CN105564530A - Hybrid power system and optimal control method for mechanical outer skeleton - Google Patents

Abstract

A hybrid power system and optimal control method applied to a mechanical exoskeleton, the system is a parallel power system, including a mechanical power transmission system, an electric power transmission system and a hydraulic oil transmission system; the mechanical power transmission system includes a gasoline engine and an electric motor, a gasoline engine The gasoline engine and the electric motor are respectively connected to the hybrid transmission, and the gasoline engine and the electric motor can provide power to the hybrid transmission alone or together to provide power to the hybrid transmission; the power transmission system includes a generator and a conversion system, and the generator is connected to the hybrid transmission to generate power. The machine provides power to the motor through the conversion system; the hydraulic oil transmission system includes an oil pump and a transmission system, the oil pump is connected to the hybrid transmission, and the oil pump provides power to the mechanical exoskeleton through the transmission system. The invention can switch between the power compensation mode and the power storage mode in real time according to working conditions, realizes the rational distribution of energy between the gasoline engine and the electric motor, and maximizes the overall efficiency.

Description

A Hybrid Power System and Optimal Control Method Applied to Mechanical Exoskeleton

technical field

The invention relates to a hybrid power system, in particular to a hybrid power system applied to a mechanical exoskeleton and an optimal control method, belonging to the field of power systems.

Background technique

Based on the harsh conditions of the coal mine working environment, the core difficulty of the individual environmental control system is the contradiction between the human body's load-bearing capacity and the weight of the environmental control system, and the mechanical exoskeleton is an effective way to break through this contradiction.

Utilize the function of mechanical exoskeleton to solve the heat damage protection, dust and gas protection in deep coal mining. At the same time, the exoskeleton has a life-saving oxygen breathing system, which can greatly reduce the labor load of personnel. It is of great significance, and it also provides strong support for the steady advancement of my country's energy industry.

The difficulty in the study of mechanical exoskeleton lies in the study of its power system. At present, the power system of mechanical exoskeletons at home and abroad is mainly powered by batteries. Under the same quality and size, compared with liquid fuel gasoline, the energy density of batteries is lower, and the power is obviously insufficient, which makes the exoskeleton's moving range and load weight limited. The capacity and efficiency of the battery are limited. However, if liquid fuel is simply used to replace the battery for power supply, due to the complexity of the coal mine underground operation environment, the engine is often operated at low speed or idle speed, which is difficult to meet the energy demand of various working conditions in the coal mine operation, and the engine The fuel economy is poor and the exhaust emissions are large. Therefore, how to equip a mechanical exoskeleton power system that is durable and efficient and can meet the energy requirements of various working conditions in coal mine operations is an urgent problem to be solved.

Contents of the invention

According to the deficiencies of the existing technology, a hybrid power system and an optimal control method applied to mechanical exoskeletons are provided. This system realizes long-term and efficient energy supply, and also meets the requirements of mechanical exoskeletons for various operating conditions. can demand.

The present invention is realized according to the following technical solutions:

A hybrid power system applied to a mechanical exoskeleton, the system is a parallel power system, the parallel power system includes a mechanical power transmission system, an electric power transmission system and a hydraulic oil transmission system; the mechanical power transmission system includes a gasoline engine and The electric motor, the gasoline engine and the electric motor are respectively connected with the hybrid transmission, and the gasoline engine and the electric motor can provide power to the hybrid transmission alone and jointly provide power to the hybrid transmission; the power transmission system includes a generator and a conversion system, the The generator is connected to the hybrid transmission, and the generator provides power to the motor through the conversion system; the hydraulic oil transmission system includes an oil pump and a transmission system, the oil pump is connected to the hybrid transmission, and the oil pump provides power to the mechanical exoskeleton through the transmission system.

The conversion system includes an inverter and a storage battery, the inverter is connected to the generator and then connected to the storage battery, and the storage battery is connected to the motor.

Described storage battery adopts lithium battery.

The transmission system includes a servo valve and an oil cylinder, the servo valve is connected with the oil pump and then connected with the oil cylinder, and the oil cylinder is connected with the mechanical exoskeleton.

It also includes an oil tank and an accumulator, the oil tank is connected with the oil pump, and the accumulator is connected with the oil pump and then connected with the servo valve.

The gasoline engine is connected with the hybrid transmission through clutch II; the electric motor is connected with the hybrid transmission through clutch I.

The hybrid transmission includes two side plates, bearing I, bearing II and bearing III are installed between the two side plates at intervals through sleeves, gear I is installed on the bearing I, and gear I is installed on the bearing II There are coaxial gear II and gear III, gear IV is installed on the bearing III, the gear I is connected to the gear II through the belt I to form a first-stage reduction, and the gear III is connected to the gear IV through the belt II The transmission constitutes a secondary reduction.

The reduction ratio of the first-stage reduction is 3, the reduction ratio of the second-stage reduction is 4, and a flywheel is installed on the bearing I to store part of the energy and stabilize the rotational speed.

An optimal control method for a hybrid power system of a mechanical exoskeleton. The gasoline engine is used as the main drive source of the hybrid power system, and the electric drive system is used as the auxiliary drive source of the hybrid power system. According to the change of the motor current, the feedback of the motor current is used , the feedback current value is used as the switch signal to turn on and off the gasoline engine, so that the motor can cut the peak and fill the valley of the output torque of the gasoline engine; then use the least square method to fit the experimental data, and get the fitting through multiple sets of experimental data Finally, use the fitted function polynomial to calculate the extreme value to obtain the degree of mixing. The fitting formula obtained through multiple sets of experimental data is:

.

When the mixing degree is 0.33, the ratio of the peak power of the electric motor to the peak power of the gasoline engine is 1:3, the efficiency of the hybrid power system is the highest, and the fuel saving rate is the largest.

Principle of the present invention:

The hybrid power system needs to be carried on the back of the person and moves with the human body. The power system as a whole adopts a parallel type, which allows the power of the two power sources of the gasoline engine and the electric motor to be superimposed, so that a low-power gasoline engine and electric motor can be used. The quality and size of the entire power system are reduced to meet the space requirements of the back of the human body. Due to the complexity of the working environment such as underground coal mines, it is easy for the gasoline engine to run at low speed or idling. The fuel economy of the gasoline engine is poor and the emission is large. In the parallel system, on the one hand, the gasoline engine can be turned off at this time. And only the electric motor is used to drive the system. On the other hand, the load of the gasoline engine can also be increased to drive the generator to generate electricity and charge the battery for later use. In order to meet the energy demand under each working condition and achieve the effect of energy saving and emission reduction, the hybrid transmission of the entire power system can meet three working modes according to the design, and can be selected according to the energy demand.

If the driving power required by the exoskeleton operation is less than the minimum power of the gasoline engine, it will be powered by the battery and started in the motor alone working mode. In this mode, the control system sends a signal to the clutch I of the motor to close it, and the gear of the motor will The power is transmitted to the output shaft to drive the oil pump to work. At this time, the other gear sets are idling. As the opening of the throttle valve gradually decreases, the output pressure will continue to increase to meet the energy demand for the mechanical exoskeleton to start and walk. As it becomes larger, the output pressure decreases accordingly. The flow of the system also decreases with the reduction of the valve opening, and the excess flow flows back to the oil tank after passing through the overflow valve.

If the driving power required by the exoskeleton exceeds the limit, the clutch of the gasoline engine will be closed at this time, and the gasoline engine will replace the electric motor to drive the system. The motor shaft is idling, and as the speed of the gasoline engine increases, the two-stage reduction gears are put into operation to transmit the torque of the gasoline engine to the output shaft, and the torque of the gasoline engine, the outlet pressure of the pump, and the flow of the system all increase accordingly, which can meet the requirements of the mechanical exoskeleton. Energy requirements for weight bearing and brisk walking. The output pressure of the system increases to the highest value and then decreases for a period of time, and the flow rate of the overflow valve first increases and then decreases. This is because after being throttled by the valve, the excess flow at the pump outlet flows back to the fuel tank through the overflow valve.

When the system encounters heavy working conditions such as running, rushing, jumping, etc., at this time, the clutches of the gasoline engine and the electric motor are both closed, and they work together as a power source to drive the hydraulic oil pump. The electric motor starts quickly, and first drives the load to work, and the gasoline engine needs to be started for a period of time before it is put into work. Therefore, the hybrid power system can shorten the start-up time of the gasoline engine system alone, and at the same time improve the acceleration performance of the system. At this time, the power ratio of the gasoline engine and the electric motor is quantified by the mixing degree. With the increase of the mixing degree, the gasoline engine gradually decreases and the electric motor gradually increases. In principle, the overall energy-saving effect can be fully exerted. However, since the increase in the weight of the motor will lead to a substantial increase in the weight of the entire system, the value of the mixing degree of the system is between 0 and 0.5, and the power of the total power is designed by measuring the amount of hydraulic oil consumed when driving the load. This constraint establishes an optimal mix of motor power and engine power of 1:3. At this time, the fuel saving rate of the system is the largest and the efficiency is the highest.

Beneficial effects of the present invention:

On the premise of satisfying the requirements of the power of the system, other basic technical performance and cost, the present invention can switch between the power compensation mode and the power storage mode in real time according to the working conditions, and at the same time can smoothly realize the switching between various modes by adopting the clutch control mode. The seamless switching can eliminate the power impact brought by the switching process; the control strategy can realize the effective and reasonable distribution of energy between the gasoline engine and the electric motor, so that the overall efficiency can be maximized, and the overall maximum fuel economy and the lowest emissions and smooth running characteristics.

Description of drawings

Figure 1 is a schematic diagram of the parallel arrangement of the hybrid system;

Figure 2 is a schematic diagram of the power system;

Fig. 3 is a schematic structural diagram of a hybrid transmission;

Figure 4 is the front view of the mechanical exoskeleton (with human body design added);

Fig. 5 is a left view of the mechanical exoskeleton;

1-side plate, 2-bearing Ⅰ, 3-bearing Ⅱ, 4-bearing Ⅲ, 5-gear Ⅰ, 6-gear Ⅱ, 7-gear Ⅲ, 8-gear Ⅳ, 9-belt Ⅰ, 10-belt Ⅱ, 11-flywheel, 12-sleeve, 100-ankle joint part, 101-calf support rod, 102-ankle joint pressure sensor, 103-bare joint hydraulic drive, 104-traction rope Ⅰ, 200-knee joint part, 201-thigh Rod, 202-displacement sensor, 203-knee joint hydraulic driver, 204-traction rope II, 300-hip joint component, 301-multifunctional support, 302-hip joint pressure sensor, 303-hip rear hydraulic drive drive, 304- Hip front hydraulic drive, 305-rigid belt, 306-traction ropeⅢ, 400-control components, 401-AD analog-to-digital converter group, 402-analog comparator group, 403-DA digital-to-analog converter group, 404-signal Amplifier group, 500-hybrid system.

detailed description

The present invention will be further described through specific embodiments below in conjunction with the accompanying drawings.

As shown in Fig. 1 to Fig. 5, a kind of mechanical exoskeleton, this mechanical exoskeleton comprises ankle joint part 100, knee joint part 200, hip joint part 300 and control part 400, and ankle joint part 100 connects knee joint part 101 through shank The joint component 200, the knee joint component 200 is connected to the hip joint component 300 through the thigh strut 201, the ankle joint component 100, the knee joint component 200, and the hip joint component 300 realize the mechanical exoskeleton through the control component 400 to complete actions similar to the human body; it also includes A hybrid system 500 for powering a mechanical exoskeleton.

The hybrid power system 500 is a parallel power system. The parallel power system includes a hybrid transmission. The hybrid transmission includes two side plates 1. Between the two side plates 1, bearings I2, II 3 and Bearing Ⅲ4, bearing Ⅰ2 is equipped with gear Ⅰ5, bearing Ⅱ3 is equipped with coaxial gear Ⅱ6 and gear Ⅲ7, bearing Ⅲ4 is equipped with gear Ⅳ8, gear Ⅰ5 is connected with gear Ⅱ6 through belt Ⅰ9 to form a first-stage reduction, and the gear Ⅲ7 is connected with gear Ⅳ8 through belt Ⅱ10 to form a two-stage reduction. The reduction ratio of the first-stage reduction is 3, and the reduction ratio of the second-stage reduction is 4. The flywheel 11 is also installed on the bearing I2. One end of the bearing I2 is connected to the clutch II, and the clutch II is connected to the gasoline engine. The gasoline engine is a DLA32 type with a power of 2.83KW, and the other end is connected to the generator. The generator is connected to the inverter and then connected to the battery, which is connected to the motor. , the motor is connected with the bearing II3 through the clutch I, the bearing III4 is connected with the oil pump through the coupling, the oil pump is connected with the servo valve and then connected with the oil cylinder, and the oil cylinder is connected with the drivers of each joint in the mechanical exoskeleton. It also includes a fuel tank and an accumulator, the fuel tank is connected with the oil pump, and the accumulator is connected with the oil pump and then connected with the servo valve.

The control unit 400 includes receiving sensors located at each joint, the receiving sensors are connected to the AD digital-to-analog conversion group 401, the AD digital-to-analog conversion group 401 is connected to the analog comparator group 402, and the analog comparator group 402 is connected to the DA digital-to-analog conversion group 403 , the DA digital-to-analog conversion 403 is connected with the signal amplifier group 404, the signal amplifier group 404 is connected with the servo valve group, and the servo valve group is connected with the drivers at each joint through the oil cylinder. The receiving sensors include an ankle joint pressure sensor 102 located at the ankle joint, a displacement sensor 202 located at the knee joint and a hip joint pressure sensor 302 located at the hip joint. The drivers include the bare joint hydraulic driver 103 and the knee joint hydraulic driver 203 located on the back multifunctional support 301 , the hip joint rear hydraulic driver 303 and the hip joint front hydraulic driver 304 located on the rigid waist belt 305 .

The whole working process:

When the bare joint pressure sensor 102 detects the movement of the ankle of the human body, the signal of the bare joint pressure sensor 102 is processed by the AD analog-to-digital converter group 401, the analog comparator group 402, the DA digital-to-analog converter group 403, and the signal amplifier group 404, and then sent to The servo valve controls the action of the ankle joint hydraulic driver 103 through the oil cylinder, the ankle joint hydraulic drive 103 pulls the traction rope I 104, and the traction rope I 104 pulls the ankle joint part 100 to complete the ankle lifting action until the rotation range of the ankle part of the mechanical exoskeleton is comparable to that of a human ankle. same size.

When the human knee joint moves, the signals obtained by the two displacement sensors 202 on the knee joint are processed by the AD analog-to-digital converter group 401, the analog comparator group 402, the DA digital-to-analog converter group 403, and the signal amplifier group 404, and then sent to the servo The valve controls the action of the knee joint hydraulic driver 203 through the oil cylinder, the knee joint hydraulic driver 203 pulls the traction rope II 204, and the traction rope II 204 pulls the knee joint part 200 to complete the knee joint action until the knee joint of the mechanical exoskeleton has a rotation range equal to that of a human knee joint. The rotation is the same.

When the hip joint moves, the hip joint pressure sensor 302 at this part processes the signal through the AD analog-to-digital converter group 401, the analog comparator group 402, the DA digital-to-analog converter group 403, and the signal amplifier 404, and then sends it to the servo valve. Oil supply is controlled by the oil cylinder to the front hydraulic driver 303 of the hip joint, oil is returned by the rear hydraulic driver 304, the traction rope III 306 is pulled, and the traction rope III 306 pulls the hip joint component 300 to complete the hip joint movement until the rotation angle is consistent with the human body.

Claims (10)

1. A hybrid power system applied to a mechanical exoskeleton, characterized in that: the system is a parallel power system, and the parallel power system includes a mechanical power transmission system, an electric power transmission system and a hydraulic oil transmission system; The mechanical power transmission system includes a gasoline engine and an electric motor, the gasoline engine and the electric motor are respectively connected to the hybrid transmission, and the gasoline engine and the electric motor can provide power to the hybrid transmission alone and jointly provide power to the hybrid transmission; The power transmission system includes a generator and a conversion system, the generator is connected to the hybrid transmission, and the generator provides power to the motor through the conversion system; The hydraulic oil transmission system includes an oil pump and a transmission system, the oil pump is connected with the hybrid transmission, and the oil pump provides power to the mechanical exoskeleton through the transmission system. 2. A hybrid power system applied to a mechanical exoskeleton according to claim 1, wherein the conversion system includes an inverter and a battery, and the inverter is connected to the generator and then connected to the battery, The storage battery is connected to the electric motor. 3. A hybrid power system applied to a mechanical exoskeleton according to claim 1, wherein the storage battery is a lithium battery. 4. A hybrid power system applied to a mechanical exoskeleton according to claim 1, wherein the transmission system includes a servo valve and an oil cylinder, the servo valve is connected to the oil pump and then connected to the oil cylinder, and the oil cylinder Connected to a mechanical exoskeleton. 5. A hybrid power system applied to a mechanical exoskeleton according to claim 4, characterized in that: it also includes a fuel tank and an accumulator, the fuel tank is connected to the oil pump, and the accumulator is connected to the oil pump and then connected to the connected to the servo valve. 6. A hybrid power system applied to a mechanical exoskeleton according to claim 1, wherein the gasoline engine is connected to the hybrid transmission through clutch II; the electric motor is connected to the hybrid transmission through clutch I. 7. A hybrid power system applied to a mechanical exoskeleton according to any one of claims 1 to 6, characterized in that: the hybrid transmission includes two side plates (1), and the two side plates ( 1) Bearing I (2), bearing II (3) and bearing III (4) are installed at intervals through sleeves (12), and gear I (5) is installed on the bearing I (2), and the bearing Coaxial gear II (6) and gear III (7) are installed on II (3), gear IV (8) is installed on the bearing III (4), and gear I (5) passes through belt I (9 ) is connected to gear II (6) to form a first-stage reduction, and the gear III (7) is connected to gear IV (8) through a belt II (10) to form a second-stage reduction. 8. A hybrid power system applied to a mechanical exoskeleton according to claim 7, characterized in that: the reduction ratio of the first-stage reduction is 3, the reduction ratio of the second-stage reduction is 4, and the bearing I (2) Flywheel (11) is also installed. 9. An optimal control method utilizing the hybrid power system of the mechanical exoskeleton described in any one of claims 1 to 6, characterized in that: The gasoline engine is used as the main drive source of the hybrid system, and the electric drive system is used as the auxiliary drive source of the hybrid system. According to the change of the motor current, through the feedback of the motor current, the feedback current value is used as the switch signal to turn on and off the gasoline engine. The output torque of the motor to the gasoline engine can play the role of peak shaving and valley filling; then the least square method is used to fit the experimental data, and the fitting formula is obtained through multiple sets of experimental data, and finally the degree of mixing is obtained by using the fitted function polynomial to find the extreme value . 10. An optimal control method for a hybrid power system of a mechanical exoskeleton according to claim 9, characterized in that: when the degree of mixing is 0.33, the ratio of the peak power of the electric motor to the peak power of the gasoline engine is 1:3, and the hybrid power The system efficiency is the highest and the fuel saving rate is the largest.