DE102019209685A1 - Hybrid energy system and method for determining the aging of a battery in a hybrid energy system - Google Patents

Abstract

The invention relates to a hybrid energy system (1), comprising at least one primary unit (2) and at least one secondary unit (4), the at least one secondary unit (4) being designed as a battery (5), the primary unit (2) having at least one Converter device is connected to the battery (5) in such a way that the primary unit (2) can charge the battery (5) electrically, the hybrid energy system (1) having at least one control device which is designed to control the flow of energy from the hybrid To control energy system (1), there being at least one operating state (I) in which the energy flow from the hybrid energy system (1) is supplied exclusively by the primary unit (2), and there is at least one second operating state (II) in which at least partially the energy flow from the hybrid energy system (1) is supplied by the battery (5), the hybrid energy system (1) having a device (15) for determining the alteration g (SOH) of the battery (5). The device (15) for determining the aging (SOH) of the battery (5) is designed in such a way that the hybrid energy system (1) is switched to the second operating state (II) in order to target the battery (5) up to a first predetermined one To discharge voltage, after discharging the battery (5), a first state of charge (SOC 1) is assigned, then switching to an operating state in which the battery (5) is charged up to a second predetermined voltage, during which Charging process by means of coulomb counting, the amount of charge of the charging process is determined, after which the battery (5) is assigned a second state of charge (SOC 2), using the first state of charge (SOC 1), second state of charge (SOC 2) and the amount of charge a remaining capacity of the battery is determined and the SOH is determined from this, as well as a method for determining the aging (SOH) of a battery (5)

Description

The invention relates to a hybrid energy system and a method for determining the aging of a battery in a hybrid energy system.

The aging of a battery is also known as SOH (state of health) and indicates the ratio of remaining capacity to a nominal capacity. This is an important parameter of a battery.

Basically, the above-mentioned method for determining the SOH is what is known as Coulomb counting, whereby the battery is fully discharged and then fully charged, with the charging current being integrated over time. Such a method is for example in the US 9,759,776 B2 described, but rejected there as disadvantageous.

Hybrid energy systems are characterized by a primary unit and a secondary unit that combine different forms of energy. Such hybrid energy systems are used in a variety of ways, one of the most well-known areas of application being in a hybrid vehicle. The primary unit is usually an internal combustion engine (Otto or diesel engine) or a fuel cell and the secondary unit is a battery. The energy flow can usually be controlled so that, for example, the energy is only supplied by the primary unit, which then possibly charges the battery at the same time. In other operating states, the energy can only be supplied by the battery (purely electrical operation) or by both units (boost operation).

Such a generic hybrid energy system is, for example, from DE 10 2007 020 935 A1 known.

The invention is based on the technical problem of creating a hybrid energy system with a battery as a secondary unit, in which an exact determination of the age of the battery is possible without significant system restriction, and of providing a corresponding method.

The solution to the technical problem results from a hybrid energy system with the features of claim 1 and a method with the features of claim 10. Further advantageous refinements of the invention emerge from the subclaims.

For this purpose, the hybrid energy system comprises at least one primary unit and at least one secondary unit, the at least one secondary unit being designed as a battery. The primary unit is connected to the battery via a converter device in such a way that the primary unit can charge the battery electrically. Furthermore, the hybrid energy system has at least one control device that is designed to control the energy flow from the hybrid energy system, there being at least one operating state in which the energy flow from the hybrid energy system is supplied exclusively by the primary unit, and there is at least one There is a second operating state in which the energy flow from the hybrid energy system is at least partially supplied by the battery. The hybrid energy system also has a device for determining the age of the battery, which is designed such that the hybrid energy system is switched to the second operating state in order to discharge the battery in a targeted manner up to a first predetermined voltage, after discharging the battery a first state of charge of the battery is assigned. A switch is then made to an operating state in which the battery is charged up to a second predetermined voltage, the amount of charge being determined during the charging process by means of Coulomb counting. After the battery has been charged, the battery is assigned a second state of charge. The assignment of the first and second state of charge takes place via the battery voltage, the relationship having been determined empirically in advance, for example. A remaining capacity of the battery is then determined by means of the first state of charge, the second state of charge and the amount of charge, and the aging SOH is determined from this. Due to the possible redirection of the energy flow, the SOH can be determined very precisely without affecting the system.

In one embodiment, the energy flow is supplied exclusively by the battery in the first operating state, so that the first predefined value is reached more quickly.

In a further embodiment, there is at least one third operating state, wherein in the third operating state the energy flow from the hybrid energy system is supplied exclusively by the primary unit without charging the battery, the hybrid energy system being designed in such a way after the first predetermined voltage and / or to switch the second predetermined voltage to the third operating state for a predetermined minimum time, the voltage being measured again after the third operating state has elapsed, the first state of charge and / or the second state of charge being determined based on the newly measured voltage. This significantly improves the accuracy of the SOH determination. The minimum time is thereby preferably selected such that relaxation processes in the battery are completed so that the subsequently measured voltage values of the battery correlate better with the states of charge. The minimum time is preferably between 10-30 minutes.
In a further embodiment, the energy system is designed in such a way that it is switched to the third operating state in predefined phases or at certain time intervals during operation of the energy system for predetermined periods of time. These resting phases of the battery without charging or discharging help to further improve the accuracy of the SOH determination.

In a further embodiment, the hybrid energy system is designed in such a way that the battery is charged up to the second predetermined voltage in the first operating state by the primary unit. In this case, the hybrid energy system can work without interruption and, for example, a hybrid vehicle can continue to drive. Alternatively, the battery can also be charged at an external charging station. For example, a future charging process is known. In this case, the battery can be specifically discharged when approaching the charging station. If the relaxation time described above is to be adhered to before charging, this must be taken into account in terms of time and the primary unit only supplies the drive energy required for this. When the hybrid vehicle then arrives at the charging station, the first part of the method is complete and the first state of charge is determined.

In a further embodiment, the hybrid energy system has a device for predicting the required energy, the energy system being designed in such a way that the SOH is determined in phases of low energy demand. In the case of hybrid vehicles in particular, this can be easily determined using planned routes. It can also be taken into account that the SOH determination is preferably carried out in phases where no recuperation has to be carried out. On the other hand, this can also be used in a targeted manner so that the battery is discharged before these recuperation phases, with part of the battery charging being carried out without recuperation and not by the primary unit.

The primary unit is preferably designed as an internal combustion engine or a fuel cell, the fuel cell having the advantage that the first operating state is emission-free.

The converter device preferably has an electrical converter. A preferred field of application of the hybrid energy system is use in a hybrid vehicle.

• 1 ein schematisches Blockschaltbild eines hybriden Energiesystems als Bestandteil eines Hybridfahrzeuges und
• 2 eine Ladezustand SOC einer Batterie zur Ermittlung des Alters über der Zeit.

The invention is explained in more detail below on the basis of a preferred exemplary embodiment. The figures show:

• 1 a schematic block diagram of a hybrid energy system as part of a hybrid vehicle and
• 2 a state of charge SOC of a battery to determine the age over time.

In the 1 is a hybrid energy system 1 shown, comprising a primary unit 2 in the form of an internal combustion engine 3 and a secondary unit 4th in the form of a battery 5 . The battery 5 is about power electronics 6th in the form of an inverter with an electric machine 7th connected. Via an optional coupling 8th is the internal combustion engine 3 with the electric machine 7th connected. Via another optional coupling 9 is the electric machine 7th with a gear 10 connected. The electric machine forms 7th the output of the energy system 1 . The transmission 10 is a transmission control unit 11 , the internal combustion engine 3 is an engine control unit 12th and the battery 5 is a battery control unit 13th assigned. There is also an optional higher-level hybrid control unit 14th . In the battery control unit 13th is a facility 15th to determine the age (SOH) of the battery 5 intended. In the battery lead 5 is a shunt resistor 16 arranged, the data with the facility 15th connected is. The control units 11-14 are interconnected via a bus 17.

Based on 2 shall now be the procedure for determining the age (SOH) of the battery 5 explained. At the start of the method, the battery points at time to 5 has any SOC value and is in any operating state. First is the hybrid energy system 1 in a second operating state II switched. In this second operating state II the flow of energy to the electric machine 7th exclusively or mainly from the battery 5 delivered. The internal combustion engine 3 is switched off and the clutch 8th opened (if present). The second operating state II is fixed until the battery 5 has a first predetermined voltage. A first state of charge SOC 1 is assigned to this voltage. The second operating state can be used to improve the determination of the state of charge II a third operating state III connect where the battery 5 is neither charged nor discharged. The internal combustion engine that was previously switched off 3 is started again for this. In this case, at the end of the third operating mode III the voltage on the battery 5 measured again and this voltage value the first state of charge SOC 1 assigned. A first operating state is then switched to. The internal combustion engine 3 supplies in this first operating state I both the energy for the drive and for charging the battery 5 . The charging current is fed through the shunt resistor 16 measured and integrated. This represents a coulomb counting. The first operating state I is continued until the battery voltage of the battery 5 has reached a second predetermined voltage. It then goes back to the third operating state III switched so that the relaxation processes in the battery 5 Are completed. At the end of the third operating mode III or if the third operating state III a minimum time has passed, voltage is again applied to the battery 5 measured. This stress can differ from the second predetermined stress (due to the relaxation processes). A further state of charge SOC 2 is then assigned to the measured voltage. It should be noted that the representation in 2 is greatly simplified, because the SOC at the end of the first operating state I is not 100%, but rather smaller.

The remaining capacity of the battery can then be calculated using the two states of charge SOC 1, SOC 2 and the integrated amount of charge 5 determined and from this the SOH can be determined. The integrated amount of charge clearly indicates which amount of charge leads to a Δ SOC = SOC 2 - SOC 1, so that the total amount of charge that can be stored can be determined from this.

List of reference symbols

1)

Energy system

2)

Primary aggregate

3)

Internal combustion engine

4)

Secondary unit

5)

battery

6)

Power electronics

7)

Electric machine

8th)

coupling

9

coupling

10)

transmission

11)

Transmission control unit

12)

Engine control unit

13)

Battery control unit

14)

Hybrid control unit

15)

Device for determining the aging (SOH) of the battery

16)

Shunt resistance

I - III)

Operating states

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 9759776 B2 [0003]
• DE 102007020935 A1 [0005]

Claims (10)

Hybrid energy system (1), comprising at least one primary unit (2) and at least one secondary unit (4), the at least one secondary unit (4) being designed as a battery (5), the primary unit (2) via at least one converter device in such a way is connected to the battery (5) so that the primary unit (2) can charge the battery (5) electrically, the hybrid energy system (1) having at least one control device which is designed to control the flow of energy from the hybrid energy system (1) to control, there is at least one operating state (I) in which the energy flow from the hybrid energy system (1) is supplied exclusively by the primary unit (2), and there is at least one second operating state (II) in which at least partially Energy flow from the hybrid energy system (1) is supplied through the battery (5), the hybrid energy system (1) having a device (15) for determining the aging (SOH) of the battery (5) characterized in that the device (15) for determining the aging (SOH) of the battery (5) is designed in such a way that the hybrid energy system (1) is switched to the second operating state (II) in order to power the battery (5) specifically to discharge up to a first predetermined voltage, after discharging the battery (5) a first state of charge (SOC 1) is assigned, then switching to an operating state in which the battery (5) up to a second predetermined voltage is charged, during the charging process by means of Coulomb counting the amount of charge of the charging process is determined, with a second state of charge (SOC 2) being assigned after the battery (5) has been charged, with the first state of charge (SOC 1), the second state of charge ( SOC 2) and the amount of charge, a remaining capacity of the battery is determined and the SOH is determined from this. Hybrid energy system according to Claim 1 , characterized in that in the second operating state (II) the energy flow is supplied exclusively by the battery (5). Hybrid energy system according to Claim 1 or 2 , characterized in that there is at least one third operating state (III), wherein in the third operating state (III) the flow of energy from the hybrid energy system (1) is supplied exclusively by the primary unit (2) without charging the battery (5) , wherein the hybrid energy system (1) is designed to switch to the third operating state (III) for a specified minimum time after the first specified voltage and / or the second specified voltage has been reached, the voltage again after the third operating state (III) has expired is measured, the first state of charge (SOC 1) and / or the second state of charge (SOC 2) being determined on the basis of the again measured voltage. Hybrid energy system according to Claim 3 , characterized in that the energy system (1) is designed in such a way that it is switched to the third operating state (III) in predefined phases or at certain time intervals during operation of the energy system (1) for predetermined periods of time. Hybrid energy system according to one of the preceding claims, characterized in that the hybrid energy system (1) is designed such that the charging of the battery (5) takes place up to the second predetermined voltage in the first operating state (I) by the primary unit (2) or over an external charging station takes place. Hybrid energy system according to one of the preceding claims, characterized in that the hybrid energy system (1) has a device for predicting the required energy, the energy system (1) being designed to determine the SOH in phases with low energy requirements. Hybrid energy system according to one of the preceding claims, characterized in that the primary unit (2) is designed as an internal combustion engine (3) or as a fuel cell. Hybrid energy system according to one of the preceding claims, characterized in that the converter device has an electric machine (7). Hybrid energy system according to Claim 8 , characterized in that the hybrid energy system (1) is arranged in a hybrid vehicle. Method for determining the aging (SOH) of a battery (5) in a hybrid energy system (1), the hybrid energy system (1) having a primary unit (2) and a battery (5) as a secondary unit (4), the primary unit ( 2) is connected to the battery (5) via at least one converter device in such a way that the primary unit (2) can charge the battery (5) electrically by means of a control device that controls the flow of energy from the hybrid energy system (1), wherein There is at least one operating state (I) in which the energy flow from the hybrid energy system (1) is supplied exclusively by the primary unit (2), and there is at least one second operating state (II) in which at least partially the energy flow from the hybrid Energy system (1) is supplied by the battery (5), comprising the following process steps: a) switching to the second operating state (II) in order to discharge the battery (5) in a targeted manner up to a first predetermined voltage, b) assigning a first state of charge (SOC 1) after the battery (5) has been discharged; c) Switching to an operating state in which the battery is charged up to a second predetermined voltage, the charge amount of the charging process being determined during the charging process by means of Coulomb counting, d) Assigning a second state of charge (SOC 2) after charging the battery (5), e) determining a remaining capacity of the battery (5) using the first state of charge (SOC 1) and the amount of charge, and f) determining the SOH using the determined remaining capacity.

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