CN204526866U - A kind of automobile three voltage power system - Google Patents

Abstract

The utility model relates to a power supply for automobiles, in particular to a three-voltage power supply system for automobiles. The system includes a 12V power supply unit, a 48V power supply unit, a 300V power supply unit, and a DC/DC converter Z1 Z2; the low-voltage end of the DC/DC converter Z1 is electrically connected to the 12V power supply in the 12V power supply unit, and the high-voltage end is connected to the 48V power supply unit. The 48V power supply in the power supply unit is electrically connected; the low-voltage end of the DC/DC converter Z2 is electrically connected to the 48V power supply, and the high-voltage end is electrically connected to the 300V power supply in the 300V power supply unit; the 12V power supply, 48V power supply, and 300V power supply , the DC/DC converter Z1, the DC/DC converter Z2 and the main controller communicate with each other through data lines and in the form of CAN network communication. The utility model is a three-voltage power supply system for automobiles which overcomes the problems of excessive current in the low-voltage power supply circuit in the automobile, too high matching of the engine, which easily leads to high fuel consumption rate, and difficult discharge of the vehicle-mounted lithium-ion storage battery in cold regions.

Description

A three-voltage power supply system for automobiles

technical field

The utility model relates to a power supply for automobiles, in particular to a three-voltage power supply system for automobiles.

Background technique

At present, the development of automobiles is facing four problems: first, due to the severe situation of energy consumption and environment, new energy vehicles have become an important direction for future transportation development; second, lithium-ion batteries have poor low-temperature characteristics and are not suitable for discharging at low temperatures; The third is that in order to meet the power requirements when the vehicle is matched with the engine, the engine displacement is often selected too large, causing the engine to often not work in the high-efficiency working area, and the fuel consumption rate is high at this time; the fourth is that the degree of electrification of automobiles continues to increase Correspondingly, the electric power demand of the electric accessories in the car continues to rise, which may easily cause excessive current in the low-voltage circuit. The total power of low-voltage electrical appliances in the car has increased from less than 2 kilowatts in traditional cars to more than 5 kilowatts in future cars. This will cause huge pressure on the current 12V low-voltage system of the car. For example, when 2 kW of power is required, the current flowing through the 12V power supply will reach 166A; and if 5 kW of power is required, the current flowing through the 12V power supply will reach 416A. Generally speaking, when the current exceeds 150A, the power loss on the wiring harness will be very large. At this time, the system has high requirements on the wires, causing the cost of the wiring harness to rise rapidly.

Contents of the invention

The utility model provides a three-voltage power supply system for automobiles in view of the above problems, which overcomes the problems of excessive current in the low-voltage power supply circuit in the automobile, high fuel consumption rate of the engine due to matching problems, and difficult discharge of the on-board lithium-ion battery in cold regions. problems and contribute to the development of new energy vehicles.

The technical scheme of the utility model is described as follows in conjunction with the accompanying drawings of the description:

A three-voltage power supply system for automobiles, the system includes a 12V power supply unit, a 48V power supply unit, a 300V power supply unit, a DC/DC converter Z1, and a DC/DC converter Z2; wherein the DC/DC converter Z1 low-voltage terminal It is electrically connected to the 12V power supply in the 12V power supply unit, and the high voltage end is electrically connected to the 48V power supply in the 48V power supply unit; the low voltage end of the DC/DC converter Z2 is electrically connected to the 48V power supply, and the high voltage end is connected to the 300V power supply in the 300V power supply unit. Power supply electrical connection; the 12V power supply, 48V power supply, 300V power supply, DC/DC converter Z1, DC/DC converter Z2 and the main controller are connected through the CAN bus.

The 12V power supply unit includes a 12V power supply, a load F1, an unnecessary load F2, a normally closed switch S4, a normally open switch S7, a resistance wire R1, and a Hall-type current sensor C1; the 48V power supply unit includes a 48V power supply , load F3, normally open switch S5, normally open switch S8, resistance wire R2, Hall type current sensor C2; the 300V power supply unit includes 300V power supply, load F4, normally open switch S6, Hall type current sensor Sensor C3, generator G5; wherein the DC/DC converter Z1 low voltage terminal is electrically connected to the 12V power supply, and the high voltage terminal is electrically connected to the 48V power supply; the DC/DC converter Z2 low voltage terminal is connected to the 48V power supply, high voltage The terminal is connected to the 300V power supply;

The positive pole of the 12V power supply is respectively electrically connected to the load F1, the non-essential load F2, the positive pole of the low-voltage end of the DC/DC converter Z1, and the normally open switch S7; the Hall-type current sensor C1 is set on the external bus harness of the positive pole of the 12V power supply, The negative pole of the 12V power supply is electrically connected to the other end of the load F1, the normally closed switch S4, the negative pole of the low voltage end of the DC/DC converter Z1, and one end of the resistance wire R1. The switch S7 is connected to the resistance wire R1;

The positive pole of the 48V power supply is electrically connected to one end of the normally open switch S5, and the other end of the normally open switch S5 is electrically connected to the positive pole of the high voltage end of the DC/DC converter Z1, the load F3, and the positive pole of the low voltage end of the DC/DC converter Z2. , Normally open switch S8; Hall-type current sensor C2 is set on the external bus harness of the positive pole of the 48V power supply; the negative pole of the 48V power supply is respectively electrically connected to the negative pole of the high voltage end of the DC/DC converter Z1, the other end of the load F3, and the DC/DC converter The negative pole of the low-voltage end of Z2 and one end of the resistance wire R2; wherein the normally open switch S8 is connected to the resistance wire R2;

The positive pole of the 300V power supply is electrically connected to the normally open switch S6, and the other end of the normally open switch S6 is electrically connected to the positive pole of the high voltage end of the DC/DC converter Z2, the load F4, and the generator G5; the Hall-type current sensor C3 is set on The positive pole of the 300V power supply is connected to the external bus harness; the negative pole of the 300V power supply is respectively electrically connected to the negative pole of the high voltage terminal of the DC/DC converter Z2, the load F4 and the other end of the generator G5.

The beneficial effects of the utility model are:

1. The design of the three power sources and DC/DC control method of the utility model realizes the protection of the lithium-ion battery in a cold environment through step-by-step heating, and prevents the low-temperature discharge of the lithium-ion battery from affecting the service life of the battery. 12V lead-acid battery It is used to heat the 48V lithium-ion battery, and the 48V lithium-ion battery is used to heat the 300V high-voltage battery pack; considering the characteristics of 12V lead-acid battery with good low-temperature discharge characteristics but limited capacity, the overall energy utilization efficiency is improved through the step-by-step heating method. 2. The utility model upgrades the voltage level of some low-voltage components, that is, adds a 48V power supply to share the power supply pressure of the original 12V power supply, reduces the current value in the low-voltage power supply system, and realizes reasonable control of the low-voltage power supply system. For hybrid vehicles, the engine, clutch, gearbox, transmission shaft, final drive and half-bridge are the traditional power systems that drive the wheels of the vehicle, and a set of high-voltage batteries and drive motors are equipped here as the second set of drive vehicles The power system of the wheels to increase the maximum power that the vehicle can achieve. In this way, an on-board power supply configuration including a three-voltage power supply system can be realized. There are three power supplies of a high-voltage power battery, a 48V battery and a 12V low-voltage battery, which can reduce the engine specification during the vehicle design process, that is, reduce the displacement and achieve savings The purpose of fuel: through the SOC feedback control of the high and low voltage end power supply of the DC/DC converter, it can not only ensure that the power supply has sufficient electric energy, but also prevent the power supply from overcharging and prolong the battery life.

3. The utility model limits the load power or isolates the load through the power limitation based on the SOC of the three power supplies, which is beneficial to the rapid replenishment of the energy of each power supply and prolongs the service life of the power supply.

Description of drawings

Fig. 1 is the schematic diagram of the principle of the utility model three-voltage power supply system;

Fig. 2-a is a schematic diagram of the utility model DC/DC converter;

Fig. 2-b is a schematic diagram of the principle of the utility model normally open switch;

Fig. 2-c is the schematic diagram of the principle of the utility model normally closed switch;

Fig. 3 is a schematic diagram of the connection of the three-voltage power supply system of the present invention, wherein the dotted line represents the signal line, and the solid line represents the energy flow;

Fig. 4 is the flowchart of the control method of the three-voltage power supply system of the present invention;

Fig. 5-a is the temperature-based control flowchart of the utility model 48V power supply;

Fig. 5-b is the temperature-based control flowchart of the utility model 300V power supply;

Fig. 6-a is the flow chart of charge and discharge control of the utility model 12V power supply;

Fig. 6-b is the charging and discharging control flowchart of the utility model 48V power supply;

Fig. 6-c is the charging and discharging control flowchart of the utility model 300V power supply;

Fig. 7 is the control method of the utility model 300V power intervention driving.

Detailed ways

Referring to Figure 1 and Figure 3, a three-voltage power supply system for automobiles, the system includes a 12V power supply unit, a 48V power supply unit, a 300V power supply unit, a DC/DC converter Z1, and a DC/DC converter Z2; wherein the DC /DC converter Z1 low voltage terminal is electrically connected with 12V power supply in 12V power supply unit, high voltage terminal is electrically connected with 48V power supply in 48V power supply unit; described DC/DC converter Z2 low voltage terminal is electrically connected with 48V power supply, high voltage terminal It is electrically connected to the 300V power supply in the 300V power supply unit; the signal interaction between the 12V power supply, 48V power supply, 300V power supply, DC/DC converter Z1, DC/DC converter Z2 and the main controller is through the data line, Carried out by means of CAN network communication. The main controller is the vehicle controller, which receives various signal inputs, analyzes the driver's driving intention, and is responsible for controlling the vehicle power system. The main controller, sensors and electromagnetic relays on the vehicle constitute a control system. 12V power supply, 48V power supply and 300V power supply exist at the same time, and a three-voltage power supply system is formed by two step-down DC/DC converters.

The 12V power supply unit includes a 12V power supply, a load F1, an unnecessary load F2, a normally closed switch S4, a normally open switch S7, a resistance wire R1, and a Hall-type current sensor C1;

Among them, the 12V power supply is a lead-acid battery with a capacity of 60AH, which is responsible for supplying power to traditional electrical accessories, including lighting, entertainment audio equipment, spark plug ignition device and resistance wire R1 for heating the 48V power supply; for loads that will not affect driving safety, such as Entertainment audio equipment, called non-essential load, represented by load F2. Powering off the non-essential load F2 will not affect the power safety of the vehicle, and can reduce the power loss of the 12V power supply. For other electrical accessories powered by 12V power supply, they are collectively referred to as necessary loads, represented by F1.

The positive pole of the 12V power supply is respectively connected to the load F1, the non-essential load F2, the positive pole of the low-voltage end of the DC/DC converter Z1, and the normally open switch S7; the negative pole of the 12V power supply is respectively connected to the other end of the load F1, the normally closed switch S4, and DC/DC conversion The negative pole of the low-voltage end of the device Z1 and one end of the resistance wire R1; the non-essential load F2 is connected to the normally closed switch S4, and the normally open switch S7 is connected to the resistance wire R1; the connection methods are all electrical connections. The Hall-type current sensor C1 is set on the positive external bus harness of the 12V power supply, not connected in series in the circuit.

The 48V power supply unit includes a 48V power supply, a load F3, a normally open switch S5, a normally open switch S8, a resistance wire R2, and a Hall-type current sensor C2;

Among them, the 48V power supply is a lithium-ion battery with a capacity of 20AH, which is responsible for supplying power to the active chassis system of the vehicle, the air compressor of the electric air conditioner, and the resistance wire R2 for heating the 300V power supply. Among them, these components powered by 48V power supply are represented by load F3.

The positive pole of the 48V power supply is connected to one end of the normally open switch S5, and the other end of the normally open switch S5 is respectively connected to the positive pole of the high voltage end of the DC/DC converter Z1, one end of the load F3, the positive pole of the low voltage end of the DC/DC converter Z2, the normal Open switch S8; the negative pole of the 48V power supply is respectively connected to the negative pole of the high voltage terminal of the DC/DC converter Z1, the other end of the load F3, the negative pole of the low voltage terminal of the DC/DC converter Z2, and one end of the resistance wire R2, wherein the normally open switch S8 and The resistance wire R2 is electrically connected. The connection methods are all electrical connections. The Hall-type current sensor C2 is set on the positive external bus harness of the 48V power supply, not connected in series in the circuit.

The 300V power supply unit includes a 300V power supply, a load F4, a normally open switch S6, a Hall-type current sensor C3, and a generator G5;

Among them, the 300V power supply is a high-voltage lithium-ion battery with a capacity of 35AH, which is responsible for supplying power to the drive motor and recovering the braking energy when the vehicle brakes. Among them, the driving motor is represented by the load F4.

The positive pole of the 300V power supply is connected to one end of the normally open switch S6, and the other end of the normally open switch S6 is respectively connected to the positive pole of the high voltage terminal of the DC/DC converter Z2, the load F4, and the generator G5, and the negative pole of the 300V power supply is respectively connected to the DC/DC converter Z2 The negative pole of the high voltage end, the load F4 and the other end of the generator G5 are all connected electrically. The Hall-type current sensor C3 is set on the positive external bus harness of the 300V power supply, not connected in series in the circuit.

The model of Hall-type current sensors C1, C2, and C3 is Honeywell CSLA2EL, which can measure the instantaneous current flowing through the wire harness and transmit it to the main controller. For the switches in the loop, they are connected in series in the circuit.

Refer to Figure 2—a is a schematic diagram of the DC/DC converter Z1 and the DC/DC converter Z2, where the two ends are connected to a low-voltage circuit and a high-voltage circuit, and the circuits at both ends are DC circuits, and the DC/DC converter Z1 and The DC/DC converter Z2 is responsible for converting direct current from one voltage level to another, and can detect and transmit real-time voltage values of high and low voltage terminals. The DC/DC converters Z1 and Z2 used in the utility model are all step-down DC/DC converters, that is, the direct current of higher voltage is converted into direct current of lower voltage, and the model selected by DC/DC converter Z1 It is MDK500-48S24, and the model selected for DC/DC converter Z2 is MDM600-300S48.

Referring to Fig. 2-b is a schematic diagram of the principle of a normally open switch, the normally open switches S5, S6, S7 and S8 used in the utility model are all realized by a normally open electromagnetic relay, and the g and m ports of the relay are connected to The low-voltage control circuit connects the 1 and 2 ports to the actual controlled circuit to realize the control of the high-voltage circuit between the 1 and 2 ports by the low-voltage control circuit between the g and m ports. When the g and m ports are not powered, the relay is in the initial state, that is, the circuit between the 1 and 2 ports is in the disconnected state; when the g and m ports are powered on, the circuit between the 1 and 2 ports of the relay is in the connected state. The low-voltage control circuit connected to the g and m ports is a vehicle-mounted 5V voltage signal, which is sent by the main controller.

Referring to Fig. 2-c is the schematic diagram of the principle of a normally closed switch, the normally closed switch S4 used in the utility model is realized by a normally closed electromagnetic relay, the g and m ports of the relay are connected to the low-voltage control circuit, 1, 2 The port is connected to the actual controlled circuit to realize the control of the low-voltage control circuit between the g and m ports on the high-voltage circuit between the 1 and 2 ports. When the g and m ports are not powered, the relay is in the initial state, that is, the circuit between the 1 and 2 ports is in the connected state; when the g and m ports are powered on, the circuit between the 1 and 2 ports of the relay is in the disconnected state. The low-voltage control circuit connected to the g and m ports is a vehicle-mounted 5V voltage signal, which is sent by the main controller.

Refer to Figure 3, which is a schematic diagram of the signal transmission of the three power supply system, 12V power supply, 48V power supply, 300V power supply, DC/DC converter Z1, DC/DC converter Z2 and the main controller are all connected to the CAN bus, and the connection ports used are all 9-core RS232 interface, that is, the standard DB9 interface. The information transmitted on the CAN bus includes: the temperature, current, and voltage information of the three power supplies, the control word information of the DC/DC converter Z1, and the DC/DC converter Z2, that is, the duty cycle. Among them, the dotted line indicates the signal line, and the CAN bus is used to transmit the signal; the solid line indicates the energy flow line, and the connection method is electrical connection.

Referring to Fig. 4, a control method of a three-voltage power supply system for an automobile, the steps include:

Step 1. When the driver turns the key of the vehicle to connect the system to the low-voltage power supply, the vehicle is ready to start. The system first detects the temperature of the power supply. Here, the 12V power supply is allowed to discharge at low temperature, so only the temperature of the 48V power supply and the 300V power supply need to be detected. ; If the temperature is low and does not reach the temperature threshold that allows the power supply to discharge, the power supply will enter the temperature control link of step-by-step preheating, and the 48V power supply will be preheated through the 12V power supply. When the temperature of the 48V power supply rises to the threshold temperature, the 12V power supply will Stop preheating the 48V power supply. At this time, the 48V power supply has the discharge capacity to supply power to the load F3 connected to the 48V power supply. At the same time, if the temperature of the 300V power supply is detected to be lower than the threshold, the 48V power supply will preheat the 300V power supply. When the 300V power supply After the temperature rises to the threshold temperature, the 48V power supply stops preheating the 300V power supply. At this time, the 300V power supply has the discharge capacity; The power supply is heated until the temperature of the 48V power supply is higher than the temperature threshold suitable for discharging the lithium-ion battery, and the 48V power supply is discharged to heat the 300V power supply;

Step 2. When the temperature of the power supply reaches above the threshold temperature, the control system calculates the SOC of the three power supplies, and the main controller controls the three-voltage power supply system to perform charging and discharging operations according to the SOC of the power supply. This process can be carried out with the vehicle driving ;

Step 3. During driving, the control system calculates the required power of the vehicle. When the high-efficiency working area of the engine during driving does not match the required power of the vehicle, the control system will coordinate and determine the joint working mode of the three power sources and the engine;

Step 4. Repeat steps 1 to 3 until the vehicle arrives at the destination and stops.

The specific steps for the 12V power supply to preheat the 48V power supply in the above step 1 include:

1) The control system continuously collects the temperature of the 48V power supply. When the temperature of the 48V power supply is lower than the threshold value, the normally open switch S5 is turned off, and the normally open switch S7 is closed. The 12V power supply supplies power to the resistance wire R1, and the heat generated by the resistance wire R1 increases The temperature of the 48V power supply, that is, the 12V power supply preheats the 48V power supply;

2) When the temperature of the 48V power supply exceeds the threshold temperature, the normally open switch S5 on the external circuit of the 48V power supply is closed. At this time, the 48V power supply has the ability to supply power to the outside, and then supplies power to the load F3 or preheats the 300V power supply. The always-on switch S7 is disconnected, and the 12V power supply stops preheating the 48V power supply;

The specific steps for the 48V power supply to preheat the 300V power supply in the above step 1 include:

1) The control system continuously collects the temperature of the 300V power supply. When the temperature of the 300V power supply is lower than the threshold value, the normally open switch S6 is turned off, and the normally open switch S8 is closed. The 48V power supply supplies power to the resistance wire R2, and the heat generated by the resistance wire R2 increases The temperature of the 300V power supply, that is, the 48V power supply preheats the 300V power supply;

2) When the temperature of the 300V power supply reaches above the threshold temperature, the normally open switch S6 on the external circuit of the 300V power supply is closed. At this time, the 300V power supply has the ability to supply power to the load F4. At this time, the normally open switch S8 is off. On, the 48V power supply stops preheating the 300V power supply.

Referring to Figures 5-a and 5-b are temperature-based control flow charts for the 48V power supply and the 300V power supply in the three-power supply system. Regarding heating and temperature control, the method of step-by-step preheating is adopted. Make full use of lead-acid batteries with good low-temperature characteristics but low energy density, and lithium-ion batteries with poor low-temperature characteristics but high energy density. When the working environment of the lithium-ion battery is preheated to a suitable temperature and then discharged, the discharge efficiency of the power supply can be improved, and the overall energy utilization efficiency of the car can be improved. The suitable temperature threshold of the lithium-ion battery is specifically determined by the material of the lithium-ion battery. In the selection of the resistance wire, the resistance wire R1 chooses a resistance wire with a heating power of 1kW, and the resistance wire R2 chooses a resistance wire with a heating power of 3kW. The power of the resistance wire should not be selected too high to prevent local overheating inside the battery pack. In the temperature control flow chart in Figures 5a-5b of the utility model, the temperature threshold is set to 5 degrees Celsius as an example for illustration:

Refer to Figure 5—a is the temperature-based control flow chart of the 48V power supply. The control system collects the temperature of the 48V power supply from time to time. When the temperature of the 48V power supply is lower than the threshold value, the normally open switch S5 remains open, and the normally open switch S7 is closed. 12V The power supply preheats the 48V power supply. The 12V power supply supplies power to the resistance wire R1, and the resistance wire R1 generates heat to increase the temperature of the 48V power supply. When the temperature of the 48V power supply reaches above the threshold temperature, the normally open switch S5 on the external circuit of the 48V power supply in Figure 1 is closed. At this time, the 48V power supply has the ability to supply external power, and then supply power to the load F3 or preheat the 300V power supply. Now the normally open switch S7 is disconnected, and the 12V power supply stops preheating the 48V power supply.

Referring to Figure 5-b is the temperature-based control flow chart of the 300V power supply. The control system collects the temperature of the 300V power supply from time to time. When the temperature of the 300V power supply is lower than the threshold value, the normally open switch S6 remains open, and the normally open switch S8 is closed. 48V The power supply preheats the 300V power supply. The 48V power supply supplies power to the resistance wire R2, and the resistance wire R2 generates heat to increase the temperature of the 300V power supply. When the temperature of the 300V power supply reaches above the threshold temperature, the normally open switch S6 on the external circuit of the 300V power supply in Figure 1 is closed. At this time, the 300V power supply has the ability to supply power to the outside, and then supplies power to the load F4. Now the normally open switch S8 is disconnected, and the 48V power supply stops preheating the 300V power supply. Utilize the characteristics of each power supply, through the step-by-step preheating control, realize the efficient utilization of energy.

The temperature threshold in the preheating control in the utility model is set at 5 degrees Celsius, but it is not limited to the specific temperature value listed, and can be adjusted according to the actual situation.

The charging control method in the utility model comprises three parts:

(1) When the SOC of the 12V power supply is lower than the threshold, the DC/DC converter Z1 is turned on for charging, energy flows from the 48V power supply to the 12V power supply, and when the SOC of the 12V power supply reaches 90%, the DC/DC converter Z1 stops working ;When the SOC of the 48V power supply is lower than the threshold, the DC/DC converter Z2 is turned on for charging, and the energy flows from the 300V power supply to the 48V power supply, and when the SOC of the 48V power supply reaches 90%, the DC/DC converter Z2 stops working; when the 300V power supply When the SOC of the power supply is lower than the threshold, the generator G5 is turned on for charging, and the energy flows from the generator G5 to the 300V power supply, and when the SOC of the 300V power supply reaches 90%, the generator G5 stops working; during this process, the DC/DC converter Z1 and the DC/DC converter Z2 are turned on and off under the control of the SOC value of the low-voltage side power supply.

(2) When the vehicle brakes, part of the kinetic energy of the vehicle will be converted into electric energy, and the 300V power supply can receive and store the regenerative braking energy of the vehicle; if in this process, the SOC of the 300V power supply reaches 95 due to the recovery of braking energy %, the DC/DC converter Z2 will turn on, and then charge the 48V power supply, and the energy will flow from the 300V power supply to the 48V power supply. When the SOC of the 300V power supply drops below 95%, the DC/DC converter Z2 will be turned off; if the 48V power supply When the SOC of the 48V power supply reaches 95%, the DC/DC converter Z1 will be turned on to charge the 12V power supply, and the energy will flow from the 48V power supply to the 12V power supply. When the SOC of the 48V power supply drops below 95%, the DC/DC converter Z1 will be turned off; During this process, the DC/DC converter Z1 and the DC/DC converter Z2 are turned on and off under the control of the SOC value of the high-voltage side power supply.

(3) When the SOC of the 12V power supply reaches 98%, the DC/DC converter Z1 stops working; when the SOC of the 48V power supply reaches 98%, the DC/DC converter Z2 stops working; when the SOC of the 300V power supply reaches 98% During this process, the DC/DC converter Z1 and DC/DC converter Z2 are turned on and off controlled by the SOC value of the low-voltage power supply, and the braking energy recovery circuit of the 300V power supply is controlled by Its SOC control, when the SOC of the 300V power supply exceeds 98%, only the 300V power supply is allowed to discharge, and charging is not allowed.

Among the above three charging methods, the highest priority is (3), and the lowest priority is (1). Specifically: if the SOC of the 12V power supply rises from less than 40% to 90% because it is continuously charged, at this time, according to the control method in 1), the DC/DC converter Z1 stops working; at the same time, if the 48V The SOC of the power supply makes the SOC of the 48V power supply exceed 95% because it receives the energy of the 300V power supply. At this time, according to the control method of 2), the DC/DC converter Z1 should start working; in order to deal with the appearance of the DC/DC converter Z1, different methods should be met at the same time In the phenomenon of opening and closing conditions, the priority of 2) is defined in the control method to be higher than the priority of 1), that is, when the above situations occur at the same time, the control method with high priority is executed. Here, the DC/DC converter Z1 Start working. Then, because the 12V power supply continues to receive the power input of the 48V power supply, the SOC of the 12V power supply continues to rise. When the SOC of the 12V power supply rises to 98%, the condition of closing the DC/DC converter Z1 in 3) is met; here The priority of definition 3) is higher than the priority of 2), and the DC/DC converter Z1 stops working, avoiding the phenomenon that the DC/DC converter Z1 is always on and causing the 12V power supply to be overcharged, and preventing potential safety hazards. Similarly, the control of the DC/DC converter Z2 is consistent with the control of the DC/DC converter Z1. If the SOC of the 48V power supply rises from less than 40% to 90% because it is continuously charged, at this time, according to the control method in 1), the DC/DC converter Z2 stops working; at the same time, if the SOC of the 300V power supply is More than 95%, at this time, according to the control method in 2), the DC/DC converter Z2 should start working; in order to deal with the phenomenon that the DC/DC converter Z2 simultaneously satisfies the opening and closing conditions in different methods, in the control method The priority of definition 2) is higher than the priority of 1), that is, when the above situations occur at the same time, the control method with higher priority is executed, and here the DC/DC converter Z2 starts to work. Then, because the 48V power supply continues to receive the power input of the 300V power supply, the SOC of the 48V power supply continues to rise. When the SOC of the 48V power supply rises to 98%, the condition of closing the DC/DC converter Z2 in 3) is met; here The priority of definition 3) is higher than the priority of 2), and the DC/DC converter Z1 stops working, avoiding the phenomenon that the DC/DC converter Z2 is always on and causing the 48V power supply to be overcharged, and preventing potential safety hazards. When multiple control operations meet the conditions at the same time, execute the operations with the highest priority that meet the conditions. This is to give priority to protecting the battery and prevent potential safety hazards caused by charging after the SOC of the power supply exceeds 98%. On the basis of ensuring safety, the braking energy is recovered as much as possible to improve energy utilization. Although the third case is rare, this setting can improve power security. The SOC threshold in the charging control method in the present invention is set to 40%, but it is not limited to the listed specific SOC threshold, and can be adjusted according to the actual situation.

The discharge control method in the utility model comprises three parts:

(1) When the SOC of the 12V power supply is above the high threshold, the power of the 12V power supply is in a sufficient state, and the 12V power supply can perform normal discharge operations; when the SOC of the 12V power supply is between the low threshold and the high threshold, the 12V power supply is in a light deficit In the power state, the control system starts the DC/DC converter Z1 to charge the 48V power supply to the 12V power supply. At this time, the 12V power supply still supplies power to the outside world; when the SOC of the 12V power supply is below the low threshold, the 12V power supply is in a serious power loss state. To limit the output power of the power supply, it is carried out by isolating the non-essential load F2, disconnecting the normally closed switch S4, cutting off the power supply to the non-essential load F2, and ensuring the power supply of the power supply to the necessary load;

(2) When the SOC of the 48V power supply is above the high threshold, the 48V power supply is in a state of sufficient power, and the 48V power supply can perform normal discharge operations; when the SOC of the 48V power supply is between the low threshold and the high threshold, the 48V power supply is in a light deficit In the power state, the control system starts the DC/DC converter Z2 to charge the 48V power supply from the 300V power supply. At this time, the 12V power supply still supplies power to the outside world; when the SOC of the 48V power supply is below the low threshold, the 48V power supply is in a serious power loss state. It is necessary to perform partial load power limitation;

(3) When the SOC of the 300V power supply is above the high threshold, the 300V power supply is in a state of sufficient power, the 300V power supply can perform normal discharge operations, and will not start the generator G5 to generate electricity; when the SOC of the 300V power supply is at the low threshold and high threshold When the 300V power supply is in a light deficit state, it is necessary to control the engine to generate power to supplement the high-voltage battery pack; when the SOC of the 300V high-voltage power supply is below the low threshold, it is necessary to limit the load power.

The high threshold and low threshold of SOC in the discharge control method in the utility model are respectively set as 40% and 30%, but they are not limited to the listed specific SOC thresholds, and can be adjusted according to actual conditions.

Due to the low temperature environment, it is difficult for lithium-ion batteries to discharge externally. Although the low-temperature characteristics of lead-acid batteries are better, the energy density of lead-acid batteries is small, and the stored electric energy is less. Therefore, when the vehicle is started in a cold area, the lead-acid battery is allowed to discharge at low temperature because the low-temperature characteristics of the lead-acid battery are better than that of the lithium-ion battery, that is, the 12V power supply can supply power to the load F1 and the non-essential load F2, and use 12V The lead-acid battery warms up the lithium-ion battery.

Therefore, after a certain temperature threshold is set according to the characteristics of the 48V power supply, when the temperature of the 48V power supply is lower than the temperature threshold, the normally open switch S7 is closed, and the normally open switch S5 remains open. At this time, the 12V power supply is supplied to the 48V power supply The built-in heating resistance wire R1 supplies power, and the heat generated by the resistance wire R1 will increase the temperature of the 48V power supply. When the temperature reaches a certain threshold, the normally open switch S5 is closed. At this time, the 48V power supply has the conditions for external power supply and can Power is supplied to the load F3, and the normally open switch S7 is turned off at the same time, so that the power supply to the resistance wire R1 is stopped, so as to save energy. When the 48V power supply is discharging, it will generate heat due to the internal resistance, and this part of the heat is enough to keep the temperature of the 48V power supply higher than the temperature threshold. After that, the 48V power supply can be discharged normally. Similarly, for a 300V power supply, after a certain temperature threshold is set according to the characteristics of the 300V power supply, when the temperature of the 300V power supply is lower than the temperature threshold, the normally open switch S8 is closed, and the normally open switch S6 remains open. At this time, the 48V The power supplies power to the heating resistance wire R2 built in the 300V power supply. The heat generated by the resistance wire R2 increases the temperature of the 300V power supply. When the temperature reaches a certain threshold, the normally open switch S6 is closed, and the 300V power supply has external power supply. Under certain conditions, the load F4 can be powered, and the normally open switch S8 is turned off at the same time, so that the power supply to the resistance wire R2 is stopped to save energy. The 300V power supply will generate heat due to internal resistance during discharge, and this part of the heat is enough to keep the temperature of the 300V power supply higher than the temperature threshold. After that, the 300V power supply can be discharged normally. The above step-by-step preheating method is adopted, that is, the 12V power supply preheats the 48V power supply, and the 48V power supply preheats the 300V power supply. The reason is that although the 12V power supply can be discharged at low temperature, the energy density of the lead-acid battery is small and the stored energy is less. , so it can only preheat the 48V power supply with smaller capacity and volume, but cannot preheat the 300V power supply with larger capacity and volume. The 48V power supply is a lithium-ion battery with high energy density and stored energy, which can preheat the 300V power supply, but the premise is that the 48V power supply must work at a suitable temperature. When the power supply is working, when the temperature of the lithium-ion battery is lower than the temperature threshold again, the above four normally open switches S5, S6, S7, and S8 will repeat the above operations, avoiding the low-temperature discharge of the lithium-ion battery. occurs, thereby protecting the lithium-ion battery. When the SOC of the 12V power supply is insufficient, the normally closed switch S4 will be disconnected, and the power system will isolate unnecessary electrical equipment, that is, stop supplying power to the unnecessary load F2, so as to ensure the power consumption of necessary electrical equipment such as load F1 , It also avoids the rapid drop of the SOC of the 12V power supply. When the SOC of the 300V power supply is too low, the generator G5 will start to supply power to the 300V power supply. During braking energy recovery, the drive motor will work in the power generation state, and use braking to generate electric energy to charge the 300V power supply.

When the voltages of the three power supplies reach their respective highest voltage values, the SOC is considered to be 100%, that is, the power supplies are in a fully charged state at this time. The mapping relationship with the power supply SOC assigns the power supply SOC at the initial power-on, which is the correction algorithm in the calculation process of the power supply SOC. Thereafter, the main controller calculates the SOC value of the power supply according to formula (1). In the fully charged state, the power supply will not continue to charge to prevent potential safety hazards caused by overcharging.

The charge and discharge control of the three-voltage power supply system is based on the SOC of the power supply as a basis for joint control of the three power supplies. The biggest key is to calculate the SOC as accurately as possible. The SOC calculation formula (1) for the three power supplies is:

${\mathrm{<span\; class="notranslate">\; SOC</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; SOC</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\frac{{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; Idt</span>}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; full</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, SOC ₂ represents the SOC value of the power supply at the next moment, SOC ₁ represents the SOC value of the power supply at the previous moment, t1 and t2 are two moments, and the t2 moment is later than the t1 moment, so t2-t1 is the time of the two moments In order to calculate accurately, the time interval taken in the integral algorithm should be as small as possible. I represents the current flowing through the positive pole of the power supply, which is measured by the Hall-type current sensors C1, C2, and C3. When the power supply is in the charging state, I is a positive number; when the power supply is in the discharging state, I is a negative number. C _full indicates the power stored in the power supply when it is fully charged, and this value has been determined when the battery is produced.

Referring to Figures 6-a, 6-b, and 6-c are the control methods based on SOC for the power supply in the three-voltage power supply system of the present invention. The SOC thresholds of the three power supplies involved in the control method can be determined according to actual needs. In the present invention, the SOC thresholds here are respectively set to 40% and 30%.

Referring to Fig. 6-a is the charging and discharging control flow chart of the utility model 12V power supply, the load F1 connected with the power supply is mainly traditional electric accessories, including lighting system, entertainment system, spark plug ignition system and electric heating system of 48V power supply wait. When the SOC is above 40%, it is considered that the electric power of the power supply is sufficient at this time, and the power supply can perform a normal discharge operation. However, when the SOC of the power supply is 30%-40%, it is considered that the power supply is in a state of light power loss. At this time, the DC/DC converter Z1 is started to charge the 12V power supply with a constant power of 1kW, but at this time the 12V power supply is still providing normal power to the outside world. ; When the SOC is lower than 30%, the DC/DC converter Z1 continues to charge the 12V power supply with a constant power of 1kW. At the same time, it is considered that the power supply is in a serious power loss state at this time, and the output power of the power supply should be limited by isolating unnecessary loads. The method is carried out, and only the normal power consumption of the necessary load is reserved. This process is realized by disconnecting the normally closed switch S4 in Figure 1.

Referring to Fig. 6-b is a flow chart of charge and discharge control of the 48V power supply of the present invention, and the load F3 connected to the power supply is an active chassis system, an air compressor of an electric air conditioner, and the like. When the SOC is above 40%, it is considered that the power supply is sufficient, and the power supply can discharge normally. When the SOC is 30%-40%, it is considered that the power supply is in a state of light power loss, and DC/DC is started at this time Converter Z2 charges the 48V power supply with a constant power of 3kW, but at this time the 48V power supply still supplies power to the outside; when the SOC is lower than 30%, the DC/DC converter Z2 continues to charge the 48V power supply with a constant power of 3kW, and at the same time considers At this time, the power supply is in a state of severe power loss, and it is necessary to limit the power of some loads. For example, the air conditioning system can only be controlled to work at a low gear to limit the power consumption of the air conditioner, but it will not affect the power supply operation of necessary components such as active control of the chassis to ensure It can meet the rigidity requirements of the vehicle. Through the setting of the 48V system, it can not only ensure the ever-increasing power demand of the low-voltage electrical equipment in the car, but also change the driving of the air-conditioning compressor from the engine in the traditional car to the 48V power supply. Because the air conditioner is only used in a colder or hotter environment, and when matching the engine in a traditional car, it must be considered that the air conditioner is turned on, so if the vehicle is driving at a suitable temperature, there will be a certain amount of power waste. By letting the 48V power supply drive the air-conditioning system, the air-conditioning load does not need to be considered when designing the engine matching, and the target power of the engine can be reduced, and the engine with a smaller displacement can be selected to achieve the purpose of reducing fuel consumption.

Referring to Fig. 6-c is the flow chart of charge and discharge control of the 300V power supply of the utility model, and the load F4 connected with the power supply is the driving motor. When the SOC is above 40%, it is considered that the power of the power supply is sufficient, and the power supply can perform normal discharge operation at this time, and the generator G5 will not start. This can reduce the total power of the external load that the engine normally works, and when matching, an engine with a smaller displacement can be selected to achieve the purpose of reducing fuel consumption. When the SOC is between 30% and 40%, it is considered that the power supply is in a state of light power deficit at this time, and it is necessary to control the engine to drive the generator G5 to generate electricity to supplement electric energy for the high-voltage battery pack. The engine is engaged with the generator G5 to drive the generator G5 to rotate and generate electricity to charge the 300V power supply, but the 300V power supply still supplies power to the outside normally. When the SOC is lower than 30%, it is considered that the power supply is in a state of severe power loss. At this time, the engine still continues to drive the generator to charge the 300V power supply, and at the same time, the power limit of the load must be carried out, such as controlling the driving motor to only work in a low power state. , reduce the maximum power allowed for the motor to work.

After the three power supplies start charging, when the SOC of the power supply rises to 40%, the charging process will not stop immediately, but will not stop until the SOC of the power supply reaches 90%, so as to avoid frequent startup of the charging operation, specifically: For 12V power supply , the charging process will stop after the SOC reaches 90%, that is, the DC/DC converter Z1 stops working. For the 48V power supply, the charging process will not stop until the SOC reaches 90%, that is, the DC/DC converter Z2 stops working. For the 300V power supply, the charging process will stop after the SOC reaches 90%, that is, the generator G5 stops working. During this process, the DC/DC converter is turned on and off under the control of the SOC value of the low-voltage side power supply. The purpose is to ensure that the three power supplies can store sufficient energy for use after charging.

Referring to Fig. 7 is a flow chart of the control method of the 300V power supply intervention drive of the present invention.

When the vehicle is running in a low power state, the 300V power supply does not need to intervene to work. Therefore, this three-power structure can reduce the size of the engine. The engine of the car only needs to work in the high-efficiency power range, and when the engine works in this range, the fuel consumption rate is low. During the operation of the vehicle, the control system continuously calculates the required power of the vehicle, and compares the required power with the efficient working range of the engine configured on the vehicle.

The calculation formula of the required power involved in the utility model is (2):

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; require</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; pedal</span>}}}{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; full</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, P _require represents the required power; P _max represents the maximum power that the power system can provide, which is numerically equal to the maximum power value that can be achieved after the dynamic coupling between the engine and the drive motor; D _full represents the maximum stroke that the accelerator pedal can achieve, That is, the maximum depth that can be stepped on; D _pedal represents the actual depth of the accelerator pedal being stepped on.

When it is detected that the required power of the vehicle is greater than the upper limit of the high-efficiency working range of the engine, that is, when the required power exceeds the set power threshold 1, the 300V power supply will drive the drive motor to work together with the engine to drive the vehicle. effective supplement. By configuring a 300V power supply, the motor can be cut in quickly when the vehicle is running at high power, and the peak power that the vehicle can achieve can be increased. When the required power of the vehicle is between threshold 1 and threshold 2, only the engine drives the vehicle, and the drive motor neither provides power to the driving system nor is driven by the engine to generate electricity. If the required power of the vehicle is less than the set power threshold 2, that is, the power of the engine is surplus. At this time, the engine not only drives the vehicle, but also drives the drive motor to generate electricity, so that the drive motor works in the power generation state to generate electric energy, and supplies 300V power Charge. The threshold 1 is greater than the threshold 2, and the two thresholds respectively represent the upper limit and the lower limit of the power in the high-efficiency region of the engine. Each engine has its own high-efficiency working range. In this range, the engine works smoothly and the fuel consumption rate is low. The specific upper and lower power limits of the high-efficiency area of the engine are determined by the universal characteristic map of the engine. Therefore, when matching the engine, it is not necessary to match the engine power to a large extent, only need to consider that the high-efficiency working area just covers the average power demand of the vehicle, so that the engine can work in the low fuel consumption power area as much as possible, reducing fuel consumption .

Claims (2)

1. automobile three voltage power system, is characterized in that, this system comprises 12V power subsystem unit, 48V power subsystem unit, 300V power subsystem unit, DC/DC conv Z1, DC/DC conv Z2; Wherein said DC/DC conv Z1 low tension terminal is connected with the 12V power electric in 12V power subsystem unit, high-pressure side is connected with the 48V power electric in 48V power subsystem unit; Described DC/DC conv Z2 low tension terminal is connected with 48V power electric, high-pressure side is connected with the 300V power electric in 300V power subsystem unit; Described 12V power supply, 48V power supply, 300V power supply, between DC/DC conv Z1, DC/DC conv Z2 and master controller by CAN be connected.

2. a kind of automobile three voltage power system according to claim 1, it is characterized in that, described 12V power subsystem unit comprises 12V power supply, load F1, inessential load F2, normally closed switch S 4, switch S open in usual 7, resistor wire R1, Hall-type current sensor C1; Described 48V power subsystem unit comprises 48V power supply, load F3, switch S open in usual 5, switch S open in usual 8, resistor wire R2, Hall-type current sensor C2; Described 300V power subsystem unit comprises 300V power supply, load F4, switch S open in usual 6, Hall-type current sensor C3, electrical generator G5; Wherein said DC/DC conv Z1 low tension terminal is connected with 12V power electric, high-pressure side is connected with 48V power electric; Described DC/DC conv Z2 low tension terminal is connected with 48V power supply, high-pressure side is connected with 300V power supply;

Described 12V positive source is electrically connected low tension terminal positive pole, the switch S open in usual 7 of load F1, inessential load F2, DC/DC conv Z1 respectively; Hall-type current sensor C1 is enclosed within the external total wire harness of 12V positive source, 12V power cathode is electrically connected the load F1 other end, normally closed switch S 4, the low tension terminal negative pole of DC/DC conv Z1, one end of resistor wire R1 respectively, wherein inessential load F2 is connected with normally closed switch S 4, and switch S 7 open in usual is connected with resistor wire R1;

Described 48V positive source is electrically connected switch S 5 one end open in usual, and the other end of switch S 5 open in usual is electrically connected low tension terminal positive pole, the switch S open in usual 8 of the high-pressure side positive pole of DC/DC conv Z1, load F3, DC/DC conv Z2 respectively; Hall-type current sensor C2 is enclosed within the external total wire harness of 48V positive source; 48V power cathode is electrically connected the high-pressure side negative pole of DC/DC conv Z1, the load F3 other end, the low tension terminal negative pole of DC/DC conv Z2, one end of resistor wire R2 respectively; Wherein switch S 8 open in usual is connected with resistor wire R2;

Described 300V positive source is electrically connected switch S 6 open in usual, and switch S 6 other end open in usual is electrically connected high-pressure side positive pole, load F4, the electrical generator G5 of DC/DC conv Z2 respectively; Hall-type current sensor C3 is enclosed within the external total wire harness of 300V positive source; 300V power cathode is electrically connected the high-pressure side negative pole of DC/DC conv Z2, the other end of load F4 and electrical generator G5 respectively.