Power amplifier for electric personal vehicle

Abstract

The invention relates to the field of electrical engineering and is intended for powering a load from a rechargeable battery of an electric personal vehicle, such as an electric motorbike, an electric car, or the like. A supercapacitor-based power amplifier for an electric personal vehicle consists of a DC-to-DC converter and several series-mounted supercapacitors. The DC-to-DC converter is mounted in series between a rechargeable battery of the electric vehicle and an input of an electric drive of the vehicle, and the supercapacitors are mounted in parallel to the DC-to-DC converter. The DC-to-DC converter contains a bypass switch. The invention enables the motor of an electric personal vehicle to reach maximum power within a short space of time, and also increases the service life of a rechargeable battery of an electric personal vehicle by allowing control of the battery current.

Description

[0001] POWER AMPLIFIER FOR AN INDIVIDUAL ELECTRIC VEHICLE

[0002] The present invention relates to a device in the field of electrical engineering and is intended for powering a load from a battery, for example, an electrochemical or capacitor battery, for individual electric vehicles, such as electric motorcycles, electric cars, etc.

[0003] Electric vehicles are currently offering an alternative to internal combustion engine vehicles, particularly for short-distance urban travel. These vehicles typically have a simple power system consisting of a power source, inverter, and electric motor. The power source is typically a lithium-ion battery with a battery management system. Compact and reliable electric vehicles, as well as reliable electric drives to control them, have recently been actively developed. However, the technology developed in the claimed invention relies on the power source—the battery. Electric vehicles typically require a power boost to overtake other vehicles, climb hills, or simply get moving.This power boost is provided by the battery, and while it's being provided, the battery voltage drops, causing the battery voltage to drop. As the battery discharges, the voltage drop increases, preventing the electric drive from delivering maximum power to the wheels. The result is reduced power as the battery becomes increasingly discharged.

[0004] Similar solutions are known in the prior art. One of them (see patent FR2757806, published February 5, 1999) proposes using supercapacitors connected in series with batteries at specific points during vehicle movement. A drawback of this solution is that the supercapacitors' performance is limited, and the current in the battery is not properly controlled, increasing the risk of reduced battery life.

[0005] The solution to this drawback was the use of two energy converters: one for the battery and one for the supercapacitor. For example, a motor power conversion device (see patent CN208424249, January 22, 2019) made it possible to achieve increased power and regenerative braking; however, this device is not efficient and reliable enough, since the energy passes through two voltage converters. A similar solution (see patent CN211265582, published August 14, 2020) was aimed at lead-acid batteries and vehicle heating systems. There is also a solution (see patent CN211543271, September 22, 2020), in which the battery and supercapacitor are connected via additional DC / DC converters and DC / AC converters. However, using this alternative requires more components, making the system bulkier, more expensive, and less reliable.

[0006] Another solution involves using three energy sources (see patent CN114179632, published March 15, 2022), two independent supercapacitor banks for lifting and braking, and a single battery for non-accelerating driving. This solution is not ideal for electric vehicles due to the limited vehicle volume. Other similar inventions relate to control methods for achieving optimal hybrid system performance (see patent CN109450063, published May 13, 2022).

[0007] The objective of this technical solution is to create a device that adds energy to the primary source of an individual electric vehicle to ensure maximum engine power can be achieved in a short period of time.

[0008] The technical result of the claimed invention consists in ensuring the possibility of achieving the maximum engine power of an individual electric vehicle in a short period of time, as well as in increasing the service life of the battery of the electric vehicle by providing the possibility of controlling the battery current.

[0009] The technical result is achieved in that the power amplifier based on supercapacitors for an individual electric vehicle consists of a DC converter and several supercapacitors installed in series with each other, wherein the DC converter is installed in series between the output of the battery of the electric vehicle and the input of the electric drive of said vehicle, and the supercapacitors are installed in parallel to the DC converter, wherein the DC converter contains a bypass switch.

[0010] The essence of the claimed invention is explained by the figure, which depicts its structural diagram. The following is indicated by numbers:

[0011] 1 - battery of an electric vehicle, 2 - electric drive of a vehicle,

[0012] 3 - DC converter,

[0013] 4 - supercapacitors.

[0014] The proposed invention involves adding an additional energy source—supercapacitors 4—to the vehicle's primary power source, battery 1. These supercapacitors can quickly deliver the energy needed to maintain the vehicle's maximum power when maneuvering, climbing, or starting off. Compared to prior art, the claimed solution is more flexible, as it can be installed on any individual electric vehicle (e.g., an electric motorcycle, electric bicycle, electric car, etc.). The invention is not a complete power system, but rather a supplement to an existing power system, and therefore can be installed on any individual electric vehicle.

[0015] The invention comprises a single device—a set of supercapacitors 4 connected in series with one another, a bypass switch, and a DC / DC converter 3, which is to be connected between the electric drive 2 and the battery 1 of the electric vehicle. This ensures that the current of battery 1 is monitored, as well as the input voltage of electric drive 2 is monitored by current converter 3 with supercapacitors 4. Furthermore, the invention is reliable, since in the event of a lack of energy in supercapacitors 4, the device is bypassed and battery 1 is connected, as is the case in the absence of an additional energy source in the power system.

[0016] The minimum number of supercapacitors used in the power amplifier is 4, sufficient to ensure maximum engine power is achieved in a short period of time. A set of 15 supercapacitors is recommended. A larger number is possible, but the vehicle weight will also increase. Fewer supercapacitors are also possible. For example, the minimum number of units for using a half-bridge converter topology is limited by the minimum voltage of the supercapacitor set. For half-bridge converters, it is recommended that the minimum voltage of the supercapacitor set be at least 25% of the expected output voltage. For example, if the expected voltage is 96 V, the minimum voltage of the supercapacitor set is 24 V, which means 15 supercapacitors (charged to half voltage, 1.5 V) are required.The number of supercapacitors (4) used in the claimed device is proportional to the time during which the driver can use this additional energy. For example, if the additional energy can be used for 3 to 10 seconds, the device uses 10 supercapacitors. This example is given for a 15 kW electric motor and supercapacitors with a nominal capacitance of 3000 F and a voltage of up to 3 V. The exact time for which additional energy can be used can be configured by the user. For example, the minimum additional energy use time (3 seconds) occurs when the supercapacitors have transferred all the energy, and the battery does not contribute anything. However, the battery can also supply some energy. This way, both the battery and the supercapacitors can share the load and have an extended runtime. In this particular example, more than 10 seconds would be too much current for the battery.

[0017] The invention utilizes a bidirectional DC / DC converter 3 to control battery current and maintain the readiness of supercapacitors 4 for operation. The device is activated by pressing a trigger button connected via a communication channel to the microcontroller of DC / DC converter 3. When the button is pressed, supercapacitors 4 release energy by increasing the input voltage of electric motor drive 2, enabling it to deliver maximum power. This power is delivered for approximately 8 seconds. The time is user-adjustable from 1 to 10 seconds. Automatic operation is also possible. In this case, the trigger is not the button, but the current consumed by electric motor drive 2, as set in the settings of DC / DC converter 3.

[0018] Using only one DC-DC converter 3 allows the power amplifier to have a simple design with a minimum of components and a smaller footprint. In the event of a power shortage in the supercapacitors 4 or their failure, battery 1 is connected directly to electric drive 2 via a bypass switch located inside DC-DC converter 3, increasing system reliability.

[0019] The power amplifier is a plug-in device housed in a metal housing that can be connected to any individual electric vehicle. This device will provide new functions: current protection for battery 1, power boosting using supercapacitors 4 for lifting, starting, and overtaking vehicles in a short period of time, and energy recovery without the current limitations inherent in batteries. The power amplifier operates as follows. The power amplifier is connected between battery 1 and the vehicle's electric drive 2. The electric vehicle is started and controlled in a known manner. At this point, the power amplifier is inactive, and all power is supplied by battery 1. Supercapacitors 4 contain a certain power reserve, being charged by a small current (approximately 0.1-0.2 C for 5-10 A) from battery 1.Energy is stored until the driver decides to release additional energy to increase the vehicle's output (during overtaking, driving over an obstacle, etc.). When this need arises, the driver presses the trigger button, sending a signal to the microcontroller of DC / DC converter 3. DC / DC converter 3 adapts its values ​​to release energy from supercapacitors 4, and supercapacitors 4 release energy, thereby supplying electric drive 2 and the vehicle's electric motor with power from both battery 1 and supercapacitors 4.In other words, DC-DC converter 3 receives energy from the input of battery 1 and energy from supercapacitors 4 using short-term energy storage devices (magnetic elements), and then releases this energy at a higher output voltage. Supercapacitors 4 receive this energy and provide continuous maximum power to electric drive 2 and the electric motor, which the motor can withstand for several seconds, sufficient to overtake another vehicle, climb a hill, or perform other efforts in a short time. Moreover, the design of the device does not damage or reduce the service life of battery 1, since the battery current will be limited by the proposed device.Connecting the power booster in series with battery 1 and electric drive 2, which controls the engine, allows for the current to battery 1 to be controlled when it exceeds the limits set in current converter 3, avoiding peaks. Values ​​are limited from 1 to 3 C (e.g., 150 A) and are controlled by the vehicle user. 1 C ensures longer battery life, while 3 C provides greater available power. This extends the life of battery 1. The number of seconds of acceleration and the power values ​​are inversely proportional to each other due to the fixed amount of energy stored in supercapacitors 4. For example, the power can be increased by 50% in 5 seconds or by 25% in 10 seconds. These values ​​can be adjusted programmatically by changing the parameters in the control system of current converter 3.When supercapacitors 4 are depleted and unable to continue to transfer energy, but additional power is still needed, the bypass switch is automatically activated. If supercapacitors 4 fail, the bypass switch will also be active.

[0020] After discharging, supercapacitors 4 are recharged in a known manner. The charging time depends on the size of battery 1 and the number of supercapacitors 4. The greater the number of supercapacitors, the longer the charging time, while the greater the battery capacity, the faster the charging. Supercapacitors 4 should be charged at a low current that does not interfere with the normal operation of the battery. The recommended maximum charging current is "C / 5." Therefore, a standard 50 Ah battery requires approximately 100 seconds to be ready for use. The charging time can be adapted to the specific battery 1.

[0021] The presented invention is aimed at improving battery utilization, increasing vehicle power during critical moments, and utilizing the benefits of regenerative braking. The power booster can be connected to any individual electric vehicle whose battery is connected to an electric drive that controls the electric motor. The claimed device utilizes both a battery and supercapacitors when the user requires maximum power for a few seconds. This function is controlled by a bypass switch, distinguishing the invention from prior art solutions where the user has no control over the battery current. The claimed solution, however, allows energy to be extracted from two energy sources when maximum power is needed.

Claims

INVENTION CLAUSE A power amplifier based on supercapacitors for an individual electric vehicle, consisting of a DC converter and several supercapacitors installed in series with each other, wherein the DC converter is installed in series between the output of the battery of the electric vehicle and the input of the electric drive of said vehicle, and the supercapacitors are installed in parallel with the DC converter, wherein the DC converter contains a bypass switch.

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