CN103042926B - The trailer guard method of new-energy automobile and realize circuit - Google Patents

Abstract

This application discloses a trailer protection method for a new energy vehicle. When the new energy vehicle is towed, the three-phase short-circuit mode of the high voltage side of the inverter is turned on, and the cooling equipment is turned on at the same time as the high voltage side of the inverter and the permanent magnet Synchronous motor cooling. When the new energy vehicle stops towing, turn off the three-phase short-circuit mode of the high-voltage side of the inverter, and turn off all cooling equipment at the same time. The three-phase short-circuit mode of the high-voltage side of the inverter is: the power switch devices of the three upper bridge arms are all turned off, and the power switch devices of the three lower bridge arms are all turned on at the same time; or the power switch devices of the three upper bridge arms are all turned on. All are turned on, and at the same time, the power switching devices of the three lower bridge arms are all turned off. The application also discloses a corresponding realization circuit. The method and the circuit enable the new energy vehicle to be towed freely without using a special trailer, and without limitation on towing time or speed when a fault occurs and the new energy vehicle is towed.

Description

Trailer protection method and implementation circuit for new energy vehicles

technical field

The present application relates to a trailer protection method for new energy vehicles (including electric vehicles, hybrid vehicles, etc.), and a circuit structure for realizing the trailer protection method.

Background technique

Please refer to Figure 1, which is a simplified schematic diagram of a motor control system for a new energy vehicle. The motor control system includes:

——Permanent magnet synchronous motor 1, whose mechanical output shaft is connected with the transmission system of the new energy vehicle to output torque and power for the new energy vehicle. When the permanent magnet synchronous motor 1 is driven at high speed, it also generates three-phase alternating current in reverse.

- The inverter 2 is divided into a high-voltage side 21 and a low-voltage side 22 which are electrically isolated from each other.

- High voltage battery 3, the voltage is usually above several hundred volts.

——Low-voltage battery 4, the voltage is generally tens of volts, such as 12V, 24V and so on.

The DC terminal of the high-voltage side 21 is connected to the high-voltage battery 3, and the AC terminal is connected to the three-phase AC port of the permanent magnet synchronous motor 1 to drive the output torque and power of the permanent magnet synchronous motor 1 and to feed back the permanent magnet synchronous motor 1. The effect of braking energy. A common high-voltage side 21 adopts a three-phase bridge inverter circuit, which is composed of a bus capacitor C1 and three bridge arms connected in parallel. Each bridge arm is composed of two power switching devices connected in series, and each power switching device is further connected with a diode in antiparallel. Commonly used power switching devices include IGBT devices, MOS tubes, and the like.

The low-voltage side 22 includes a low-voltage control system, a sensor signal acquisition module, a communication module, and the like. The low-voltage control system is the control chip of the motor control system, including DSP (Digital Signal Processor), MCU (Micro Control Unit) and the like. The low-voltage side 22 supplies power to the low-voltage equipment with the low-voltage battery 4 on the one hand, and controls the low-voltage equipment with the drive signal output by the low-voltage control system on the other hand. For example, the working power and control signals of each power switching device on the high voltage side 21 come from the low voltage side 22 .

When the vehicle is running normally, the high voltage battery 3 drives the permanent magnet synchronous motor 1 through the high voltage side 21 of the inverter 2 . When the vehicle fails and is dragged, the permanent magnet synchronous motor 1 rotates due to the dragging, which will generate a counter electromotive force, and charge the bus capacitor C1 through each diode in the high-voltage side 21 of the inverter 2 . The power switching device and the bus capacitor C1 in the high voltage side 21 are all voltage sensitive devices. When the vehicle is towed, the counter electromotive force generated by the permanent magnet synchronous motor 1 may cause damage to these voltage sensitive devices.

An existing new energy vehicle trailer protection method is: lift the driving wheel of the permanent magnet synchronous motor 1 when towing the vehicle, so that the permanent magnet synchronous motor 1 will not rotate during the vehicle towing process, so that no reaction will occur. electric potential. This method must be realized by a special trailer.

Another existing trailer protection method for new energy vehicles is: limit the rotational speed of the permanent magnet synchronous motor 1 when towing the trailer, so that the back EMF generated by it will not cause damage to voltage sensitive devices. This method brings difficulties to the design of the motor drive system of new energy vehicles.

Contents of the invention

The technical problem to be solved in this application is to provide a trailer protection method for new energy vehicles, which can allow new energy vehicles to be towed without time and speed restrictions, while still ensuring the protection of permanent magnet synchronous motors, inverters, etc. Security of core equipment. For this reason, the present application also provides a realization circuit of the trailer protection method of the new energy vehicle.

In order to solve the above technical problems, the trailer protection method of the new energy vehicle of the present application is as follows: when the new energy vehicle is towed, the three-phase short-circuit mode of the high-voltage side of the inverter is turned on, and the cooling equipment is turned on at the same time as the inverter and the permanent magnet. synchronous motor cooling;

When the new energy vehicle stops towing, turn off the three-phase short-circuit mode of the high-voltage side of the inverter, and turn off all cooling equipment at the same time;

The three-phase short-circuit mode of the high-voltage side of the inverter is as follows: the power switch devices of the three upper bridge arms are all turned off, and the power switch devices of the three lower bridge arms are all turned on at the same time; or the power switch devices of the three upper bridge arms are all turned on. All are turned on, and at the same time, the power switch devices of the three lower bridge arms are all turned off.

The implementation circuit of the trailer protection method of the new energy vehicle includes:

- a linear voltage stabilizing circuit, connected in parallel with the busbar capacitors to obtain power supply and generate a temporary low-voltage power supply;

——Parallel circuit, receiving normal low-voltage power supply and temporary low-voltage power supply input independently of each other, and supplying power to the half-bridge drive module;

——The half-bridge drive module, controlled by the drive signal sent by the logic circuit, turns on or off each power switching device on the high-voltage side of the inverter;

——The logic circuit receives the input of normal low-voltage power supply and normal driving signal, and sends a driving signal to the half-bridge driving module; when the normal low-voltage power supply is invalid, the logic circuit outputs a preset level signal to the half-bridge driving module; when normal When the low-voltage power supply is effective, the logic circuit outputs a normal driving signal.

Once the high-voltage side of the inverter enters the three-phase short-circuit mode, the reverse electromotive force generated by the permanent magnet synchronous motor will not continue to rise, which prevents possible overvoltage damage to electronic devices. However, in the three-phase short-circuit mode, the high-voltage side of the inverter and the permanent magnet synchronous motor will have relatively large phase currents, thus generating large amounts of heat. Therefore, the present application turns on the cooling equipment while entering the three-phase short-circuit mode, so as to prevent possible overheating damage of the inverter and the permanent magnet synchronous motor. Therefore, the method and implementation circuit described in this application enable the new energy vehicle to be towed freely without using a special trailer and without restrictions on towing time or speed when a fault occurs and the new energy vehicle is towed.

Description of drawings

Figure 1 is a schematic structural diagram of a motor control system of a new energy vehicle;

Fig. 2 is the flow chart of the trailer protection method of the new energy vehicle of the present application;

Figure 3 is a schematic diagram of the motor control system of a new energy vehicle when the vehicle is towed due to a fault;

Fig. 4 is a schematic diagram of an implementation circuit of a trailer protection method for a new energy vehicle of the present application;

Fig. 5 is a schematic diagram of another implementation circuit of the trailer protection method for new energy vehicles of the present application.

Explanation of the reference signs in the figure:

1 is a permanent magnet synchronous motor; 2 is an inverter; 21 is a high voltage side; 211 is a linear voltage regulator circuit; 212 is a parallel circuit; 213 is a half-bridge drive module; 214 is a logic circuit; 215 is an isolation transformer; 22 is a low voltage 3 is a high-voltage battery; 4 is a low-voltage battery; 41 is a low-voltage power supply relay; 5 is a cooling device.

detailed description

Referring to FIG. 2 and FIG. 3 , the method for protecting a trailer of a new energy vehicle of the present application will be described in detail below with a specific embodiment.

The motor control system of the new energy vehicle includes a permanent magnet synchronous motor 1 , an inverter 2 , a high voltage battery 3 and a low voltage battery 4 . The inverter 2 is further divided into a high-voltage side 21 and a low-voltage side 22, which are electrically isolated from each other. During normal operation, the high-voltage side 21 converts the high-voltage direct current of the high-voltage battery 3 into three-phase alternating current to drive the permanent magnet synchronous motor 1 . The feedback energy of the permanent magnet synchronous motor 1 is also converted through the high voltage side 21 to charge the high voltage battery 3 . The low-voltage side 22 supplies power to the low-voltage equipment with the low-voltage battery 4 , and controls the low-voltage equipment with the driving signal of the low-voltage control system. The cooling device 5 is a typical low-pressure device, which includes a cooling fan, a cooling water pump, and the like. The low-voltage side 22 also provides low-voltage power and drive signals for the power switching devices and the like on the high-voltage side 21 .

When the new energy vehicle breaks down, in order to ensure safety, the high-voltage battery 3 is disconnected from the high-voltage side 21 of the inverter 2, and the low-voltage battery 4 and the low-voltage side 22 of the inverter 2 are also connected by a relay (equivalent to a switch) 41 is disconnected, and the six power switching devices in the three bridge arms of the high voltage side 21 of the inverter 2 are all turned off. At this time, the low-voltage side 22 cannot obtain power from the low-voltage battery 4 , so all low-voltage devices including the cooling device 5 and the power switching device of the high-voltage side 21 have no power supply and drive.

At this time, when the new energy vehicle is towed, the application will open the three-phase short-circuit mode of the high-voltage side 21 of the inverter 2, and simultaneously open the cooling device 5 to perform the cooling on the high-voltage side 21 of the inverter 2 and the permanent magnet synchronous motor 1. Heat dissipation. The high voltage side 21 of the inverter 2 and the permanent magnet synchronous motor 1 may share the cooling device 5 , or each may have an independent cooling device 5 . When the new energy vehicle stops towing, exit the three-phase short-circuit mode of the high-voltage side 21 of the inverter 2 (that is, all six power switching devices in the three bridge arms returning to the high-voltage side 21 of the inverter 2 are all turned off ), while turning off all cooling equipment 5.

The three-phase short-circuit mode of the high-voltage side 21 of the inverter 2 is: the power switch devices of the three upper bridge arms are all turned off, and the power switch devices of the three lower bridge arms are all turned on at the same time; or the power of the three upper bridge arms All the switching devices are turned on, and at the same time, the power switching devices of the three lower bridge arms are all turned off.

Please refer to FIG. 4 , which shows the implementation circuit 1 of the trailer protection method for new energy vehicles of the present application, which is used to make the three-phase bridge arm of the high-voltage side 21 of the inverter 2 enter a three-phase short-circuit mode. The realization circuit one is all on the high-voltage side of the inverter, which includes:

——The linear voltage stabilizing circuit 211 is connected in parallel with the bus capacitor C1 to obtain power supply and generate a temporary low-voltage power supply. When the new energy vehicle is towed due to a fault, the bus capacitor C1 is in a charging state, and the linear voltage stabilizing circuit 211 is connected in parallel with the bus capacitor C1 to obtain power supply.

—The parallel circuit 212 receives the input of the normal low-voltage power supply and the temporary low-voltage power supply, and supplies power to the half-bridge driving module 213 . The normal low-voltage power supply refers to the low-voltage power supply generated by the low-voltage battery 4 through the isolated conversion of the low-voltage side and the high-voltage side of the inverter 2 . When the new energy vehicle breaks down, the normal low-voltage power supply is unavailable because the low-voltage battery 4 is disconnected from the low-voltage side 22 of the inverter 2 . The temporary low-voltage power supply is generated by the linear voltage stabilizing circuit 211 , which is the same as the normal low-voltage power supply, for example, both are 15V, and both are connected to the parallel circuit 212 independently of each other. In this way, as long as one of the normal low-voltage power supply or the temporary low-voltage power supply is valid (ie 15V), the parallel circuit 212 can supply power to the half-bridge driving module 213 .

——The half-bridge driving module 213 is controlled by the driving signal sent by the logic circuit 214 to turn on or turn off each power switching device of the high-voltage side 21 of the inverter 2 . FIG. 4 exemplarily shows that the half-bridge driving module 213 is only connected to the power switching devices of the three lower bridge arms, so as to control the power switching devices of the three lower bridge arms to be turned on or off. In other embodiments, the half-bridge driving module 213 may also only be connected to the power switching devices of the three upper bridge arms, or be connected to all the power switching devices of the three-phase bridge arms at the same time.

——The logic circuit 214 receives the input of the normal low-voltage power supply and the normal driving signal, and sends the driving signal to the half-bridge driving module 213 . The normal driving signal refers to the driving signal sent by the low-voltage control system in the low-voltage side 22 of the inverter 2 and after isolation and conversion of the low-voltage side and the high-voltage side of the inverter 2 . When the new energy vehicle breaks down, because the low-voltage battery 4 is disconnected from the low-voltage side 22 of the inverter 2, the low-voltage control system loses power supply and no longer outputs normal driving signals. When the normal low-voltage power supply is invalid (that is, when it is 0V), the logic circuit 214 directly outputs a high-level driving signal to the half-bridge driving module 213, and the high-level driving signal makes the three-phase voltage of the high-voltage side 21 of the inverter 2 The bridge arm enters the three-phase short-circuit mode. When the normal low-voltage power supply is active, the logic circuit 214 outputs a normal driving signal to control the half-bridge driving module 213 to realize the normal operation of the three-phase bridge arm of the high-voltage side 21 of the inverter 2 .

The first implementation circuit above obtains energy directly from the bus capacitor C1 , and is independent from the motor control system of the vehicle located at the low-voltage side 22 of the inverter 2 . Even if the normal motor control system fails, the trailer protection function described in this application can be ensured.

Please refer to Fig. 5, which provides the implementation circuit 2 of the trailer protection method of the new energy vehicle of the present application, which includes all of the implementation circuit 1 shown in Fig. 4, and increases on this basis, and the added circuit uses to drive cooling equipment. The added circuits are all on the low-voltage side of the inverter (or the isolated part between the high-voltage side and the low-voltage side), which include:

- The isolation transformer 215 is used to generate an activation signal on the low voltage side 22 to close the relay 41 through the isolated conversion of the high voltage side and the low voltage side of the inverter 2 according to a temporary low voltage power supply generated by the linear voltage stabilizing circuit 211 . The isolation transformer 215 can also be realized by an optocoupler scheme or a photorelay scheme.

- a relay 41 for controlling the connection of the low-voltage battery 4 to the low-voltage side 22 of the inverter 2 . The existing relay 41 is only closed by the vehicle start signal, but in this application, the relay 41 can be closed by one of the vehicle start signal or the activation signal. When the relay 41 is closed, the low-voltage side 22 can obtain power from the low-voltage battery 4 and generate a normal low-voltage power supply. The low-voltage control system is then powered to generate normal drive signals. The normal low-voltage power supply then turns on the cooling device 5, such as turning on the cooling water pump and the cooling fan to dissipate heat from the permanent magnet synchronous motor 1 and the high-voltage side 21 of the inverter 2, etc. The normal drive signal also takes over the control of the three-phase short-circuit mode of the high voltage side 21 . The relay 41 is not turned off until the rotational speed of the permanent magnet synchronous motor 1 is close to 0, thereby shutting down each cooling device, and a driving signal is sent to exit the three-phase short-circuit mode of the high-voltage side 21 .

The above are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, various modifications and changes may occur in this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (7)

1. A trailer protection method for a new energy vehicle, characterized in that: when the new energy vehicle is towed, the three-phase short-circuit mode of the high-voltage side of the inverter is turned on, and the cooling device is turned on at the same time as the high-voltage side and the high-voltage side of the inverter. Permanent magnet synchronous motor heat dissipation; When the new energy vehicle stops towing, turn off the three-phase short-circuit mode of the high-voltage side of the inverter, and turn off all cooling equipment at the same time; The three-phase short-circuit mode of the high-voltage side of the inverter is as follows: the power switch devices of the three upper bridge arms are all turned off, and the power switch devices of the three lower bridge arms are all turned on at the same time; or the power switch devices of the three upper bridge arms are all turned on. All are turned on, and the power switching devices of the three lower bridge arms are all turned off at the same time; When the new energy vehicle is towed due to a fault, a linear voltage regulator circuit connected in parallel with the bus capacitor is added on the high-voltage side, which obtains power from the bus capacitor and generates a temporary low-voltage power supply; The temporary low-voltage power supply is connected to the half-bridge drive module in parallel with the normal low-voltage power supply; When the normal low-voltage power supply is valid, the normal drive signal directly drives all the power switching devices on the high-voltage side; when the normal low-voltage power supply is invalid, the fixed high-level signal turns on the three-phase short-circuit mode through the half-bridge drive module. 2. The trailer protection method for new energy vehicles according to claim 1, wherein the cooling equipment includes a cooling fan and a cooling water pump; the high-voltage side of the inverter and the permanent magnet synchronous motor or a shared cooling equipment, or has Each independent cooling equipment. 3. The trailer protection method for new energy vehicles according to claim 1, characterized in that, when the new energy vehicle breaks down, the high voltage battery is disconnected from the high voltage side of the inverter, and the low voltage battery is disconnected from the low voltage side of the inverter. The relays are also disconnected between the two sides, and the six power switching devices in the three bridge arms on the high voltage side of the inverter are all turned off. 4. The trailer protection method for new energy vehicles according to claim 1, wherein the temporary low-voltage power supply also generates an activation signal at the low-voltage side to close the relay; When the relay is closed, the low-voltage side can obtain power from the low-voltage battery, start the low-voltage control system and generate a normal driving signal; the normal driving signal takes over the control of the three-phase short-circuit mode on the high-voltage side, and turns on the cooling device; until the permanent When the speed of the magnetic synchronous motor is close to 0, the relay is disconnected, thereby shutting down each cooling device, and exiting the three-phase short-circuit mode on the high-voltage side. 5. A realization circuit of a trailer protection method for a new energy vehicle, characterized in that it comprises: - a linear voltage stabilizing circuit, connected in parallel with the busbar capacitors to obtain power supply and generate a temporary low-voltage power supply; ——Parallel circuit, receiving normal low-voltage power supply and temporary low-voltage power supply input independently of each other, and supplying power to the half-bridge drive module; ——The half-bridge drive module, controlled by the drive signal sent by the logic circuit, turns on or off each power switching device on the high-voltage side of the inverter; ——The logic circuit receives the input of normal low-voltage power supply and normal driving signal, and sends a driving signal to the half-bridge driving module; when the normal low-voltage power supply is invalid, the logic circuit outputs a preset level signal to the half-bridge driving module; when normal When the low-voltage power supply is effective, the logic circuit outputs a normal driving signal. 6. The implementation circuit of the trailer protection method for new energy vehicles according to claim 5, further comprising: - an isolation transformer generating an activation signal on the low voltage side of the inverter depending on said temporary low voltage supply; - The relay, located between the low-voltage battery and the low-voltage side of the inverter, is opened and closed by the vehicle start signal or one of the activation signals. 7. The implementation circuit of the trailer protection method for new energy vehicles according to claim 6, wherein the isolation transformer is replaced by an optocoupler or an optorelay.