CN115621989A

CN115621989A - Active short circuit of motor and electric automobile

Info

Publication number: CN115621989A
Application number: CN202211393831.0A
Authority: CN
Inventors: 姚峰; 杭孟荀; 陈士刚; 王晓辉; 钱兆刚
Original assignee: Chery New Energy Automobile Co Ltd
Current assignee: Chery New Energy Automobile Co Ltd
Priority date: 2022-11-08
Filing date: 2022-11-08
Publication date: 2023-01-17

Abstract

The application relates to the technical field of electric automobiles, in particular to an active short circuit of a motor and an electric automobile, wherein, include: the logic circuit is used for receiving an overvoltage signal generated when the bus voltage of the electric automobile is greater than a preset threshold value and a feedback signal of the driving chip, and performing logic operation on the overvoltage signal and the feedback signal to obtain a level signal; and the level conversion chip drives the enabling state of the enabling pin in the level conversion chip according to the level signal, and when the enabling state is enabled, a plurality of output pins of the level conversion chip respectively output preset level signals, and the motor is driven to generate three-phase short circuit based on the three-phase lower bridge or three-phase upper bridge short circuit of the IGBT of the motor driven by the preset level signals. Therefore, the problems that the active short circuit action in the related technology is controlled by software, the effect of timely protection under the condition of extreme fault or out-of-control of the whole vehicle or abnormal program cannot be guaranteed, the reliability and timeliness are insufficient and the like are solved.

Description

Active short circuit of motor and electric automobile

Technical Field

The application relates to the technical field of electric automobiles, in particular to an active short-circuit of a motor and an electric automobile.

Background

In the running process of the electric automobile, active Short Circuit (ASC) protection is required under certain fault conditions, that is, an upper three-bridge arm short circuit or a lower three-bridge arm short circuit is realized through a switch of an Insulated Gate Bipolar Transistor (IGBT), so that a three-phase short circuit of a motor is realized. The motor safety protection mechanism is a motor safety protection mechanism, in some serious fault conditions, a controller is protected or prevented from further damage through an ASC three-phase short circuit mode, if ASC is not carried out, when the motor is at a high rotating speed, counter electromotive force generated by the motor may exceed the bus voltage of a high-voltage battery, if IGBT is naturally rectified, unpredictable braking torque may be generated, further damage is caused, and therefore an active short circuit protection function is very necessary.

In the related art, the active short-circuit action is to output a control signal to drive the active short-circuit protection circuit to work after detecting a fault state through software. However, the scheme controlled by software may fail or fail in time of protection under the conditions of some extreme fault conditions, vehicle runaway and program abnormity, and has insufficient reliability and timeliness.

Disclosure of Invention

The application provides an initiative short-circuit and electric automobile of motor to solve the scheme that initiative short-circuit action passes through software control among the correlation technique, can't guarantee to play the effect of timely protection under extreme fault condition or whole car out of control or the unusual circumstances of procedure, reliability and timeliness are not enough scheduling problem.

An embodiment of a first aspect of the present application provides an active short circuit of a motor, including: the logic circuit is used for receiving an overvoltage signal generated when the bus voltage of the electric automobile is greater than a preset threshold value and a feedback signal of a driving chip, and performing logic operation on the overvoltage signal and the feedback signal to obtain a level signal; and the level conversion chip drives the enabling state of an enabling pin in the level conversion chip according to the level signal, and when the enabling state is enabled, a plurality of output pins of the level conversion chip respectively output preset level signals, and drives a three-phase lower bridge or a three-phase upper bridge of an IGBT of the motor to be short-circuited based on the preset level signals, so that the motor generates a three-phase short circuit.

Optionally, the plurality of output pins include first to sixth output pins, where the first to third output pins are respectively connected to each phase of the three-phase upper bridge, and the fourth to sixth output pins are respectively connected to each phase of the three-phase lower bridge; or, the first to third output pins are respectively connected with each phase of the three-phase lower bridge, and the fourth to sixth output pins are respectively connected with each phase of the three-phase upper bridge.

Optionally, when the enable state is enable, the first to third output pins output a first level signal, and the fourth to sixth output pins output a second level signal, where a level of the first level signal is lower than a level of the second level signal.

Optionally, when the preset level signal is the first level signal, the three-phase lower bridge or the three-phase upper bridge is switched on; and when the preset level signal is the second level signal, the three-phase lower bridge or the three-phase upper bridge is switched off. The logic circuit includes: the NOT gate is used for inverting the overvoltage signal and then converting the overvoltage signal into a second level signal; and the input signals of the NAND gate are the output signal of the NOT gate and the feedback signal respectively, wherein if the feedback signal is a first level signal, the NAND gate outputs the first level signal, and if the feedback signal is a second level signal, the NAND gate outputs the second level signal.

Optionally, the overvoltage signal is the first level signal that is generated when the bus voltage is greater than a preset threshold value and the generated second level signal is skipped into.

Optionally, if the IGBT is in a fault state, the feedback signal is the first level signal, otherwise, the feedback signal is the second level signal.

Optionally, if the bus voltage is less than or equal to the preset threshold, the input signal of the not gate is the second level signal, and the nand gate outputs the first level signal.

Optionally, when the enable state is not enabled, all output pins of the level conversion chip are in a high-resistance state with a resistance value larger than a preset value.

In a second aspect of the present application, an electric vehicle is provided, which includes an active short circuit of an electric machine as described in the above embodiments.

Therefore, the application has at least the following beneficial effects:

according to the embodiment of the application, the motor can be controlled to be actively short-circuited in a pure hardware action mode when the motor fails, the defects of protection delay and low reliability caused by software control are avoided, and the timeliness of the system entering the active short-circuit protection action is improved.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a block diagram illustrating an active short circuit of an electric machine according to an embodiment of the present disclosure;

fig. 2 is a schematic diagram of a hardware active short circuit according to an embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application and should not be construed as limiting the present application.

An active short circuit of a motor and an electric vehicle according to an embodiment of the present application will be described with reference to the drawings. In the active short-circuit of the motor, a logic circuit receives an overvoltage signal generated by the bus voltage of the electric vehicle being greater than a set threshold and a feedback signal of a driving chip, and performs logic operation on the overvoltage signal and the feedback signal to obtain a level signal, and a level conversion chip drives an enabling state of an enabling pin in the level conversion chip according to the level signal, and when the enabling state is enabling, a plurality of output pins of the level conversion chip respectively output set level signals, and drives a three-phase lower bridge or a three-phase upper bridge of an IGBT of the motor to be short-circuited based on the level signal, so that the motor generates a three-phase active short-circuit. Therefore, the problems that the active short-circuit action in the related technology is controlled by software, the effect of timely protection under the condition of extreme fault or out-of-control of the whole vehicle or abnormal program cannot be guaranteed, the reliability and the timeliness are insufficient and the like are solved.

Specifically, fig. 1 is a block diagram illustrating an active short circuit of a motor according to an embodiment of the present disclosure.

As shown in fig. 1, the active short circuit 10 of the motor includes: a logic circuit 100 and a level conversion chip 200.

The logic circuit 100 is configured to receive an overvoltage signal and a feedback signal of a driving chip, which are generated when a bus voltage of the electric vehicle is greater than a preset threshold, and perform logic operation on the overvoltage signal and the feedback signal to obtain a level signal; the level conversion chip 200 drives the enabling state of the enabling pin in the level conversion chip according to the level signal, and when the enabling state is enabled, the plurality of output pins of the level conversion chip respectively output a preset level signal, and drives the three-phase lower bridge or the three-phase upper bridge of the IGBT of the motor to be short-circuited based on the preset level signal, so that the motor generates a three-phase short circuit.

The preset threshold may be a threshold set by a user in advance, and may be specifically set according to an actual vehicle condition, which is not specifically limited herein.

The enabling means that a certain pin (pin) of the electronic device, the chip or the module starts a certain preset function and enters a preset state.

The preset level signal may be a high level signal or a low level signal, and is determined according to an actual output state of the circuit, which is not specifically limited herein.

The plurality of output pins comprise first to sixth output pins, wherein the first to third output pins are respectively connected with each phase of the three-phase upper bridge, and the fourth to sixth output pins are respectively connected with each phase of the three-phase lower bridge; or the first to third output pins are respectively connected with each phase of the three-phase lower bridge, and the fourth to sixth output pins are respectively connected with each phase of the three-phase upper bridge.

It can be understood that, in the embodiment of the present application, when the logic circuit receives an overvoltage signal and a feedback signal of the driving chip, which are generated when the bus voltage of the electric vehicle is greater than a set threshold, and performs a logic operation on the overvoltage signal and the feedback signal to obtain a level signal, the level conversion chip drives the enabling state of the enabling pin in the level conversion chip according to the level signal, and when the enabling state is enabled, the multiple output pins of the level conversion chip respectively output the set level signal, and drives the three-phase lower bridge or the three-phase upper bridge of the IGBT of the motor based on the level signal to cause the motor to generate a three-phase short circuit.

In the embodiment of the present application, the logic circuit 100 includes: the NOT gate is used for inverting the overvoltage signal and then converting the overvoltage signal into a second level signal; the input signals of the NAND gate are respectively an output signal and a feedback signal of the NOT gate, wherein if the feedback signal is a first level signal, the NAND gate outputs the first level signal, and if the feedback signal is a second level signal, the NAND gate outputs the second level signal.

It can be understood that, in the logic circuit in the embodiment of the present application, the not gate is used to invert the overvoltage signal into a high level, the input signals of the nand gate are the output signal and the feedback signal of the not gate, respectively, if the feedback signal is a low level, the nand gate outputs a low level, if the feedback signal is a high level, the nand gate outputs a high level, and the application of the nand gate and the not gate performs related logic operations to ensure a preparation action of the hardware active short circuit function.

In the embodiment of the application, when the enable state is enable, the first to third output pins output a first level signal, and the fourth to sixth output pins output a second level signal, wherein the level of the first level signal is lower than that of the second level signal.

Wherein, the first level signal may be a low level signal; the second level signal may be a high level signal, and is not particularly limited herein.

When the preset level signal is a first level signal, the three-phase lower bridge or the three-phase upper bridge is switched on; and when the preset level signal is a second level signal, the three-phase lower bridge or the three-phase upper bridge is switched off.

It can be understood that, when the enable state is enable, the first to third output pins output a low level; and the fourth to sixth output pins output high levels, and the upper bridge is switched off corresponding to the switching-on of the three-phase lower bridge, so that active short circuit is realized.

In the embodiment of the present application, when the enable state is not enabled, all output pins of the level shift chip are in a high-resistance state with a resistance value greater than a preset value.

The preset value may be a value preset by a user, and may be set according to performance of the level conversion chip, which is not specifically limited herein.

It can be understood that, in the embodiment of the present application, when the enable state is the disable state, all output pins of the level conversion chip are in the high resistance state, that is, in the open circuit state, so that the voltage impact resistance of the chip is increased to a certain extent.

In the embodiment of the present application, if the IGBT is in a fault state, the feedback signal is a first level signal, otherwise, the feedback signal is a second level signal.

It can be understood that, in the embodiment of the present application, when the IGBT is in a fault state, since the IGBT is not suitable for entering an active short-circuit state, in order to avoid occurrence of a direct short-circuit of the upper and lower pipes, the feedback signal is at a low level, otherwise the feedback signal is at a high level.

In the embodiment of the present application, the overvoltage signal is a first level signal that is generated when the bus voltage is greater than a preset threshold, and the generated second level signal is skipped into.

If the bus voltage is less than or equal to the preset threshold, the input signal of the not gate is a second level signal, and the not gate outputs the first level signal.

It can be understood that in the embodiment of the present application, when a vehicle has a serious fault and a motor is in a high rotation speed, a generated back electromotive force may raise a bus voltage, an active short circuit needs to be performed to generate a braking torque to reduce the rotation speed in order to prevent the high voltage from damaging high-voltage devices such as a thin film capacitor, an IGBT module, and the like, when the bus voltage is greater than a set threshold, an overvoltage signal jumps a generated second level signal into a first level signal, and when the bus voltage is less than the set threshold, an input signal of a not gate is the second level signal, and the not gate outputs the first level signal.

According to the active short-circuit of the motor, when the logic circuit receives an overvoltage signal and a feedback signal of the driving chip, which are generated when the bus voltage of the electric automobile is larger than a set threshold value, and performs logic operation on the overvoltage signal and the feedback signal to obtain a level signal, the level conversion chip drives the enabling state of an enabling pin in the level conversion chip according to the level signal, and when the enabling state is enabled, a plurality of output pins of the level conversion chip respectively output the set level signal, and the motor is driven to generate three-phase short circuit based on the three-phase lower bridge or three-phase upper bridge short circuit of an IGBT (insulated gate bipolar translator) of the motor by the level signal.

The active short circuit of the motor will be explained with reference to fig. 2, specifically as follows:

u15 is a level conversion chip, which has 8 input/output channels, A1-A8 are input terminals, B1-B8 are corresponding output terminals, when An is high level, bn is also high level, in this example, the input/output terminal is set to 5V on average. The 22 nd pin of the chip is an output enable pin, when the input level of the pin is high, the chip is not enabled, namely, the output end is in a high-impedance state no matter the input level is high or low; when the input level of the pin is low, the chip is enabled, and the output level follows the input end.

A driving chip fault feedback signal DESAT _ FLT is used as an input signal and simultaneously connected to pins A4-A6, and outputs B4-B6 of the driving chip fault feedback signal DESAT _ FLT are respectively connected to lower bridge driving signals of U, V and W phases; meanwhile, the DESAT _ FLT is connected to pins A1-A3 after being inverted by a NOT gate of U3, and outputs B1-B3 of the DESAT _ FLT are respectively connected to upper bridge driving signals of U, V and W phases.

When a vehicle has a serious fault and a motor is in a high rotating speed, the generated counter electromotive force can increase the voltage of a bus, and in order to avoid the high voltage from damaging high-voltage devices such as a film capacitor, an IGBT module and the like, active short circuit needs to be executed, braking torque is generated, and the rotating speed is reduced. When the bus voltage is higher than the set threshold value, the overvoltage signal OU _2 jumps from high level to low level and changes to high level after inversion through a U3 NOT gate. And meanwhile, the DESAT _ FLT driving fault signal is at a high level, the DESAT _ FLT driving fault signal and the DESAT _ FLT driving fault signal are subjected to logic operation of a U16 NAND gate, then a low level is output and connected to an enable pin of the U15, the U15 outputs normally, B4-B6 are at high levels, and B1-B3 are at low levels. Namely, the three-phase lower bridge is switched on, the upper bridge is switched off, and the active short circuit is realized through the lower bridge.

It should be noted that if the DESAT _ FLT drives the fault signal low when the IGBT is in a fault state, such as a short-circuit fault, this time it is not appropriate to enter an active short-circuit state, which may cause a straight-through short between the upper and lower pipes.

Therefore, the DESAT _ FLT driving fault signal is also to be included in the hardware active short circuit triggering condition, and the embodiment of the present application takes this factor into account, and performs related logic operations through the application of the nand gate and the nor gate, thereby ensuring the preparation of the hardware active short circuit function.

Table 1 truth table for logical operations

As can be seen from the above table, the active short circuit function of the circuit according to the design scheme can be activated only when an overvoltage occurs (OU _2 is at a low level) and the driver chip fault signal is normal (DESAT _ FLT is at a high level), so that the accuracy and reliability of the scheme function under the condition that no software participates and the pure hardware circuit works are ensured.

The method comprises the following specific steps: the active short circuit is realized by uniformly controlling the turn-on of the lower three-bridge arm IGBT and the turn-off of the upper three-bridge arm IGBT through one path of hardware signal. The hardware signal is taken from a fault signal (the high level is normal, the low level is fault) fed back by a driving chip in a driving board and is connected to the first three input ports of the level shifter, and meanwhile, the signal is inverted through a NOT gate of a logic chip and is connected to the last three input ports of the level shifter. Three output ports corresponding to the first three input ports are respectively connected to the lower three-bridge IGBT driving signals, and three output ports corresponding to the last three input ports are respectively connected to the upper three-bridge IGBT driving signals. Therefore, the three-phase lower bridge and the three-phase upper bridge are simultaneously controlled to be switched on and switched off by one path of hardware signal, and the state of active short circuit is achieved.

Meanwhile, the condition of active short-circuit protection triggering needs to be used as the output enabling of the level shifter, in the design of the embodiment of the application, an overvoltage signal of the bus voltage of the electric drive system is used as the triggering condition of the active short-circuit, the overvoltage signal is also a pure hardware signal, and the overvoltage signal is a level signal (the high level is normal, and the low level is overvoltage) which is output after the bus voltage detection signal is compared with the threshold level through the comparator. In addition, the active short-circuit protection action trigger needs to be combined with a fault signal fed back by the driving chip besides the overvoltage signal, if the driving chip reports a fault, the problem of the IGBT is shown, the IGBT is possibly in a short-circuit state, and the active short-circuit is not suitable to be executed at the moment.

In summary, the embodiment of the present application designs an active short-circuit protection circuit with pure hardware action, which avoids the disadvantages of protection delay and low reliability caused by software control, and improves the timeliness of the system entering the active short-circuit protection action.

The embodiment of the application also provides an electric automobile, which comprises the active short circuit of the motor.

In the description of the present specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or N embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are 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 the description of the present application, "N" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

Claims

1. An active short circuit of an electric machine, comprising:

the logic circuit is used for receiving an overvoltage signal generated when the bus voltage of the electric automobile is greater than a preset threshold value and a feedback signal of a driving chip, and performing logic operation on the overvoltage signal and the feedback signal to obtain a level signal;

and the level conversion chip drives the enabling state of an enabling pin in the level conversion chip according to the level signal, and when the enabling state is enabled, a plurality of output pins of the level conversion chip respectively output preset level signals, and drives a three-phase lower bridge or a three-phase upper bridge of an IGBT of the motor to be short-circuited based on the preset level signals, so that the motor generates a three-phase short circuit.

2. The active short circuit of an electric motor according to claim 1, wherein the plurality of output pins includes first to sixth output pins, wherein the first to third output pins are respectively connected to each phase of the three-phase upper bridge, and the fourth to sixth output pins are respectively connected to each phase of the three-phase lower bridge; or, the first to third output pins are respectively connected with each phase of the three-phase lower bridge, and the fourth to sixth output pins are respectively connected with each phase of the three-phase upper bridge.

3. The active short circuit of an electric machine of claim 2, wherein when the enable state is enable, the first to third output pins output a first level signal, and the fourth to sixth output pins output a second level signal, wherein a level of the first level signal is lower than a level of the second level signal.

4. The active short circuit of an electric motor according to claim 3, wherein when the preset level signal is the first level signal, the three-phase lower bridge or the three-phase upper bridge is turned on; and when the preset level signal is the second level signal, the three-phase lower bridge or the three-phase upper bridge is switched off.

5. The active short circuit of an electric machine of claim 1, wherein the logic circuit comprises:

the NOT gate is used for inverting the overvoltage signal and then converting the overvoltage signal into a second level signal;

and the input signals of the NAND gate are the output signal of the NOT gate and the feedback signal respectively, wherein if the feedback signal is a first level signal, the NAND gate outputs the first level signal, and if the feedback signal is a second level signal, the NAND gate outputs the second level signal.

6. The active short circuit of an electric machine of claim 5, wherein the overvoltage signal is the first level signal that the second level signal generated is jumped to when the bus voltage is greater than a preset threshold.

7. The active short circuit of an electric machine of claim 5 wherein the feedback signal is the first level signal if the IGBT is in a fault state and the second level signal otherwise.

8. The active short circuit of an electrical machine of claim 5, wherein if the bus voltage is less than or equal to the preset threshold, the input signal of the not gate is the second level signal, and the not gate outputs the first level signal.

9. The active short circuit of an electric machine according to any one of claims 1 to 8, wherein when the enabled state is disabled, all output pins of the level conversion chip are in a high impedance state with a resistance value greater than a predetermined value.

10. An electric vehicle, characterized in that it comprises an active short-circuit of an electric machine according to any one of claims 1-9.