Adaptive power management system for armoured series hybrid vehicles

Abstract

The invention relates to a power management system used in armoured hybrid vehicles. In particular, the invention relates to a power management system comprising input pre-processing, state machine boundary determination, state detection, state function caller, and generator drive systems.

Description

[0001] ADAPTIVE POWER MANAGEMENT SYSTEM FOR ARMOURED SERIES HYBRID VEHICLES

[0002] TECHNICAL FIELD

[0003] The invention relates to a power management system used in armoured hybrid vehicles.

[0004] In particular, the invention relates to a power management system comprising input pre-processing, state machine boundary determination, state detection, state function caller, and generator drive systems.

[0005] KNOWN STATUS OF ART

[0006] Today, new traction system solutions are being investigated due to the depletion of fossil fuels, whose use is increasing day by day, their environmental impact and their high cost. Hybrid electric powertrain technology was developed as a result of efforts to build solutions which are environmentally friendly, cost effective, and capable of running on an energy source other than fossil fuels. Thanks to hybrid vehicles, which are produced with the sole purpose of reducing fuel consumption, carbon emissions have been reduced to the lowest possible level. Equipped with both electric and internal combustion engines, hybrid vehicles are the product of a technology that does not require charging and brings convenience to the user. It is expected that vehicles with hybrid technology, which are environmentally friendly and cost effective, will become more popular every day.

[0007] Vehicles with both an electric motor and a internal combustion engine are called hybrid vehicles. The primary goal for the development of these vehicles is to minimize fuel consumption. In heavy stop-and-go traffic, the vehicle is powered by an electric motor instead of an internal combustion engine. Thus, fuel is saved. When the electric energy stored is depleted, the vehicle's electric storage is recharged by self-charging thanks to the activation of the internal combustion engine. This eliminates the need to charge the hybrid vehicle at an electric charging station.

[0008] Currently, hybrid electric drives are more commonly used in passenger cars, and this technology is not widely available in armoured vehicles. However there are related studies in the literature not specific to tracked vehicles. Most of these studies use the generator as a "Range Extender" and these applications do not require a complicated control algorithm. In such an application, the primary power source is the battery and the generator unit is used to charge the battery. The power demanded from the generator unit is determined according to the most efficient operating point of the internal combustion engine of the generator and is intended to operate the unit at a constant speed. In the majority of these studies, the operation of the generator depends on the charge level of the battery, and when the battery falls below a certain state of charge level, the generator unit kicks in to extend the range of the vehicle.

[0009] Studies on series hybrid land vehicles available in the present technique have shown that power management strategies do not take into account many parameters such as state of charge / fuel levels, state of equipment, environmental factors and demands of the driver. In such applications, the speed and torque at which the generator unit will operate are determined during the design stage and the unit operates in on / off mode. Therefore, these power management strategies cause the following technical problems;

[0010] The generator unit cannot interfere with vehicle dynamics unless the battery charge falls below a certain level and the vehicle's performance is limited by the battery power.

[0011] It is not possible to control the rate at which the battery state of charge level decreases. In cases where the generator unit is operated, the power requirement of the driver is not taken into account and the full potential of the system cannot be utilized because the unit is operated at a constant speed and a constant torque.

[0012] Since the operation of the generator unit is independent of the aforementioned parameters, it cannot be guaranteed that the battery will be charged with maximum charge power at low charge levels as the power generated by the generator is constant and is used by both the electric motors and the battery. As the power drawn by electric motors increases, the power used to charge the battery decreases.

[0013] Since the current limits of the battery are not monitored by the controller, it is possible that the generator unit may generate a current that exceeds the current limits. If precautions are not taken by the battery management system, this can lead to loss of vehicles and lives.

[0014] Consequently, the demand for a novel, cost-effective, and convenient power management system has arisen to address the challenges posed by current technology and the limitations of existing solutions in the relevant technical field. This necessitated a developmental breakthrough in this domain.

[0015] PURPOSE OF THE INVENTION

[0016] The present invention relates to a power management system used in armoured hybrid vehicles, which has been developed to eliminate the disadvantages mentioned above and to bring new advantages to the related technical field.

[0017] The most important purpose of the invention is to take into account the driver demand, system voltage, current limits of the battery during charging / discharging phases, battery temperature, instantaneous power limit of the generator unit, additional loads, coolant temperature of the alternator and many similar conditions. A wide range of data, including temperature sensors, speed sensors, voltmeters, ammeters, pedal position sensors and test data from various equipment is processed to provide input to the power management strategy. This allows the generator unit to be operated at a constant power level when required, and to be switched on and off in different power zones according to the driver's demands and the battery's state of charge. The power limit allocated for the traction of the electric motors is also an output of this power management strategy and depends on the abovementioned parameters.

[0018] Another important purpose of the invention is to operate the generator unit in the maximum power zone when high power is demanded and to increase the vehicle performance significantly.

[0019] Another important purpose of the invention is to limit the traction power linearly to the charge level and to reduce the rate of decrease of the state of charge level when the battery charge level falls below a certain level when high power is required.

[0020] Another important object of the invention is to switch off the generator unit depending on the system state of charge level in low power demand zones, to operate it at constant speed and torque or to operate it with a function based on demand and charge. Thus, the state of charge level of the battery is kept within the desired range.

[0021] Another important purpose of the invention is to operate the generator unit at its maximum power when the battery charge level is too low, and to limit the electric motors to the difference between the power generated by the generator unit and the maximum charging power of the battery. Thus, it is ensured that the battery is charged with maximum charge capacity at low state of charge levels.

[0022] Another important purpose of the invention is to ensure that the instantaneous charge / discharge current limits of the battery are continuously read by the system and the power generation of the generator unit and the traction power of the electric motors are regulated in such a way that these limits are not exceeded. The following figures and their detailed descriptions will make the invention's structural and characteristic features and its advantages easier to understand. Therefore, the assessment should be made by considering the images and their detailed descriptions.

[0023] FIGURES PROVIDED TO HELP UNDERSTAND THE INVENTION

[0024] FIGURE -1: Depicting the power management system according to the invention.

[0025] FIGURE -2; Depicting the power management algorithm architecture according to the invention.

[0026] REFERENCE NUMBERS

[0027] 10. Power Management System

[0028] 11. Driver

[0029] 12. Power Distribution Unit

[0030] 13. Battery

[0031] 14. Electric Traction System

[0032] 15. Generator

[0033] 15.1 Generator Cooling System

[0034] 16. Internal Combustion Engine

[0035] 17. Sensor

[0036] 18. Voltmeter DETAILED DESCRIPTION OF THE INVENTION

[0037] This detailed description describes the preferred configurations of the power management system (10) only for a better understanding of the subject matter and no limitations should be construed.

[0038] Series hybrid vehicles use the battery (13) and generator (15) unit as their power source. The distribution of power between these sources shall be done by taking into account the condition of the equipment, state of charge / fuel levels, environmental factors and the demands of the driver (11) under the relevant scenario. Certain sensors (17) were used to estimate the instantaneous power limits of this equipment. The battery temperature and bus voltage are measured by external or internal sensors (17). The instantaneous power limits of the battery (13) will be determined using the measured values. By measuring the coolant temperature in the generator cooling system (15.1), the generator (15) speed and the bus voltage, the maximum power level that the generator (15) unit can generate will be estimated. Therefore, the temperature sensor (17) installed in the battery (13) assembly, the voltmeter (18) installed in the power distribution unit (12), the fluid temperature sensor (17) installed in the generator cooling system (15.1) and the speed sensor (17) installed in the shaft of the generator (15) unit are essential measuring equipment of the power management system (10).

[0039] Figure 1- 2 shows the power management system (10) of the invention and its details. In our invention, the power management system (10) consists of Input Pre-processing System, State Machine Boundary Determination System, State Detection System, State Function Caller and Generator Drive System.

[0040] Input Pre-Processing System, which is the first stage of the power management system (10), converts the data (current, voltage, temperature) collected by the battery (13) and Generator (15) Unit into the maximum power values that can be generated / consumed at that moment. It converts the inputs received from the electric traction system (14) and the driver (11) into a percentage of the power demand, by normalising them with the total maximum power limit. The total power is calculated according to the value of the traction torque demanded by the driver (11), and the maximum permissible power levels in the battery (13) and generator (15) unit are determined by assessing the conditions of the equipment. For example, if the driver's input on the accelerator is equivalent to a tractive force of lOkN and the vehicle speed is 10 m / s, the total tractive force demand will be (lOkN) x (10 m / s) = lOOkW. In addition, if the accessory power demand (air conditioning, mission equipment, etc.) is around 20 kW, the total drive power demand from the power management unit will be calculated as 100 + 20 = 120kW. The instantaneous maximum charge / discharge values for the battery (13) are determined by using the instantaneous temperature and bus voltage values taken from the sensors (17) and the tables shared by the manufacturer. As an example, in a system with a bus voltage of 600 V, while the discharge limit of the battery (13) at 25°C is lOOkW, this limit will be 40kW at 35°C, and when 60°C is exceeded, the discharge limit will be 0 kW and drawing power will not be allowed. The same calculation is also made for the generator (15) unit using the variables of fluid temperature, generator (15) speed and bus voltage. Finally, the drive power demand is normalised with the total discharge and generator (15) power limits. For example, in a case where the drive demand is 120kW and the limits for battery maximum discharge and generator maximum power are 100 and 140kW respectively, the percentage of drive power demand will be calculated as (120) / (100 + 140) = 0.5 = 50%. In this case, the drive will be demanding 50 per cent of the total power reserve.

[0041] The State Machine Boundary Determination System generates an instantaneous adaptive state map using the maximum / minimum power levels and calibration parameters as shown in Figure 2. It will be possible to calibrate this map according to the vehicle and its modes. The power levels are the battery (13) maximum charge power, battery (13) maximum discharge power, and the maximum and minimum producible power levels of the generator, calculated in the previous point. These levels are normalised by the sum of the battery (13) maximum discharge and generator maximum power limits to establish the vertical boundaries of the map. For example, in a case where the battery (13) maximum charge, battery (13) maximum discharge and generator (15) maximum power limits are 50, 100 and 150kW respectively, the relevant levels will be calculated as [50, 100, 150] / (100 + 150) = [20%, 40%, 60%]. In such a case, the transition from zone 1 to zone 2 in figure 22 will take place at a vertical limit of 40%. And the calibration parameters are the battery charge level, function multipliers and vertical boundary values required in the transition function named Pm in Figure 2 which is aimed to be obtained. The boundary values are the vertical values of the arrows defining the boundaries on the representative map shown. These parameters are defined by the developer through an interface.

[0042] The State Detection System uses the battery (13) charge level and percentage drive power demand variables to determine the active zone of the state map. The State Function Caller process calls the function of the decided state and calculates the power value to be demanded from the generator (15) unit and the maximum traction power limit value to be allowed in the electric traction system (12). Therefore, it calculates the power values to be demanded from the generator (15) and the power values to be allowed for traction by executing the relevant function of the determined zone. The main approach for calculating the generator (15) power demand is to calculate the power demand to discharge the battery (13) at charge levels above the target charge value of the battery (13) determined during calibration, and to calculate the power demand to charge the battery (13) below this value. Above a certain charge level and in zones with low power demand, the electric vehicle mode is activated. For example, in a scenario where the charge level is 70% and the percentage drive power demand is 90%, state 5 will be recognised in the map in Figure 2 and the calculated power will be demanded from the generator by calling the relevant transition function. In a scenario where the charge level is 70% and the percentage drive power demand is 5%, the state

[0043] 3 will be recognised, and the vehicle will be operated in electric mode without demanding power from the generator (15).

[0044] In the Generator (15) Unit, the power value to be demanded from the Generator (15) unit is converted to the values of speed demand from the internal combustion engine and torque demand from the generator (15) by performing the relevant efficiency calculations. Demand messages are sent to the relevant equipment through the CAN line. For example, in a case where the internal combustion engine (16) is operated at 200 rad / s, if the power demand from the generator (15) is lOOkW, a torque of (lOOkW) / (200rad / s) = 0.5 kNm will be demanded from the generator (15).

[0045] A series hybrid tracked armoured vehicle will be driven with the power management system (10) algorithm developed. The model-based algorithm was verified with the "simulation with real-time model" method. The distribution of the power demanded from the generator (15) unit in the state machine was made as intended. While no power was demanded from the generator (15) at high charge levels, maximum power was demanded from the generator (15) at low charge levels. Transition was achieved without exceeding the limits in the intermediate zones.

[0046] The scope of protection for this application is defined by the claims and is not restricted to the illustrative description provided above. It is evident that a skilled person in the field can establish the novelty of the invention by employing similar embodiments. Furthermore, this embodiment can be applied to other fields with similar purposes within the relevant art. It is therefore obvious that such structures will lack the criterion of innovation and particularly the criterion of exceeding the prior art.

Claims

CLAIMS1- The invention claimed relates to the power management system used in armoured hybrid vehicles (10) and it is characterized with the fact that it containsAn input pre-processing system that converts the data (current, voltage, temperature) collected from the battery (13) and Generator (15) Unit into the maximum power values that can be generated / consumed at that moment, and converts the inputs received from the electric traction system (14) and the driver (11) into percentage power demand by normalising them with the total maximum power limit, a state machine boundary detection system that generates an instantaneous adaptive state map using maximum / minimum power levels and calibration parameters, a state detection system that determines the active zone of the state map by using the battery (13) charge level and percentage drive power demand variables, a state function caller which, by calling up the function of the decided state, power value to be demanded from the generator (15) unit and the maximum traction power limit value to be allowed in the electric traction system (14), a generator (15) driving system that converts the power value to be demanded from the generator (15) unit to the values of the internal combustion engine (16) speed demand and generator (15) torque demand by performing the relevant efficiency calculations2- It is an input pre-processing system according to claim 1, and is characterised in that it calculates the total power according to the traction torque value demanded by the driver (11), and determines the maximum permissible power levels in the battery (13) and generator (15) unit by assessing the conditions of the equipment.3- It is a state machine boundary determination system according to claim 1, and is characterised in that the battery (13) maximum charging power, battery (13) maximum discharging power, generator maximum and minimum producible power levels calculated in the input pre-processing system are normalised by the sum of the battery (13) maximum discharging power and generator maximum power limits to establish the vertical boundaries of the map.4- It is a state function caller according to claim 1, and is characterised in that it calculates the power values to be demanded from the generator (15) and the power values to be allowed for traction by executing the corresponding function of the determined zone.5- It is a state function according to claim 1, and is characterised in that the power demand for discharging the battery (13) is calculated at state of charge levels above the charge value of the battery (13), while the power demand for the generator (15) to charge the battery (13) is calculated below this value.

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