Open circuit load detection

Abstract

The invention relates to open circuit load detection. A method of online detection of an open load condition at an inductive load is presented. The inductive load is driven by using a circuit arrangement. The circuit arrangement includes at least a switching circuit and a control circuit. The method comprises the following steps: if the output voltage of the switching circuit to the inductive load exceeds a preset high voltage threshold value, starting a high voltage overrun counter; if the output voltage exceeds a preset low voltage threshold value, a low voltage overrun counter is started; if the low-voltage overrun counter is started, the high-voltage overrun counter is reset; if the high-voltage overrun counter is started, the low-voltage overrun counter is reset; an open load condition is identified if either of the high voltage and low voltage overrun counters exceed a predetermined time threshold. The invention also relates to a circuit arrangement for carrying out the method, and to the use of the method or circuit arrangement in motor vehicle applications.

Description

Technical Field

[0001] The present disclosure relates to a method for online detection of an open load state at an inductive load, and a circuit arrangement for performing the method for online detection of an open load state at an inductive load. Background Art

[0002] Open load conditions at inductive loads can be difficult to detect, especially online, especially in automotive applications. Automotive applications often use field oriented control solutions. With the development of automotive zone controllers, especially zone ECUs, more and more actuators often require open load detection during operation. The reason for this is often that the actuators are located further away from the zone ECU than the main device ECU using an integrated housing solution. Often, one problem is the high risk of bad wiring harness connections due to, for example, vibration or aging. Summary of the invention

[0003] In a first aspect of the present disclosure, a method for online detection of an open load state at an inductive load is provided. The inductive load is driven by using a circuit arrangement. The circuit arrangement comprises at least a switching circuit and a control circuit. The method comprises at least the following steps performed by using the control circuit:

[0004] a) if the output voltage of the switching circuit to the inductive load exceeds a predetermined high voltage threshold, a high voltage exceed counter is started;

[0005] b) if the output voltage of the switching circuit to the inductive load exceeds a predetermined low voltage threshold, starting a low voltage limit counter;

[0006] c) If the low voltage limit counter is activated, the high voltage limit counter is reset;

[0007] d) if the high voltage limit limit counter is enabled, resetting the low voltage limit limit counter; and

[0008] e) If either the high voltage exceedance counter and the low voltage exceedance counter exceeds a predetermined time threshold, an open load condition is identified.

[0009] In a further aspect of the present disclosure, a circuit arrangement is provided for performing a method for online detection of an open load state at an inductive load. The method for online detection of an open load state at an inductive load is a method according to any one of the embodiments of the method disclosed above or disclosed in further detail below. The circuit arrangement comprises a switching circuit. The switching circuit is configured to perform at least one switching operation at the inductive load. The circuit arrangement further comprises a control circuit. The control circuit is configured to perform at least steps a) to e).

[0010] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present disclosure is illustrated in the figures of the accompanying drawings by way of example and not limitation, wherein the same reference numerals refer to similar or identical elements. The elements in the figures are not necessarily drawn to scale relative to each other. The features of the various illustrated examples may be combined unless they exclude each other.

[0012] Figure 1 A circuit diagram illustrating an exemplary circuit arrangement;

[0013] Figure 2A and Figure 2B illustrates experimental results of measurements on a circuit arrangement; and

[0014] Figure 3 A flow chart of an exemplary method for online detection of an open load condition at an inductive load is illustrated. DETAILED DESCRIPTION

[0015] In a first aspect of the present disclosure, a method for detecting an open circuit load state at an inductive load is proposed. The term "inductive load" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or custom meaning. An inductive load may specifically be an electrical load configured to store energy in a magnetic field. Therefore, when the current stops or changes direction, the magnetic energy can be released as electrical energy, as will now be understood by those skilled in the art. An inductive load may specifically resist changes in current, such as when the current flowing through it is suddenly interrupted. As a result, a sudden voltage spike may occur in the opposite direction, which may also be referred to as a flyback voltage spike. As will be further outlined in detail below, one way to handle the flyback voltage spike may be to provide a current path for discharge by using a diode. Such a diode may then also be referred to as a flyback diode. The inductive load may include at least one inductor. However, the inductive load may also include additional non-inductors, such as resistors and / or capacitors. The inductive load may include at least one motor, in particular at least one brushless DC motor.

[0016] The term "open load state" as generally used herein is a broad term, and for those skilled in the art, it should be given its ordinary and customary meaning, without being limited to a special or customized meaning. The open load state can be a state or condition in which a load (particularly an inductive load) can be disconnected from a power supply. Specifically, the load can be disconnected from the output of the power supply (such as the output of a circuit arrangement for power supply and / or load control). As will also be described in further detail below, and as the technician will appreciate, such a circuit arrangement can generally include at least one transistor in the transistor for switching the load. Therefore, the load can be specifically disconnected from the output of the transistor. As described, the inductive load can be a motor. Therefore, the open load state can be specifically a state or condition in which the motor is disconnected from the circuit arrangement configured for motor control. In general, the motor can be driven by using multiple transistors, such as multiple transistors of a half-bridge configuration or a full-bridge configuration. Therefore, the open load state can be specifically a state or condition in which the motor is disconnected from the output of the circuit arrangement for motor control, particularly a state or condition in which the output of the transistor is disconnected.

[0017] The term "online detection" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or customized meaning. Online detection can be a detection or measurement or observation performed during operation, particularly a detection or measurement or observation performed during driving a load (such as an inductive load). As an example, online detection can be performed when at least one transistor of the drive motor is in an on state. Therefore, online detection can ensure that the inductive load is connected during operation. In contrast, offline detection can be performed before or after operation, but not during operation.

[0018] The inductive load is driven by using a circuit arrangement. The term "circuit arrangement" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or custom meaning. The circuit arrangement may be or may include at least one electronic circuit. The circuit arrangement may include at least one electronic component that may be connected to at least one other electronic component. The circuit arrangement may be an assembly of at least two electronic components that are at least partially interconnected by conductive elements. As an example, the electronic component may include a resistor, an inductor, a capacitor, a diode and / or a transistor. As an example, the conductive element may include a wire and / or a trace. Specifically, the circuit arrangement may be or may include at least one integrated circuit. Therefore, the circuit arrangement or at least a portion of the circuit arrangement may be arranged on at least one piece of semiconductor material (specifically silicon, silicon carbide and / or gallium nitride).

[0019] The circuit arrangement may be or may include at least one electronic control unit (in particular, a regional electronic control unit), such as used in automotive applications. Other options are also possible. The electronic control unit may also be, for example, a master electronic control unit. The master electronic control unit may be configured to control at least one smart load, wherein the smart load includes integrated electronic devices. In particular, the smart load may include at least one printed circuit board within a load housing. As an example, the smart load may be an electronic motor with integrated electronic devices (such as a motor drive). In contrast, the regional electronic control unit may be configured to control at least one non-intelligent load. Therefore, the corresponding electronic device (e.g., a motor drive) may not be integrated at the load (e.g., not integrated in the motor housing), but at the regional electronic control unit. Therefore, the regional electronic control unit can be connected to the non-intelligent load by using only a power line without using a bus system. In particular, the electronic control unit may be from MOTIX of Infineon Technologies. TM TLE989x product family selection.

[0020] The circuit arrangement may comprise at least one electronic subcircuit. The electronic subcircuit itself may be an electronic circuit, in particular an electronic circuit as defined above. Thus, the electronic subcircuit may comprise at least one electronic component, which may be connected to at least one further electronic component, such as a further electronic component of a further electronic subcircuit within a superordinate electronic circuit. The electronic subcircuit may be configured to perform at least one task or function, in particular to perform at least one task or function within a superordinate electronic circuit. At least two electronic subcircuits may at least partially work together or act together to perform a task or function. At least two electronic subcircuits may at least partially share electronic components and / or conductive elements. As indicated, at least two electronic subcircuits may be electronically connected to each other.

[0021] The circuit arrangement includes at least a switching circuit and a control circuit. The term "switching circuit" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or custom meaning. The switching circuit may be an electronic circuit arranged within the circuit arrangement. In other words, the switching circuit may be an electronic subcircuit of the circuit arrangement. The switching circuit may be configured to switch at least one element, specifically a load, more specifically an inductive load. The switching circuit may include at least one switching element, such as a transistor, specifically a field effect transistor (FET) or a bipolar junction transistor (BJT) or an insulated gate bipolar transistor (IGBT). However, other options for the switching element are also feasible and are generally known to those skilled in the art.

[0022] The switching circuit may include at least a high-side switching circuit and a low-side switching circuit. Therefore, the high-side switching circuit and the low-side switching circuit may be sub-circuits of the switching circuit. The term "high side" generally used herein is a broad term, and for those skilled in the art, it should be given its ordinary and customary meaning, without being limited to a special or customized meaning. The prefix high side may refer to an element, specifically an electronic component, arranged at the high side or positive side (specifically, the battery side) of the load power supply. The high-side element may be connected to a high power supply voltage (specifically, a battery voltage). Specifically, the high-side element may be arranged between the high power supply voltage and the load (specifically, an inductive load). Therefore, the high-side switching circuit may be connected to a high power supply voltage (specifically, connected to a battery voltage) on one side, and to an inductive load on the other side.

[0023] The term "low side" commonly used herein is a broad term, and for those skilled in the art, it should be given its common and customary meaning, without being limited to special or customized meanings. The prefix low side can refer to an element (specifically an electronic component) arranged at the low side or negative side (specifically, the ground side) of the load power supply. The low side element can be connected to a low power supply voltage (specifically, connected to the ground). Specifically, the low side element can be arranged between the low power supply voltage and the load (specifically, the inductive load). Therefore, the low side switching circuit can be connected to the low power supply voltage (specifically, connected to the ground) on one side, and connected to the inductive load on the other side.

[0024] The high-side switching circuit may include at least a high-side transistor and a high-side diode. The high-side transistor may be a metal oxide semiconductor field effect transistor (MOSFET). The high-side diode may be a body diode of the MOSFET. The low-side switching circuit may include at least a low-side transistor and a low-side diode. The low-side transistor may be a metal oxide semiconductor field effect transistor (MOSFET). The low-side diode may be a body diode of the MOSFET. Various alternative types of transistors and diodes are also feasible and are generally known to those skilled in the art.

[0025] The term "transistor" as generally used herein is a broad term and should be given its common and customary meaning to those skilled in the art, without being limited to a special or custom meaning. A transistor can be a semiconductor device configured to switch and / or amplify an electrical signal and / or electrical power. A transistor can specifically include at least three contacts, which are also referred to as electrodes or terminals. A transistor can be constructed in such a way that a voltage and / or current applied to a first pair of contacts can control the current flowing through a second pair of contacts. As already noted, a transistor can specifically be a field effect transistor (FET) including a gate contact, a drain contact, and a source contact. More specifically, a transistor can be a MOSFET.

[0026] The term "diode" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or custom meaning. A diode may be a semiconductor device configured to conduct current in substantially one direction. Therefore, a diode may have a low resistance in a forward direction and a high resistance in a reverse direction. As known to those skilled in the art, a diode may be or may include a pn junction. Switching a diode from a forward bias to a reverse bias may specifically result in a reverse recovery voltage spike, due to the inherent properties of a pn junction, specifically due to the charge stored in the depletion region of the pn junction that needs to be removed. Therefore, during the reverse recovery time, a diode may provide a current spike in the reverse direction. As already noted, a diode may be a flyback diode. Therefore, when dealing with a flyback voltage spike of an inductive load in a switching operation, a diode may be used in the forward direction to provide a current path for discharge. Therefore, in a subsequent switching operation, a reverse recovery voltage spike may occur at the diode. The reverse recovery voltage spike may increase other voltages in the circuit arrangement, specifically the power supply voltage. As already pointed out, the diode may be a parasitic diode inherent in a transistor, such as the body diode of a MOSFET. However, the diode may also be a separate discrete electronic component arranged within the circuit arrangement.

[0027] As described, the circuit arrangement also includes a control circuit. The term "control circuit" commonly used herein is a broad term, and for those skilled in the art, it should be given its ordinary and customary meaning, without being limited to a special or custom meaning. The control circuit can be an electronic circuit arranged in the circuit arrangement. In other words, the control circuit can be an electronic subcircuit of the circuit arrangement. The control circuit can be a microcontroller, or can be a part of a microcontroller. The control circuit can be configured to control or operate or adjust at least one other element (specifically, a switching circuit), and further control the inductive load at least indirectly. The control circuit can be configured to control at least one switching operation of the switching circuit. Specifically, the control circuit can be configured to control at least one switching operation of at least one of the high-side switching circuit and the low-side switching circuit. More specifically, the control circuit can be configured to control the switching operation of the high-side switching circuit and the low-side switching circuit. Even more specifically, the control circuit can be configured to control the alternating switching operation of the high-side switching circuit and the low-side switching circuit. In other words, the control circuit can be configured to turn on and off the high-side switching circuit and the low-side switching circuit in an alternating manner. Thus, when the low-side switching circuit may be turned off, the high-side switching circuit may be turned on, and vice versa.In addition, as noted, the control circuit may also be configured to control or monitor an inductive load, as will be outlined in further detail below.

[0028] A method for online detection of an open load condition at an inductive load comprises the following steps performed by using a control circuit:

[0029] a) if the output voltage of the switching circuit to the inductive load exceeds a predetermined high voltage threshold, a high voltage limit counter is started;

[0030] b) if the output voltage of the switching circuit to the inductive load exceeds a predetermined low voltage threshold, starting a low voltage limit counter;

[0031] c) If the low voltage limit counter is activated, the high voltage limit counter is reset;

[0032] d) if the high voltage limit limit counter is enabled, resetting the low voltage limit limit counter; and

[0033] e) If either the high voltage exceedance counter and the low voltage exceedance counter exceeds a predetermined time threshold, an open load condition is identified.

[0034] When performing the method, additional elements may be involved, in particular electrical elements of a circuit arrangement (such as a switching circuit). One or more of the method steps may be performed once or repeatedly. In addition, two or more of the method steps may be performed simultaneously or in a time-overlapping manner. Specifically, as long as there is no open circuit load state, steps a) and b) may be performed in an alternating manner. Specifically, steps b) and c) may be performed simultaneously or in a time-overlapping manner. Specifically, steps a) and d) may be performed simultaneously or in a time-overlapping manner. The method may include additional method steps that are not listed. Specifically, the method may also include:

[0035] f) controlling at least one switching operation of the switching circuit by using the control circuit.

[0036] Specifically, as described, the switching circuit may include at least a high-side switching circuit and a low-side switching circuit, wherein step f) may include: by using a control circuit, to control at least one switching operation of at least one of the high-side switching circuit and the low-side switching circuit. More specifically, step f) may include: by using a control circuit, to control the alternating switching operation of the high-side switching circuit and the low-side switching circuit. Therefore, during driving an inductive load (e.g., an electronic motor), the high-side switching circuit and the low-side switching circuit can be turned on and off in an alternating manner. During this process, as long as there is no open-circuit load state (such as, the case where the motor is disconnected) at the inductive load, the high voltage threshold and the low voltage threshold can therefore be exceeded by the output voltage of the switching circuit in an alternating manner. Thereafter, the high voltage overrun counter and the low voltage overrun counter can be started and reset, respectively, as will be further outlined below. The term "reset" can generally refer to setting the counter to an initial value, specifically to 0.

[0037] The term "output voltage" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or custom meaning. The output voltage of an element (such as a switching circuit) can be a voltage present at the output of the element, which can be an input voltage to another element (such as an inductive load). Therefore, the output voltage of a switching circuit can be a voltage present at the output of the switching circuit (such as at a circuit node at the output of the circuit node). In addition, the output voltage of the switching circuit can be an input voltage to an inductive load, specifically an input voltage to a motor.

[0038] The term "threshold" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or customized meaning. A threshold value may be a limit that triggers at least one event, such as an upper voltage limit or a lower voltage limit or a time limit. In other words, an event may be triggered when the threshold value is reached. The term "high voltage threshold" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or customized meaning. A high voltage threshold may be a voltage upper limit that triggers at least one event (specifically, an activation), such as the start of a counter or the reset of a counter. Specifically, the high voltage threshold may be a voltage upper limit that triggers the start of a high voltage over-limit counter. In addition, the high voltage threshold may be a voltage upper limit that triggers the reset of a low voltage over-limit counter. Therefore, if the output voltage of the switching circuit reaches or exceeds the high voltage threshold, the high voltage over-limit counter may be started and the low voltage over-limit counter may be reset. The high voltage threshold may be a high power supply voltage, specifically a battery voltage V bat Alternatively, the high voltage threshold can be at V bat -2V to V bat-2.5V range.

[0039] The term "low voltage threshold" generally used herein is a broad term, and for those skilled in the art, it should be given its ordinary and customary meaning, without being limited to a special or custom meaning. The low voltage threshold can be a voltage lower limit that triggers at least one event (specifically, activation), such as the start of a counter or the reset of a counter. Specifically, the low voltage threshold can be a voltage lower limit that triggers the start of a low voltage overrun counter. In addition, the low threshold voltage can be a voltage lower limit that triggers the reset of a low voltage overrun counter. Therefore, if the output voltage of the switching circuit reaches or exceeds the low voltage threshold, the low voltage overrun counter can be started, and the high voltage overrun counter can be reset. The low voltage threshold can be a low power supply voltage, specifically 0V. In other words, the ground can be used as a low power supply voltage, or the low power supply voltage can be a ground. Alternatively, the low voltage threshold can be in the range of 2V to 2.5V.

[0040] The term "counter" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without limitation to a special or custom meaning. A counter may be a device (specifically, an electronic circuit) configured to count an entity (specifically, time) incrementally. In other words, a counter may be specifically configured to track time. A counter may be a timer. A counter may be a clock. A counter may be configured to count using an internal or external clock rate. A counter may be part of a microcontroller. Thus, a counter may be configured to use a clock or clock rate of a microcontroller. A counter may be hardware implemented and / or software implemented. A counter may be an analog counter. A counter may be a digital counter.

[0041] The term "high voltage limit counter" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without limitation to a special or custom meaning. The high voltage limit counter may be a counter configured to be activated in response to a high voltage threshold being exceeded or reached or crossed (specifically, crossed). The term "low voltage limit counter" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without limitation to a special or custom meaning. The low voltage limit counter may be a counter configured to be activated in response to a low voltage threshold being exceeded or reached or crossed (specifically, crossed).

[0042] Step a) may comprise starting a high voltage over-limit counter if the output voltage of the switching circuit becomes higher than the high supply voltage. As already indicated, during switching, the output voltage of the switching circuit may become higher than the high supply voltage due to additional recovery voltage spikes of the diodes, in particular, the high-side diodes. Step b) may comprise starting a low voltage over-limit counter if the output voltage of the switching circuit becomes lower than the low supply voltage. As already indicated, during switching, the output voltage of the switching circuit may become lower than the low supply voltage due to additional recovery voltage spikes of the diodes, in particular, the low-side diodes. Depending on the specific circumstances, the term "additional" may refer to the addition or subtraction of a recovery voltage spike.

[0043] Starting the low voltage overrun counter can also trigger the high voltage overrun counter to be reset. Similarly, starting the high voltage overrun counter can also trigger the low voltage overrun counter to be reset. Therefore, in normal operation, particularly during the alternating switching of the high side switching circuit and the low side switching circuit connected with the inductive load, both the high voltage overrun counter and the low voltage overrun counter should be reset regularly. If the high voltage overrun counter or the low voltage overrun counter runs too long, this should be an indication that the inductive load is disconnected, i.e., an open circuit load state. In this case, there should no longer be a flyback voltage spike from the inductive load during switching because the inductive load has been disconnected. Therefore, there should no longer be a reverse recovery voltage spike from the diode, and therefore the voltage threshold should no longer be exceeded.

[0044] This situation (where the high voltage overrun counter or the low voltage overrun counter runs too long) can be quantified by using a time threshold as in step e). The term "time threshold" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or custom meaning. The time threshold can be a time limit for a triggering event, specifically an identification of an open circuit load state at an inductive load. The time threshold can be a predetermined value on a count. The time threshold can be or include a counter threshold. The time threshold can be or include a counter threshold of a high voltage overrun counter. The time threshold can be or include a counter threshold of a low voltage overrun counter. For the high voltage overrun counter and the low voltage overrun counter, the time threshold can be specifically the same. However, in principle, the time threshold can also be different for the high voltage overrun counter and the low voltage overrun counter.

[0045] The time threshold may vary depending on at least the minimum motor speed, the number of pole pairs and the pulse width modulation period. The minimum motor speed, the number of pole pairs and the pulse width modulation period may refer in particular to properties of the motor as an inductive load and to properties of the motor drive. The time threshold t th It can be specifically given by the following formula:

[0046]

[0047] Where N min is the minimum motor speed per minute, p is the number of pole pairs, and t pwm is the pulse width modulation period in seconds. Additionally or alternatively, the time threshold may be a predetermined value in seconds. The time threshold may be in the range of 1 second to 10 seconds, specifically in the range of 2 seconds to 5 seconds.

[0048] As described, the control circuit may also be configured to control or monitor an inductive load. The control circuit may include at least one comparator, specifically at least a high-side comparator and a low-side comparator. The term "comparator" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art, without being limited to a special or custom meaning. A comparator may be an electronic circuit configured to compare at least two input voltages. The comparator may be configured to generate at least one output signal (specifically, a digital output signal) indicating the result of the comparison, specifically indicating which input voltage is greater. As an example, in the case where the first input voltage is higher than the second input voltage, the comparator may generate an output "HIGH" or "1", and in the case where the first input voltage is lower than the second input voltage, the comparator may generate an output "LOW" or "0". The output signal may be generated continuously over time, specifically for a varying input voltage.

[0049] As described, the control circuit may include at least a high-side comparator. The high-side comparator may be configured to compare the output voltage of the switching circuit with a high voltage threshold. As described, the high voltage threshold may be a high power supply voltage. Therefore, the high-side comparator may be arranged so that the output voltage of the switching circuit and the high power supply voltage are inputs to the high-side comparator. Step a) may include: by using the control circuit, the output voltage of the switching circuit is compared with the high voltage threshold. The comparison may include using the high-side comparator. Similarly, as described, the control circuit may include at least a low-side comparator. The low-side comparator may be configured to compare the output voltage of the switching circuit with a low voltage threshold. As described, the low voltage threshold may be a low power supply voltage. Therefore, the low-side comparator may be arranged so that the output voltage of the switching circuit and the low power supply voltage are inputs to the low-side comparator. Step b) may include: by using the control circuit, the output voltage of the switching circuit is compared with the low voltage threshold. The comparison may include using the low-side comparator.

[0050] The method for detecting an open load state at an inductive load may be at least partially implemented by a computer. As described, the control circuit may be specifically a microcontroller or may be part of a microcontroller. The comparator may also generate a digital output signal. The microcontroller may include at least one processor configured to evaluate the digital output signal. The microcontroller may also be configured to start and / or reset at least one counter (such as a high voltage overrun counter and / or a low voltage overrun counter) according to the digital output signal of the comparator. The term "computer implementation" as generally used herein is a broad term and should be given its ordinary and customary meaning to those skilled in the art without being limited to a special or custom meaning. The term may specifically refer to a method involving at least one computer and / or at least one microcontroller and / or at least one processor (such as a microprocessor). Specifically, the computer and / or microcontroller may include at least one processor configured to perform at least one method step in the method steps according to the present disclosure. The method steps may be at least partially performed automatically, specifically without user interaction.

[0051] In another aspect of the present disclosure, a circuit arrangement is proposed for performing a method for detecting an open-circuit load state at an inductive load online. The method for detecting an open-circuit load state at an inductive load online is a method according to any one of the embodiments of the method disclosed above or further disclosed in detail below. The circuit arrangement includes a switching circuit. The switching circuit is configured to perform at least one switching operation at an inductive load (specifically a motor, more specifically a brushless DC motor). The circuit arrangement also includes a control circuit. The control circuit is configured to perform at least steps a) to e). If the output voltage of the switching circuit becomes higher than the high power supply voltage (specifically, higher than the battery voltage), the control circuit can be configured to start a high voltage overrun counter. If the output voltage of the switching circuit becomes lower than the low power supply voltage (specifically, lower than 0V), the control circuit can be configured to start a low voltage overrun counter. For other embodiments and definitions of the circuit arrangement, reference can be made to the embodiments and definitions already given above.

[0052] In a further aspect of the present disclosure, the use of a method according to any one of the embodiments relating to the method disclosed above or disclosed in further detail below, or the use of a circuit arrangement according to any one of the embodiments relating to the circuit arrangement disclosed above or disclosed in further detail below, for use in automotive applications, in particular, for motor control. As indicated, the method and / or the circuit arrangement may be used in automotive applications, in particular for motor control, wherein the inductive load may be a motor. As described, the circuit arrangement may be or may include an electronic control unit (in particular, a regional electronic control unit), such as used in automotive applications.

[0053] The methods and devices proposed herein have significant advantages over the prior art, as already indicated throughout the specification. They can provide a reliable solution for performing online open-circuit load detection, i.e. detection during operation, and not just offline detection, without the need for additional components. In particular, when using a regional electronic control unit in a motor vehicle application, the actuators may require online open-circuit load detection, since they may be arranged remotely from the regional electronic control unit. The solution provided can also be adapted to a variety of different inductive loads, such as various different types of electronic motors, both from a hardware point of view and from a software point of view.

[0054] As used herein, the terms "having", "including" or "comprising" or any arbitrary grammatical variant thereof are used in a non-exclusive manner. Thus, these terms may refer both to the absence of additional features in the entity described in this context in addition to the features introduced by these terms, and to the presence of one or more additional features. As an example, the expressions "A has B", "A includes B", and "A contains B" may refer both to the absence of other elements in A in addition to B (i.e., A consists solely and exclusively of B), and to the presence of one or more additional elements in entity A in addition to B, such as element C, elements C and D, or even additional elements.

[0055] In addition, it should be noted that the terms "at least one", "one or more" or similar expressions indicating that a feature or element can occur one or more times are usually used only once when introducing the corresponding feature or element. In most cases, when referring to the corresponding feature or element, the expression "at least one" or "one or more" is not repeated, although the corresponding feature or element can occur one or more times.

[0056] In addition, as used herein, the terms "preferably", "more preferably", "particularly", "more specifically", "specifically", "more specifically" or similar terms are used in conjunction with optional features without limiting the possibilities of alternatives. Therefore, the features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. As will be appreciated by those skilled in the art, the present disclosure can be implemented through the use of alternative features. Similarly, the features introduced by "in an embodiment of the present disclosure" or similar expressions are intended to be optional features, without any limitation on the alternative embodiments of the present disclosure, without any limitation on the scope of the present disclosure, and without any limitation on the possibility of combining the features introduced in this manner with other optional or non-optional features of the present disclosure.

[0057] As a summary and without excluding further possible embodiments, the following embodiments may be contemplated:

[0058] Embodiment 1: A method for online detection of an open load state at an inductive load, wherein the inductive load is driven by using a circuit arrangement, wherein the circuit arrangement comprises at least a switching circuit and a control circuit, the method comprising the following steps performed by using the control circuit:

[0059] a) if the output voltage of the switching circuit to the inductive load exceeds a predetermined high voltage threshold, a high voltage limit counter is started;

[0060] b) if the output voltage of the switching circuit to the inductive load exceeds a predetermined low voltage threshold, starting a low voltage limit counter;

[0061] c) If the low voltage limit counter is activated, the high voltage limit counter is reset;

[0062] d) if the high voltage limit limit counter is enabled, resetting the low voltage limit limit counter; and

[0063] e) If either the high voltage exceedance counter and the low voltage exceedance counter exceeds a predetermined time threshold, an open load condition is identified.

[0064] Embodiment 2: The method according to the above embodiment, wherein the inductive load comprises at least one motor, specifically a brushless DC motor.

[0065] Embodiment 3: The method according to any one of the preceding embodiments, wherein the high voltage threshold is a high power supply voltage.

[0066] Embodiment 4: The method according to any one of the preceding embodiments, wherein step a) comprises: comparing the output voltage of the switching circuit with a high voltage threshold by using a control circuit.

[0067] Embodiment 5: The method according to the preceding embodiment, wherein the control circuit comprises at least a high-side comparator, wherein the comparison is performed by using the high-side comparator.

[0068] Embodiment 6: The method according to any one of the preceding embodiments, wherein step a) comprises: starting a high voltage over-limit counter if the output voltage of the switching circuit becomes higher than the high power supply voltage.

[0069] Embodiment 7: The method according to any one of the preceding embodiments, wherein the low voltage threshold is a low power supply voltage.

[0070] Embodiment 8: The method according to any one of the preceding embodiments, wherein step b) comprises: comparing the output voltage of the switching circuit with a low voltage threshold by using a control circuit.

[0071] Embodiment 9: The method according to any of the preceding embodiments, wherein the control circuit comprises at least a low-side comparator, wherein the comparison is performed by using the low-side comparator.

[0072] Embodiment 10: The method according to any one of the preceding embodiments, wherein step b) comprises: starting a low voltage limit limit counter if the output voltage of the switching circuit becomes lower than the low power supply voltage.

[0073] Embodiment 11: The method according to any of the preceding embodiments, wherein the time threshold varies depending on at least the minimum motor speed, the number of pole pairs and the pulse width modulation period.

[0074] Embodiment 12: The method according to the above embodiment, wherein the time threshold t th It is given by the following formula:

[0075]

[0076] Where N min is the minimum motor speed per minute, p is the number of pole pairs, t pwm is the pulse width modulation period in seconds.

[0077] Embodiment 13: The method according to any one of the preceding embodiments, wherein the time threshold is in the range of 1 second to 10 seconds, specifically in the range of 2 seconds to 5 seconds.

[0078] Embodiment 14: The method according to any one of the preceding embodiments further includes step f), wherein step f) includes: controlling at least one switching operation of the switching circuit by using a control circuit.

[0079] Embodiment 15: A method according to the above embodiment, wherein the switching circuit comprises at least a high-side switching circuit and a low-side switching circuit, wherein step f) comprises: controlling at least one switching operation of at least one of the high-side switching circuit and the low-side switching circuit by using a control circuit.

[0080] Embodiment 16: The method according to the above embodiment, wherein step f) comprises: controlling the alternating switching operation of the high-side switching circuit and the low-side switching circuit by using a control circuit.

[0081] Embodiment 17: A method according to any one of the preceding embodiments, wherein the method is at least partially implemented by a computer.

[0082] Embodiment 18: A circuit arrangement for performing the method for online detection of an open load state at an inductive load according to any one of the preceding embodiments, the circuit arrangement comprising:

[0083] A switching circuit configured to: perform at least one switching operation at an inductive load; and

[0084] The control circuit is configured to: perform at least steps a) to e).

[0085] Embodiment 19: The circuit arrangement according to the preceding embodiment, wherein the inductive load comprises at least one motor, in particular a brushless DC motor.

[0086] Embodiment 20 The circuit arrangement according to any of the preceding embodiments relating to a circuit arrangement, wherein the circuit arrangement is an electronic control unit, in particular a regional electronic control unit.

[0087] Embodiment 21 The circuit arrangement according to any of the preceding embodiments relating to circuit arrangements, wherein the high voltage threshold is a high supply voltage.

[0088] Embodiment 22 The circuit arrangement according to any of the preceding embodiments relating to the circuit arrangement, wherein the control circuit comprises at least a high-side comparator configured to compare the output voltage of the switching circuit with a high voltage threshold.

[0089] Embodiment 23 The circuit arrangement according to any of the preceding embodiments relating to the circuit arrangement, wherein the control circuit is configured to start a high voltage limit limit counter if the output voltage of the switching circuit becomes higher than the high supply voltage.

[0090] Embodiment 24: The circuit arrangement according to any of the preceding embodiments relating to circuit arrangements, wherein the low voltage threshold is a low supply voltage.

[0091] Embodiment 25 The circuit arrangement according to any of the preceding embodiments relating to the circuit arrangement, wherein the control circuit comprises at least a low-side comparator configured to compare the output voltage of the switching circuit with a low voltage threshold.

[0092] Embodiment 26 The circuit arrangement according to any of the preceding embodiments relating to the circuit arrangement, wherein the control circuit is configured to start a low voltage limit limit counter if the output voltage of the switching circuit becomes lower than the low supply voltage.

[0093] Embodiment 27 The circuit arrangement according to any of the preceding embodiments relating to the circuit arrangement, wherein the control circuit is configured to control at least one switching operation of the switching circuit.

[0094] Embodiment 28 The circuit arrangement according to any of the preceding embodiments relating to circuit arrangements, wherein the switching circuit comprises at least a high-side switching circuit and a low-side switching circuit.

[0095] Embodiment 29: The circuit arrangement according to the preceding embodiment, wherein the control circuit is configured to: control at least one switching operation of at least one of the high-side switching circuit and the low-side switching circuit.

[0096] Embodiment 30: The circuit arrangement according to the preceding embodiment, wherein the control circuit is configured to: control the alternating switching operations of the high-side switching circuit and the low-side switching circuit.

[0097] Embodiment 31 The circuit arrangement according to any one of the three preceding embodiments relating to circuit arrangements, wherein the high-side switching circuit comprises at least a high-side transistor and a high-side diode.

[0098] Embodiment 32: The circuit arrangement according to any one of the four previous embodiments relating to circuit arrangements, wherein the high-side transistor is a metal oxide semiconductor field effect transistor (MOSFET), wherein the high-side diode is a body diode of the MOSFET.

[0099] Embodiment 33 The circuit arrangement according to any one of the five preceding embodiments relating to circuit arrangements, wherein the low-side switching circuit comprises at least a low-side transistor and a low-side diode.

[0100] Embodiment 34: The circuit arrangement according to any one of the six preceding embodiments relating to circuit arrangements, wherein the low-side transistor is a metal oxide semiconductor field effect transistor (MOSFET), wherein the low-side diode is a body diode of the MOSFET.

[0101] Embodiment 35 Use of the method according to any of the preceding method embodiments or use of the circuit arrangement according to any of the preceding claims relating to a circuit arrangement for use in automotive applications, in particular for motor control.

[0102] Further specific optional features and embodiments will be disclosed in more detail in the subsequent description of embodiments in conjunction with the accompanying drawings. Wherein, the corresponding optional features can be implemented in an independent manner and in any arbitrary feasible combination, as will be appreciated by those skilled in the art. The scope of the present disclosure is generally not limited by the preferred embodiments. The embodiments may only be schematically depicted in the drawings.

[0103] Figure 1A circuit diagram of an exemplary circuit arrangement 110 is illustrated for performing a method for online detection of an open-circuit load state at an inductive load 112, the method being according to any of the embodiments relating to a method described above or described in further detail below. The inductive load may include at least one motor, in particular a brushless DC motor. The circuit arrangement 110 may be an electronic control unit, in particular a regional electronic control unit. In particular, the electronic control unit may be from the product line MOTIX® of Infineon Technologies AG. TM TLE989x is selected.

[0104] The circuit arrangement 110 includes a switching circuit 114. The switching circuit 114 is configured to perform at least one switching operation at the inductive load 112. The circuit arrangement 110 also includes a control circuit 116. The control circuit 116 is configured to perform at least steps a) to e) of the method, which is a method according to any one of the embodiments related to the method described above or described in more detail below. The circuit arrangement 110 may also include at least one high power supply voltage source 118. The high power supply voltage source 118 may specifically be a battery, such as a battery in a motor vehicle application. The high power supply voltage source 118 may be configured to provide a high power supply voltage, specifically to provide a high power supply voltage to the circuit arrangement 110, more specifically to provide a high power supply voltage to the switching circuit 114. The circuit arrangement 110 may also include at least one low power supply voltage source 120. The low power supply voltage source 120 may specifically be a ground. The low voltage power supply 120 may be configured to provide a low power supply voltage, specifically to provide a low power supply voltage to the circuit arrangement 110, more specifically to provide a low power supply voltage to the switching circuit 114.

[0105] The switching circuit 114 may include at least a high-side switching circuit 122 and a low-side switching circuit 124. The high-side switching circuit 122 may include at least a high-side transistor 126 and a high-side diode 128. The high-side transistor 126 may be a metal oxide semiconductor field effect transistor (MOSFET). The high-side diode 128 may be the body diode of the MOSFET. For example, an insulated gate bipolar transistor (IGBT) may also be used instead of the MOSFET. Instead of parasitic elements, a separate discrete electronic component may also be arranged in the high-side switching circuit 122 as the high-side diode 128. The low-side switching circuit 124 may include at least a low-side transistor 130 and a low-side diode 132. The low-side transistor 130 may be a metal oxide semiconductor MOSFET. The low-side diode 132 may be the body diode of the MOSFET. Similarly, an insulated gate bipolar transistor (IGBT) may also be used instead of the MOSFET. In addition, instead of parasitic elements, a separate discrete electronic component may also be arranged in the low-side switching circuit 124 as the low-side diode 132.

[0106] The switching circuit 114 may include at least one output 134. The switching circuit output 134 may specifically be an output to the inductive load 112. Starting from the high power supply voltage source 118, the high side diode 128 may be arranged in the opposite direction to the switching circuit output 134. Therefore, the high side diode 128 may be configured to block the current flowing from the high power supply voltage source 118 to the switching circuit output 134 and further to the inductive load 112. In addition, the high side diode 128 may be configured to pass the current flowing from the switching circuit output 134 to the high power supply voltage source 118. Starting from the switching circuit output 134 and further from the inductive load 112, the low side diode 132 may be arranged in the opposite direction to the low power supply voltage source 120. Therefore, the low side diode 132 may be configured to block the current flowing from the switching circuit output 134 and further from the inductive load 112 to the low power supply voltage source 120. Furthermore, the low-side diode 132 can be configured to pass current from the low supply voltage source 120 to the switching circuit output 134, and further to the inductive load 112. The switching circuit output 134 can also be an output to the control circuit 116. Therefore, the control circuit 116 can be configured to monitor the switching circuit output 134, specifically the voltage at the switching circuit output 134. The voltage at the switching circuit output 134 can be specifically referred to as the output voltage of the switching circuit 114.

[0107] The control circuit 116 may include at least a high-side comparator 136. The high-side comparator 136 may be configured to compare the output voltage of the switching circuit 114 with a high voltage threshold. Therefore, the high-side comparator 136 may be connected to the switching circuit output 134. In addition, the high-side comparator 136 may be connected to a high power supply voltage source 118. Therefore, the high-side comparator 136 may be configured and / or arranged in the circuit arrangement 110 to use the output voltage of the switching circuit 114 and the high power supply voltage as input. Therefore, the high-side comparator 136 may be configured to compare the output voltage of the switching circuit 114 with the high power supply voltage. The control circuit 116 may include at least a low-side comparator 138. The low-side comparator 138 may be configured to compare the output voltage of the switching circuit 114 with a low voltage threshold. Therefore, the low-side comparator 138 may be connected to the switching circuit output 134. In addition, the low-side comparator 138 may be connected to the low power supply voltage source 120. Therefore, the low side comparator 138 can be configured and / or arranged within the circuit arrangement 110 to use the output voltage of the switching circuit 114 and the low supply voltage as input. Therefore, the low side comparator 138 can be configured to compare the output voltage of the switching circuit 114 with the low supply voltage.

[0108] The control circuit 116 may include at least one controller 140. The controller 140 may be or may include an analog circuit, specifically an integrated circuit. However, the control circuit 116 may also be a microcontroller, or may be part of a microcontroller. Therefore, the controller 140 may be or may include a processor, specifically a microprocessor. As an example, the controller 140 may include at least a central processing unit and peripherals, such as an input-output interface. The controller 140 may be configured to monitor at least one other element of the circuit arrangement 110. Specifically, the controller 140 may be configured to monitor at least a high-side comparator 136 and / or a low-side comparator 138. The controller 140 may be configured to process at least one comparator output signal, specifically an output signal of a high-side comparator 136 and / or a low-side comparator 138. The controller 140 may be connected to the high-side comparator 136 and / or the low-side comparator 138. The controller 140 may also be configured to control at least one element of the circuit arrangement 110.

[0109] The control circuit 116 may also include at least a high-side gate driver 142 and / or a low-side gate driver 144. The controller 140 may be configured to control at least the high-side gate driver 142 and / or the low-side gate driver 144. The controller 140 may be configured to provide at least one pulse width modulation signal, specifically providing at least one pulse width modulation signal to the high-side gate driver 142 and / or the low-side gate driver 144. In addition, specifically, via the high-side gate driver 142 and / or the low-side gate driver 144, the controller 140 may be configured to control at least the switching circuit 114, specifically the high-side switching circuit 122 and / or the low-side switching circuit 124. The high-side gate driver 142 and / or the low-side gate driver 144 may include at least a level shifter and an amplifier. The high-side gate driver 142 may be connected to the controller 140 on one side, and may be connected to the high-side switching circuit 122 on the other side, specifically to the MOSFET of the high-side switching circuit 122, more specifically to the gate contact of the MOSFET of the high-side switching circuit 122. Thus, the high-side gate driver 142 may be configured and / or arranged to receive a low-power input from the controller 140 and to generate a high-power output to the high-side switching circuit 122. The low-side gate driver 144 may be connected to the controller 140 on one side and to the low-side switching circuit 124, specifically to the MOSFET of the low-side switching circuit 124, and more specifically to the gate contact of the MOSFET of the low-side switching circuit 124, on the other side. Thus, the low-side gate driver 144 may be configured and / or arranged to receive a low-power input from the controller 140 and to generate a high-power output to the low-side switching circuit 124.

[0110] Therefore, the control circuit 116 can be configured to: control at least one switching operation of the switching circuit 114. Specifically, the control circuit 116 can be configured to: control at least one switching operation of at least one of the high-side switching circuit 122 and the low-side switching circuit 124. More specifically, the control circuit 116 can be configured to: control the alternating switching operation of the high-side switching circuit 122 and the low-side switching circuit 124. In other words, the control circuit 116 can be configured to: activate and deactivate the high-side switching circuit 122 and the low-side switching circuit 124 in an alternating manner over time. In other words, the control circuit 116 can be configured to: close and open the high-side switching circuit 122 and the low-side switching circuit 124 in an alternating manner over time. In other words, the control circuit 116 can be configured to: turn on and off the high-side switching circuit 122 and the low-side switching circuit 124 in an alternating manner over time. Therefore, the inductive load 112 can be powered by a high power supply voltage and a low power supply voltage in an alternating manner.

[0111] As an example, initially, the high-side switching circuit 122 may be activated and the low-side switching circuit 124 may be deactivated. Thus, the high-side transistor 126 may be turned on by using the control circuit 116. Furthermore, the low-side transistor 130 may be turned off by using the control circuit 116. Thus, current may flow from the high supply voltage source 118 through the high-side transistor 126 and the switching circuit output 134 to the inductive load 112. Figure 1 , the current path is indicated by arrow 146. In general, the current flowing through a transistor (specifically, through a MOSFET) can refer to the current flowing through a conductive channel between two contacts of the transistor, specifically, in the case of a MOSFET, the current flowing through a conductive channel between a source contact and a drain contact. In a subsequent switching operation, the high-side switching circuit 122 can be deactivated and the low-side switching circuit 124 can be activated. Therefore, the high-side transistor 126 can be turned on by using the control circuit 116. In addition, the low-side transistor 130 can be turned on by using the control circuit 116. This may result in a sudden change in the current at the inductive load 112. As a result, a sudden voltage spike may occur in the reverse direction, which may also be referred to as a flyback voltage spike. Therefore, the flyback current can be dissipated via the high-side diode 128. In Figure 1 , this current path is indicated by arrow 148. In addition, current can now flow from the inductive load 112 through the switching circuit output 134 and the low-side transistor 130 to the low supply voltage source 120. Figure 1, the current path is indicated by arrow 150. In further subsequent switching operations, the high-side switching circuit 122 can be activated and the low-side switching circuit 124 can be deactivated again. Therefore, the high-side transistor 126 can be turned on again by using the control circuit 116. In addition, the low-side transistor 130 can be turned off again by using the control circuit 116. This may also lead to a sudden change in the current at the inductive load 112 and a corresponding flyback voltage spike. The corresponding flyback current can now be dissipated via the low-side diode 132. In Figure 1 , this current path is indicated by arrow 152 .

[0112] The flyback current can further generate the corresponding reverse recovery voltage spikes of the high-side diode 128 and the low-side diode 132 respectively. When the flyback current is dissipated, the high-side diode 128 and the low-side diode 132 are briefly operated with forward bias. However, afterwards, they are in reverse bias again. The current then flows through the high-side transistor 126 and the low-side transistor 130 respectively, instead of flowing through the high-side diode 128 and the low-side diode 132 respectively. In general, switching the diode from forward bias to reverse bias may cause a reverse recovery voltage spike, which is due to the inherent properties of the pn junction of the diode, specifically due to the charge stored in the depletion region of the pn junction that needs to be removed. This reverse recovery voltage spike may be added to another voltage. Specifically, during the switching operation, the output voltage of the switching circuit 114 present at the switching circuit output 134 can be a reverse recovery voltage spike and a superposition of the power supply voltage applied to the inductive load 112 via the high-side transistor 126 and the low-side transistor 130 respectively. As described, the output voltage of the switching circuit 114 may be monitored using the high-side comparator 136 and / or the low-side comparator 138 of the control circuit 116 .

[0113] The control circuit 116 may be configured to start a high voltage overrun counter if the output voltage of the switching circuit 114 becomes higher than a high threshold voltage. The high voltage threshold may be a high power supply voltage. The high power supply voltage may be compared to the output voltage of the switching circuit 114 by using a high side comparator 136. Due to the reverse recovery spike of the high side diode 128, the output voltage of the switching circuit 114 may become higher than the high power supply voltage at least temporarily. Therefore, the high side comparator 136 may send a signal to the controller 140, for example by using a digital signal such as "1" or "0", indicating that the output voltage of the switching circuit 114 exceeds the high power supply voltage. The output of the high side comparator 136 to the controller 140 may be inverted. Therefore, as an example, "1" may become "0" and vice versa. The controller 140 may be configured to start a high voltage overrun counter, and thus the high voltage overrun counter may be started in this event.

[0114] Similarly, the control circuit 116 can be configured to: if the output voltage of the switching circuit 114 becomes lower than the low voltage threshold, the low voltage overrun counter is started. The low voltage threshold can be a low power supply voltage. The low power supply voltage can be compared with the output voltage of the switching circuit 114 by using a low-side comparator 138. Due to the reverse recovery spike of the low-side diode 132, the output voltage of the switching circuit 114 can at least temporarily become lower than the low power supply voltage. Therefore, the low-side comparator 138 can send a signal to the controller 140, for example, by using a digital signal such as "1" or "0", which indicates that the output voltage of the switching circuit 114 exceeds the low power supply voltage. The controller 140 can be configured to start the low voltage overrun counter, and therefore the low voltage overrun counter can be started in this event.

[0115] The controller 140 may also be configured to reset the high voltage overrun counter if the low voltage overrun counter is enabled. The controller 140 may also be configured to reset the low voltage overrun counter if the high voltage overrun counter is enabled. The controller 140 may also be configured to identify an open load state if any one of the high voltage overrun counter and the low voltage overrun counter exceeds a predetermined time threshold. In an open load state, such as when the inductive load 112 is disconnected, there may no longer be a flyback voltage spike from the inductive load 112, and therefore there may no longer be a reverse recovery voltage spike from the high side diode 128 and the low side diode 132, respectively. As a result, the output voltage of the switching circuit 114 may no longer exceed the high power supply voltage and the low power supply voltage, as monitored by the high side comparator 136 and the low side comparator 138 connected to the controller 140. Therefore, the controller 140 may not reset the high voltage overrun counter and / or the low voltage overrun counter within a predetermined time threshold, and may exceed the predetermined time threshold.

[0116] Figure 2A and Figure 2B The diagram shows experimental results of measuring the circuit arrangement 110. Specifically, Figure 2A Experimental results are shown of measurements taken on the circuit arrangement 110 during normal operation (ie, with the inductive load 112 connected to the circuit arrangement 110 ). Figure 2B 1 shows experimental results of measuring the circuit arrangement 110 under an open load condition (ie, the inductive load 112 is disconnected from the circuit arrangement 110). Figure 2A, curve 154 indicates a pulse width modulated signal provided by controller 140 over time for performing a switching operation at inductive load 112. Curve 156 indicates a corresponding comparator output signal. As described above, during normal operation, the comparator output signal exhibits alternating behavior over time due to the flyback voltage spike from inductive load 112 and the subsequent reverse recovery voltage peaks from high-side diode 128 and low-side diode 132 superimposed on the high supply voltage and the low supply voltage, respectively. Figure 2B , curve 158 indicates an additional pulse width modulated signal provided by the controller 140. As described, at this time, the inductive load 112 is disconnected. Therefore, there is no longer a flyback voltage peak and a subsequent reverse recovery voltage peak. Curve 160 shows the corresponding comparator output signal in this case. Since there is no flyback voltage peak superimposed on the supply voltage, the output voltage of the switching circuit 114 no longer exceeds the supply voltage. Therefore, the comparator output signal no longer exhibits an alternating behavior over time as before.

[0117] Figure 3 A flow chart of an exemplary method for online detection of an open load state at an inductive load 112 is illustrated. The inductive load 112 is driven by using a circuit arrangement 110. The circuit arrangement 110 includes at least a switching circuit 114 and a control circuit 116. The method includes the following steps performed by using a control circuit. Additional entities (specifically, the switching circuit 114) may be additionally used to perform the method.

[0118] a) (indicated by reference numeral 162) if the output voltage of the switching circuit 114 to the inductive load 112 exceeds a predetermined high voltage threshold, a high voltage limit limit counter is started;

[0119] b) (indicated by reference numeral 164) if the output voltage of the switching circuit 114 to the inductive load 112 exceeds a predetermined low voltage threshold, a low voltage limit limit counter is started;

[0120] c) (indicated by reference numeral 166) resetting the high voltage limit limit counter if the low voltage limit limit counter is enabled;

[0121] d) (indicated by reference numeral 168) resetting the low voltage limit limit counter if the high voltage limit limit counter is enabled; and

[0122] e) (denoted by reference numeral 170) If either the high voltage exceedance counter and the low voltage exceedance counter exceeds a predetermined time threshold, an open load condition is identified.

[0123] The method may include further method steps. Specifically, the method may also include:

[0124] f) (denoted by reference numeral 172 ) controlling at least one switching operation of the switching circuit 114 by using the control circuit 116 .

[0125] Specifically, as described, the switching circuit 114 may include at least a high-side switching circuit 122 and a low-side switching circuit 124. Step f) may include: controlling at least one switching operation of at least one of the high-side switching circuit 122 and the low-side switching circuit 124 by using the control circuit 116. More specifically, step f) may include: controlling the alternating switching operation of the high-side switching circuit 122 and the low-side switching circuit 124 by using the control circuit 116. Therefore, during driving the inductive load 112, the high-side switching circuit 122 and the low-side switching circuit 124 may be turned on and off in an alternating manner over time.

[0126] like Figure 3As indicated in , the method may include at least a path division, at which different paths may be followed, depending on the result of the query, and the cycle may be repeated. Thus, one or more of the method steps may be performed once or repeatedly. In addition, two or more of the method steps may be performed simultaneously or in a time-overlapping manner. Specifically, the switching operation described in step f) may be performed continuously in the background. In each switching operation, at least one query may be performed. The query may specifically refer to exceeding a threshold (specifically, a voltage threshold and / or a time threshold). If the output voltage of the switching circuit 114 exceeds a predetermined high voltage threshold, a high voltage overrun counter is started, as described in step a). At the same time, a low voltage overrun counter may be reset, in particular if it has been started before, as described in step d). Thus, steps a) and d) may be performed simultaneously, or in a time-overlapping manner. If the output voltage of the switching circuit 114 exceeds a predetermined low voltage threshold, a low voltage overrun counter is started, as described in step b). At the same time, a high voltage overrun counter may be reset, in particular if it has been started before, as described in step c). Thus, step b) and step c) may be performed simultaneously, or in a time-overlapping manner. If the inductive load 112 is connected to the circuit arrangement 110, the process may be repeated continuously. Specifically, steps a) and b) may be performed in an alternating manner as long as there is no open-load state. If the inductive load 112 is disconnected or disconnected during operation (e.g. due to aging or vibration (such as, in a moving motor vehicle)), at least one of the high voltage overrun counter and the low voltage overrun counter should exceed a predetermined time threshold, as further detailed above. In this case, an open-load state should be identified, as described in step e). The method may be at least partially implemented by a computer. Thus, as an example, at least one of the high voltage overrun counter and the low voltage overrun counter may be implemented by software.

[0127] As further detailed above, the inductive load 112 may include at least one motor (specifically, a brushless DC motor). The high voltage threshold may be a high power supply voltage. Step a) may include comparing the output voltage of the switching circuit 114 with the high voltage threshold by using the control circuit 116. The control circuit 116 may include at least a high-side comparator 136. Thus, the comparison may be performed by using the high-side comparator 136. Step a) may include starting a high voltage overrun counter if the output voltage of the switching circuit 114 becomes higher than the high power supply voltage. Similarly, the low voltage threshold may be a low power supply voltage. Step b) may include comparing the output voltage of the switching circuit 114 with the low voltage threshold by using the control circuit 116. The control circuit 116 may include at least a low-side comparator 138. The comparison may be performed by using the low-side comparator 138. Step b) may include starting a low voltage overrun counter if the output voltage of the switching circuit 114 becomes lower than the low power supply voltage.

[0128] The time threshold may be a counter threshold. The time threshold may vary depending on at least the minimum motor speed, the number of pole pairs, and the pulse width modulation period. Specifically, the time threshold t th It can be given by the following formula:

[0129]

[0130] Where N min is the minimum motor speed per minute, p is the number of pole pairs, and t pwm is the pulse width modulation period in seconds. In addition, the time threshold may be in the range of 1 second to 10 seconds, specifically in the range of 2 seconds to 5 seconds.

[0131] As mentioned, the disclosed method and / or circuit arrangement 110 may be used in automotive applications, in particular for motor control.

[0132] Although specific examples have been illustrated and described herein, it will be appreciated by those skilled in the art that various alternatives and / or equivalent implementations may be used to replace the specific examples shown and described without departing from the scope of the present disclosure. The present application is intended to cover any adaptation or variation of the specific examples discussed herein. Therefore, the present disclosure is intended to be limited only by the claims and their equivalents.

[0133] It should be noted that the methods and apparatuses outlined in this document (including preferred embodiments thereof) may be used independently or in combination with other methods and apparatuses disclosed in this document. Furthermore, features outlined in the context of an apparatus also apply to the corresponding method, and vice versa. Furthermore, all aspects of the methods and apparatuses outlined in this document may be combined in any manner. In particular, features of the claims may be combined with each other in any manner.

[0134] It should be noted that the description and drawings illustrate only the principles of the proposed method and system. Those skilled in the art will be able to implement various arrangements, which, although not explicitly described or shown herein, embody the principles of the present disclosure and are included in its spirit and scope. In addition, all examples and embodiments summarized in this document are primarily and explicitly used only for explanatory purposes to help the reader understand the principles of the proposed method and system. In addition, all statements of the principles, aspects, and embodiments of the present disclosure and specific examples thereof provided herein are intended to cover their equivalents.

Claims

1. A method for online detection of an open load state at an inductive load (112), wherein the inductive load (112) is driven by using a circuit arrangement (110), wherein the circuit arrangement (110) comprises at least a switching circuit (114) and a control circuit (116), the method comprising the following steps performed by using the control circuit (116): a) if the output voltage of the switching circuit (114) to the inductive load (112) exceeds a predetermined high voltage threshold, starting a high voltage over-limit counter; b) if the output voltage of the switching circuit (114) to the inductive load (112) exceeds a predetermined low voltage threshold, starting a low voltage limit counter; c) if the low voltage limit counter is enabled, resetting the high voltage limit counter; d) resetting the low voltage limit exceeding counter if the high voltage limit exceeding counter is enabled; and e) identifying an open load condition if either of the high voltage exceedance counter and the low voltage exceedance counter exceeds a predetermined time threshold.

2. The method according to the preceding claim, wherein the inductive load (112) comprises at least one electric motor, in particular a brushless DC motor.

3. A method according to any one of the preceding claims, wherein the high voltage threshold is a high supply voltage.

4. The method according to any one of the preceding claims, wherein step a) comprises: The output voltage of the switching circuit (114) is compared to the high voltage threshold by using the control circuit (116), wherein the control circuit (116) includes at least a high-side comparator (136), wherein the comparison is performed by using the high-side comparator (136).

5. A method according to any one of the preceding claims, wherein the low voltage threshold is a low supply voltage.

6. The method according to any one of the preceding claims, wherein step b) comprises: The output voltage of the switching circuit (114) is compared with the low voltage threshold by using the control circuit (116), wherein the control circuit includes at least a low-side comparator (138), wherein the comparison is performed by using the low-side comparator (138).

7. A method according to any one of the preceding claims, wherein the time threshold varies as a function of at least a minimum motor speed, a number of pole pairs and a pulse width modulation period.

8. The method according to any one of the preceding claims, further comprising step f), wherein step f) comprises: At least one switching operation of the switching circuit (114) is controlled by using the control circuit (116).

9. The method according to the preceding claim, wherein the switching circuit (114) comprises at least a high-side switching circuit (122) and a low-side switching circuit (124), wherein step f) comprises: At least one switching operation of at least one of the high-side switching circuit (122) and the low-side switching circuit (124) is controlled by using the control circuit (116).

10. The method according to the preceding claim, wherein step f) comprises: By using the control circuit (116), the alternating switching operations of the high-side switching circuit (122) and the low-side switching circuit (124) are controlled.

11. A method according to any one of the preceding claims, wherein the method is at least partially computer-implemented.

12. A circuit arrangement (110) for performing the method for online detection of an open load condition at an inductive load (112) according to any one of the preceding claims, the circuit arrangement (110) comprising: A switching circuit (114) configured to: perform at least one switching operation at the inductive load (112); as well as The control circuit (116) is configured to: execute at least steps a) to e).

13. The circuit arrangement (110) according to any of the preceding claims relating to a circuit arrangement (110), wherein the circuit arrangement (110) is an electronic control unit, in particular a regional electronic control unit.

14. A circuit arrangement (110) according to any of the preceding claims relating to a circuit arrangement (110), wherein the control circuit (116) comprises at least a high-side comparator (136), the high-side comparator (136) being configured to compare the output voltage of the switching circuit (114) with the high voltage threshold.

15. A circuit arrangement (110) according to any of the preceding claims relating to a circuit arrangement (110), wherein the control circuit (116) comprises at least a low-side comparator (138), the low-side comparator (138) being configured to compare the output voltage of the switching circuit (114) with the low voltage threshold.

16. The circuit arrangement (110) according to any of the preceding claims relating to a circuit arrangement (110), wherein the control circuit (116) is configured to control at least one switching operation of the switching circuit (114).

17. The circuit arrangement (110) according to any of the preceding claims relating to a circuit arrangement (110), wherein the switching circuit (114) comprises at least a high-side switching circuit (122) and a low-side switching circuit (122).

18. The circuit arrangement (110) according to the preceding claim, wherein the high-side switching circuit (122) comprises at least a high-side transistor (126) and a high-side diode (128).

19. The circuit arrangement (110) according to any of the two preceding claims, wherein the low-side switching circuit (124) comprises at least a low-side transistor (130) and a low-side diode (132).

20. Use of a method according to any of the preceding method claims or use of a circuit arrangement (110) according to any of the preceding claims relating to a circuit arrangement (110) for use in automotive applications, in particular for motor control.

Images