Variable short circuit protection device based on SIC MOS tube driving and monitoring circuit

Abstract

A variable short-circuit protection device based on an SIC MOS tube driving and monitoring circuit comprises an SIC MOS tube driving and monitoring unit, a resistance sampling unit and a power distribution SIC MOS tube unit, and monitoring of high-voltage power current flowing through after a power distribution SIC MOS tube is connected and short-circuit protection are achieved by monitoring the voltage at the two ends of the resistance sampling unit and the power distribution SIC MOS tube unit. Meanwhile, different resistors are connected into a short-circuit protection loop by controlling access switches of the resistors in the switching resistor sampling unit, and flexible change of short-circuit protection points is achieved. According to the method, different short-circuit protection points can be set according to different load short-circuit protection requirements, and short-circuit protection on the load is accurately implemented.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage power distribution short-circuit protection for special vehicle integrated power systems, and in particular to a variable short-circuit protection device based on a SIC MOS tube drive and monitoring circuit. Background Art

[0002] With the vigorous development and widespread application of vehicle motor drive technology, the development of electric drive special vehicles is also accelerating. Different from traditional vehicles, the internal electrical equipment of electric drive vehicles is mainly motor drive equipment. The power of this type of load is larger than that of traditional drive forms, so electric drive vehicles mostly use high-voltage power grid to provide energy supply. Therefore, in the process of power supply and distribution of high-voltage power grid, reliable power distribution protection has become an indispensable and important guarantee for the operation of electric drive vehicles.

[0003] In order to ensure the safety of vehicle operation, prevent equipment short-circuit failures during the power distribution process of the high-voltage power grid, and isolate the faulty equipment from the high-voltage power grid in time, each high-voltage distribution branch of the electric drive vehicle is equipped with a solid-state power controller. If a short-circuit failure occurs in the load of the high-voltage distribution branch, the solid-state power controller will promptly shut down the distribution output, isolate the faulty equipment from the high-voltage power grid, and ensure the normal operation of other equipment. At the same time, the corresponding short-circuit protection value can be reasonably set according to the different high-voltage load equipment to meet the needs of different load equipment. Summary of the invention

[0004] The present invention provides a variable short-circuit protection device based on a SIC MOS tube driving and monitoring circuit, which is used to timely shut down the distribution output when a short-circuit fault occurs in the load equipment of each distribution branch of the internal high-voltage power grid of an electric drive special vehicle.

[0005] The variable short-circuit protection device based on the SIC MOS tube driving and monitoring circuit provided by the present disclosure mainly includes: a SIC MOS tube driving and monitoring unit, a resistance sampling unit, and a power distribution SIC MOS tube unit, which are connected in series with each other, wherein:

[0006] The SIC MOS tube driving and monitoring unit is used to drive the power distribution SIC MOS tube, and the high-voltage power current flows through the power distribution SIC MOS tube;

[0007] The SIC MOS tube driving and monitoring unit monitors the current flowing through the power distribution SIC MOS tube by monitoring the voltage across the resistance sampling unit and the power distribution SIC MOS tube unit, and turns off the power distribution SIC MOS tube when the monitored voltage exceeds a certain threshold;

[0008] The resistance sampling unit is used to provide a variable resistance value to obtain a variable short-circuit protection current value.

[0009] Furthermore, the resistance sampling unit and the power distribution SIC MOS tube are connected in series between two ports of the SIC MOS tube driving and monitoring unit, and the first port outputs a constant current power supply relative to the second port, while monitoring the voltage value between the first port and the second port;

[0010] A diode connected in series with the resistance sampling unit and the power distribution SIC MOS tube is also provided between the two ports;

[0011] The constant current power source passes through the resistance sampling unit, the diode, and the power distribution SIC MOS tube to the second port to form a path; at the same time, the power distribution SIC MOS tube flows through the high-voltage power current;

[0012] When the voltage value between the first port and the second port exceeds a certain threshold, the power distribution SIC MOS tube is turned off.

[0013] Furthermore, after the power distribution SIC MOS tube is turned on, the relationship between the voltage value V between the first port and the second port, the variable resistance value R provided by the resistance sampling unit, and the high-voltage power current I flowing through the power distribution SIC MOS tube is:

[0014] Assume that the current flowing out of the constant current source is I0, the conduction voltage of the diode is U1, and the internal resistance of the power distribution SIC MOS tube is Ω, then:

[0015] V=I0﹡R+U1+Ω﹡I

[0016] According to the above formula and the required short-circuit protection current value, the threshold V of the voltage V can be calculated. max setting, or selection of variable resistance value R.

[0017] Furthermore, the SIC MOS tube driving and monitoring unit adopts ACPL-336J series chips;

[0018] The resistance sampling unit, the diode, and the power distribution SIC MOS tube are connected in series between the DESAT terminal and the VE terminal of the SIC MOS tube driving and monitoring unit, and the current flowing through the power distribution SIC MOS tube is monitored by monitoring the voltage drop between the DESAT terminal and the VE terminal to achieve short circuit protection.

[0019] Furthermore, the constant current output by the DESAT port is 1 mA, the default on-voltage of the diode is selected to be 0.7 V, the internal resistance of the power distribution SIC MOS tube is selected to be 45 mΩ, and the voltage drop threshold between the DESAT port and the VE port is set to 7 V.

[0020] Furthermore, the resistance sampling unit includes: a plurality of resistance branches connected in parallel, each resistance branch includes: a resistor connected in series and a switch, and the switch is used to control whether the resistor connected in series with it is connected to the short-circuit protection circuit.

[0021] Furthermore, the switches on each resistance branch of the resistance sampling unit are switched by an external control device.

[0022] Compared with the prior art, the beneficial effects of the present invention are: (1) it can realize timely shutting down of distribution output when short-circuit fault occurs in load equipment of each distribution branch of the high-voltage power grid inside the electric-drive special vehicle, isolate the faulty equipment from the high-voltage power grid, and ensure the normal operation of other equipment; (2) it can realize short-circuit current protection point switching by switching the internal relay of the circuit according to the different load characteristics of the high-voltage load equipment, and set the corresponding short-circuit protection value in the load distribution branch to meet the short-circuit fault protection requirements of different load equipment, and the short-circuit protection value is easy to set; (3) the circuit structure is simple; (4) it has good versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0024] Figure 1 A block diagram of the working principle of an exemplary embodiment according to the present disclosure;

[0025] Figure 2 Short-circuit protection value calculation equivalent circuit diagram. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0027] The present disclosure provides a variable short-circuit protection device based on a SIC MOS tube drive and monitoring circuit. The schematic circuit structure diagram under an exemplary embodiment is shown in the attached figure. Figure 1 As shown:

[0028] The variable short-circuit protection includes a SIC MOS tube driving and monitoring unit, a resistance sampling unit, and a power distribution SIC MOS tube unit, which are connected in series.

[0029] When the driving unit receives the instruction to turn on the power distribution MOS tube, Vout outputs the driving signal, the power distribution SIC MOS tube Q is turned on, the DESAT port outputs a constant constant current power supply, and at the same time monitors the voltage value relative to the VE port.

[0030] like Figure 2 As shown, the short circuit protection detection method is as follows:

[0031] When the drive unit receives the instruction to turn on the power distribution SIC MOS tube, Vout outputs a drive signal, the power distribution SIC MOS tube Q is turned on, and the DESAT port of the SIC MOS monitoring unit outputs a constant current power supply with a constant value of 1mA relative to the VE port, and monitors the voltage value of the VE port (the threshold voltage is 7V). The constant current power supply passes through the resistor R, the diode V, and the power distribution SIC MOS tube Q to the VE port of the drive unit to form a path. At the same time, the power distribution SIC MOS tube flows through the high-voltage power current.

[0032] When a 1mA constant current source passes through the resistor R, a voltage drop will be generated on the resistor R. The default conduction voltage of the diode is 0.7V. Since the internal resistance between the D pole and the S pole of the power distribution SIC MOS tube is small (the internal resistance of different types of SIC MOS tubes is different, and 45mΩ is used as an example in this embodiment), the voltage drop generated at both ends can be ignored. Therefore, the voltage drop V1 generated at both ends of the DESAT port and the VE port can be calculated as:

[0033] V1=1mA﹡R+0.7V ①

[0034] When the power distribution MOS tube is turned on and high-voltage power flows through it, since the internal resistance of the SIC MOS tube is 45mΩ, the voltage drop V2 generated at its two ends is:

[0035] V2=45mΩ﹡I ②

[0036] From the above, it can be obtained that when the power distribution SIC MOS tube is turned on and high-voltage power current flows, the voltage drop V3 generated across the DESAT port and the VE port is:

[0037] V3=V1+V2=1mA﹡R+0.7V+45mΩ﹡I ③

[0038] It can be seen from formula ③ that the larger the current flowing through the power distribution SIC MOS tube, the larger V3 will be, and the larger the voltage drop between the DESAT port and the VE port will be. When the voltage drop between the DESAT port and the VE port reaches more than 7V, the SIC MOS tube driving unit will turn off the power distribution MOS tube.

[0039] Since the high-voltage power grid can generate hundreds to thousands of amperes of current at the moment of power distribution short circuit, the voltage drop between the DESAT port and the VE port is instantly greater than 7V, thus achieving short-circuit protection.

[0040] Depend on Figure 1 From formula ③, we can know that changing the resistance value of resistor R can change the short circuit protection. Figure 1 In the example, the host computer controls the switching switches K1 and K2 to connect R1 or R2 to the short-circuit protection circuit, thereby changing the short-circuit protection point. This method can set different short-circuit protection points according to different load short-circuit protection requirements and accurately implement short-circuit protection for the load.

[0041] The above technical scheme is only an exemplary embodiment of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the application methods and principles disclosed in the present invention, and it is not limited to the method described in the above specific embodiment of the present invention. Therefore, the method described above is only preferred and does not have a restrictive meaning.

Claims

1. A variable short-circuit protection device based on SIC MOS tube driving and monitoring circuit, characterized in that: include: The SICMOS tube driving and monitoring unit, the resistance sampling unit, and the power distribution SIC MOS tube unit are connected in series, where: The SIC MOS tube driving and monitoring unit is used to drive the power distribution SIC MOS tube, and the high-voltage power current flows through the power distribution SIC MOS tube; The SIC MOS tube driving and monitoring unit monitors the current flowing through the power distribution SIC MOS tube by monitoring the voltage across the resistance sampling unit and the power distribution SIC MOS tube unit, and turns off the power distribution SICMOS tube when the monitored voltage exceeds a certain threshold; The resistance sampling unit is used to provide a variable resistance value to obtain a variable short-circuit protection current value.

2. The device according to claim 1, characterized in that The resistance sampling unit and the power distribution SIC MOS tube are connected in series between the two ports of the SIC MOS tube driving and monitoring unit, and the first port outputs a constant current power supply relative to the second port, while monitoring the voltage value between the first port and the second port; A diode connected in series with the resistance sampling unit and the power distribution SIC MOS tube is also provided between the two ports; The constant current power source passes through the resistance sampling unit, the diode, and the power distribution SIC MOS tube to the second port to form a path; at the same time, the power distribution SIC MOS tube flows through the high-voltage power current; When the voltage value between the first port and the second port exceeds a certain threshold, the power distribution SIC MOS tube is turned off.

3. The device according to claim 2, characterized in that After the power distribution SIC MOS tube is turned on, the relationship between the voltage value V between the first port and the second port, the variable resistance R provided by the resistance sampling unit, and the high-voltage power current I flowing through the power distribution SIC MOS tube is: Assume that the current flowing out of the constant current source is I0, the conduction voltage of the diode is U1, and the internal resistance of the power distribution SIC MOS tube is Ω, then: V=I0﹡R+U1+Ω﹡I According to the above formula and the required short-circuit protection current value, the threshold V of the voltage V can be calculated. max setting, or selection of variable resistance value R.

4. The device according to claim 2 or 3, characterized in that The SIC MOS tube driving and monitoring unit adopts ACPL-336J series chips; The resistance sampling unit, the diode, and the power distribution SIC MOS tube are connected in series between the DESAT terminal and the VE terminal of the SIC MOS tube driving and monitoring unit, and the current flowing through the power distribution SIC MOS tube is monitored by monitoring the voltage drop between the DESAT terminal and the VE terminal to achieve short circuit protection.

5. The device according to claim 4, characterized in that The constant current output by the DESAT port is 1mA, the default on-voltage of the diode is selected to be 0.7V, the internal resistance of the power distribution SIC MOS tube is selected to be 45mΩ, and the voltage drop threshold between the DESAT port and the VE port is set to 7V.

6. The device according to claim 1, characterized in that The resistance sampling unit comprises: a plurality of parallel resistance branches, each resistance branch comprises: a resistor and a switch connected in series, and the switch is used to control whether the resistor connected in series with it is connected to a short-circuit protection circuit.

7. The device according to claim 6, characterized in that The switches on each resistance branch of the resistance sampling unit are switched under the control of an external control device.

Images