WO2019172789A1

WO2019172789A1 - A method of charging and discharging capacitors in a vehicle with a combustion engine and system thereof

Info

Publication number: WO2019172789A1
Application number: PCT/PL2019/050011
Authority: WO
Inventors: Michal WENDEKER; Tytus Tulwin
Original assignee: Vers Produkcja Sp. Z O.O. Sp. K.
Priority date: 2018-02-14
Filing date: 2019-02-13
Publication date: 2019-09-12
Also published as: PL424591A1

Abstract

The present invention relates to a method of charging and discharging capacitors according to the invention in a vehicle with a combustion engine. The essence of the method of controlling the capacitor system is the process of recuperation of electrical energy from engine braking, generated by at least one vehicle alternator in braking mode, to the supercapacitors system, and then transferring that energy to the electrical devices onboard, thereby relieving the alternator in the vehicle. The controller controls the energy flow through the energy distribution unit so that in the braking mode, the excess mechanical energy of the vehicle is converted into electric energy stored in a capacitor system. The invention also includes a system for carrying out the method according to the invention.

Description

A method of charging and discharging of capacitors in a vehicle with a combustion engine and the system for charging and discharging of capacitors in a vehicle with combustion engine

Description

The subject of the invention is a method of charging and discharging capacitors in a vehicle with a combustion engine and a system for charging and discharging capacitors in a vehicle with a combustion engine. The technical field of the invention relates to the automotive industry. The invention can be installed in vehicles with an internal combustion engine, especially in city buses. Its aim is to implement mechanical energy recuperation for internal combustion vehicles with no electric engine. Modem hybrid and electric cars use technologies that increase energy efficiency, such as charging the battery by recovering energy from braking instead of converting it into unproductive thermal energy generated by brake friction. The purpose of this micro-hybrid invention is to convert part of the redundant kinetic and potential energy of the vehicle to electrical energy, store it in a supercapacitor reservoir 15 and then after direct braking - without the mediation of the battery - transfer to electrical and electronic on-board devices.

In a combustion engine vehicle, the recuperative braking device is most often connected to the electric system of the vehicle, which contains an electric energy storage for storing the recuperative electricity. Recuperative electricity is stored in a form of chemical energy in batteries (i.e. secondary electrochemical cells), and because electrodes and electrolyte are actively involved in the chemical reactions, this results in a gradual deterioration of technical parameters and reduced battery life. In addition, the batteries are characterized by low power density, large internal energy losses and a narrow range of operating temperatures.

The US patent US2004021448 describes a recuperative battery charging method. After detecting the driving conditions that meet the criteria for storing redundant energy, the power generator increases the nominal value of the voltage of the electrical installation. Because the electric battery has a lower voltage, the generator charges the battery to a higher level. After completing the conditions for recovering the braking energy, the set voltage value in the generator is again lower and the battery, with the increased preloading voltage, transfers the previously stored electrical energy to the on-board devices.

From the US patent US2007221422 a method for activating the charging of batteries is known, including simultaneous fulfilment of the conditions for pressing the brake, closing the throttle, correspondingly low pressure in the internal combustion engine intake system, respectively high braking acceleration and, as in the previous example, the appropriate voltage ratio of the alternator controller and the voltage of the electric battery. Also in this solution, recuperative electricity is accumulated in the battery.

Technically, compared to a battery, the electric energy storage solution is made up of capacitors that store energy in an electric field. Traditional capacitors are characterized by a small amount of electric charge, i.e. low energy density. Supercapacitors (also called ultracapacitors) are a specific construction of electrolytic capacitors that accumulate electric charges within the double electric layer that arises at the interface of electrode-electrolyte centres. Because there are no chemical reactions in supercapacitors, the batteries are characterized by high power density, low internal energy losses, high efficiency, very high durability, the ability to work in a wide temperature range and a small degradation of functional properties for repeated charging and discharging. By connecting the single supercapacitors in series, modules capable of charging with electric energy with a total voltage of several hundred volts are obtained. The disadvantage of supercapacitors is the dependence of the supercapacitors operating voltage on the value of the current from the point of view of supplying the electric power network with a constant and stable voltage value. When charging a fully discharged supercapacitor, its voltage increases with the accumulated charge up to a permissible value, usually around 2.7 V. During unloading, the situation reverses and the voltage decreases to zero again with the fully discharged supercapacitor. Serial connected supercapacitors form a module with a working voltage which is the sum of individual elements. All disclosed technical solutions, converting the excess kinetic and potential energy of the vehicle into electricity, ultimately transmit it to the battery and then to the onboard electrical equipment, and the supercapacitor module, if any, is designed to reduce the intensity of recuperated energy to the battery, reduce its power charging and thus increasing durability.

The next step in the development of the technique of using supercapacitors to recuperate the mechanical energy of vehicles was the use of voltage converters - electrical devices that allow the supply of electricity receivers from power systems whose current- voltage parameters do not allow direct connection to the receiver. The role of the voltage converter is to change the value of current and voltage in a manner corresponding to the requirements of the powered receiver, with possibly the lowest power losses. The most technically advanced solution in a recuperative systems is the use of a bi-directional voltage converter placed between the generator and the supercapacitor module. In this solution, the generator, characterized by a constant value of the charging voltage, supplies electrical energy to the capacitance reservoir, which voltage may be even close to zero. Similarly, the voltage boost converter is able to match the lower voltage of the charged supercapacitor module (even close to zero) to the nominal value required by the on-board receivers of the vehicle.

European Patent EP2032383 describes a system comprising a serial connection of a rotating AC generator, a converter changing AC voltage into a constant voltage of the connected electricity network. The use of DC voltage converter for permanent charging and discharging of a supercapacitor module in a vehicle has been described. A high volume supercapacitor module was used. A system that transmits recuperated electricity also to a vehicle battery is disclosed.

The US patent US8092338 describes a system in which recuperative energy is stored in a supercapacitor module with a high voltage value and then, thanks to a DC voltage converter used to charge a battery with a lower nominal voltage value. The charging phase of the recuperation process is activated by measuring the depression of the brake pedal.

International patent application publication WO2016125852 discloses a system comprising a supercapacitor module that stores electrical energy supplied from an alternator; DC to DC converter which converts a larger output voltage from the supercapacitor module to a lower rated voltage of the battery and electrical energy consumers, a current sensor that measures the discharge current from the supercapacitor module and the control unit. The patented method includes operations that based on the measured discharge current signal regulate the operating parameters of the voltage converter. The system manages the flow of recuperated electricity to the vehicle battery.

US patent US2015300307 presents an engine starting system comprising an additional rechargeable battery connected parallel to the main vehicle battery. The described method includes the operations of switching on and disconnecting the rechargeable battery based on the measurement of the voltage in the electrical system. The patent discloses a method of starting support by simultaneous transfer of electric energy from two energy storage devices: a battery and a supercapacitor module.

The US patent US8860244 discloses a power supply circuit for on-board energy receivers by a unit comprising a battery charged by a generator coupled to the motor and a supercapacitor module connected parallel with the battery. The electric power flow management system includes a controller and an on-board sensor unit. The system also regulates the flow of electric energy to the vehicle battery.

European patent application EP2773526 discloses a battery storage system comprising a battery, a supercapacitor module, a voltage and current regulator connected to the battery and the supercapacitor module, an electronic controller and a sensor unit measuring voltage and current input signals to at least one energy store. The method of controlling the energy flow between the battery and the supercapacitor module as well as the method of detecting the vehicle's working modes and the state of charge of both energy stores was also disclosed. The system controls the flow of electricity to the vehicle battery. WO2011000630 discloses an apparatus for storing energy in a hybrid or electric vehicle in which both types of electric energy storage are incorporated: a battery and a supercapacitor module. The disclosed method includes activities that limit the current flowing between the battery and the supercapacitor module. The system thus controls the flow of electrical energy to the vehicle battery.

Chinese patent application CN103441561 discloses a device comprising a supercapacitor module, an electronic controller, a DC voltage converter for a larger DC voltage, a DC voltage converter for a smaller DC voltage, a generator, electric energy receivers, a battery and a starter. The device can be used in non-hybrid combustion vehicles. The recuperation controller communicates with the combustion engine controller via the CAN bus. A method of controlling a supercapacitor module, including a method of managing the flow of electric energy to a vehicle battery, is disclosed. The device has no information about the value of the electricity flow rate.

Publication of German patent application DE102004016292 discloses a starting and supplying system for a motor vehicle that includes a starter connected to a supercapacitor module, at least one battery and a generator driven by an internal combustion engine. The electric energy storage system has a switch designed for multi-variant interconnection of the supercapacitor module, battery, starter and generator depending on the difference in voltage values of the energy storage devices. Also disclosed is a control method for the starter and the power system of the internal combustion engine. The device controls the flow of electricity to the vehicle battery.

The German patent application DE102011109709 presents a system and method for supplying electrical energy from a battery and a supercapacitor module to the vehicle's electrical network. Both energy storage devices are connected in parallel. The connection of the battery to the electric network of the vehicle is controlled based on the ratio of the battery voltage to the voltage of the supercapacitor module. The device controls the flow of electricity to the vehicle battery.

Japanese patent JP4170177 describes a device capable of storing high volumes of electric energy, adopting rapid and high electric power values, protecting the battery life due to the use of a capacitance module which in a short but sufficient time can power the starter during the start-up of the internal combustion engine. Supplementary electrical power can also be supplied to the starter from the battery in a stable way. The intensity of electric current flowing to the starter from the battery and from the supercapacitor module is adjustable.

French Patent Application FR2935156 discloses a method for electrically connecting a supercapacitor module to a vehicle's electrical network to provide electrical energy to the vehicle's starter. The supercapacitor module is autonomously controlled by its own electronic controller based on on-board sensor signals. In addition, the application discloses a method of dependent control of the supercapacitors module using the additional "start" button signal.

The American application US2012095644 reserves the right to protect the super capacitor system from excessive temperature by turning off the system's functions when a certain temperature threshold is reached. This system refers to the recuperation of energy by means of an electromechanical machine, which is an electric motor and generator. Examples of the invention describe in detail the methods of controlling the temperature of a package of supercapacitors. There are no detailed steps of activating the regenerative braking mode, or releasing energy.

Application US200214040405 refers to a system that does not contain a current sensor designed to detect start-up and instantaneous activation of a package of super capacitors while the starter is running. It is not relieving the main battery of the vehicle. Electromechanical machine in a given solution provides "start-stop", "torque-assist" functions and has a specific, coaxial construction with mounting on the motor shaft. In this US application, the regenerative braking energy mode is activated when energy is drawn from super capacitors. The American application does not describe the conditions for releasing energy other than "when the energy storage module absorbs the braking energy". There are no detailed steps of activating the regenerative braking mode or releasing energy.

Application US9211855 shows that regenerative braking is activated in vehicle deceleration traction and when the level of charge is low and super-continent energy is released in the remaining time to charge the vehicle's main battery. Also, starting is detected based on information from the vehicle controller and not from the current sensor measuring the current flowing through the main battery. Shifting power from super capacitors to the primary battery translates into increased load cycles of the vehicle's primary battery.

Application CN105984347 describes a "start-stop" system without specifying how algorithms work. In the Chinese application, the starter also acts as a generator. It does not present the conditions under which each mode of operation is activated.

Application US2013320931 refers to a device that solves the problem of sensitivity of electrical receivers on board the vehicle to voltage drop during vehicle start-up. In the American description capacitors are connected in front of the voltage regulator and have an additional bypass relay. In addition, the system contains two separate systems of energy receivers, powered in different ways. The American application describes the bypass relay operation algorithms, the method of energy recovery during vehicle deceleration and the way of releasing energy to the receivers.

The EP115787878 application describes a hybrid vehicle system, i.e. an electric motor with generator function. The way of activating the regeneration mode is on the basis of vehicle acceleration. The operating algorithm is based on an energy balancing strategy, as in typical hybrid vehicles: "The control modes of the hybrid vehicle include the "idle mode", "idle stop mode", "deceleration mode", "acceleration mode", and "cruise mode...".

The application WO2013067292 describes a system consisting of a "starter-generator" device, which acts as a starter, generator and drive motor. In this solution, the vehicle's main battery is used to store braking energy. Start-up support is also based on the "start/stop" function and the start energy comes only from super capacitors, charged from the vehicle's main battery.

Vehicle systems known as supercapacitors for storing electric energy from recuperation are known from the vehicle state of the art described above, but all solutions consider the battery as an important element of the accumulated energy collection system. The use of a supercapacitor module together with the charging current control system serves to reduce the dynamics of battery charging. The battery charging current is limited by the specifics of chemical reactions and the supercapacitor module, capable of receiving much higher charging current, recharges the battery with its electric energy with much smaller discharge current values than the charging current. The battery in the recuperation system generates numerous disadvantages. First of all, charging and discharging the batteries is not fully reversible. Due to ohmic losses associated with the internal resistance, there is a heat release to the environment during charging and discharging. During charging in acidic batteries there is a phenomenon of hydrogen leakage. It is estimated that the total efficiency of the acid battery is about 60-80%, which is significantly lower compared to the efficiency of supercapacitors in the range of 95-98%. Secondly, starter batteries, most commonly installed in vehicles, are not designed for frequent discharge but for functioning in a fully charged state. The use of the recuperation function for a classic vehicle battery causes a significant reduction of the life of the device, which entails additional operating and ecological costs.

Thirdly, after using a supercapacitor module together with DC converters in the recuperation system and starting the charging mode, the instantaneous lower voltage of the capacitance module compared to the battery voltage value causes that the supercapacitor module is affected not only by the electric generator but also by the battery. This is particularly apparent in the first phase of charging the supercapacitor module, when the voltage regulator in the generator failed to set the increased power of the device. In addition to the current flowing to the supercapacitors from the generator there is a harmful phenomenon of reverse flow of current from the battery to the supercapacitors, which reduces the recuperative charging capacity. In addition, after the end of the charging phase of the supercapacitors, the discharged battery is recharged with the electrical energy which it has given to the supercapacitors. In this way, the effectiveness of the recuperation process decreases.

During the operation of the vehicle, energy is consumed for the purpose of driving at the set speed and power for on-board devices which are not used while driving. In combustion vehicles, the most common source of energy is fuel that releases heat during combustion. Moving the vehicle at a given speed causes energy consumption to overcome rolling resistance and air resistance. At the same time, energy is used for internal mechanical resistance of moving mechanisms and energy for powering on-board devices. When driving at a constant speed, energy consumption in constant ambient conditions is also unchanged. At the same time, during the movement of the vehicle at variable speed in the variable terrain, the accumulated kinetic energy and potential energy changes in the vehicle's mass. When driving in conditions of frequent braking and frequent accelerations, the momentary energy consumption of the vehicle changes. When increasing its kinetic energy, the vehicle requires additional power to be supplied by the propulsion engine, while the energy consumption of the motor decreases during deceleration of the vehicle. Similarly, when climbing hills, a vehicle that increases its potential energy requires additional energy consumption and a vehicle that descends from a hill requires less energy for the drive engine. If the consumption of a portion of energy per unit of time is the power then the vehicle power is the balance which includes the power of rolling resistance, the power of air resistance, the internal power consumed and the kinetic power and potential power. Both kinetic and potential energy can be recuperated while driving due to the fact that the acceleration and deceleration phases as well as accelerating and decelerating are very close to each other. The vehicle which is accelerating will be braking in the conditions of the city traffic, while the vehicle that drives up the hill will descend from it. Hence the idea of recuperation of mechanical energy, both kinetic and potential was made up. If the total kinetic and potential power is greater than the sum of the power of motion resistance and the internal power consumed, the vehicle will increase its total energy. Excess mechanical power over the power of motion resistance can then be accumulated in the battery and stored until the total kinetic and potential power ceases to be greater than the sum of the power of motion resistance and internal power consumed. For the correct operation of the recuperation of mechanical energy in a vehicle, the key is the method of detecting the state of kinetic and potential power redundancy over the total power of motion resistance and the power transmitted to the on-board devices. This condition is called the braking mode. The braking mode can thus be understood as a state in which it is possible to recuperate the energy of the vehicle without adding energy from the internal combustion engine.

The essence of the method of servicing the charging and discharging system of the capacitors in the combustion vehicle is recuperation of the electric braking power generated by at least one vehicle alternator in the braking mode to the capacitor system, and then transferring this energy to the electric energy consumers, thereby relieving the alternator in the vehicle. The alternator is unloaded during the power supply mode, because the alternator voltage regulator compensates for voltage variations caused by switching the capacitor system.

The disclosed method is based on a system comprising a capacitor system connected in parallel to the vehicle's electrical system. The vehicle's electrical system includes energy distribution teams, energy consumers and energy producers. The energy distribution unit includes a supercapacitor system and is used to selectively store and discharge electricity in appropriate conditions, beneficial from the point of view of reducing fuel consumption. This is done by a switch and a controller that are part of the capacitor system. The capacitor system consists of at least one capacitor, especially a supercapacitor type.

A group of energy producers is connected parallel with a set of consumers and a distribution set. The group of energy producers refers to all electrical devices in the electric system of the vehicle that can produce electricity. In the case of this invention, it is an alternator that generates electrical energy in a form of a flow rate of alternating electrical current then converted via a rectifier to the constant electric current flow rate.

The consumers is connected parallel with the team of producers and the distribution set and includes all electric energy receivers in the vehicle's electrical system. They can be both capacitive, inductive and resistive elements. Also, the vehicle battery belongs to the consumer team, because when the engine is running, the alternator supplies electricity to the energy consumers, not the battery. This is due to active voltage regulation of the vehicle's electrical system with a voltage regulator. The capacitor system also includes a controller responsible, among others, for switching and controlling the flow of energy in the form of the current flow through the distribution set. The control uses signals coming from the vehicle's communication system. The vehicle communication system includes a CAN bus, ABS signals or signals from sensors in the vehicle's electrical system. It provides information such as vehicle speed and engine load. The engine load is understood as the value of the fuel dose injected in the internal combustion engine. The controller also controls the state of charge of the capacitor system, especially by measuring the voltage of the capacitor system.

The controller controls the energy flow through the power distribution unit so that in the braking mode the excess mechanical energy of the vehicle is converted into electric energy stored in the capacitor system. The braking mode is activated during the period of redundancy of the kinetic and potential power over the total power of movement resistance and the power transmitted to the on-board devices during the zero load of the internal combustion engine. The load is understood as the instantaneous consumption of the chemical energy of the injected fuel into the engine. Another important condition for activating the braking mode is to find a higher vehicle speed than the assumed vehicle speed limit. Electricity is then transmitted from the alternator via a voltage regulator included in the alternator via a switch, in particular a DC voltage converter that charges the capacitor system.

When the capacitor system has sufficient amount of electricity, it can be given to power consumers of the vehicle in power mode. The power supply mode is activated when a non-zero engine load is detected and the alternator performs power operation of the consumer unit when the capacitor system has the appropriate amount of energy and when the vehicle's electrical system voltage does not exceed the limit value. The power mode is designed to relieve the alternator from the production of electricity, feeding the energy consumers to the lower limit energy level of the capacitor system. Therefore, it is activated after the correspondingly high load of the internal combustion engine is detected. Electricity is transmitted from the capacitor system via a switch, especially a DC voltage converter. The controller ensures that the output voltage of the boost converter does not exceed the limit value. This is to protect the vehicle's electrical system from excessive voltage when the alternator voltage regulator is not able to lower the voltage value in the vehicle's electrical system. Excessive voltage of the vehicle's electrical system could harm energy consumers, especially the battery.

Additional variants of the invention include methods comprising activation of an excess mode and a boot mode. The excess mode requires the presence of a sensor system measuring the current flow in the vehicle's electrical system. Excess mode is designed to reduce the excessive current flowing from the alternator caused by a large voltage difference between the manufacturer's team and the consumer team. The excess mode is recognized by the controller on the basis of the energy flow measurement in the vehicle's electrical system, and in particular the measurement of the electric current. Measurement can be made on electrical connections between a group of producers and a group of consumers. After detection of exceeding the first limiting energy flow from the group of producers by the measured value of energy flow from the producers to the consumer group, the excess mode is activated, provided that the degree of charge of the capacitor system is below the first load limit level.

The start-up mode is a specific mode of the system operation. Due to the low speed of the combustion engine, the alternator generates insufficient electrical power in relation to the needs of the starter. Additional electrical power must be generated from the starter battery and / or from the capacitor bank. The start-up mode is activated thanks to measuring signals of the current sensor placed in the producers group or a set of consumers, and is based on the measurement of the charge of the capacitor system. The sensor detects energy flow to the vehicle's starter, and especially measures the electric current. The start-up mode is activated after exceeding the adopted second limit energy flow threshold towards the starter. Then the controller switches on and connects the power distribution unit to the energy consumers, allowing energy to flow from the capacitor system to the vehicle starter. Start-up mode 50 is not activated when the capacitor system charge level is less than the second capacitor charge level, i.e. when the capacitors are discharged. In start-up mode, the capacitor system may be able to supply the start-up phase. A battery that can be mounted in a vehicle does not have a significant role in recuperating energy from braking, powering the receivers or taking over excess energy. The battery in this solution is treated as a receiver of electricity, therefore, it is part of the energy consumers group. After starting the internal combustion engine, the alternator is the main source of energy for all the receivers and the voltage regulator included in the alternator ensures the voltage stability of the vehicle's electrical system. The present invention is based on this idea and thanks to this the transfer of recuperative electricity achieves high energy efficiency.

The energy flow in the vehicle's electrical system can be represented indirectly by measuring the intensity of the electric current. The location of the electric current flow sensor may be between the manufacturer team and the consumer group, in particular between the battery and the vehicle starter and the alternator. The energy flow measurement can also be carried out indirectly on the basis of the measurement of the voltage drop in relation to the reference voltage.

The method is based on a circuit including a switch. The switch is to selectively transmit the electrical energy flow or block it depending on the signal of the controller. The switch can be a transistor, a relay, a reed switch or a DC voltage converter. The DC voltage converter can be single and bi-directional and of the type increasing voltage and decreasing voltage. The system may especially comprise at least one bi-directional DC voltage converter. The capacitor may be a supercapacitor, i.e. an electrochemical condenser with a double layer. It can also be a pseudo-random capacitor or a hybrid condenser. The main feature of this energy store is the possibility of fast charging and discharging as well as low sensitivity to temperature and the number of 25 charging cycles compared to electrochemical batteries. The engine load can be determined in particular on the basis of the amount of fuel injected into the engine. The control may also use other indirect signals corresponding to the engine load type of the accelerator position or the degree of throttle opening. The signals supplied to the controller may come from the vehicle communication system, which may include CAN bus signals, ABS system or separate sensors.

The essence of the capacitor charging and discharging system in the combustion vehicle is the recuperation of the electric braking power generated by the vehicle alternator in the braking mode to the capacitor system, and then transferring this energy to the electrical energy receivers in power mode, thus relieving the alternator in the vehicle. The alternator is unloaded during the power supply mode, because the alternator voltage regulator compensates for voltage variations caused by switching the capacitor system. Thus, the invention having braking and power modes results in a significant reduction in the fuel consumption of the vehicle's combustion engine.

The start-up mode allows the use of previously recovered electricity to support the start-up of the internal combustion engine. Therefore, braking energy, which would otherwise be completely lost, is used to power the vehicle's starter. This results in a reduction of the fuel consumption of the vehicle's combustion engine and the protection of other devices in the electric system of the vehicle through which excessive electric current flows during the start-up of the vehicle's combustion engine. Excess mode limits the negative effects of reduced voltage in the vehicle's electrical system immediately after starting. The alternator, due to the increased voltage difference, transmits increased values of the electric current to the consumer group. High electric current is not beneficial for the receivers in terms of durability. Thus, relieving the consumer group by taking a portion of the electrical current from the alternator to the condenser system instead of the consumer group brings them beneficial effects. In addition to increasing the durability of the receivers, a part of the electricity is recovered, which would otherwise be lost to the useless heat emitted by the resistive elements of the vehicle's electrical system.

The first embodiment of the invention consists of three main electrical units: a set of producers, a distribution unit and a group of consumers. Such a division allows the segregation of components in a vehicle according to their nature of work. The system is installed in a city bus with a 24 V electric vehicle. The producers, the distribution group and the consumers are electrically connected parallel. The producer group consists of a device in a form of an alternator producing electricity in a combustion vehicle. The alternator converts the mechanical energy transmitted therein by a belt transmission from the crankshaft of the combustion engine to electric energy. The alternator consists of an electric energy generator in a form of a three-phase AC and a voltage regulator, which converts the AC into constant current with constant voltage. The voltage regulator regulates the voltage so that regardless of the load of the vehicle's electrical system its voltage is constant and equals the nominal value of the vehicle's electrical system. Thus, each voltage deviation in the vehicle's electrical system is offset by the voltage regulator. The consumer group consists of electric energy receivers of the vehicle and the starter. The electric energy consumers are all devices that receive electricity from the vehicle's electrical system during its operation. These include devices such as the vehicle lighting system, electric power steering system, electrical elements of the pneumatic system, electrical elements of the braking system or the battery system. Since the rated voltage of the vehicle's electric system regulated by the voltage regulator of the alternator is usually greater than the voltage resulting from the charge of the battery system, during the operation of the vehicle the battery system is charged with electric current generated by the alternator and it is not a source of energy for other electric energy consumers the battery is an electricity receiver. The distribution unit consists of a capacitor system and connections for signals from the vehicle's communication system. The capacitor system consists of capacitors which are supercapacitors connected in series. Each capacitor is operated by a charge balancing system so that all capacitors have an evenly distributed electric charge. The controller contained in the capacitor system corresponds to balancing the capacitance of capacitors. The capacitor system also includes a switch in the form of a double-directional DC converter. Both converters are connected parallel to each other and their one end is connected to the positive terminal of the first capacitor. One inverter is responsible for charging the capacitors and is of a voltage-reducing type. Such an inverter is able to regulate the current and voltage charging the capacitors with any lower voltage than the voltage of the vehicle's electric system. Due to the use of such a converter, the capacitor system is protected against excessive thermal load resulting from the flow of electric current over the permissible limit. The second converter is of the booster type and is responsible for discharging the capacitor system. It allows for increasing the output voltage of the capacitor system over the voltage value of the vehicle's electrical system. As a result, regardless of the charge level of the capacitor system, the distribution unit is always able to transmit the energy contained in the capacitor system to the vehicle's electrical system in a controlled manner. Both voltage reducing and boosting converters are electronically connected to the controller. The controller is responsible for selectively controlling the energy flow through the power distribution unit via the switch. The controller also receives signals from the vehicle communication system, which consists of the vehicle's CAN bus. The vehicle's CAN bus provides information to the controller including: vehicle speed and fuel dose equivalent to the engine load. In addition, the controller receives signals from the voltage measurement of the electrical system with the sensor connected to the vehicle's electrical system on the terminals to which the energy distribution unit is connected to the vehicle's electrical system. The controller also receives voltage signals of the capacitors and electric current through the capacitors from the sensors in the capacitor system. The capacitor system is contained in the housing in a compact manner and separated to it electrically. Due to its compact design, this arrangement is placed depending on the design of the city bus in any place.

A second, the preferred embodiment of the arrangement of the invention includes a system such as in the first embodiment of the invention, except that it includes a start-up mode and an excess mode. In addition, the system includes a sensor detecting the current flow rate in the energy consumers on the positive conductor near the vehicle's battery terminal. The main function of the current sensor is the detection of the start-up and the detection of excessive battery charging current. The analog sensor is of the Hallotron type, which means that the measurement of the energy flow in the conductors is determined on the basis of indirect measurement of the magnetic field. When the controller detects conditions favorable to the start-up mode, the capacitor system is autonomously connected to the vehicle's electrical system to transmit electrical power to the consumer, especially to the starter. When the controller detects the excess mode, the capacitor system is autonomously connected to the electric system of the vehicle, to reduce the flow of electrical energy from the vehicle alternator to the consumers, especially immediately after completion of the combustion engine start.

The first embodiment of the method of the invention comprises of a system according to the first embodiment of the invention. This example includes activities related to braking mode and power mode, which are the essence of the idea of recuperating the braking energy. During the active braking mode, the switch, including the DC converter reducing the voltage, switches on the capacitor system to the vehicle's electrical system. The switching time is regulated by the switch so as not to exceed the capacitor’s charging current. The controller receives signals from the bus CAN for vehicle speed and fuel dose as a measure of engine load. The controller also detects the voltage in the vehicle's electrical system. In braking mode, part of the electrical energy produced by the alternator is sent to the capacitor system and the rest of the electrical energy flows to the consumers. Activation of the braking mode is based on the fulfilment of three conditions. The first condition for activation of braking mode is met when the current vehicle speed is greater than the vehicle's speed limit. The vehicle speed limit value depends on the vehicle in which the capacitor system is mounted. The vehicle speed limit is set as a condition because at lower vehicle speeds, the vehicle's transmission control system disconnects the chassis from the vehicle's engine. Vehicle operation in coast down mode at lower speeds is used to save fuel. The second condition for the activation of the braking mode is fulfilled when the load on the motor is less than the limit load. The load on the motor is represented by the value of the fuel dose. The fuel dose is the best equivalent of the engine load, because it clearly determines the situation when the kinetic energy and potential energy accumulated in the vehicle mass allows to overcome any resistance, so the surplus energy can be partially recovered, otherwise it is lost. The fuel dose also determines when the accelerator is not depressed when braking or when the vehicle is in coasting mode. The load limit is set near the zero load value. The third condition for the activation of the braking mode is fulfilled when the charge level of the capacitors is smaller than the first limiting charge level of the capacitor system. This level is continuously monitored by the controller based on the voltage measured on the capacitors. This limitation protects the capacitor system before a very dangerous overcharge. When at least one of the three conditions for activating the braking mode during the active braking mode is not satisfied, the braking mode is deactivated. In this case, the switch disconnects the capacitor system from the electric system of the vehicle. In power mode, the electric energy accumulated in the capacitor system is sent to the energy consumers, relieving the alternator. As a result, the combustion engine consumes less energy for the drive of the alternator. It is crucial to return the energy from capacitors to the receivers as soon as possible so that the next time the braking mode is activated, the capacitor system is able to absorb as much energy as possible. The most advantageous case is when the discharge current of the capacitor system is large enough that the alternator is completely unloaded and does not generate electricity. Then the total consumer demand for electricity is provided by the capacitor system. Any increase of the energy transfer above this level causes an unfavorable increase in the voltage in the vehicle's electrical system. For this reason, there is a condition limiting the excessive voltage generated by the switch comprising a DC converter increasing the voltage. Activation of power mode is based on the fulfilment of three conditions. The first condition of the power mode is satisfied when the load on the engine is greater than the limit load of the engine. When the load of the engine manifested by the fuel dose is greater than zero, the engine performs work and converts the chemical energy of the fuel into mechanical energy. In this situation, the mechanical energy that is converted into electrical energy in the alternator always comes at least partly from the energy generated in the combustion process. Thus, unloading the alternator by switching on the capacitor system to power the consumers directly affects the reduction of fuel consumption in the combustion vehicle. The second condition for the activation of the power mode is satisfied when the charge level of the capacitors is greater than the second limiting charge level. Such a condition protects the capacitor system from excessive discharging. The third condition for activating the power mode is met when the voltage of the vehicle's electrical system is less than the limit voltage. This condition is a safeguard against excessive power transmission above the consumer’s demand. When at least one of the three conditions of activation of the power mode during active mode power supply is not satisfied, power mode is deactivated. In this case, the switch disconnects the capacitor system from the vehicle's electrical system

The second, preferred embodiment of the method of the invention comprises a system according to a second embodiment of the invention. The method includes operations such as the first embodiment of the inventive method, while having additional engine start and excess modes. Both modes are an addition to the idea of energy recuperation. The start-up mode allows the previously recovered electricity to be used to support the start-up of the combustion engine. Thus, the braking energy, which would otherwise be completely lost, is used to energize the vehicle's starter. Excess mode limits the negative effects of reduced voltage in the electrical system of the vehicle immediately after start-up. The alternator, due to the increased voltage difference, transmits increased values of the electric current to the consumer group. The high level of electric current is not favorable for the receivers in terms of durability, and in particular for the battery. Thus, relieving the consumer group by taking a portion of the electrical current from the alternator into the capacitor system instead of the consumers brings them beneficial effects. In addition to increasing the durability of the receivers, part of the electric energy is recovered, which would otherwise be lost to the useless heat emitted by the resistive elements of the vehicle's electrical system. Activation of the start-up mode is based on the fulfilment of two conditions. The first condition for activation of the start-up mode is fulfilled when the energy flow to the starter is less than the first energy flow limit. This energy flow is represented by electric current measurement in the vehicle's positive battery lead, because the battery first transfers electricity to the starter. The second condition for activation of the start-up mode is satisfied when the capacitor charge level is greater than the second charge level. This condition does not allow the discharged capacitor system to be connected. When at least one of the two conditions for activating the start-up mode during the active start-up mode is not satisfied, the start-up mode is deactivated. In this case, the switch disconnects the capacitor system from the electrical system of the vehicle. Activation of the excess mode takes place based on the fulfilment of two conditions. The first condition of activation of the excess mode is satisfied when the energy flow from the alternator is smaller than the second limiting energy flow level. Such energy flow is represented by electric current measurement in the vehicle's positive battery lead, because directly after the start-up, the battery is at highest risk. The second condition for the activation of the start-up mode is satisfied when the charge level of the capacitors is smaller than the first limiting charge level. This condition does not allow the capacitor system to be connected when it is charged to the maximum charge level. When at least one of the two conditions for activating the excess mode during the active excess mode is not satisfied, the overrun mode is deactivated. In this case, the switch disconnects the capacitor system from the vehicle electrical system.

Description of drawings

Fig. 1 shows a schematic circuit for charging and discharging capacitors in an internal combustion vehicle according to the first embodiment of the system. The electrical system of the vehicle 7 comprises three units of devices connected in parallel: a set of electricity producers 1, a set of consumers of electric energy 3 and an electricity distribution unit 2 that performs functions of charging and discharging capacitors. Parallel connection of the units is used to supply them with the same electrical voltage. A set of 10 electricity producers 1 includes at least one alternator 4 driven by an internal combustion engine comprising a voltage converter 6 converting a variable generator voltage into a constant output voltage from a power generator 1. The combined receiver system 8 and the starter 9 form a set of consumers of electricity 3, for which All electrical energy produced in the producer group is intended for the first time. The 15 consumer group 3 are vehicle electrical and electronic devices connected in series or in parallel. The consumer group may include a battery fulfilling in system 3 the role of the electricity receiver in the set of producers 1. The electric power distribution unit 2 consists of a capacitor system 10 connected electronically to the vehicle communication system 12 that contains the vehicle's CAN bus 17. System 20 of capacitors 10 has a switch 14 connected in series to the electrical network of the vehicle and a package of capacitors 11 comprising at least one capacitor. The switch 14 is designed to connect or disconnect the supercapacitor package 10 to the electric network of the vehicle 7 and consists of at least one transistor or at least one relay or at least one reed switch or at least one DC converter, in particular of the bidirectional type of boosting and decreasing. Turning the switch 14 to a closed or open position controls the controller 13 of the capacitor charging and discharging system utilizing the vehicle communication system signals.

The method of the invention in the second embodiment is explained in more detail with reference to the drawing, Fig. 2, which schematically shows the energy flow in four modes of operation 30: braking mode 20, in which energy is supplied to the power distribution unit 2; a power supply mode 21, in which energy is supplied by the power distribution unit 2; an excess mode 23, in which energy is supplied to the power distribution unit and a start mode 22, in which energy is supplied by the energy distribution unit. The drawing according to Fig. 3 allows a better understanding of the device's operating algorithm. The conditions for activation of braking mode 20 based on signals of vehicle speed 18, engine load 19 and charge level of capacitors 16 are described. Conditions for activating power mode 21 are also presented based on signals: electrical system voltage 15, motor load 19 and charge level of capacitors 16. Shown activation conditions for the excess 23 mode based on the capacitor charge level signals and the energy flow from the alternator. In addition, the activation conditions of the start-up mode 22 are shown based on the capacitor charge level signals 16 and the energy flow to the starter 24. Fig. 4 of the drawing shows the effects of the activation of the start-up mode 22, the supply mode 21, the braking mode 20 and the excess mode 23 in the form of the capacitor system switching and disconnecting the capacitor system.

The method according to the invention in the first embodiment is explained in more detail on the basis of the actual measurements of the work of the invention shown in Fig. 5. The course of the vehicle speed 18 and the threshold of speed 24 for the braking mode 20 are shown. The course of the engine load 19 in the form of the fuel dose course and the threshold of the load 25 for the braking mode 20 and the supply mode 21. Also shows the course of the charge level of the capacitor bank 16 and two thresholds of charge level 50 of capacitors: first 24 and second 27. The method according to the invention in the second embodiment is explained in more detail on the basis of the actual measurements of the work of the invention shown in Fig. 6. The course of the current flow through the sensor, the threshold of the first limit current 29 used in excess mode 23 and the threshold of the second limit current 30 used in the starting mode 22 are shown. Furthermore, the course of the charge level of the capacitor bank 16 and the two thresholds of the capacitor charge level 5 are shown: first 24 and second 27.

Claims

1. A method for controlling a capacitor charging and discharging system in a combustion engine vehicle comprising: a capacitor system connected parallel in a vehicle's electrical system comprising at least one capacitor; a switch connected in series with a capacitor system configured to selectively control electrical communication between energy distribution group, energy consumer group and energy producers group; and a controller; the method is characterized in that it detects a capacitor charge level; reads the vehicle speed and the engine load from the vehicle communication system; it is characterized in that it turns the switch to closed state and connects the power distribution group to the energy producers group when all of the following conditions are met: the vehicle speed is above the target speed, the engine load is less than the target load, the capacitor charge level is less than a first charge level, activating a braking mode, and when at least one of the following conditions is met: the vehicle speed is not above the target speed, the engine load is not less than the target load, the capacitor charge level is at least at the first charge level, turns the switch to open state and disconnects the power distribution group from the energy producers group deactivating the braking mode; it is characterized in that turns the switch to closed state and connects the energy distribution group to the energy consumers group when all following conditions are met: the engine load is greater than the target load, the capacitor charge level is greater than a second charge level, and when a vehicle's electrical system voltage is less than a voltage threshold activating a supply mode, and when at least one of the following conditions is met: the engine load is not greater than the target load , the capacitor charge level is not greater than the second charge level, and when the vehicle's electrical system voltage is not less than the voltage threshold, turns the switch to open state and disconnects the energy distribution group from the energy consumers group, deactivating the supply mode.

2. The method according to claim 1, wherein the system additionally comprises at least sensor connected to the vehicle's electrical system configured to detect the energy flow from an alternator in the vehicle's electrical system; the method is characterized in that it turns the switch to closed state and connects the energy distribution group with the energy consumer group when all of the following conditions are met: the energy flow of the vehicle's electrical system is greater than a first energy flow threshold, and when the capacitor charge level is lower than the first charge level , activating an excess mode, and when at least one of the following conditions is met: the energy flow of the vehicle's electrical system is not greater than the first energy flow threshold, and when the capacitor charge level is not less than the first charge level, turns the switch to open state and disconnects the energy distribution group from the energy consumer group, deactivating the excess mode.

3. The method according to claim 1 or 2, wherein the system additionally comprises at least one sensor connected to the vehicle's electrical system, configured to detect the energy flow flowing into a starter motor in the vehicle's electrical system; the method is characterized in that it turns the switch to closed state and connects the energy distribution group with the energy consumers group when all following conditions are met: the energy flow of the vehicle's electrical system is less than the second energy flow threshold, and when the capacitor charge level is greater than the second charge level, activating a start mode, and when at least one of the following conditions is met: the energy flow of the vehicle's electrical system is not less than the a second energy flow threshold, and when the capacitor charge level is not greater than the second charge level turns the switch to open state and disconnects the energy distribution group with the energy consumers group, deactivating the start mode.

4. The method according to claim 1, wherein the energy consumers additionally comprise at least one electric battery;

5. The method according to claim 1, is characterized in that the measurement of the energy flow in the vehicle's electrical system affecting the control signals of the switch from the controller relies in particular on: measuring the current flow through the least one battery, at least one alternator or a receiver group, or the starter motor; or that the energy flow in the vehicle's electrical system is measured indirectly by analyzing voltage difference between the vehicle's electrical system voltage and a reference voltage.

6. The method according to claim 1, wherein the switch comprises: at least one transistor, at least one relay, at least one reed switch, or at least one DC/DC converter which is bi-directional boosting and lowering type.

7. The method according to claim 1, wherein the capacitor is a supercapacitor, an electric double-layer capacitor, a pseudo capacitor, or a hybrid capacitor.

8. The method according to claim 1, is characterized in that the engine load is determined by a fuel dose amount, by an accelerator pedal position, or by a throttle opening degree.

9. The method according to claim 1, characterized in that the parameters processed in the controller are from the vehicle communication system, favorably from a vehicle's CAN system, from a vehicle's ABS system, or from an independent sensors.

10. A capacitor charging and discharging system in a combustion engine vehicle characterized in that it comprises: the energy distribution group comprising the capacitor system comprising at least one capacitor, the energy producer group connected in parallel to the energy distribution group containing at least one alternator mechanically coupled to a combustion engine; the energy consumer group connected in parallel to the energy distribution group containing a set of receivers; the switch connected in series with the capacitor system configured to selectively control electrical communication between the energy distribution group, the energy consumer group and the energy producer group; and the controller configured to regulate the energy flow between the energy distribution group and the vehicle electrical system based on the signals from the vehicle communication system such that in the braking mode the power distribution group takes up part of the electricity generated by the one or more alternator and in the supply mode that the energy distribution group would give electrical energy to the energy consumers group.

11. The system according to claim 10, characterized in that it further comprises: the least one sensor for detecting energy flow in the vehicle electrical system; at least one battery in the energy consumer group; the controller is further configured to regulate the flow of electrical energy between the energy distribution group and the vehicle electrical system based on the signals of the vehicle communication system and at least one sensor in such a way that in the start mode the energy distribution group transfers electric energy contained in the capacitor system to the consumer group, where it goes mainly to the motor starter.

12. The system according to claim 10 or 11, characterized in that it further comprises at least one sensor for detecting the energy flow in the vehicle electrical system, the controller is further configured to regulate the energy flow between the energy distribution group and the vehicle electrical system based on the vehicle communication system signals and at least one sensor in such a way that, in the excess mode, the energy distribution group takes up electrical energy to the capacitor system.

13. The system according to claim 10, characterized in that the energy consumers group comprise at least one battery or at least one motor starter.

14. The system according to claim 10, characterized in that the switch comprises: at least one transistor, at least one relay, at least one reed switch, or at least one DC/DC voltage converter, in particular the bi-directional boosting and lowering voltage type.

15. The system according to claim 10, characterized in that the capacitors are the supercapacitor type, the electric double layer capacitor type, the pseudo capacitor type, or the hybrid capacitor type.

16. The system according to claim 10, characterized in that the engine load is determined by the fuel dose amount, by the accelerator pedal position, or by the throttle opening degree.

17. The system according to claim 10, characterized in that the information provided to the controller come from the vehicle communication system in particular from the vehicle's CAN system, from the vehicle's ABS system, or from the independent sensors.