A range extender control method

Abstract

This invention discloses a range extender control method, comprising the following steps: S1, the range extender receives a start signal and controls the range extender according to the maximum allowable discharge power P of the current battery pack. dischargemax With engine coolant temperature T coolant S1. The target torque signal is sent to the GCU, which controls the generator to output positive torque to drive the engine; S2. When the engine reaches the target speed, the GCU outputs zero torque and exits the start-up process, and the ECU performs fuel injection and ignition; S3. Based on the maximum allowable charging power P... chargemax Set the target torque for the ECU and the target speed for the GCU. S4, after a set time, simultaneously reset the closed-loop status of the front oxygen sensor. oxygen After the closed loop is reported, ignition is completed. S5, after ignition is completed, enter the first power generation mode.

Description

Technical Field

[0001] This invention belongs to the field of automotive technology, and in particular relates to a range extender control method. Background Technology

[0002] As national regulations continue to tighten on fuel consumption and emissions standards for automobiles, hybrid technology is considered a better approach to meet the next phase of fuel consumption and emissions regulations. Range-extended electric vehicles (REEVs) are easy to implement, low-cost, can alleviate range anxiety associated with pure electric vehicles, and effectively reduce overall fuel consumption and emissions. Due to these advantages, they are considered a superior technology and have been adopted by major automakers.

[0003] Currently, the control strategies for range extenders mainly favor either power following (the range extender's power output equals the vehicle's power demand) or fixed-point control. While these strategies can reduce overall vehicle fuel consumption to some extent, they are not suitable for all vehicle operating conditions. Using current control methods can lead to problems such as faster battery pack degradation, suboptimal fuel consumption, and reduced driving range. Summary of the Invention

[0004] To address the problems in related technologies, this application provides a range extender control method that, without changing the controller hardware, can automatically select a control strategy based on the actual vehicle operating conditions for vehicles with a pure electric range (e.g., >50km), thereby significantly reducing the high-power charging and discharging time of the battery pack, extending battery life, reducing fuel consumption, and increasing the overall vehicle range.

[0005] The technical solution is as follows: A range extender control method, comprising the following steps:

[0006] S1, the range extender receives the start signal and determines the maximum allowable discharge power P of the current battery pack. dischargemax With engine coolant temperature T coolant The target torque signal is sent to the GCU, and the GCU controls the generator to generate positive torque to drive the engine.

[0007] S2, when the engine reaches the target speed, the GCU generates zero torque and exits the start-up, and the ECU performs fuel injection and ignition;

[0008] S3, based on the maximum allowable charging power P chargemax Set the target torque for the ECU and the target speed for the GCU.

[0009] S4, after a set time, the closed-loop state of the front oxygen sensor S oxygen Once the closed-loop reporting is completed, ignition is finished.

[0010] After S5, when the ignition is completed, enter the first power generation mode. The specific content of the first power generation mode is as follows: According to the comprehensive efficiency map obtained by superimposing the engine fuel consumption map and the generator system efficiency map, subtract the set value ΔP from the vehicle demand power P. The obtained power value is used as the target power to select the target torque on the optimal efficiency line and send it to the ECU, and select the target speed and send it to the GCU. demand Subtract the set value ΔP from the vehicle demand power P. The obtained power value is used as the target power to select the target torque on the optimal efficiency line and send it to the ECU, and select the target speed and send it to the GCU.

[0011] Optionally, in S2, simultaneously detect whether the engine speed N engine remains above the target value. If so, the startup is completed; otherwise, the startup fails.

[0012] Optionally, in S2, if the ECU does not receive the target speed after a set time, it is determined that the startup fails.

[0013] Optionally, in S5, when the actual SOC value < SOC low or the actual vehicle speed V vehicle < V1, the vehicle exits the first power generation mode. And when the SOC value < SOC low , enter the second power generation mode. In other working conditions, the range extender stops and enters the pure electric mode. The specific content of the second power generation mode is as follows:

[0014] If the actual SOC1 < SOC < SOC low at this time, if P demand < P, the range extender stops, and the pure electric mode continues. When the stop time reaches the set time, the range extender starts again.

[0015] Optionally, P max、 P min are respectively the maximum power point and the minimum power point on the best efficiency curve;

[0016] When P demand < P min , output according to P min . When P demand > P max , output according to P max . If P demand < P min , when the SOC rises to SOC high (SOC high > SOC low ). The range extender stops and enters the pure electric mode until the SOC drops below < SOC low again, and then continue to execute the above steps;

[0017] When P min < P demand < P max , in order to ensure that the SOC of the battery pack is controlled, set P demandIncreasing or decreasing ΔP1 makes the battery pack SOC at a certain level. low With SOC low1 (SOC1 <SOC low1 <SOC low Fluctuations between )

[0018] Such as actual SOC1 <SOC<SOC low At this time, if P demand >P1, and the vehicle speed V vehicle >V2, the range extender continues to operate, according to the above P demand <P min P demand >P max P min <P demand <P max Time-based strategy execution;

[0019] If SOC < SOC1, then according to the above P demand <P min P demand >P max P min <P demand <P max Execution of the strategy at any time.

[0020] When P min <P demand <P max When the vehicle is accelerating, the range extender needs to respond to the power request. Based on the air-fuel ratio lambda signal, the range extender adjusts the rate of power increase to ensure that the vehicle's fuel consumption and emissions do not deteriorate under transient conditions compared to steady-state conditions.

[0021] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit the invention. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0023] Figure 1 This is a flowchart illustrating the startup phase of the present invention;

[0024] Figure 2 This is a schematic diagram of the ignition process of the present invention;

[0025] Figure 3 This is a schematic diagram of the first power generation mode of the present invention;

[0026] Figure 4 This is a schematic diagram of the process for exiting the first power generation mode according to the present invention;

[0027] Figure 5 This is a schematic diagram of the second power generation mode of the present invention. Detailed Implementation

[0028] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0029] As attached Figure 1-5 As shown:

[0030] S1, the range extender receives the start signal and determines the maximum allowable discharge power P of the current battery pack. dischargemax With engine coolant temperature T coolant The target torque signal is sent to the GCU, and the GCU controls the generator to generate positive torque to drive the engine.

[0031] S2, when the engine reaches the target speed, the GCU generates zero torque and exits the start-up, and the ECU performs fuel injection and ignition; at the same time, it detects the engine speed N. engine If the target speed is maintained above the target value, the start-up is complete; otherwise, the start-up fails. Additionally, if the ECU receives the target speed and the target speed is not reached after a certain period of time, the start-up is also considered to have failed.

[0032] S3, based on the maximum allowable charging power P chargemax The target torque is set for the ECU, and the target speed is set for the GCU; the range extender is started under a fixed low-power output condition, which can significantly reduce cold-start emissions. During start-up, the range extender does not respond to the vehicle's power demand P. demand Signal. After the engine has started, it is in a cold state. If the engine is directly put into high power output at this time, the emissions will be worse. Therefore, the ignition condition is set.

[0033] S4, after a set time, the closed-loop state of the front oxygen sensor S oxygen Once the closed-loop reporting is completed, ignition is finished.

[0034] S5, after ignition is complete, it enters the first power generation mode. Specifically, the first power generation mode involves: based on the combined efficiency map obtained by overlaying the engine fuel consumption map and the generator system efficiency map, finding the optimal efficiency point on different iso-power lines on this map and drawing a line, ensuring that the engine and generator operate on this optimal efficiency line. The total vehicle power demand P is then calculated. demandSubtract the set value △P, and use the obtained power value as the target power. Select the target torque on the optimal efficiency line and send it to the ECU, and select the target speed and send it to the GCU. In this way, the battery pack will discharge according to the power of △P. △P is a fixed value. When the steady-state P demand changes, the range extender adjusts, and the discharge power of the battery pack remains unchanged. However, when the vehicle accelerates, the range extender does not respond to the power change during acceleration, and the battery pack provides the transient power change. In this way, the discharge power of the battery pack decreases, which can extend the life of the battery pack and also reduce the power loss of the battery pack, thereby improving the vehicle's cruising range.

[0035] Optionally, in S2, simultaneously detect whether the engine speed N engine remains above the target value. If so, the startup is completed; otherwise, the startup fails.

[0036] Optionally, in S2, if the ECU does not reach the target speed after a set time when receiving the target speed, it is determined that the startup fails.

[0037] Optionally, in S5, when the actual SOC value < SOC low or the actual vehicle speed V vehicle < V1, the vehicle exits the first power generation mode. And when the SOC value < SOC low , it enters the second power generation mode, and the range extender stops and enters the pure electric mode under other working conditions; the second power generation mode is specifically:

[0038] If the actual SOC1 < SOC < SOC low at this time, if P demand < P1, the range extender stops, and the pure electric mode continues to be executed. When the stop time reaches the set time, the range extender starts again.

[0039] Optionally, P max、 P min are respectively the maximum power point and the minimum power point of the points on the best efficiency curve;

[0040] When P demand < P min , output according to P min When P demand > P max , output according to P max ; If P demand < P min , when the SOC rises to SOC high (SOC high > SOC low ), the range extender stops and enters the pure electric mode until the SOC drops again to < SOC low , and continue to execute the above steps;

[0041] When Pmin <P demand <P max To ensure that the battery pack's SOC is under control, P demand Increasing or decreasing ΔP1 makes the battery pack SOC at a certain level. low With SOC low1 (SOC1 <SOC low1 <SOC low Fluctuations between )

[0042] Such as actual SOC1 <SOC<SOC low At this time, if P demand >P1, and the vehicle speed V vehicle >V2, the range extender continues to operate, according to the above P demand <P min P demand >P max P min <P demand <P max Time-based strategy execution;

[0043] If SOC < SOC1, then according to the above P demand <P min P demand >P max P min <P demand <P max Execution of the strategy at any time.

[0044] When P min <P demand <P max When the vehicle is accelerating, the range extender needs to respond to the power request. Based on the air-fuel ratio lambda signal, the range extender adjusts the rate of power increase to ensure that the vehicle's fuel consumption and emissions do not deteriorate under transient conditions compared to steady-state conditions.

[0045] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention described herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not invented herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the appended claims.

[0046] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A range extender control method, characterized in that, Includes the following steps: S1, the range extender receives the start signal and determines the maximum allowable discharge power P of the current battery pack. dischargemax With engine coolant temperature T coolant The system determines and sends a target torque signal to the GCU, which then controls the generator to generate positive torque to drive the engine. S2, when the engine reaches the target speed, the GCU stops starting at zero torque, and the ECU performs fuel injection and ignition; simultaneously, the engine speed N is detected. engine If the value remains above the target value, the startup is complete; otherwise, the startup fails. S3, based on the maximum allowable charging power P chargemax The target torque is set for the ECU, and the target speed is set for the GCU, so that the range extender starts with a fixed low power output, and does not respond to the vehicle's required power P during this process. demand ; S4, after a set time, the front oxygen sensor simultaneously enters closed-loop state S oxygen After the closed-loop operation is completed, ignition is initiated to reduce cold-start emissions; S5, after ignition is completed, the first power generation mode is entered. The first power generation mode specifically involves: based on the comprehensive efficiency map obtained by superimposing the engine fuel consumption map and the generator system efficiency map, the total vehicle power demand P is calculated. demand Subtracting the set value ΔP, the resulting power value is used as the target power. On the optimal efficiency line, the target torque is selected and sent to the ECU, and the target speed is selected and sent to the GCU.

2. The range extender control method according to claim 1, characterized in that, In step S2, if the ECU receives the target speed and fails to reach the target speed after a set time, it determines that the start-up has failed.

3. The range extender control method according to claim 1, characterized in that, In S5, when the actual SOC value < SOC low Or the actual vehicle speed V vehicle <V1, the vehicle exits the first power generation mode, and when the SOC value is <SOC low When the second power generation mode is activated, the range extender shuts down and enters pure electric mode for all other operating conditions. The second power generation mode is specifically as follows: If the actual SOC1 < SOC < SOC low At this time, if P demand <P1, the range extender stops and continues to operate in pure electric mode. When the stop time reaches the set time, the range extender restarts.

4. The range extender control method according to claim 3, characterized in that, P max P min These are the maximum and minimum power points on the optimal efficiency curve, respectively, when P demand <P min At that time, according to P min Output, when P demand >P max At that time, according to P max Output; if P demand <P min SOC rises to SOC high SOC high >SOC low The range extender shuts down and enters pure electric mode until the SOC drops below SOC again. low If necessary, continue with the above steps; When P min <P demand <P max To ensure that the battery pack's SOC is under control, P demand Increasing or decreasing ΔP1 makes the battery pack SOC at a certain level. low With SOC low1 (SOC1<SOC low1 <SOC low Fluctuations between ) If the actual SOC1 < SOC < SOC low At this time, if P demand >P1, and the vehicle speed V vehicle >V2, the range extender continues to operate, according to the above P demand <P min P demand >P max P min <P demand <P max Time-based strategy execution; If SOC < SOC1, then according to the above P demand <P min P demand >P max P min <P demand <P max Time-based strategy execution; When P min <P demand <P max When the vehicle is accelerating, the range extender needs to respond to the power request. Based on the air-fuel ratio lambda signal, the range extender adjusts the rate of power increase to ensure that the vehicle's fuel consumption and emissions do not deteriorate under transient conditions compared to steady-state conditions.

Images