CN116155075A

CN116155075A - Active discharging circuit and method for electric vehicle

Info

Publication number: CN116155075A
Application number: CN202310061916.7A
Authority: CN
Inventors: 刘蕾; 焦民胜; 宋天才; 肖雨
Original assignee: Jee Automation Equipment Shanghai Co ltd
Current assignee: Jee Automation Equipment Shanghai Co ltd
Priority date: 2023-01-17
Filing date: 2023-01-17
Publication date: 2023-05-23

Abstract

The invention discloses an active discharging circuit and method of an electric vehicle, wherein the discharging circuit comprises an active discharging resistor, a switching tube, a bus capacitor, a logic management unit, a low-voltage control unit and a driving unit; the active discharging resistor and the switching tube are connected in series at two ends of the bus capacitor; one end of the logic management unit is connected with the driving unit in series and then connected with the switch tube, and the other end of the logic management unit is connected with the low-voltage control unit; the driving unit is used for controlling the switching tube to be opened and closed. By independently designing the power supply network at the high-voltage side, the high-voltage side discharging logic and the driving unit can reliably and continuously operate after the low-voltage power failure, and the high-voltage safety of the whole vehicle is ensured.

Description

Active discharging circuit and method for electric vehicle

Technical Field

The invention relates to the technical field of electric vehicles, in particular to an active discharging circuit and method of an electric vehicle.

Background

With the rapid development of the modern electric automobile technology, the voltage and the safety level of the electric automobile are higher and higher, and the safety protection requirements under the fault state are also more and more severe. Under the working condition that the automobile collides or has an extreme fault, the controller is required to complete the discharge of the charges in the bus capacitor within a specified time, and meanwhile, the attenuation influence on the performance of the controller is avoided. At present, the measures adopted by the electric control product for discharging the bus capacitor have three strategy guarantees of passive discharging, general active power generation and emergency active discharging, so that the safety requirement of the system can be met under normal discharging working conditions and abnormal discharging working conditions.

At present, the passive discharge of the controller mostly adopts a mode of connecting a discharge resistor in series on a high-voltage bus to generate certain continuous power consumption. The general active discharge is controlled by adopting a low-voltage MCU (micro control unit) to perform algorithm control, and the rapid discharge is performed through a motor winding. The emergency active discharge is usually in the form of a discharge resistor series control switch, and when the active discharge needs to be executed, a closed switch logic is executed so as to realize the rapid discharge of the charge of the bus capacitor.

The emergency active discharge scheme of the current controller can effectively realize the execution of the active discharge logic when the power supply of the low-voltage side is normal, and can realize the diagnosis of the emergency active discharge fault logic through the on-line monitoring of the bus voltage, thereby avoiding the cutting off of the active discharge process under the adhesion condition of the main contactor and protecting the discharge resistor. However, when the low-voltage power supply falls off due to an abnormal collision event, the emergency active discharge diagnosis logic cannot be realized, the voltage of the high-voltage bus terminal cannot be discharged, and huge hidden danger is brought to personnel safety.

Disclosure of Invention

The invention aims to provide an active discharging circuit and method for an electric vehicle, which are used for realizing reliable and continuous operation of a high-voltage side discharging logic and a driving unit after low-voltage power failure by independently designing a power supply network at a high-voltage side, so that the high-voltage safety of the whole vehicle is ensured.

In order to achieve the above object, the present invention provides an electric vehicle active discharge circuit, for example, the discharge circuit includes an active discharge resistor, a switching tube, a bus capacitor, a logic management unit, a low voltage control unit and a driving unit;

the active discharging resistor and the switching tube are connected in series at two ends of the bus capacitor;

one end of the logic management unit is connected with the driving unit in series and then connected with the switch tube, and the other end of the logic management unit is connected with the low-voltage control unit;

the driving unit is used for controlling the switching tube to be opened and closed.

Further, the other end of the logic management unit is connected with the isolation unit in series and then connected with the low-voltage control unit;

the isolation unit is used for receiving the low-voltage discharge signal transmitted by the low-voltage control unit and sending a low-voltage discharge instruction to the logic management unit;

the isolation unit is also used for sending a high-voltage discharge enabling signal to the logic management unit.

Further, the discharging circuit further comprises an emergency power supply unit,

one end of the emergency power supply unit is connected with one end of the bus capacitor, and the other end of the emergency power supply unit is connected with the driving unit;

the emergency power supply unit is used for stably supplying power to the high-voltage side after the low-voltage side is powered down.

Further, the emergency power supply unit and the diagnosis latch unit are connected in series and then connected with the logic management unit;

the diagnosis latch unit is used for monitoring the potential state of the high-voltage side bus voltage and identifying the on-off state of the main contactor.

Further, the emergency power supply unit and the fixed opening unit are connected in series and then connected with the logic management unit;

the fixed opening unit is used for realizing trial discharge of the high-voltage side when the main contactor is adhered;

the fixed opening unit is also used for discharging the bus capacitor charge when the main contactor is disconnected.

Further, a diode is connected in parallel inside the switching tube.

Further, the switching tube is a MOS tube.

Based on the same inventive concept, the present invention also provides an electric vehicle driving discharge method, which is applied to the discharge circuit of any one of claims 1 to 7, the discharge method comprising:

when the low-voltage side power supply is abnormal, the low-voltage control unit diagnoses the low-voltage side discharge abnormality, changes the level, sends the level change to the isolation unit, and enables the fixed opening unit;

the logic management unit receives a fixed opening unit signal sent by the fixed opening unit and a high-voltage discharge enabling signal sent by the isolation unit;

the logic management unit integrates various signals and finally outputs an active discharge signal to the driving unit so that the driving unit performs narrow pulse width active discharge.

Further, when the adhesion fault of the main contactor is removed and the main contactor is disconnected, the fixed opening unit discharges the capacitance charge of the bus, so that the voltage of the bus drops;

when the diagnosis latch unit recognizes that the bus voltage drops, level overturning latching is carried out, and diagnosis latch signals are sent to the logic management unit;

the logic management unit sends an active discharge signal to the driving unit, so that the driving unit is switched from a narrow pulse discharge state to a continuous discharge state, and the rapid discharge of the bus voltage is completed.

The invention has the technical effects and advantages that: 1. according to the invention, a circuit optimization design is adopted for the design of the controller, active discharge logic can be effectively executed under the normal condition of low-voltage side power supply, the controller can be powered in an emergency way by a high-voltage side and perform logic management when the low-voltage side is abnormally powered down, when the main contactor is stuck, discharge can be tried through narrow pulse, the continuous heating and burning of a discharge resistor are prevented, and when the main contactor is disconnected, the continuous discharge state can be switched to realize rapid charge discharge, so that the whole operation is reliable and safe;

2. by designing the high-low voltage isolation unit in the active discharging circuit, effective active discharging logic can be executed during normal low-voltage power supply, and when abnormal low-voltage power is lost, the abnormal state of the low-voltage side can be accurately diagnosed, the high-voltage side discharging logic is triggered, and the structure implementation form is simple and reliable; the diagnosis latch unit is designed through the high-voltage side voltage, so that the on-off state of the main contactor can be indirectly and effectively identified, the self-protection and rapid active discharge logic of the resistor are realized, and the structure is simple and reliable;

3. through the design of the fixed narrow pulse opening unit, the hardware circuit can realize the trial discharge logic when the main contactor is adhered, so that the overheat damage of the discharge resistor is prevented, meanwhile, the charge is discharged when the main contactor is disconnected, the dual function is realized, and the safety discharge requirement of the system is improved; by independently designing the power supply network at the high-voltage side, the high-voltage side discharging logic and the driving unit can reliably and continuously run after the low-voltage power failure, and the high-voltage safety of the whole vehicle is ensured.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of an electric vehicle main discharge circuit according to an embodiment of the present invention;

fig. 2 is a waveform diagram of an execution flow of an electric vehicle main discharging circuit according to an embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In order to solve the defects in the prior art, the invention discloses an active discharging circuit of an electric vehicle, which is shown in figure 1, and comprises an active discharging resistor, a switch tube, a bus capacitor, a logic management unit, a low-voltage control unit and a driving unit,

the active discharging resistor and the switching tube are connected in series at two ends of the bus capacitor, namely in series at the positive electrode and the negative electrode of the high-voltage bus;

one end of the logic management unit is connected with the driving unit in series and then connected with the switching tube, and the other end of the logic management unit is connected with the isolation unit in series and then connected with the low-voltage control unit;

the logic management unit is used for receiving a discharging instruction output by the low-voltage side.

The driving unit is used for receiving the output signal of the logic management unit and outputting a switching signal to drive the switching tube and control the switching tube to be opened and closed;

the driving unit is also used for receiving power supply of the high-voltage side, and can maintain an active discharging state after low-voltage power failure.

The isolation unit is used for receiving the low-voltage discharge signal transmitted by the low-voltage control unit;

when the power supply of the low-voltage side is normal, the isolation unit can effectively execute the low-voltage side transmission discharging logic, namely, the isolation unit sends a low-voltage discharging instruction to the logic management unit; the isolation unit adopts an isolation chip to realize the function of transmitting a low-voltage discharge signal to high-voltage isolation;

when the low-voltage side power supply is abnormal, the isolation unit can maintain a default design state, and the isolation unit transmits a high-voltage discharge enable signal like the logic management unit of the high-voltage side.

In some specific embodiments, the discharging circuit further comprises an emergency power supply unit, one end of the emergency power supply unit is connected with one end of the bus capacitor, and the other end of the emergency power supply unit is connected with the driving unit;

the emergency power supply unit is used for carrying out power supply conversion on the high-voltage side bus voltage, and is used for stably supplying power to a circuit on the high-voltage side after the low-voltage side is powered down.

In some specific embodiments, the emergency power supply unit and the diagnostic latch unit are connected in series and then connected with the logic management unit;

the diagnosis latch unit is used for monitoring the potential state of the high-voltage side bus voltage and making corresponding actions; the method comprises the following steps:

outputting a latch state signal to a logic management unit when the diagnosis latch unit detects that the bus voltage has an unexpected drop state;

and when the diagnosis latch unit detects that the bus voltage has no obvious change, maintaining a default forbidden continuous discharge state.

Namely, the diagnosis latch unit can realize the state diagnosis of prohibiting continuous discharge when the high-voltage main contactor is stuck and executing continuous active discharge after the main contactor is disconnected.

In some specific embodiments, the emergency power supply unit and the fixed opening unit are connected in series and then connected with the logic management unit;

the fixed switching-on unit is used for executing narrow pulse switching-on logic on a high-voltage side by default; the fixed opening unit is used for actively attempting intermittent discharge at the high voltage side after the power is off at the low voltage side, so that the active discharge resistor is effectively protected when the main contactor is adhered;

meanwhile, the fixed opening unit is used for discharging bus capacitor charges to cause the drop of bus voltage after the active contactor is disconnected, so that the diagnosed latching unit can effectively identify that the main contactor is in an on-off state.

In some specific embodiments, the switch tube is internally provided with a diode connected in parallel, and the diode is used for preventing the switch tube from being broken down and protecting the switch tube better.

In some specific embodiments, the switching tube is a MOS tube.

The active discharge circuit of the present invention performs signal timing performed by the high-side circuit when performing active discharge, as shown in fig. 2:

in the phase t0-t 1: the high-low voltage side is in a normal power supply state, the fixed on logic of the high-voltage side is in a non-enabling stage, a narrow pulse signal is not output, the active discharge driving unit does not execute the discharge logic, the active discharge resistor is in an idle state, and the bus voltage maintains a given value unchanged.

In the stage t1-t 2: at time t1, the active discharging circuit receives an active discharging instruction of the low-voltage side or a power-down condition of the low-voltage side, the low-voltage control logic received by the high-voltage side changes in level, so that the fixed switching-on logic is enabled, and the driving logic is controlled by the fixed switching-on logic to perform narrow pulse width active discharging; the main contactor is stuck at this time, so that the busbar voltage does not drop.

In the phase t2-t 3: at the time t2, the adhesion fault of the main contactor is disconnected, and the charge of the bus capacitor is discharged due to the discharging process of a narrow pulse width, so that the voltage of the bus is dropped.

After the t3 phase: the diagnosis latch logic at the high-voltage side recognizes that the bus voltage drops at the time t3, and performs level inversion latch, so that the active discharge driving logic unit is switched from a narrow pulse discharge state to a continuous discharge state, and rapid discharging of the bus voltage is completed.

when the low-voltage side discharge is abnormal, the low-voltage control unit diagnoses the low-voltage side discharge abnormality, changes the level, sends the level change to the isolation unit, and enables the fixed opening unit;

When the adhesion fault of the main contactor is removed and the main contactor is disconnected, the fixed opening unit discharges the bus capacitor charge to enable the bus voltage to drop;

The existing controller emergency active discharge scheme can effectively realize the execution of active discharge logic when the power supply of the low-voltage side is normal, and can realize the diagnosis of emergency active discharge fault logic through the on-line monitoring of bus voltage. However, when the low-voltage side power supply drops due to collision, the existing logic cannot effectively operate, two unexpected logic states can be generated, and the active discharge logic is continuously and not continuously performed. When the main contactor is not disconnected, the continuous active discharge logic can cause the discharge resistor to bear overload and generate failure risk; when the main contactor is opened, the non-continuous active discharging logic can cause that the bus voltage cannot be discharged within a specified time, and the safety target of the whole vehicle high voltage is violated.

Therefore, the invention adopts the circuit optimization design for the design of the controller, can realize the effective execution of the active discharge logic under the normal condition of low-voltage side power supply, can realize emergency power supply and logic management by the high-voltage side when the low-voltage side is abnormally powered down, can try to discharge through narrow pulse when the main contactor is stuck, can prevent the continuous heating and burning of the discharge resistor, and can switch the continuous discharge state to realize the rapid charge discharge when the main contactor is disconnected, thereby ensuring the reliable and safe integral operation.

Finally, it should be noted that: the foregoing description is only illustrative of the preferred embodiments of the present invention, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements or changes may be made without departing from the spirit and principles of the present invention.

Claims

1. The electric motor car active discharge circuit is characterized by comprising an active discharge resistor, a switching tube, a bus capacitor, a logic management unit, a low-voltage control unit and a driving unit;

2. An electric vehicle active discharge circuit according to claim 1, wherein,

the other end of the logic management unit is connected with the isolation unit in series and then connected with the low-voltage control unit;

3. An electric motor car active discharge circuit according to claim 2, wherein the discharge circuit further comprises an emergency power supply unit,

4. An electric motor car main power discharge circuit as set forth in claim 2 or 3, wherein,

the emergency power supply unit and the diagnosis latch unit are connected in series and then connected with the logic management unit;

5. An electric vehicle active discharge circuit as claimed in claim 4, wherein,

the emergency power supply unit and the fixed opening unit are connected in series and then connected with the logic management unit;

6. An electric motor car main power discharge circuit as set forth in claim 1 or 5, wherein,

and a diode is connected in parallel inside the switching tube.

7. An electric motor car main power discharge circuit as set forth in claim 1 or 5, wherein,

the switch tube is an MOS tube.

8. An electric vehicle driving discharge method, characterized in that the discharge method is applied to the discharge circuit of any one of claims 1 to 7, the discharge method comprising:

9. The method of claim 8, wherein,