Method for correcting target soc according to vehicle speed in plug-in hybrid vehicle

Abstract

The application discloses a method for correcting target SOC according to vehicle speed in a plug-in hybrid electric vehicle, and preset starting charging SOC threshold and stopping charging SOC threshold of the vehicle; when the vehicle accelerates from the starting charging SOC threshold to a first high speed, the starting charging SOC threshold is corrected and reduced to a first high speed charging SOC threshold according to the first high speed; when the vehicle decelerates from the first high speed, the battery is charged until the battery power reaches the stopping charging SOC threshold to stop charging. In the application, the starting charging SOC threshold of the power battery is reduced after the vehicle accelerates, so that a greater difference between the starting charging SOC threshold and the preset stopping charging SOC threshold is obtained. In this way, the power battery can obtain a greater charging interval when the vehicle decelerates, the deceleration kinetic energy can be converted into electric energy to the greatest extent and stored, and thus the economy of the vehicle is improved.

Description

Technical Field

[0001] This invention relates to a method, and more particularly to a method for correcting a target state of charge (SOC) based on vehicle speed in a plug-in hybrid electric vehicle. Background Technology

[0002] In the existing technology, for plug-in hybrid electric vehicles, the power battery capacity is identified by SOC (State of Charge, remaining battery capacity).

[0003] To ensure the vehicle functions properly, it is necessary to pre-set the starting charging SOC threshold and the stopping charging SOC threshold. That is, charging begins when the power battery's charge level drops to the starting charging SOC threshold, and charging ends when the power battery's charge level rises to the stopping charging SOC threshold.

[0004] Setting the charging range described above can maximize the vehicle's driving performance, but there is still room for improvement. For example... Figure 1 As shown, when the vehicle is traveling at its current first speed, the SOC of the power battery (at the critical state of initial charging) remains unchanged. When the vehicle increases from the first speed to the second speed, the SOC of the power battery decreases. When the vehicle is traveling at a stable second speed, since the SOC of the power battery is already below the initial charging SOC threshold, the power battery will be charged to raise its SOC to the initial charging SOC threshold. As the vehicle continues to move forward, the SOC of the power battery remains stable (still at the critical state of the initial charging SOC threshold, and the power battery is not charged). Only when the vehicle decelerates from its current second speed will there be an action to convert kinetic energy into electrical energy, that is, the power battery will be charged during deceleration.

[0005] Because a charging stop SOC threshold has been set—that is, the difference between the starting charging SOC threshold and the stopping charging SOC threshold has been pre-defined—charging will stop when the battery's SOC reaches the stopping charging SOC threshold during vehicle deceleration. This means the charging process begins at the starting charging SOC threshold and ends at the stopping charging SOC threshold. This predetermined charging control method often results in the charging process ending before the vehicle deceleration is complete (reaching the set stopping charging condition and ceasing charging). This leads to excess energy during deceleration not being recovered and being wasted as braking heat, which is highly uneconomical. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a method for correcting the target state of charge (SOC) based on vehicle speed in a plug-in hybrid electric vehicle.

[0007] The method for correcting the target SOC based on vehicle speed in the plug-in hybrid electric vehicle described in this invention pre-sets the vehicle's initial charging SOC threshold and the stopping charging SOC threshold.

[0008] When the vehicle accelerates from the speed corresponding to the initial charging SOC threshold to the first high speed, the initial charging SOC threshold is corrected and reduced to the first high-speed charging SOC threshold according to the first high speed.

[0009] When the vehicle decelerates from the first high speed, it begins to charge the battery until the battery charge reaches the SOC threshold for stopping charging.

[0010] In the method for correcting the target SOC based on vehicle speed in a plug-in hybrid electric vehicle described in this invention,

[0011] The first high-speed charging SOC threshold is marked as SOC. 高速充电阈值 The SOC 高速充电阈值 =SOC 起始充电阈值 —SOC 修正量 ;

[0012] The SOC 修正量 It can be determined according to the following formula, namely:

[0013] SOC 修正量 = ((E / battery capacity) / 3600)*100; where E is the corrected energy, in kWs; and the battery capacity is in kWh.

[0014] E = (1 / 2 * m * V^2) / 1000; where m is the vehicle weight in kg; and V is the current vehicle speed in meters per second.

[0015] In the method for correcting the target SOC based on vehicle speed in the plug-in hybrid electric vehicle described in this invention, the battery is not charged during the process of the vehicle accelerating from the initial charging SOC threshold to the first high speed, until the vehicle starts charging the battery when it is traveling at the first high speed, and charging is stopped when the battery is charged to the first high-speed charging SOC threshold.

[0016] In the method for correcting the target SOC based on vehicle speed in a plug-in hybrid electric vehicle described in this invention, the initial charging SOC threshold of the power battery is reduced after the vehicle accelerates, in order to obtain a larger difference between the initial charging SOC threshold and the preset stopping charging SOC threshold. This ensures that the power battery has a larger charging range when the vehicle decelerates, maximizing the conversion of deceleration kinetic energy into electrical energy for storage, thereby improving the vehicle's fuel economy. Attached Figure Description

[0017] Figure 1This is a schematic diagram illustrating the relationship between vehicle speed and SOC in the prior art.

[0018] Figure 2 This diagram illustrates the relationship between vehicle speed and SOC after applying the method for correcting the target SOC based on vehicle speed in a plug-in hybrid electric vehicle as described in this invention. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0020] In the method for correcting the target SOC based on vehicle speed in a plug-in hybrid electric vehicle according to the present invention, a pre-set initial charging SOC threshold and a stop charging SOC threshold are established. Furthermore, when the vehicle accelerates from the speed corresponding to the initial charging SOC threshold to a first high speed, the initial charging SOC threshold is corrected and reduced to a first high-speed charging SOC threshold based on the first high speed. When the vehicle decelerates from the first high speed, charging of the battery begins until the battery charge reaches the stop charging SOC threshold, at which point charging stops. In other words, the present invention corrects the SOC threshold for the initial charging of the power battery, and this correction is related to the vehicle's driving speed. That is, after the vehicle accelerates, the initial charging SOC threshold of the power battery is reduced (reduced to the first high-speed charging SOC threshold) to obtain a larger difference between the initial charging SOC threshold and the pre-set stop charging SOC threshold. This ensures that the power battery has a larger charging range when the vehicle decelerates, maximizing the conversion of deceleration kinetic energy into electrical energy for storage, thereby improving the vehicle's fuel economy.

[0021] In this embodiment, the first high-speed charging SOC threshold is marked as SOC. 高速充电阈值 The SOC 高速充电阈值 =SOC 起始充电阈值 —SOC 修正量 And SOC 修正量 It can be determined according to the following formula, namely:

[0022] SOC 修正量 = ((E / battery capacity) / 3600)*100; where E is the corrected energy, in kWs; and the battery capacity is in kWh.

[0023] E = (1 / 2 * m * V^2) / 1000; where m is the vehicle weight in kg; and V is the current vehicle speed in meters per second.

[0024] Here is an example. Assume the current vehicle speed V is 120 km / h, which is equivalent to 33.3333 m / s after conversion; the vehicle weight m is 1800 kg, then the corrected electrical energy E = (1 / 2 * 1800 * 33.3333^2) / 1000 = 1000 kWs.

[0025] Assuming a battery capacity of 2kWh, then the SOC 修正量 = ((1000 / 2) / 3600)*100 = 13.88889%.

[0026] like Figure 2 The diagram illustrates the method for charging the power battery in a plug-in hybrid electric vehicle using the speed-based target SOC correction method described in this invention. In this example, when the vehicle is traveling at its current first speed, the power battery's SOC (at the critical state of initial charging, but not charging) remains unchanged. As the vehicle increases from the first speed to the second speed, the power battery's SOC decreases. When the vehicle reaches a stable second speed, since the power battery's SOC is now below the initial charging SOC threshold, it is charged to increase its SOC. To cope with subsequent vehicle deceleration and maximize the recovery of braking kinetic energy, the initial charging SOC threshold is corrected after the vehicle accelerates. Specifically, the difference between the set initial charging SOC threshold and the SOC correction amount derived based on the current higher speed is used as the charging SOC threshold at the current speed. When the power battery's charge reaches this current charging SOC threshold, charging stops, and the vehicle continues to travel at the current speed. When the vehicle decelerates from the current speed, charging resumes until the battery's charge reaches the set stopping charging SOC threshold. In the optimal scenario, the battery can be charged throughout the deceleration process to maximize the use of the vehicle's braking energy.

[0027] It should be noted that although the above embodiments describe in detail the method for correcting the target SOC based on vehicle speed in a plug-in hybrid electric vehicle according to the present invention, the method described in the present invention is not limited to plug-in hybrid electric vehicles (PHEVs), but can also be applied to vehicles such as HV Mode, HV (Electric Vehicle), and FCV (Fuel Cell Vehicle).

[0028] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for correcting a target State of Charge (SOC) based on vehicle speed in a plug-in hybrid electric vehicle, wherein a starting charging SOC threshold and a stopping charging SOC threshold are preset; characterized in that, When the vehicle accelerates from the speed corresponding to the initial charging SOC threshold to the first high speed, the initial charging SOC threshold is corrected and reduced to the first high-speed charging SOC threshold according to the first high speed. When the vehicle decelerates from the first high speed, charging begins and stops when the battery level reaches the stated state of charge (SOC) threshold. The first high-speed charging SOC threshold is marked as SOC. 高速充电阈值 The SOC 高速充电阈值 =SOC 起始充电阈值 —SOC 修正量 ; The SOC 修正量 It is determined according to the following formula, namely: SOC 修正量 = ((E / battery capacity) / 3600)*100; where E is the corrected energy, in kWs; and the battery capacity is in kWh. E = (1 / 2 * m * V) 2 ) / 1000; where m is the vehicle weight in kg; V is the current vehicle speed in meters per second.

2. The method for correcting the target SOC based on vehicle speed in a plug-in hybrid electric vehicle as described in claim 1, characterized in that, The battery is not charged during the process of the vehicle accelerating from the initial charging SOC threshold to the first high speed until the vehicle starts charging the battery when it is traveling at the first high speed, and charging stops when the battery is charged to the first high-speed charging SOC threshold.

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