power switch tube in a controlled manner, and the main controller 50 is used for controlling the power switch tube to be switched off according to the switch control signal.

In this embodiment, the short-circuit protection circuit further includes a main controller 50, and when the short-circuit control circuit 30 receives the short-circuit trigger signal, it outputs a switch control signal to the main controller 50, so that the main controller 50 controls the power switch to be turned off, so as to implement short-circuit protection. Main control unit 50 can choose for use control chip such as MCU, FPGA to realize, and main control unit 50 can be the controller of drive power switch tube action in the dc-to-ac converter, also can the utility model discloses additionally set up the controller that is used for realizing short-circuit protection specially.

Further, the main controller 50 and the comparator are integrated in the same integrated chip.

In this embodiment, the comparator and the main controller 50 may also be integrated in the same integrated chip, that is, the short trigger circuit 20 outputs the short detection signal to the integrated chip, so that the process of comparing the reference voltage is completed inside the integrated chip, and the power switch tube is controlled to operate according to the comparison result after the comparison is completed. So set up, can save the area of circuit board, and then reduce the whole volume of dc-to-ac converter, reduce the manufacturing cost of equipment.

Referring to fig. 1 to 3, in an embodiment, the short circuit trigger circuit 20 includes a first resistor R1, a first capacitor C1 and a diode D1, a cathode of the diode D1 is a detection terminal of the short circuit trigger circuit 20, an anode of the diode D1 is connected to a first terminal of the first resistor R1, a second terminal of the first resistor R1 is connected to a first terminal of the first capacitor C1, a second terminal of the first capacitor C1 is grounded, a common terminal of the first resistor R1 and the first capacitor C1 is an output terminal and a first charging terminal of the short circuit trigger circuit 20, and a common terminal of the first resistor R1 and the diode D1 is a second charging terminal of the short circuit trigger circuit 20.

In this embodiment, the short circuit trigger circuit 20 is as shown in fig. 3, and fig. 3 is a schematic circuit structure diagram of an embodiment of the disclosure, wherein the first resistor R1 is a current limiting resistor, and can play a role of current limiting protection. The cathode of the diode D1 is a detection end of the short circuit trigger circuit 20, and exits from a saturation region when the power switch tube has a short circuit fault, the voltage at the output end of the power switch tube increases rapidly, and when the voltage at the output end of the power switch tube increases to a detection threshold of the short circuit trigger circuit 20, the diode D1 is blocked, that is, when the short circuit trigger circuit 20 detects a short circuit of the power switch tube, the charging current source I1 charges the first capacitor C1, and when the voltage value of the first capacitor C1 reaches a preset threshold, outputs a short circuit detection signal to the short circuit control circuit 30. The capacitance value of the first capacitor C1 may be set according to a preset threshold, for example, the first capacitor C1 whose voltage just reaches the preset threshold when fully charged may be selected, or the first capacitor C1 whose voltage is slightly greater than the preset threshold when fully charged may be implemented. In addition, the first capacitor C1 may be a blanking capacitor C1, and the blanking time of the short-circuit protection may be adjusted by adjusting the capacitance value of the blanking capacitor C1 through the energy storage function of the blanking capacitor C1, and the protection is not performed within the blanking time, thereby effectively preventing the false protection.

Referring to fig. 1 to 3, in an embodiment, the short circuit control circuit 30 includes a comparator U1 and a reference voltage source Vref, a first input terminal of the comparator U1 is connected to a positive terminal of the reference voltage source Vref, a negative terminal of the reference voltage source Vref is grounded, a second input terminal of the comparator U1 is connected to an output terminal of the short circuit trigger circuit 20, and an output terminal of the comparator U1 is an output terminal of the short circuit control circuit 30.

In this embodiment, short circuit control circuit 30 is as shown in fig. 3, and fig. 3 is the circuit structure schematic diagram of an embodiment of the present invention, short circuit control circuit 30 is composed of comparator U1 and reference voltage source Vref, wherein, reference voltage source Vref is connected with the first input terminal of comparator U1 as the reference voltage, and the second input terminal of comparator U1 is connected with the output terminal of short circuit trigger circuit 20. When the short circuit trigger circuit 20 outputs the short circuit detection signal, that is, when the voltage value of the second input terminal of the comparator U1 is greater than the reference voltage value of the reference voltage source Vref, the comparator U1 outputs a low-level switch control signal to the main controller 50, so that the main controller 50 controls the power switch tube to be turned off according to the switch control signal, thereby implementing short circuit protection.

The utility model also provides an inverter, this inverter include main control unit 50, power switch pipe and foretell short-circuit protection circuit, and this short-circuit protection circuit's concrete structure refers to above-mentioned embodiment, because this inverter has adopted the whole technical scheme of above-mentioned all embodiments, consequently has all beneficial effects that the technical scheme of above-mentioned embodiment brought at least, and the repeated description is no longer given here. Wherein the content of the first and second substances,

the detection end of the short-circuit protection circuit is connected with the output end of the power switch tube, and the output end of the short-circuit protection circuit is connected with the controlled end of the power switch tube.

In this embodiment, the power switch may be an IGBT or an SiC MOSFET, and the power switch is preferably an SiC MOSFET, and since the SiC MOSFET only relies on electrons for conducting, the electrons may be quickly pumped away when the SiC MOSFET is turned off, there is no trailing current, and the turn-off loss is smaller and does not substantially change with temperature. The SiC MOSFET is selected as the power switch tube, so that the device loss can be reduced, the system efficiency is improved, and the power switch tube is more suitable for being applied to the inverter in the embodiment.

The utility model discloses still provide a motor element, this motor element includes motor and foretell dc-to-ac converter, and the concrete structure of this dc-to-ac converter refers to above-mentioned embodiment, because this motor element has adopted the whole technical scheme of all above-mentioned embodiments, consequently has all beneficial effects that the technical scheme of above-mentioned embodiment brought at least, gives unnecessary detail here one by one.

The above only is the preferred embodiment of the present invention, not so limiting the patent scope of the present invention, all under the inventive concept of the present invention, the equivalent structure transformation made by the contents of the specification and the drawings is utilized, or the direct/indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims (10)

1. A short-circuit protection circuit is applied to an inverter, the inverter comprises a power switch tube, and the short-circuit protection circuit is characterized by comprising:

the short circuit trigger circuit is provided with a detection end and a first charging end, the detection end of the short circuit trigger circuit is connected with the output end of the power switch tube, and the first charging end of the short circuit trigger circuit is connected with a charging current source;

the short circuit trigger circuit is used for connecting a charging current source to charge when detecting that the power switch tube is short-circuited, and outputting a short circuit trigger signal when the charging is saturated;

the voltage lifting circuit is connected with the output end of the short circuit trigger circuit and is used for lifting the voltage value of the output end of the short circuit trigger circuit;

and the input end of the short-circuit control circuit is connected with the output end of the short-circuit trigger circuit, and the short-circuit control circuit can output a switch control signal to control the turn-off of the power switch tube when receiving the short-circuit trigger signal.

2. The short-circuit protection circuit of claim 1, wherein the short-circuit trigger circuit further has a second charging terminal;

the short-circuit protection circuit further comprises a pull-up charging circuit, wherein the input end of the pull-up charging circuit is used for being connected with a power supply, and the output end of the pull-up charging circuit is connected with the second charging end of the short-circuit trigger circuit;

the short circuit trigger circuit is also used for connecting a power supply and a charging current source to charge when detecting that the power switch tube is short-circuited, and outputting a short circuit trigger signal when the charging is saturated.

3. The short-circuit protection circuit of claim 2, wherein the short-circuit trigger circuit comprises:

the detection circuit is used for outputting a short-circuit detection signal when the short circuit of the power switching tube is detected;

the input end of the blanking circuit is connected with the output end of the detection circuit, the output end of the blanking circuit is connected with the input end of the short-circuit control circuit, the second charging end of the blanking circuit is connected with the output end of the pull-up charging circuit, and the first charging end of the blanking circuit is connected with a charging current source;

and the blanking circuit is used for blanking the short-circuit detection signal and outputting a short-circuit trigger signal to the short-circuit control circuit when receiving the short-circuit detection signal.

4. The short-circuit protection circuit of claim 2, wherein the pull-up charging circuit comprises a second resistor, a first terminal of the second resistor being connected to the power supply, and a second terminal of the second resistor being an output terminal of the pull-up charging circuit.

5. The short-circuit protection circuit of claim 1, further comprising:

and the receiving end of the main controller is connected with the output end of the short-circuit control circuit, the control end of the main controller is connected with the power switch tube in a controlled manner, and the main controller is used for controlling the power switch tube to be switched off according to the switch control signal.

6. The short-circuit protection circuit according to claim 5, wherein the short-circuit control circuit comprises a comparator and a reference voltage source, a first input terminal of the comparator is connected with a positive terminal of the reference voltage source, a negative terminal of the reference voltage source is grounded, a second input terminal of the comparator is connected with an output terminal of the short-circuit trigger circuit, and an output terminal of the comparator is an output terminal of the short-circuit control circuit;

the main controller and the comparator are integrated in the same integrated chip.

7. The short-circuit protection circuit of claim 1, wherein the short-circuit trigger circuit comprises a first resistor, a first capacitor and a diode, a cathode of the diode is a detection terminal of the short-circuit trigger circuit, an anode of the diode is connected to a first terminal of the first resistor, a second terminal of the first resistor is connected to a first terminal of the first capacitor, a second terminal of the first capacitor is grounded, a common terminal of the first resistor and the first capacitor is an output terminal and a first charging terminal of the short-circuit trigger circuit, and a common terminal of the first resistor and the diode is a second charging terminal of the short-circuit trigger circuit.

8. The short-circuit protection circuit according to claim 1, wherein the short-circuit control circuit comprises a comparator and a reference voltage source, a first input terminal of the comparator is connected with a positive terminal of the reference voltage source, a negative terminal of the reference voltage source is grounded, a second input terminal of the comparator is connected with an output terminal of the short-circuit trigger circuit, and an output terminal of the comparator is an output terminal of the short-circuit control circuit.

9. An inverter, characterized by comprising a power switching tube and a short-circuit protection circuit according to any one of claims 1 to 8; wherein the content of the first and second substances,

the detection end of the short-circuit protection circuit is connected with the output end of the power switch tube, and the output end of the short-circuit protection circuit is connected with the controlled end of the power switch tube.

10. An electric motor assembly comprising an electric motor and the inverter of claim 9.

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