DE102022200410A1 - Method for operating a solenoid valve arrangement with a plurality of coils connected in parallel for a vehicle dynamics system - Google Patents

Abstract

Method for operating a solenoid valve arrangement (12) with a plurality of coils (13) for a vehicle dynamics system, the coils (13) being connected in parallel to one another and in series with a common measurement shunt (6), the actual current (9) flowing in each coil (13) being regulated to a desired current by means of a PWM specification (14), and a resistance model (15) of each individual coil (13) being used to regulate the actual current (9), the resistance model ( 15) the following steps are carried out: a) determining in which coil (13) the actual current (9) is to be measured, b) switching all other coils (13) into a freewheel mode, c) determining the actual current (9) based on the measurement of an electrical variable at a common measuring shunt (6) of all coils (13), d) calculating the resistance model (15) based on the measured actual current (9), and e) repeating steps a) to d) with a different coil ( 13) for determining an actual current (9) in the other coil (13).

Description

The present invention relates to a method for operating a solenoid valve arrangement with a plurality of coils connected in parallel for a driving dynamics system. Furthermore, a control device, a computer program, a machine-readable storage medium, a solenoid valve arrangement for vehicles and a vehicle with such a solenoid valve arrangement are specified. The invention can be used in particular for vehicle dynamics systems.

State of the art

A solenoid valve is a valve that is actuated by a magnet assembly with an energizable coil due to electromagnetic induction.

Such solenoid valves are used in hydraulic brake systems with e.g. ABS and/or ESP functionality and are used to control the inlet or outlet of hydraulic fluids and/or to control and regulate their direction of flow. In this case, the electrical currents for controlling the solenoid valves can be regulated or controlled. Typically, the coils of the solenoid valves are each connected in parallel to one another via a separate channel with a current controller. The current flowing into each coil (referred to as the actual current) can be individually regulated to a specified current (referred to as the target current) via an adjustable duty cycle of a PWM specification (PWM: pulse width modulation). To do this, the actual current of each coil is measured and the duty cycle is readjusted according to the PWM specification.

Disclosure of Invention

Proceeding from this, a method is to be described here with which the parameters necessary for the operation of such solenoid valves can be obtained.

1. a) Festlegen, in welcher Spule der Ist-Strom gemessen werden soll,
2. b) Schalten aller anderen Spulen in deren Freilauf,
3. c) Bestimmen des Ist-Stroms basierend auf der Messung einer elektrischen Größe an einem gemeinsamen Messshunt aller Spulen,
4. d) Berechnen des Widerstandsmodells basierend auf dem gemessenen Ist-Strom, und
5. e) wiederholte Durchführung von Schritt a) bis d) mit einer anderen Spule zur Bestimmung eines Ist-Stroms der anderen Spule.

A method for operating a solenoid valve arrangement with a plurality of coils for a vehicle dynamics system contributes to this, the coils being connected in parallel to one another and in series with a common device for current measurement, hereinafter referred to as a measurement shunt, with the actual current flowing in each coil a setpoint current is controlled by means of a PWM specification, with a resistance model of each individual coil being used to control the actual current, with the following steps being carried out to create the resistance model:

1. a) Determine in which coil the actual current is to be measured,
2. b) switching all other coils into their freewheel mode,
3. c) Determination of the actual current based on the measurement of an electrical quantity at a common measuring shunt of all coils,
4. d) calculating the resistance model based on the measured actual current, and
5. e) repeated implementation of steps a) to d) with another coil to determine an actual current of the other coil.

The method described here is characterized in particular by the fact that exactly one measuring shunt is used to measure the actual current through all coils. Furthermore, the ohmic resistance of the coils can be determined from this, e.g. with the help of the supply voltage.

The use of a single measurement shunt pursues the goal of reducing the design and equipment costs for generating the resistance model. Instead of using a coil-specific measurement shunt for each coil to measure the actual current flowing in the coil, which results in a large amount of hardware and the associated costs, it is proposed here to use a common measurement shunt for all coils and to measure the actual current one after the other. Carry out determination for each of the coils.

The measuring shunt makes it possible to determine the actual electrical current flowing through the measuring shunt. Since only the coil to be examined is connected in series with the measurement shunt when the measurement is carried out in step c), the electrical current through this coil can be determined with the measurement shunt.

It must also be taken into account that the duty cycle of a pulse width modulation to be set is specified by software, for example. However, if the coils are controlled completely in software via a PWM specification, it is very time-consuming to determine the information about the actual current in real time in such a way that it is evaluated in the software and used for the PWM specification can.

With the method described, a real-time actual current of each coil is indirectly estimated essentially by means of the resistance model, instead of with a complex direct measurement, the resistance model in turn being adapted by occasional measurement of the individual coil currents.

In addition, with the method described, only a common measuring shunt becomes the Mes Solution of the actual current of each coil is used, whereas in the prior art a large number of individual measuring shunts assigned to the respective coils is required. With the common measuring shunt, the current measurement of each coil can be carried out cost-effectively and practically when the coils are energized.

The method described is particularly suitable for controlling a solenoid valve arrangement for a driving dynamics system. The solenoid valve arrangement serves to control the flow of a hydraulic fluid in a hydraulic brake system and to control the flow of this hydraulic fluid.

Such a magnetic valve arrangement can comprise a plurality of coils which, by applying a suitable current, can generate the desired magnetic force for the correct actuation of an actuator. Here z. B. generate a desired magnetic force by applying a controllable current to a coil in order to move a solenoid valve piston at a desired speed to a desired position.

This allows the flow of hydraulic fluid to be controlled. The actual current flowing in the coil can be controlled by a current controller by adapting the duty cycle of a PWM specification (PWM: pulse width modulation).

The duty cycle indicates the ratio of the pulse duration to the period duration for a periodic sequence of pulses. The duty cycle is specified as a ratio of the number dimension with a value range from 0 to 1 or 0% to 100%. The duty cycle is to be understood as the actually resulting duty cycle. The duty cycle can be specified here based on the resistance model and the target current in response to an activation.

The current controller can be implemented as a hardware current controller, for example in the form of an electronic circuit, or as a software current controller. In this case, the current controller can be designed or designed in such a way that it regulates an actual current value to a desired current value by adapting a pulse duty factor of a pulse width modulation.

Preferably, each coil has an associated switch z. B. is connected as a low-side switch behind this coil. The coil current can thus be increased or reduced for each coil by activating or deactivating the switch. Each coil preferably has a protective diode assigned to it, which is connected in parallel with this coil. Thus, the overvoltage can be avoided, in particular when deactivating the switch associated with this coil, while the current can continue to circulate through the coil.

Each coil with its associated switch and its associated protective diode thus forms an individually controllable channel. Each channel has a specific electrical resistance, which can also be referred to as channel specific resistance. This resistance is mainly determined by the ohmic and inductive resistance of the coil (i.e. the impedance of the coil).

The fact that the coils are connected in parallel here means in particular that the coils are essentially connected here with their assigned electronic components in the form of channels to an individual current regulator. Each coil can thus be controlled individually by the current regulator, with pulse width modulation enabling individual current to be supplied to the respective coil.

All channels of all coils go via the common measuring shunt, so that all currents flowing into the coils also flow via the common measuring shunt and can thus be measured based on the measurement of an electrical quantity at the common measuring shunt. The common measurement shunt can be designed as an ohmic resistor. The currents can also be calculated by measuring the voltage at the common measuring shunt.

In order to assign the measured current to the coil to be measured by means of voltage measurement at the common measuring shunt, it is first selected according to step a) in which coil an actual current flowing is measured. All other coils are then switched to freewheeling according to step b). This means that the respective channels are separated so that the channels not to be measured are switched to freewheel. The switch assigned to the coil to be measured can remain active or must be activated. All other switches are deactivated, causing the channels or the coils to operate freely (actively or passively). Thus, only the current of the channel to be measured or through the coil to be examined flows through the common measuring shunt. If a minimum current of the channels not to be measured must not be fallen below, the coil current can be increased before the measurement so that the current does not drop below the minimum current due to a possibly extended freewheeling during the measurement.

According to step c), the actual current is determined based on the measurement of an electrical quantity at the common measurement shunt. The electrical variable here means in particular the voltage at the common measurement shunt. A voltage drop at duty cycle to 100% or an average voltage at duty cycle to a constant value can be measured.

The actual current determined in step c) is introduced into the resistance model, so the resistance model can be adapted according to step d) based on the actual current introduced. In particular, the possible deviation between the resistance model and the actual channel-specific resistances can be adjusted. Thus, the real-time actual current of each coil can be more accurately estimated using the resistance model, which is adaptable based on an occasional current measurement.

According to step e), the actual currents flowing in the other channels or coils can be determined cyclically one after the other by repeating method steps a) to d) and the resistance model can be adapted based on the determined actual currents.

The method described can be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example in a control unit.

With the method described, the current through the respective coil based on the change in electrical property, such as. B. the voltage drop across the common measurement shunt can be measured. In order to only consider the current through the coil to be measured, all coils that are not to be measured can be briefly switched to freewheel. As a result, essentially only the current of the coil to be measured flows through the common measurement shunt, so that the measurement result can be assigned specifically to the associated coil.

With the method described, the current can be measured cyclically one after the other using the common measuring shunt for all coils inside or outside of a control, whereas in the prior art the current of each coil can only be measured at any time using a specific measuring shunt assigned to the coil. Compared to the prior art, the method described here is inexpensive and can be carried out in practice.

The method described can also be used to determine the channel-specific resistance by measuring the current during activation, which is only possible in the prior art either outside of an activation or with individual current measuring devices.

The measured current can be used directly for readjustment and/or for further calculations, e.g. B. the channel-specific resistance value can be used. The channel specific resistance value can be calculated based on the measured current and the supply voltage. The calculated channel specific resistance can be entered into a resistance model, whereby the duty cycle of the PWM command can be calculated and set.

It is preferred if the actual current is measured in step c) in such a way that the duty cycle of the PWM specification is set to 100%, so that the actual current is measured based on the voltage drop across the common measurement shunt. With a duty cycle of 100%, a direct current essentially flows into the coil, so that the inductive part of the channel impedance is equal to zero and the ohmic part of the channel impedance in connection with the voltage drop at the common measurement shunt determines the actual current flowing into the coil.

It is preferred if the actual current is determined in step c) in such a way that the duty cycle of the PWM specification is set to a constant value, so that the actual current is measured based on the average voltage at the common measurement shunt. As an alternative to 100% duty cycle, the duty cycle for current measurement can also be set to a constant value so that the frequency-dependent inductive component of the channel impedance is no longer equal to zero and the voltage measured at the common measurement shunt is an average voltage. The current flowing through the coil can be determined by considering the duty cycle and the average voltage measured. Alternatively, the current flowing through the coil can be determined by a single voltage measurement at a defined point in time during the current run-up, taking the inductance into account.

It is preferred if the voltage is detected using a sample and hold circuit and the average voltage is formed using software. Alternatively, the average voltage can also be formed using a low-pass circuit, for example, and measured using a sample-and-hold circuit.

It is preferred if, with the method described, before step c) the current has settled before the start of the measurement. Thus, the measurement time can be shortened.

It is preferred if each coil is assigned a low-side switch, so that in step b) the coils are switched to freewheeling by deactivating their assigned low-side switch. It is possible that the low-side switch can be used as a field effect transistor such as e.g. B. MOSFET is designed and the resistive and inductive load can be connected to ground.

It is preferred if each coil is controlled by adapting the duty cycle of the PWM specification, which is determined based on the actual current flowing into this coil and a coil-specific resistance determined from this actual current. In this case, it is possible for the channel-specific resistance to be calculated based on the measured actual current and the applied supply voltage. This can then be used, for example, in a resistance model that is used to calculate the target value to be set for the duty cycle.

It is preferred if a control device is set up to carry out the described method. Any type of electronic device can be understood as a control device, for example application-specific integrated circuits (ASICs), computer cores (CPU), or another device that can process data, control and/or regulate.

It is also preferred if a computer program is used to carry out a method described here. In other words, this relates in particular to a computer program (product) which comprises instructions which, when the program is executed by a computer, cause the latter to execute a method described here.

In addition, it is preferred if a machine-readable storage medium is used, on which the computer program proposed here is stored. The machine-readable storage medium is usually a computer-readable data carrier.

Furthermore, a magnetic valve arrangement with at least two coils connected in parallel is proposed, which is operated according to the method described.

Furthermore, a vehicle with at least one of the described solenoid valve arrangements is proposed.

• 1 ein beschriebenes Verfahren zum Betrieb einer Magnetventilanordnung für ein Fahrdynamiksystem,
• 2 Ersatzschaltung einer bekannten Magnetventilanordnung mit einer Mehrzahl von Spulen,
• 3 Ersatzschaltung zur Messung von Strömen der in 2 dargestellten Spule in einer bekannten Weise,
• 4 Ersatzschaltung zur erfindungsgemäßen Messung von Strömen der in 2 dargestellten Spule, und
• 5 Ersatzschaltung zur erfindungsgemäßen Messung von Strömen der in 2 dargestellten Spule bei der Durchführung der Messung.

The solution presented here and its technical environment are explained in more detail below with reference to the figures. It should be pointed out that the invention should not be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and/or findings from other figures and/or the present description. It shows schematically:

• 1 a described method for operating a solenoid valve arrangement for a driving dynamics system,
• 2 Equivalent circuit of a known solenoid valve arrangement with a plurality of coils,
• 3 Equivalent circuit for measuring currents of the in 2 coil shown in a known manner,
• 4 Equivalent circuit for measuring currents according to the invention in 2 shown coil, and
• 5 Equivalent circuit for measuring currents according to the invention in 2 shown coil when performing the measurement.

For an overview of the basic idea and the advantages of the method described, an exemplary method for operating a solenoid valve arrangement 12 with an example of three coils 13 is first described using FIG 1 explained.

Next, the advantage of using a common measurement shunt 6 compared to the use of a plurality of channel-specific measurement shunts 5 in the prior art based on the 2 until 5 shown. In doing so, 2 and 3 a known equivalent circuit and a known measurement method are shown, whereas in 4 and 5 an equivalent circuit according to the invention and a measurement method according to the invention are shown.

1 shows, schematically and by way of example, a described method for operating a solenoid valve arrangement 12 with three coils 13 operated in parallel, which are each connected to a common measurement shunt 6 .

Each coil 13 is driven with a duty cycle by means of a PWM specification 14, the duty cycle being set based on a resistance model 15 and a target current (i.e. target current).

In order to adjust the resistance model 15 due to a possible deviation from the actual resistances of the coils 13, the actual current of each coil 13 is occasionally measured here via the common measurement shunt 6. When measuring an actual current of a specific coil 13, all other coils 13 can freewheel be switched. The measured actual current is introduced into the resistance model 15, so the resistance model 15 can be adapted based on the introduced actual current.

With the method described, a real-time actual current of each coil 13 is indirectly estimated here essentially by means of the resistance model 15 instead of a complex direct measurement, with the resistance model 15 in turn being adapted in terms of its accuracy by an occasional current measurement of a coil 13 .

With the method described, the current measurement of all coils 13 can be carried out exclusively via a common measurement shunt 6, which is explained below in 4 and 5 will be shown. In contrast, shows 3 the known method for current measurement of all coils 13 via the channel-specific measuring shunts 5 assigned to the coils 13.

2 shows schematically an equivalent circuit of a known solenoid valve arrangement 12 with a plurality of coils 13. The impedances of each coil 13 are represented by an ohmic resistor 1 and an inductive resistor 2. The ohmic resistor 1 and the inductive resistor 2 are connected in series with a low-side switch 4 . The low-side switch 4 is usually designed as a transistor and connected behind the load, ie the coil 13 . By activating or deactivating the low-side switch 4, the coil 13 is energized or not energized. A protective diode 3 is connected in parallel with the ohmic resistor 1 and the inductive resistor 2 to protect against overvoltage, which is caused in particular when the low-side switch 4 is deactivated.

The series-connected ohmic resistor 1, the inductive resistor 2, and the low-side switch 4, as well as the protective diode 3 connected in parallel with the ohmic resistor 1 and the inductive resistor 2, together form a channel 10, which is connected to a current regulator (not shown) is connected. To control coil 13 in channel 10, the current controller outputs a PWM specification 14 with a set duty cycle.

2 shows two channels 10 connected in parallel, between which a plurality of channels (not shown) can be added. In the 2 until 5 The omissions shown between two channels 10 represent the expanded channels 10, which are not shown. The channels 10 can have the same structural design, but differ in terms of parameters (e.g. different ohmic resistances and/or inductances). The coils 13 in the channels 10 according to the 2 until 5 are each controllable via a PWM specification 14.

3 shows an extension based on 2 for measuring currents in all channels 10 in a known manner. In 3 It can be seen that a channel-specific measurement shunt 5 is connected behind the associated low-side switch 4 in each channel 10 . The current flowing in this channel can be measured based on the voltage at the channel-specific measurement shunt 7 . with the inside 3 In the measurement methods shown, a plurality of channel-specific measurement shunts 5 are required for a plurality of coils 13 .

Instead of the in 3 shown channel-specific measurement shunts 5 shows 4 a common measurement shunt 6, which is connected in series behind the low-side switches 4 of all channels 10, so that the current flowing in each channel 10 also flows through the common measurement shunt 6.

In order to measure only the actual current 9 flowing in a channel 10 to be measured, the low-side switches 4 of all channels not to be measured can be used, as in 5 shown can be temporarily deactivated. i.e. all coils 13 that are not to be measured can be temporarily switched to freewheel. As a result, essentially only the actual current 9 to be measured flows through the common measurement shunt 6 , so that the measurement result can be assigned specifically to the associated coil 13 . In this case, the actual current 9 to be measured can be measured based on the voltage at the common measurement shunt 8 . With the duty cycle at 100% without freewheeling current 11 , the actual current 9 to be measured can be measured based on the ohmic resistance 1 and on the voltage drop across the common measuring shunt 6 . With another constant duty cycle with freewheeling current 11, the actual current 9 to be measured can be measured based on the average voltage at the common measuring shunt 6 and the inductive resistor 2. The currents in other channels can be measured cyclically one after the other in the same way.

With the proposed method according to the 4 and 5 the currents of all channels 10 can be measured inexpensively with the common measurement shunt 6, namely within one control, whereas with the known method according to FIG 1 and 2 the currents of all channels 10 can be measured with the channel-specific measurement shunts 5, which is expensive.

Claims (13)

Method for operating a solenoid valve arrangement (12) with a plurality of coils (13) for a vehicle dynamics system, the coils (13) being related to one another are connected in parallel and in series with a common measurement shunt (6), the actual current (9) flowing in each coil (13) being regulated to a desired current by means of a PWM specification (14), and the actual - Current (9) a resistance model (15) of each individual coil (13) is used, the following steps being carried out to create the resistance model (15): a) Determining in which coil (13) the actual current (9) is measured should be, b) switching all other coils (13) into a freewheel, c) determining the actual current (9) based on the measurement of an electrical variable at a common measuring shunt (6) of all coils (13), d) calculating the Resistance model (15) based on the measured actual current (9), and e) repeated implementation of steps a) to d) with another coil (13) to determine an actual current (9) in the other coil (13) and to create a resistance model (15). procedure after claim 1 , wherein in step c) the actual current (9) is measured such that a duty cycle of the PWM specification (14) is set to 100%, so that the actual current (9) based on the voltage drop as an electrical variable on the common Measuring shunt (6) is measured. procedure after claim 1 , wherein in step c) the actual current (9) is determined in such a way that a duty cycle of the PWM specification (14) is set to a constant value, so that the actual current (9) based on an average voltage that occurs as an electric Size is measured at the common measuring shunt (6). procedure after claim 3 , where the average voltage is recorded using a sample-and-hold circuit and subsequent averaging. procedure after claim 3 , where the average voltage is formed using a low-pass circuit and recorded using a sample-and-hold circuit. Method according to one of the preceding claims, wherein the ohmic resistance (1) of each coil (13) is determined with the method and taken into account when determining the actual current (9) in step c). Method according to one of the preceding claims, wherein a switch (4) is assigned to each coil (13), so that in step b) the coils (13) are switched to freewheeling by deactivating their assigned switches (4). Method according to one of the preceding claims, wherein each coil (13) is controlled by adjusting the duty cycle of the PWM specification (14), which is based on the actual current (9) flowing into this coil (13) and one of the actual currents - Current (9) determined coil specific resistance (1, 2) is determined. Control device, which for carrying out a method according to one of Claims 1 until 8th is set up. Computer program for carrying out a method according to one of Claims 1 until 8th . Machine-readable storage medium on which the computer program claim 10 is saved. Solenoid valve arrangement (12) with at least two parallel-connected coils (13), according to one of Claims 1 until 8th is operated. Vehicle with at least one solenoid valve arrangement (12). claim 12 .

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