CN111845702A - A plug-in hybrid electric vehicle energy management method - Google Patents

Abstract

The invention provides an energy management method for a plug-in hybrid electric vehicle. The vehicle controller predicts the vehicle state in the next stage according to the current state information of the current vehicle speed, acceleration and cabin temperature; calculates the required torque and the heat demanded by the cabin; Optimal distribution of vehicle engine power and motor power; output control variables, including engine power, motor power, and heating resistance power; according to the engine state, there are three modes for heating the cabin: 1. Separate heating of engine waste heat; 2. HVAC heating resistance Individual heating; 3. Mixed heating mode. The present invention makes the electric power reasonably distributed in the whole driving cycle, improves the pure electric mileage, avoids the frequent starting of the engine, fully utilizes the residual heat of the engine, and reduces the fuel consumption.

Description

A plug-in hybrid electric vehicle energy management method

technical field

The invention relates to the technical field of hybrid electric vehicle energy control, in particular to a plug-in hybrid electric vehicle energy management method.

Background technique

In recent years, the continuous development of urban transportation and the continuous increase of car ownership have led to the increasing global fuel shortage and air pollution. To this end, governments have introduced stringent fuel consumption and emission regulations. In response to these regulations, the auto industry has devoted a lot of energy to the research and development of new energy vehicles. As the most representative technology in new energy vehicles, PHEV has been widely used in the field of urban transportation because of its good energy saving and emission reduction performance.

When a PHEV is driven in winter, the energy consumed by the heating of the cabin accounts for a large proportion of the energy consumption of the entire vehicle. At present, the PHEV cabin heating methods are as follows: 1. Use the coolant of the engine as the heat source to provide heat, which is called residual hot water heating; 2. Use the heating resistor to consume battery power for heating.

Prior Art Fig. 1 depicts a solution for heating a cabin of a plug-in hybrid electric vehicle, which combines two methods of heating with residual hot water and heating with resistance heating. The feature of this scheme is that when the engine is working, the passenger cabin is heated by the waste heat of the engine, and when the engine stops working, the passenger cabin is heated through a heating resistor. The disadvantages of this technique are:

1. During the actual operation of the PHEV, in the pure electric drive stage, the engine is turned off. If the heating resistor is used to heat the cabin at this time, the battery SOC will drop too fast, and the pure electric mileage will be greatly reduced, which will inevitably lead to an increase in fuel consumption.

2. The engine needs to have a preheating process. If the heat of the coolant is used to heat the passenger compartment at this time, the preheating process of the engine will be prolonged and the working efficiency of the engine will be reduced. And in order to use the engine waste heat for heating, the engine has to be started frequently, which is not conducive to energy saving and emission reduction.

SUMMARY OF THE INVENTION

The invention provides an energy management method for a plug-in hybrid electric vehicle, which avoids the excessively rapid decrease of the battery SOC, increases the pure electric mileage, and avoids the frequent starting of the engine.

To achieve the above purpose, the technical scheme adopted in the application is:

A plug-in hybrid electric vehicle energy management method, comprising the following steps:

(1) Accept the current state information of the vehicle, including current vehicle speed, acceleration, cabin temperature, and engine temperature;

(2) The vehicle controller predicts the vehicle state in the next stage according to the current state information of the current vehicle speed, acceleration and cabin temperature;

(3) Calculate the required torque and the heat required by the cabin;

(4) Optimize the distribution of the engine power and motor power of the vehicle; the optimization objective function F=f1+f2; f1 is the fuel consumption, and f2 is the engine startup penalty function;

(5) Output control variables, including engine power, motor power, heating resistance power;

(6) According to the engine state, there are three modes for heating the cabin: 1. The engine waste heat is heated separately; 2. The HVAC heating resistor is heated separately; 3. The hybrid heating mode.

Further, the concrete process in step (6) is:

If the engine does not start, use the HVAC heating resistor to heat it alone;

If the engine is started and the engine temperature does not reach the optimum working temperature, the engine cooling system is turned off and the HVAC heating resistor is used for heating alone;

If the engine is started and the engine cooling system is turned on, it is judged whether the engine waste heat meets the heating requirements of the cabin. If not, the engine waste heat and HVAC heating resistor mixed heating mode is used;

The present invention has technical effects:

(1) Reasonable distribution of electricity throughout the entire driving cycle to improve pure electric mileage;

(2) Avoid frequent engine start;

(3) Make full use of engine waste heat to reduce fuel consumption.

Description of drawings

FIG. 1 is a schematic diagram of a solution for heating a cabin of a plug-in hybrid electric vehicle in the prior art;

Fig. 2 is the control flow chart of the present invention;

Fig. 3 is the cabin heating structure diagram of the embodiment;

FIG. 4 is an analytic diagram of torque distribution execution for a coaxial parallel plug-in hybrid electric vehicle according to an embodiment.

Detailed ways

The specific technical solutions of the present invention are described with reference to the embodiments.

The invention is a plug-in hybrid vehicle energy management method developed in the vehicle controller, considering the thermal management of the passenger cabin, taking the cabin demand heat Q as an interference quantity, and optimizing the power distribution to the engine and the motor. FIG. 2 is a control flow of the present invention. The vehicle controller predicts the next stage of the vehicle state according to the current state information such as the current vehicle speed, acceleration, and cabin temperature. And optimize the distribution of vehicle engine power and motor power. The specific steps are:

(1) Accept the current state information of the vehicle, including current vehicle speed, acceleration, cabin temperature, and engine temperature;

(2) The vehicle controller predicts the vehicle state in the next stage according to the current state information of the current vehicle speed, acceleration and cabin temperature;

(3) Calculate the required torque and the heat required by the cabin;

(4) Optimize the distribution of the engine power and motor power of the vehicle; the optimization objective function F=f1+f2; f1 is the fuel consumption, and f2 is the engine startup penalty function;

(5) Output control variables, including engine power, motor power, heating resistance power;

(6) According to the engine state:

If the engine does not start, use the HVAC heating resistor to heat it alone;

If the engine is started and the engine temperature does not reach the optimum working temperature, the engine cooling system is turned off and the HVAC heating resistor is used for heating alone;

If the engine is started and the engine cooling system is turned on, it is judged whether the engine waste heat meets the heating requirements of the cabin. If not, the engine waste heat and HVAC heating resistor mixed heating mode is used;

Figure 3 is a diagram of the cabin heating structure. In the engine warm-up stage, valves P1, P2, and P3 are closed; when the cabin is heated by engine waste heat, valve P1 is closed and P2 and P3 are open. When the cabin does not need heating, valve P2 is closed.

In the embodiment of the present application, taking a coaxial parallel hybrid electric vehicle as an example, the control system of the hybrid electric vehicle includes an engine temperature sensor node, a cabin temperature sensor node, a wheel speed sensor node, and three cooling system valve actuator nodes. Engine actuator nodes, motor actuator nodes, heater resistor actuator nodes, vehicle controllers, CAN networks, and directly connected sensors, etc. The vehicle controller collects speed signals, temperature information, and driver instruction information through the CAN network and sensor nodes, and calculates and generates torque control commands and heating resistors according to vehicle dynamics control requirements and corresponding control strategies based on the obtained vehicle/wheel status information. Power command, and then send the calculated torque control command and heating resistance command to each actuator node through the CAN network.

FIG. 4 is an analytic diagram of the torque distribution execution of the coaxial-parallel plug-in hybrid electric vehicle according to the embodiment. The process of torque distribution of the coaxial-parallel plug-in hybrid electric vehicle is as follows: First, the engine temperature sensor collects the temperature signal of the current engine, and the cabin temperature sensor The current cabin temperature signal is collected, the wheel speed sensor collects the current vehicle speed signal, and sends it to the vehicle controller through the CAN network. After the receiving module of the vehicle controller receives the above signal and the driver's command, it controls the requirements and corresponding torque according to the vehicle dynamics. The distribution strategy is calculated to generate torque control commands, and then the torque commands of the engine and the motor are sent to the motor and the engine controller to execute the torque commands through the CAN network to realize the drive control of the vehicle. In this process, the vehicle controller takes into account the thermal demand of the passenger compartment, and optimizes the distribution of the source of its thermal energy, making full use of the preheating of the engine to achieve energy saving.

Claims (2)

1. A plug-in hybrid electric vehicle energy management method is characterized by comprising the following steps:

(1) receiving current state information of the vehicle, including current speed, acceleration, cabin temperature and engine temperature;

(2) the vehicle controller predicts the vehicle state of the next stage according to the current state information of the current speed, the acceleration and the cabin temperature;

(3) calculating a required torque and a required heat of the passenger cabin;

(4) optimally distributing the power of the whole vehicle engine and the power of the motor; optimizing the objective function F ═ F1+ F2; f1 is fuel consumption, f2 is engine starting penalty function;

(5) outputting control variables including engine power, motor power and heating resistance power;

(6) there are three modes of heating mode for the passenger cabin depending on the engine state: 1. independently heating by using the waste heat of the engine; heating by the HVAC heating resistor alone; 3. a hybrid heating mode.

2. The plug-in hybrid electric vehicle energy management method according to claim 1, wherein the specific process in the step (6) is as follows:

if the engine is not started, heating by adopting an HVAC heating resistor;

if the engine is started and the temperature of the engine does not reach the optimal working temperature, the engine cooling system is closed, and the HVAC heating resistor is used for heating independently;

if the engine is started and the engine cooling system is started, judging whether the waste heat of the engine meets the heating requirement of the passenger cabin, and if the waste heat of the engine cannot meet the heating requirement of the passenger cabin, adopting a mixed heating mode of the waste heat of the engine and an HVAC heating resistor; if so, the engine waste heat is adopted for independent heating.

Images