A control method for a range extender of a series hybrid vehicle

Abstract

The application discloses a kind of series type hybrid vehicle range extender control method, comprising the following steps: whole vehicle is high pressure;Driver hangs D, and starts driving by stepping accelerator pedal;Judge whether battery SOC is <20%, and peak discharge power is whether <40KW;Judge whether driver has quick acceleration operation;If there is quick acceleration operation, judge whether GCU allows to start APU;VCU sends start machine instruction to GCU, and GCU controls engine start;By comparing the opening threshold value of acceleration pedal judged by speed table output, VCU sends 0 power request, VCU sends stop machine instruction to GCU, and GCU controls APU stop, solve the delay judgment of engine stop when the speed is very low at present stage, and engine recognition crank angle is already inaccurate, and then lead to continuous request start-stop to cause engine work confusion, follow drag continuous injection, cause mixture combustion to be insufficient, and then most mixture enters inside catalytic converter and burns, temperature in catalytic converter sharply rises, cause the problem that catalytic converter sinters.

Description

Technical Field

[0001] This invention belongs to the field of vehicle system technology. Specifically, this invention relates to a control method for a series hybrid vehicle range extender. Background Technology

[0002] For series hybrid electric vehicles, the entire vehicle's driving force comes from the electric drive system. When the battery is fully charged, the vehicle runs on pure electric power, and the battery discharges to provide power to the electric drive system. When rapid acceleration is needed or the battery is low, the vehicle controller (hereinafter referred to as "VCU") sends a command to the range extender controller (hereinafter referred to as "GCU") to start the range extender. The GCU then controls the range extender (hereinafter referred to as "APU") to start generating electricity. At the same time, the VCU dynamically calculates the vehicle's power demand based on the electric drive system, high-voltage accessories, and whether the battery needs to be recharged. The VCU then sends the power demand to the GCU, which further controls the APU to generate electricity, working together with the battery to provide power to the vehicle. The VCU can also recharge the battery when its charge is low.

[0003] When the battery charge is low or the ambient temperature is low in winter, the battery's discharge capacity is greatly reduced. Under dynamic driving conditions, when the driver presses the accelerator pedal deeply and the torque demand is high, the VCU will issue a command to the GCU to control the APU to start and discharge together with the battery. However, when the driver releases the accelerator pedal or the drive switches to braking, the VCU judges that the driver's torque demand has suddenly decreased and issues a shutdown command to the GCU to control the APU to shut down. If the driver presses the accelerator pedal deeply again at this time, the VCU will also immediately issue a start command to the GCU to control the APU to start. For the APU, engine start-stop control presents a significant challenge. When the engine stops, the GCU initializes the crankshaft and camshaft phases and engine status after confirming that the engine has come to a complete stop, in order to prepare for the next restart. If, during the shutdown process, the engine speed is very low or has reached 0, but the engine shutdown delay judgment has not been completed, the crankshaft angle identified by the engine is no longer accurate. During the restart process, the flags used for direction determination and start-up are not initialized and may be in an erroneous state, leading to incorrect execution of the start-up process. This results in continuous start-stop requests, causing the engine to operate erratically and continuously inject fuel, leading to incomplete combustion of the air-fuel mixture. Subsequently, most of the mixture enters the catalytic converter for combustion, causing the temperature inside the catalytic converter to rise sharply, resulting in catalytic converter sintering. This is unacceptable not only for OEMs but also for vehicle customers.

[0004] Therefore, it is necessary to develop a series hybrid vehicle range extender control method to solve this problem. Summary of the Invention

[0005] This invention provides a control method for a series hybrid vehicle range extender, which solves the problems mentioned in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a heating control method for a range-extended electric vehicle, comprising a range extender system, the range extender system including a generator, an engine, and a range extender controller, comprising the following steps:

[0007] Step S10: Apply high voltage to the entire vehicle;

[0008] Step S20: The driver shifts to D gear and presses the accelerator pedal to start driving;

[0009] Step S21: Determine whether the battery SOC is <20% and the peak discharge power is <40KW. If yes, proceed to step S22; otherwise, maintain pure electric drive mode.

[0010] Step S22: Determine if the driver has performed a sudden acceleration operation. The sudden acceleration operation is determined in two ways: by calculating the rate of change of the accelerator pedal or the opening of the accelerator pedal. If not, maintain pure electric mode; if so, proceed to step S23.

[0011] Step S23: Determine whether the GCU allows the APU to be started. If not, maintain pure electric mode. If yes, proceed to step S24.

[0012] In step S24, the VCU sends a start command to the GCU, and the GCU controls the engine to start.

[0013] Step S25: Output the accelerator pedal opening threshold by looking up the vehicle speed table. Set 10 points and divide the vehicle speed from 0 to the maximum speed into 10 equal parts. Each vehicle speed corresponds to a different accelerator pedal opening. The accelerator pedal opening is evenly distributed from 10% to 100% in 10% increments. When the actual accelerator pedal opening is less than the accelerator pedal opening threshold output by looking up the vehicle speed table, Pactual < Pthreshold, or whether to press the brake pedal. If not, maintain the current driving mode. If yes, proceed to step S26.

[0014] In step S26, the VCU sends a 0 power request. After receiving the 0 power request from the VCU, the GCU controls the APU to control the power generation to be 0, the engine to control torque, and the generator to control speed. The power generation is 0, which is different from the normal control condition. The engine needs to enter the idling condition and not output torque, while the generator needs to be controlled to follow the speed to achieve the purpose of no power generation output.

[0015] Step S27: Based on the opening threshold in step S25, determine whether the accelerator pedal opening within 2 seconds is less than the accelerator pedal opening threshold output by the lookup table. If not, maintain the current driving mode. If yes, proceed to step S28.

[0016] In step S28, the VCU sends a shutdown command to the GCU, and the GCU controls the APU to shut down.

[0017] Preferably, in step S22, the method for determining rapid acceleration includes the following two approaches:

[0018] Method 1: If the accelerator pedal opening Pcurrent-P1 / z at the current moment is greater than 5%, which is 5% greater than the accelerator pedal opening at the previous sampling moment, and this condition persists for more than 0.3 seconds, then it is considered that the driver has performed a rapid acceleration operation.

[0019] Method 2: If the accelerator pedal opening at the current moment is 15% greater than the accelerator pedal opening at the previous sampling moment, then it is considered that the driver is performing a rapid acceleration operation.

[0020] Preferably, step S26 further includes the following steps:

[0021] S26.1: After receiving a 0 power request from the VCU, the GCU controls the APU to generate 0 power. It determines whether the GCU needs to request the engine control unit to allow idling control. If the engine control unit allows idling control, the GCU controls the generator to follow the rotation, and the engine control unit controls the engine to idle. Otherwise, if the engine control unit is not allowed to enter idling control due to a fault or special operating conditions, the GCU sends feedback to the VCU that it cannot enter 0 power control. The VCU then issues a shutdown command to the GCU based on the feedback. The GCU then controls the engine to shut down according to the VCU command to prevent the battery from being overcharged due to the APU generating power after special operating conditions.

[0022] Preferably, the special operating conditions include situations where charging is restricted or not allowed, such as when the battery is at a low temperature, when the battery is fully charged, or when the battery is at a high temperature.

[0023] Preferably, the following control is performed when the generator has no torque output, and the target torque is 0. That is, the torque loop control target is 0 in the vector control algorithm. The target current is calculated based on the target torque and the actual torque. The target control voltage is calculated based on the difference between the target current and the actual current. Then, through inverse PARK transformation and SVPWM algorithm, the IGBT switching of the three-phase full-bridge circuit is controlled to achieve 0 torque control.

[0024] The beneficial effects of adopting the above technical solutions are:

[0025] The VCU calculates the power demand of the APU based on requirements such as drive power and sends it to the GCU to control the APU's power generation. By first putting the APU into idle mode, it can quickly respond to the vehicle's power demand, while also avoiding the problem of engine malfunction and catalytic converter burnout caused by restarting during shutdown. Attached Figure Description

[0026] Figure 1 This is the overall flowchart provided by the present invention. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention, and to facilitate its implementation.

[0028] Example:

[0029] like Figure 1 As shown, a control method for a series hybrid vehicle range extender includes the following steps:

[0030] Step S10: Apply high voltage to the entire vehicle;

[0031] Step S20: The driver shifts to D gear and presses the accelerator pedal to start driving;

[0032] Step S21: Determine whether the battery SOC is <20% and the peak discharge power is <40KW. If yes, proceed to step S22; otherwise, maintain pure electric drive mode.

[0033] Step S22: Determine if the driver has performed a sudden acceleration operation. Sudden acceleration is determined in two ways: by calculating the rate of change of the accelerator pedal or the opening of the accelerator pedal. If not, maintain pure electric mode; if yes, proceed to step S23. The methods for determining sudden acceleration include the following two approaches:

[0034] Method 1: If the accelerator pedal opening Pcurrent-P1 / z at the current moment is greater than 5%, which is 5% greater than the accelerator pedal opening at the previous sampling moment, and this condition persists for more than 0.3 seconds, then it is considered that the driver has performed a rapid acceleration operation.

[0035] Method 2: If the accelerator pedal opening at the current moment is 15% greater than the accelerator pedal opening at the previous sampling moment, then it is considered that the driver is performing a rapid acceleration operation.

[0036] Step S23: Determine whether the GCU allows the APU to be started. If not, maintain pure electric mode; if yes, proceed to step S24.

[0037] In step S24, the VCU sends a start command to the GCU, and the GCU controls the engine to start.

[0038] Step S25: Output the accelerator pedal opening threshold by looking up the vehicle speed table. Set 10 points and divide the vehicle speed from 0 to the maximum speed into 10 equal parts. Each vehicle speed corresponds to a different accelerator pedal opening. The accelerator pedal opening is evenly distributed from 10% to 100% in 10% increments. When the actual accelerator pedal opening is less than the accelerator pedal opening threshold output by looking up the vehicle speed table, Pactual < Pthreshold, or whether to press the brake pedal. If not, maintain the current driving mode. If yes, proceed to step S26.

[0039] In step S26, the VCU sends a 0 power request. After receiving the 0 power request from the VCU, the GCU controls the APU to control the power generation to be 0, the engine to control torque, and the generator to control speed. The power generation is 0, which is different from the normal control condition. The engine needs to enter the idling condition and not output torque, while the generator needs to be controlled to follow the speed to achieve the purpose of no power generation output.

[0040] Step S26.1: After receiving the 0 power request from the VCU, the GCU controls the APU to control the generator power to be 0. It determines whether the GCU needs to request permission from the engine control unit (ECU) to enter idle speed control. If the ECU enters idle speed control, the GCU controls the generator to follow the rotation, and the ECU controls the engine to enter idle speed operation. Otherwise, if the ECU is not allowed to enter idle speed control due to a fault or special operating conditions, the GCU sends feedback to the VCU that it cannot enter 0 power control. The VCU then issues a shutdown command to the GCU based on the feedback, and the GCU controls the engine according to the VCU command. The system is shut down to prevent overcharging of the battery due to the APU generating power. These special operating conditions include situations where charging is restricted or not permitted, such as when the battery is at a low temperature, when the battery is fully charged, or when the battery is at a high temperature. The following control is implemented when the generator has no torque output, and the target torque is 0. That is, the torque loop control target is 0 in the vector control algorithm. The target current is calculated based on the target torque and the actual torque. The target control voltage is calculated based on the difference between the target current and the actual current. Then, through inverse PARK transformation and SVPWM algorithm, the IGBT switching of the three-phase full-bridge circuit is controlled to achieve 0 torque control.

[0041] Step S27: Based on the opening threshold in step S25, determine whether the accelerator pedal opening within 2 seconds is less than the accelerator pedal opening threshold output from the lookup table. If not, maintain the current driving mode; if yes, proceed to step S28.

[0042] In step S28, the VCU sends a shutdown command to the GCU, and the GCU controls the APU to shut down.

[0043] When the VCU has a low SOC and weak discharge capacity, the frequency of APU start-stop will increase significantly if the driver drives aggressively. When the driver releases the accelerator or applies the brake, the conventional strategy is for the VCU to directly control the APU to shut down. To avoid the problems described in the background, the VCU will not immediately send a shutdown request to the GCU, but will first send a 0kW power request. At this time, the GCU will control the engine to keep idling. If the driver does not press the accelerator pedal deeply within 2 seconds, the VCU will then issue a shutdown command to the GCU. At this time, the GCU can control the engine to shut down normally. If the driver presses the accelerator pedal deeply within 2 seconds, the VCU will calculate the power demand of the APU based on the drive power and other requirements, send it to the GCU, and then control the APU to generate electricity. By first putting the APU into idle mode, the system can quickly respond to the vehicle's power demands, while also avoiding the problem of engine malfunction and catalyst burnout caused by restarting during shutdown. Additionally, a new GCU start-stop permission flag signal is added. The GCU sends this signal to the VCU in real time. When the VCU sends a start command to the GCU, it simultaneously checks the start-stop permission flag. If the GCU determines that the APU does not meet the start conditions, the VCU will not issue a start command to prevent GCU control malfunction and component damage; otherwise, the VCU will issue a normal start command to the GCU.

[0044] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A control method for a series hybrid vehicle range extender, characterized in that: Includes the following steps: Step S10: Apply high voltage to the entire vehicle; Step S20: The driver shifts to D gear and presses the accelerator pedal to start driving; Step S21: Determine whether the battery SOC is <20% and the peak discharge power is <40KW. If yes, proceed to step S22; otherwise, maintain pure electric drive mode. Step S22: Determine if the driver has performed a sudden acceleration operation. The sudden acceleration operation is determined in two ways: by calculating the rate of change of the accelerator pedal or the opening of the accelerator pedal. If not, maintain pure electric mode; if so, proceed to step S23. Step S23: Determine whether the GCU allows the APU to be started. If not, maintain pure electric mode. If yes, proceed to step S24. In step S24, the VCU sends a start command to the GCU, and the GCU controls the engine to start. Step S25: Output the accelerator pedal opening threshold by looking up the vehicle speed table. Set 10 points and divide the vehicle speed from 0 to the maximum speed into 10 equal parts. Each vehicle speed corresponds to a different accelerator pedal opening. The accelerator pedal opening is evenly distributed from 10% to 100% in 10% increments. When the actual accelerator pedal opening is less than the accelerator pedal opening threshold output by looking up the vehicle speed table, Pactual < Pthreshold, or whether to press the brake pedal. If not, maintain the current driving mode. If yes, proceed to step S26. In step S26, the VCU sends a 0 power request. After receiving the 0 power request from the VCU, the GCU controls the APU to control the power generation to be 0, the engine to control torque, and the generator to control speed. The power generation is 0, which is different from the normal control condition. The engine needs to enter the idling condition and not output torque, while the generator needs to be controlled to follow the speed to achieve the purpose of no power generation output. Step S27: Based on the opening threshold in step S25, determine whether the accelerator pedal opening within 2 seconds is less than the accelerator pedal opening threshold output by the lookup table. If not, maintain the current driving mode; if so, proceed to step S28. In step S28, the VCU sends a shutdown command to the GCU, and the GCU controls the APU to shut down.

2. The control method for a series hybrid vehicle range extender according to claim 1, characterized in that: In step S22, the method for determining rapid acceleration includes the following two approaches: Method 1: If the accelerator pedal opening Pcurrent-P1 / z at the current moment is greater than 5%, which is 5% greater than the accelerator pedal opening at the previous sampling moment, and this condition persists for more than 0.3 seconds, then it is considered that the driver has performed a rapid acceleration operation. Method 2: If the accelerator pedal opening at the current moment is 15% greater than the accelerator pedal opening at the previous sampling moment, then it is considered that the driver is performing a rapid acceleration operation.

3. The control method for a series hybrid vehicle range extender according to claim 1, characterized in that: Step S26 also includes the following steps: S26.1: After receiving a 0 power request from the VCU, the GCU controls the APU to generate 0 power. It determines whether the GCU needs to request the engine control unit to allow idling control. If the engine control unit allows idling control, the GCU controls the generator to follow the rotation, and the engine control unit controls the engine to idle. Otherwise, if the engine control unit is not allowed to enter idling control due to a fault or special operating conditions, the GCU sends feedback to the VCU that it cannot enter 0 power control. The VCU then issues a shutdown command to the GCU based on the feedback. The GCU then controls the engine to shut down according to the VCU command to prevent the battery from being overcharged due to the APU generating power after the power is used in special operating conditions.

4. The control method for a series hybrid vehicle range extender according to claim 3, characterized in that: The special operating conditions mentioned include situations where charging is restricted or not allowed, such as when the battery is at a low temperature, when the battery is fully charged, or when the battery is at a high temperature.

5. The control method for a series hybrid vehicle range extender according to claim 3, characterized in that: The aforementioned follow-up control is performed when the generator has no torque output, and the target torque is 0. That is, the torque loop control target is 0 in the vector control algorithm. The target current is calculated based on the target torque and the actual torque. The target control voltage is calculated based on the difference between the target current and the actual current. Then, through inverse PARK transformation and SVPWM algorithm, the IGBT switching of the three-phase full-bridge circuit is controlled to achieve 0 torque control.

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