Motor common-mode current measurement and control

Abstract

A method for controlling an alternating current (AC) motor for a vehicle may include measuring a first current in a first AC motor conductor. The method may further include measuring a second current in a second AC motor conductor. The method may further include determining a common-mode current in an AC system comprising an inverter and an AC motor. The method may further include determining a third current in a third AC motor conductor based at least in part on the first current, the second current, and the common-mode current. The method may further include determining a DC current based at least in part on the first current, the second current, and the third current.

Description

Technical Field

[0001] This disclosure relates to systems and methods for measuring and controlling the operating status of an AC motor in a vehicle application. Background Technology

[0002] To regulate the operation of the AC motor in a vehicle, a motor control system can be employed. This system can include various sensors and control circuits configured to measure motor parameters such as current, voltage, speed, and temperature. The data collected by these sensors can be processed by the motor controller to determine the motor's operating state and apply control algorithms to achieve the desired performance. In some examples, the motor controller may employ vector control or field-oriented control (FOC) techniques to dynamically adjust the motor current and voltage to achieve the required motor torque and efficiency. Furthermore, the AC motor control system can provide multiphase control to drive the motor in electric vehicle applications, enabling precise speed and torque regulation. The motor control system can also integrate fault detection mechanisms to identify and respond to abnormal operating conditions (e.g., overvoltage, overcurrent, or thermal overload), thereby ensuring reliable motor operation.

[0003] While the systems and methods for AC motor control and measurement have achieved their intended purposes, there is still a need for novel and improved systems and methods for vehicle AC motor control. Summary of the Invention

[0004] According to several aspects, a method is provided for determining a direct current (DC) current supplied to an alternating current (AC) motor. The method may include measuring a first current in a first AC motor conductor. The method may further include measuring a second current in a second AC motor conductor. The method may further include determining a common-mode current in an AC system including an inverter and an AC motor. The method may further include determining a third current in a third AC motor conductor based at least in part on the first current, the second current, and the common-mode current. The method may further include determining a DC current based at least in part on the first current, the second current, and the third current.

[0005] In another aspect of this disclosure, determining the common-mode current may further include measuring the magnetic field induced in a common-mode choke that is in electromagnetic communication with two or more conductors of the AC system. Determining the common-mode current may also include determining the common-mode current based at least in part on the magnetic field.

[0006] In another aspect of this disclosure, measuring the magnetic field induced in the common-mode choke may further include measuring the magnetic field induced in the common-mode choke. The common-mode choke is in electromagnetic communication with the first AC motor conductor, the second AC motor conductor, and the third AC motor conductor.

[0007] In another aspect of this disclosure, measuring the magnetic field induced in the common-mode choke may further include measuring the magnetic field induced in the common-mode choke. The common-mode choke is in electromagnetic communication with the first DC conductor and the second DC conductor of the inverter.

[0008] In another aspect of this disclosure, measuring the magnetic field induced in the common-mode choke may further include using a sensing coil electromagnetically coupled to the common-mode choke to measure the magnetic field induced in the common-mode choke. The voltage induced across the sensing coil is proportional to the rate of change of the magnetic field.

[0009] In another aspect of this disclosure, determining the common-mode current may further include measuring the voltage across a shunt resistor connected in parallel with the sensing coil. Determining the common-mode current may also include determining the common-mode current itself. The common-mode current is proportional to the voltage across the shunt resistor.

[0010] In another aspect of this disclosure, determining the common-mode current may also include determining the common-mode current itself. The common-mode current is proportional to the integral of the voltage induced across the sensing coil over time.

[0011] In another aspect of this disclosure, measuring the magnetic field induced in the common-mode choke may also include using a point field detector that is in electromagnetic communication with the common-mode choke to measure the magnetic field induced in the common-mode choke.

[0012] In another aspect of this disclosure, determining the common-mode current may further include filtering the common-mode current using a low-pass filter to extract the basic motor speed-related component of the common-mode current.

[0013] In another aspect of this disclosure, determining the third current may also include using the following formula:

[0014] I3=-[(I1)+(I2)+(3*I CM )]

[0015] Where I3 is the third current, I1 is the first current, I2 is the second current, and I... CM This is the common-mode current.

[0016] According to several aspects, a system for controlling an alternating current (AC) motor for a vehicle is provided. The system may include an AC system comprising a plurality of conductors, including a first direct current (DC) conductor, a second DC conductor, a first AC motor conductor, a second AC motor conductor, and a third AC motor conductor. The AC system also includes an inverter in electrical communication with the first DC conductor and the second DC conductor. The system may further include an AC motor in electrical communication with the inverter using the first AC motor conductor, the second AC motor conductor, and the third AC motor conductor. The system may further include a first current sensor configured to measure a first current in the first AC motor conductor. The system may further include a second current sensor configured to measure a second current in the second AC motor conductor. The system may further include a common-mode choke in electromagnetic communication with two or more of the plurality of conductors of the AC system. The system may further include a common-mode choke sensor configured to measure a magnetic field in the common-mode choke. The system may further include a controller in electrical communication with the first current sensor, the second current sensor, and the common-mode choke sensor. The controller is programmed to use a first current sensor to measure a first current in the first AC motor conductor. The controller is also programmed to use a second current sensor to measure a second current in the second AC motor conductor. The controller is further programmed to use a common-mode choke sensor to determine the common-mode current in the AC system. The controller is also programmed to regulate the operation of the AC motor based at least in part on the common-mode current in the AC system.

[0017] In another aspect of this disclosure, the common-mode choke is in electromagnetic communication with the first AC motor conductor, the second AC motor conductor, and the third AC motor conductor.

[0018] In another aspect of this disclosure, the common-mode choke is in electromagnetic communication with the first DC conductor and the second DC conductor.

[0019] In another aspect of this disclosure, the common-mode choke sensor includes a sensing coil electromagnetically coupled to the common-mode choke. The voltage induced across the sensing coil is proportional to the rate of change of the magnetic field.

[0020] In another aspect of this disclosure, the common-mode choke sensor includes a point field detector that is in electromagnetic communication with the common-mode choke.

[0021] In another aspect of this disclosure, in order to regulate the operation of the AC motor, the controller is also programmed to determine the third current in the third AC motor conductor using the following formula:

[0022] I3=-[(I1)+(I2)+(3*I CM )]

[0023] Where I3 is the third current, I1 is the first current, I2 is the second current, and I... CM This refers to the common-mode current. To regulate the operation of the AC motor, the controller is also programmed to determine the torque provided by the AC motor based at least in part on the first current, the second current, and the third current. Furthermore, to regulate the operation of the AC motor, the controller is also programmed to regulate the operation of the AC motor based at least in part on the torque provided by the AC motor.

[0024] In another aspect of this disclosure, in order to regulate the operation of the AC motor, the controller is also programmed to compare the common-mode current with a predetermined common-mode current threshold. In order to regulate the operation of the AC motor, the controller is also programmed to identify a fault in response to determining that the common-mode current is greater than the predetermined common-mode current threshold. In order to regulate the operation of the AC motor, the controller is also programmed to regulate the operation of the AC motor in response to identifying a fault.

[0025] According to several aspects, a method for controlling an alternating current (AC) motor for a vehicle is provided. The method may include measuring a first current in a first AC motor conductor. The method may also include measuring a second current in a second AC motor conductor. The method may further include measuring a magnetic field induced in a common-mode choke, the common-mode choke being in electromagnetic communication with two or more conductors of an AC system including an inverter and an AC motor. The method may further include determining a common-mode current in the AC system based at least in part on the magnetic field. The method may further include regulating the operation of the AC motor based at least in part on the common-mode current in the AC system.

[0026] In another aspect of this disclosure, measuring the magnetic field induced in the common-mode choke and determining the common-mode current may further include using a sensing coil electromagnetically coupled to the common-mode choke to measure the magnetic field induced in the common-mode choke. The voltage induced across the sensing coil is proportional to the rate of change of the magnetic field. The common-mode choke is in electromagnetic communication with a first AC motor conductor, a second AC motor conductor, and a third AC motor conductor. Measuring the magnetic field induced in the common-mode choke and determining the common-mode current may further include determining the common-mode current. The common-mode current is proportional to the integral of the voltage induced across the sensing coil over time.

[0027] In another aspect of this disclosure, regulating the operation of the AC motor may further include comparing the common-mode current with a predetermined common-mode current threshold. Regulating the operation of the AC motor may further include identifying a fault in response to determining that the common-mode current is greater than the predetermined common-mode current threshold. Regulating the operation of the AC motor may further include regulating the operation of the AC motor in response to identifying the fault. The third current in the third AC motor conductor is determined using the following formula:

[0028] I3=-[(I1)+(I2)+(3*ICM )]

[0029] Where I3 is the third current, I1 is the first current, I2 is the second current, and I... CM The common-mode current is used. Regulating the operation of the AC motor may further include determining the torque provided by the AC motor based at least in part on the first current, the second current, and the third current. Regulating the operation of the AC motor may also include regulating the operation of the AC motor based at least in part on the torque provided by the AC motor.

[0030] Other application areas will become apparent from the description provided herein. It should be understood that the specification and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0031] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0032] Figure 1A This is a schematic diagram of a first exemplary embodiment of a system for controlling an AC motor for a vehicle, according to an exemplary embodiment;

[0033] Figure 1B This is a schematic diagram of a second exemplary embodiment of a system for controlling an AC motor for a vehicle, according to an exemplary embodiment;

[0034] Figure 2A This is a schematic diagram of a first exemplary embodiment of a common-mode choke sensor according to an exemplary embodiment;

[0035] Figure 2B This is a schematic diagram of a second exemplary embodiment of a common-mode choke sensor according to an exemplary embodiment;

[0036] Figure 2C This is a schematic diagram of a third exemplary embodiment of a common-mode choke sensor according to an exemplary embodiment; and

[0037] Figure 3 This is a flowchart of a method for controlling an AC motor for a vehicle, according to an exemplary embodiment. Detailed Implementation

[0038] The following description is merely exemplary in nature and is not intended to limit this disclosure, application, or use.

[0039] In various aspects of this disclosure, it is advantageous to provide precise control of alternating current (AC) motors used in vehicles and other applications. To enable precise control, it is advantageous to determine accurate data regarding the operating states of the motor (e.g., voltage, current, torque, etc.). Therefore, this disclosure provides a new and improved system and method for controlling AC motors, including a method for determining the DC current supplied to the AC motor, and more specifically, a method for compensating for the common-mode current supplied to the AC motor.

[0040] Reference Figure 1A This illustration depicts a first exemplary embodiment of a system for controlling an alternating current (AC) motor for a vehicle, and the system is generally indicated by reference numeral 10a. System 10a is shown as having an exemplary vehicle 12. Although a bus is illustrated, it should be understood that vehicle 12 can be any type of vehicle without departing from the scope of this disclosure. System 10a generally includes a controller 14, a rechargeable energy storage system (RESS) 16, an AC system 18, a common-mode choke 20, and a common-mode choke sensor 22.

[0041] The controller 14 is used to implement a method 100 for controlling the AC motor of a vehicle, as described below. The controller 14 includes at least one processor 30 and a non-transitory computer-readable storage device or medium 32. The processor 30 may be a custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among several processors associated with the controller 14, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, a combination thereof, or a device typically used for executing instructions.

[0042] Computer-readable storage device or medium 32 may include volatile and non-volatile storage devices such as read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operating variables when the processor 30 is powered off. Computer-readable storage device or medium 32 may be implemented using multiple storage devices, such as PROM (programmable read-only memory), EPROM (electrical PROM), EEPROM (electrically erasable PROM), flash memory, or another electrical, magnetic, optical, or combined storage device capable of storing data, some of which represents executable instructions that can be used by controller 14 to control various systems of vehicle 12.

[0043] Controller 14 may also include multiple controllers that are electrically communicating with each other. Controller 14 may interconnect with other systems and / or controllers of vehicle 12, thereby allowing controller 14 to access data such as the speed, acceleration, braking and steering angle of vehicle 12.

[0044] Controller 14 communicates electrically with RESS 16, AC system 18, and common-mode choke sensor 22. In an exemplary embodiment, electrical communication is established using, for example, a CAN network, FLEXRAY network, local area network (e.g., WiFi, Ethernet, etc.), Serial Peripheral Interface (SPI) network, etc. It should be understood that various other wired and wireless technologies and communication protocols used for communicating with controller 14 are within the scope of this disclosure. It should also be understood that, within the scope of this disclosure, electrical communication also includes power and / or energy transfer between electrical devices (e.g., via the use of wires and / or wireless power transfer technologies).

[0045] RESS 16 stores and provides electrical energy in the form of direct current (DC) for the operation of vehicle 12. In an exemplary embodiment, RESS 16 includes multiple battery cells (e.g., lithium-ion battery cells) connected in series and / or parallel to provide increased voltage and / or current carrying capacity. In a non-limiting example, the multiple battery cells are housed in a housing configured to protect them from mechanical vibration, water intrusion, and dust intrusion. The housing is also configured to provide temperature regulation (e.g., using a liquid cooling system, a resistance heating system, etc.). In an exemplary embodiment, RESS 16 also includes a battery management system (BMS) configured to monitor battery characteristics (e.g., state of charge (SOC), state of health (SOH), temperature, etc.) and transmit these battery characteristics to controller 14. In a non-limiting example, the BMS includes a BMS controller that is in electrical communication with multiple BMS sensors disposed within the housing of RESS 16. In an exemplary embodiment, RESS 16 provides a DC voltage across a positive output terminal and a negative output terminal. The positive and negative output terminals are connected to an AC system 18, which will be discussed below.

[0046] AC system 18 is used to propel vehicle 12 by converting DC energy from RESS 16 into mechanical energy. AC system 18 includes inverter 40, AC motor 42, a first current sensor 44a, a second current sensor 44b, and multiple conductors. Inverter 40 is used to convert DC energy from RESS 16 into three-phase AC energy to power AC motor 42. In an exemplary embodiment, inverter 40 includes multiple power semiconductor devices, such as insulated-gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and / or similar devices configured to convert DC to three-phase AC. In a non-limiting example, inverter 40 operates by switching the multiple power semiconductor devices in a mode to generate a sinusoidal AC output for each of the three phases. To control the speed, direction, and / or torque of AC motor 42 based on signals from controller 14, this mode can be adjusted to change the amplitude, frequency, and / or relative phase shift of each of the three phases.

[0047] The plurality of conductors includes a first DC conductor 46a and a second DC conductor 46b that electrically connect the inverter 40 to the RESS 16. The inverter 40 is in electrical communication with the controller 14, enabling the controller 14 to enable, disable, and otherwise regulate the operation of the inverter 40. It should be understood that various types of inverters, including, for example, multilevel inverters, are within the scope of this disclosure.

[0048] AC motor 42 is used to convert electrical energy from RESS 16 into mechanical energy (i.e., rotational energy) to propel vehicle 12. In an exemplary embodiment, AC motor 42 is a three-phase AC induction motor. In a non-limiting example, AC motor 42 includes a stator having multiple stator windings and a rotor having multiple rotor windings rotatably arranged within the stator. The stator windings are three-phase AC excited by inverter 40 to generate a rotating stator magnetic field. The rotating stator magnetic field induces a current in the rotor windings, which in turn generates a rotor magnetic field that interacts with the rotating stator magnetic field, thereby causing the rotor to rotate. The amplitude, frequency, and / or relative phase shift of the excitation of each of the three phases of the stator windings control the speed, direction, and / or torque of AC motor 42. The multiple conductors also include a first AC motor conductor 48a, a second AC motor conductor 48b, and a third AC motor conductor 48c, the third AC motor conductor electrically connecting inverter 40 to AC motor 42.

[0049] A first current sensor 44a is used to measure the current flowing through a first AC motor conductor 48a. In an exemplary embodiment, the first current sensor 44a is a Hall effect sensor. In a non-limiting example, the Hall effect sensor includes a Hall element and a signal conditioning circuit in electrical communication with the Hall element. The Hall element detects the magnetic field generated by the current flowing through the first AC motor conductor 48a, and the signal conditioning circuit processes the detected signal to determine the magnitude / direction of the current.

[0050] In another exemplary embodiment, the first current sensor 44a is a shunt resistor-based sensor. In a non-limiting example, the shunt resistor-based sensor includes a precision low-resistance shunt resistor and a differential amplifier in electrical communication with the shunt resistor. The shunt resistor is placed in series with the first AC motor conductor 48a, and the differential amplifier measures the voltage drop across the shunt resistor to calculate the current based on Ohm's law.

[0051] In yet another exemplary embodiment, the first current sensor 44a is a Rogowski coil. In a non-limiting example, the Rogowski coil includes a flexible air-core coil and an integrator circuit electrically communicating with the coil. The air-core coil wraps around the first AC motor conductor 48a without direct electrical contact and induces a voltage proportional to the rate of change of current. The integrator circuit processes this voltage to determine the actual current flowing through the first AC motor conductor 48a. It should be understood that the first current sensor 44a can be implemented using any system, method, or device operable to measure the current flowing in the conductor, including, for example, a current transformer. The first current sensor 44a is electrically communicating with the controller 14.

[0052] The second current sensor 44b is used to measure the current flowing through the second AC motor conductor 48b. In an exemplary embodiment, the second current sensor 44b is a Hall effect sensor. In a non-limiting example, the Hall effect sensor includes a Hall element and a signal conditioning circuit in electrical communication with the Hall element. The Hall element detects the magnetic field generated by the current flowing through the second AC motor conductor 48b, and the signal conditioning circuit processes the detected signal to determine the magnitude / direction of the current.

[0053] In another exemplary embodiment, the second current sensor 44b is a shunt resistor-based sensor. In a non-limiting example, the shunt resistor-based sensor includes a precision low-resistance shunt resistor and a differential amplifier in electrical communication with the shunt resistor. The shunt resistor is placed in series with the second AC motor conductor 48b, and the differential amplifier measures the voltage drop across the shunt resistor to calculate the current based on Ohm's law.

[0054] In yet another exemplary embodiment, the second current sensor 44b is a Rogowski coil. In a non-limiting example, the Rogowski coil includes a flexible air-core coil and an integrator circuit electrically communicating with the coil. The air-core coil wraps around the second AC motor conductor 48b without direct electrical contact and induces a voltage proportional to the rate of change of current. The integrator circuit processes this voltage to determine the actual current flowing through the second AC motor conductor 48b. It should be understood that the second current sensor 44b can be implemented using any system, method, or device operable to measure the current flowing in the conductor, including, for example, a current transformer. The second current sensor 44b is electrically communicating with the controller 14.

[0055] The common-mode choke 20 is used to suppress common-mode current in two or more conductors. In an exemplary embodiment, the common-mode choke 20 is an electromagnetic component that provides high impedance to common-mode signals while allowing differential-mode signals to pass through with minimal attenuation.

[0056] In an exemplary embodiment, the common-mode choke 20 includes a magnetic core that is in electromagnetic communication with the two or more conductors. Within the scope of this disclosure, electromagnetic communication refers to energy transfer achieved through electric and / or magnetic fields, for example, according to Ampere's law, Faraday's law of electromagnetic induction, and / or similar principles.

[0057] In a non-limiting example, the two or more conductors are wound around a magnetic core. The core is made of a ferrite material with high permeability, thereby increasing the inductance of the common-mode current. The windings of the two or more conductors are arranged such that the differential-mode current induces opposing magnetic fields that cancel each other out within the core, thus allowing the differential-mode current to pass through. The common-mode current induces an additional magnetic field within the core, which leads to attenuation of the common-mode signal.

[0058] In another non-limiting example, the common-mode choke 20 has a split-core design, wherein the core comprises two separate core halves joined together. The split-core design allows for easy mounting around the two or more conductors without requiring disconnection. The core halves may be constructed of high-permeability ferrite or nanocrystalline materials, which enhances common-mode impedance over a wide frequency range. The two or more conductors may be wound around each core half or pass through holes in the core. It should be understood that the examples of common-mode choke types discussed above are merely exemplary in nature, and various other and / or alternative types of common-mode chokes may be used within the scope of this disclosure.

[0059] In a first exemplary embodiment of system 10a, the common-mode choke 20 is in electromagnetic communication with the first AC motor conductor 48a, the second AC motor conductor 48b, and the third AC motor conductor 48c, such as... Figure 1A As shown. (Refer to...) Figure 1BThis illustrates a second exemplary embodiment of a system for controlling an AC motor for a vehicle, and the system as a whole is indicated by reference numeral 10b. System 10b includes the same components as system 10a. In the second exemplary embodiment of system 10b, the common-mode choke 20 is in electromagnetic communication with the first DC conductor 46a and the second DC conductor 46b, as shown below. Figure 1B As shown. The remaining components of system 10b are the same as those of system 10a, and the component descriptions provided above for system 10a also apply to system 10b.

[0060] It should be understood that the entire disclosure, including method 100 which will be discussed below, is applicable to system 10a. Figure 1A (as shown) and System 10b ( Figure 1B (As shown in the diagram). In other words, the common-mode choke 20 can electromagnetically communicate with the first AC motor conductor 48a, the second AC motor conductor 48b, and the third AC motor conductor 48c, or with the first DC conductor 46a and the second DC conductor 46b. Some embodiments may include two common-mode chokes, one of which electromagnetically communicates with the first AC motor conductor 48a, the second AC motor conductor 48b, and the third AC motor conductor 48c, while the other common-mode choke electromagnetically communicates with the first DC conductor 46a and the second DC conductor 46b.

[0061] The common-mode choke sensor 22 is used to measure the magnetic field in the common-mode choke 20. The common-mode choke sensor 22 is an electronic or electromagnetic sensor operable to measure magnetic fields. (See reference...) Figure 2A The image shows a common-mode choke 20 with a first exemplary embodiment 22a of a common-mode choke sensor 22. The first exemplary embodiment 22a of the common-mode choke sensor 22 includes a sensing coil 60 electromagnetically coupled to the common-mode choke 20. Within the scope of this disclosure, "electromagnetic coupling" means "in electromagnetic communication" as discussed above.

[0062] In a non-limiting example, the sensing coil 60 includes one or more turns of wire wound around the common-mode choke 20 (e.g., around the magnetic core of the common-mode choke 20) such that the magnetic flux in the magnetic core of the common-mode choke 20 passes through a surface substantially perpendicular to the normal vector of the sensing coil 60. Therefore, according to Faraday's law of induction, the voltage induced across the sensing coil 60 is proportional to the rate of change of the magnetic field in the common-mode choke 20. Furthermore, the common-mode current in the conductor that is electromagnetically communicating with (e.g., surrounded by) the common-mode choke 20 is proportional to the integral of the voltage induced across the sensing coil 60 over time.

[0063] Reference Figure 2BThe image illustrates a common-mode choke 20 with a second exemplary embodiment 22b of the common-mode choke sensor 22. The second exemplary embodiment 22b of the common-mode choke sensor 22 includes a sensing coil 60 electromagnetically coupled to the common-mode choke 20 and a shunt resistor 62 connected in parallel with the sensing coil 60. Therefore, the common-mode current in the conductor that is electromagnetically in communication with (e.g., surrounded by) the common-mode choke 20 is proportional to the voltage across the shunt resistor 62.

[0064] Reference Figure 2C The diagram illustrates a common-mode choke 20 with a third exemplary embodiment 22c of the common-mode choke sensor 22. The third exemplary embodiment 22c of the common-mode choke sensor 22 includes a point field detector 64 that is in electromagnetic communication with the common-mode choke 20. Within the scope of this disclosure, the point field detector 64 is a device operable to detect and measure a magnetic field at a specific point in space. In the exemplary embodiment, the point field detector 64 is arranged in a slit or gap in the magnetic core of the common-mode choke 20.

[0065] In an exemplary embodiment, the point field detector 64 is a Hall effect sensor. In a non-limiting example, the Hall effect sensor includes a Hall element and a signal conditioning circuit in electrical communication with the Hall element. The Hall element detects the magnetic field within the core of the common-mode choke 20, and the signal conditioning circuit processes the detected signal to determine the amplitude / direction of the magnetic field. The common-mode current in a conductor that is in electromagnetic communication with (e.g., surrounded by) the common-mode choke 20 is proportional to the magnetic field within the core of the common-mode choke 20.

[0066] In another exemplary embodiment, the point field detector 64 is a magnetoresistive (MR) sensor. In a non-limiting example, the MR sensor includes a magnetoresistive element and measurement circuitry in electrical communication with the magnetoresistive element. The magnetoresistive element exhibits a change in resistance in response to a magnetic field in the core of the common-mode choke 20, and the measurement circuitry converts the resistance change into a signal indicating the amplitude / direction of the magnetic field. The common-mode current in a conductor that is in electromagnetic communication with (e.g., surrounded by) the common-mode choke 20 is proportional to the magnetic field within the core of the common-mode choke 20. It should be understood that the examples of point field detectors discussed above are merely exemplary in nature, and various other and / or alternative types of point field detectors can be used within the scope of this disclosure.

[0067] It should be understood that the first exemplary embodiment 22a, the second exemplary embodiment 22b, and the third exemplary embodiment 22c of the common-mode choke sensor 22 described above can be applied to embodiment 10a as described above. Figure 1A ) and 10b Figure 1BFurthermore, it should be understood that the exemplary embodiments of the common-mode choke sensor 22 discussed above are merely exemplary in nature, and various other and / or alternative types of common-mode choke sensors are within the scope of this disclosure. (See again...) Figure 1A and Figure 1B The common-mode choke sensor 22 communicates with the controller 14.

[0068] Reference Figure 3 A flowchart of a method 100 for controlling an AC motor for a vehicle is provided. Method 100 begins at block 102 and proceeds to blocks 104 and 106. At block 104, controller 14 uses a first current sensor 44a to measure a first current in a first AC motor conductor 48a. After block 104, method 100 proceeds to block 108, which will be discussed below. At block 106, controller 14 uses a second current sensor 44b to measure a second current in a second AC motor conductor 48b. After block 106, method 100 proceeds to block 108.

[0069] At block 108, controller 14 uses common-mode choke sensor 22 to measure the magnetic field induced in common-mode choke 20. In an exemplary embodiment, as described above with reference to system 10a ( Figure 1A As discussed above, the common-mode choke 20 is in electromagnetic communication with the first AC motor conductor 48a, the second AC motor conductor 48b, and the third AC motor conductor 48c. Therefore, a magnetic field is induced by the common-mode current flowing in the first AC motor conductor 48a, the second AC motor conductor 48b, and the third AC motor conductor 48c. In another exemplary embodiment, the common-mode choke 20 is in electromagnetic communication with the first DC conductor 46a and the second DC conductor 46b, as described above with reference to system 10b. Figure 1B As discussed above, a magnetic field is induced by the common-mode current flowing in the first DC conductor 46a and the second DC conductor 46b.

[0070] It should be understood that the common-mode choke sensor 22 may include any one of the first exemplary embodiment 22a, the second exemplary embodiment 22b, the third exemplary embodiment 22c, and / or any other type of common-mode choke sensor as described above. Following block 108, method 100 proceeds to block 110.

[0071] At block 110, controller 14 determines the common-mode current in the conductor electromagnetically communicating with common-mode choke 20 based at least in part on the magnetic field in common-mode choke 20 measured at block 108. In an exemplary embodiment 22a utilizing the first exemplary embodiment 22a described above, the common-mode current in the conductor electromagnetically communicating with common-mode choke 20 is proportional to the integral of the voltage induced across sensing coil 60 over time. In a non-limiting example, controller 14 uses an analog-to-digital converter to measure the change in voltage induced across sensing coil 60 over time and performs numerical integration to calculate the common-mode current.

[0072] In another exemplary embodiment 22b utilizing the common-mode choke sensor 22, the common-mode current in the conductor electromagnetically communicating with the common-mode choke 20 is proportional to the voltage across the shunt resistor 62. In a non-limiting example, the controller 14 uses an analog-to-digital converter to measure the voltage across the shunt resistor 62 to calculate the common-mode current. In another exemplary embodiment 22c utilizing the common-mode choke sensor 22, the common-mode current in the conductor electromagnetically communicating with the common-mode choke 20 is proportional to the magnetic field within the core of the common-mode choke 20.

[0073] Typically, the common-mode current is proportional to the magnetic field measured at box 108:

[0074] I CM =k c *B (1)

[0075] Among them, I CM Let B be the common-mode current, B be the magnetic field, and k be the common-mode current. c This is a proportionality constant that takes into account factors such as the geometry of the core of the common-mode choke 20, the material properties of the core, the winding configuration of the conductor relative to the core, and physical constants.

[0076] In an exemplary embodiment, at block 110, controller 14 uses a low-pass filter to filter the common-mode current to extract the fundamental motor speed-dependent component of the common-mode current. Within the scope of this disclosure, the fundamental motor speed-dependent component of the common-mode current includes a component of the common-mode current that depends on the motor speed (i.e., rotational speed) of the AC motor 42, and excludes irrelevant components of the common-mode current attributable to noise. In a non-limiting example, controller 14 uses digital signal processing to digitally filter the common-mode current. In another non-limiting example, controller 14 uses an analog low-pass filter (integrated with controller 14 or other parts of systems 10a, 10b) to filter the common-mode current. Following block 110, method 100 proceeds to block 112.

[0077] At block 112, controller 14 compares the common-mode current determined at block 110 with a predetermined common-mode current threshold. The predetermined common-mode current threshold represents the magnitude of the common-mode current at which an isolation fault occurs between inverter 40 and / or AC motor 42. If the common-mode current determined at block 110 is greater than the predetermined common-mode current threshold, method 100 proceeds to block 114. If the common-mode current determined at block 110 is less than or equal to the predetermined common-mode current threshold, method 100 proceeds to block 116.

[0078] At block 114, controller 14 identifies a fault in response to determining that the common-mode current is greater than a predetermined common-mode current threshold. In an exemplary embodiment, controller 14 regulates the operation of AC motor 42 in response to identifying the fault. In a non-limiting example, controller 14 regulates the operation of AC motor 42 by de-energizing AC motor 42 (e.g., by disabling inverter 40 or by limiting / reducing the output power of inverter 40) and providing diagnostic warnings to the occupants of vehicle 12. After block 114, method 100 enters a standby state at block 118.

[0079] At block 116, controller 14 determines a third current in the third AC motor conductor 48c based at least in part on a first current measured at block 104, a second current measured at block 106, and a common-mode current determined at block 110. Therefore, using systems 10a, 10b, and method 100, the third current is determined without requiring a third current sensor on the third AC motor conductor 48c. In one exemplary embodiment, the third current is determined using the following formula:

[0080] I3=-[(I1)+(I2)+(3*I CM (2)

[0081] Wherein, I3 is the third current, I1 is the first current measured at box 104, I2 is the second current measured at box 106, and I... CM The common-mode current is determined at block 110. In a non-limiting example, Formula 2 may include additional correction factors that correct for known measurement errors of the first current sensor 44a, the second current sensor 44b, and / or the common-mode choke sensor 22. After block 116, method 100 proceeds to block 120.

[0082] At block 120, controller 14 determines the direct current (DC) supplied from RESS 16 to AC motor 42 based at least in part on a first current measured at block 104, a second current measured at block 106, and a third current determined at block 116. In an exemplary embodiment, the DC current is the instantaneous value of the first current measured at block 104, the second current measured at block 106, and the third current determined at block 116. In another exemplary embodiment, the DC current from RESS 16 is determined using the following formula:

[0083] I DC =S1I1+S2I2+S2I3 (3)

[0084] Among them, I DC S1 is the first switching function of the first AC motor conductor 48a, I1 is the first current measured at box 104, S2 is the second switching function of the second AC motor conductor 48b, I2 is the second current measured at box 106, S3 is the third switching function of the third AC motor conductor 48c, and I3 is the third current determined at box 116.

[0085] Within the scope of this disclosure, the switching functions relate to the operation of inverter 40. In a non-limiting example, the first switching function S1 is related to the switching duty cycle on the first AC motor conductor 48a (i.e., the first AC phase of inverter 40), the second switching function S2 is related to the switching duty cycle on the second AC motor conductor 48b (i.e., the second AC phase of inverter 40), and the third switching function S3 is related to the switching duty cycle on the third AC motor conductor 48c (i.e., the third AC phase of inverter 40). After block 120, method 100 proceeds to block 122.

[0086] At block 122, controller 14 regulates the operation of AC motor 42 based at least in part on the DC current determined at block 120. In an exemplary embodiment, controller 14 determines the torque provided by AC motor 42 based at least in part on the DC current determined at block 120. In a non-limiting example, the torque provided by AC motor 42 is proportional to the DC current:

[0087]

[0088] Where T is the torque provided by AC motor 42, and V DC For the voltage of RESS16 or the DC link voltage of inverter 40, I DC For the DC current and L determined at box 120 I For the power loss of inverter 40, L M For the power loss of AC motor 42, and Wrm The rotational speed of AC motor 42. It should be understood that other relationships between torque and DC current are also within the scope of this disclosure.

[0089] In an exemplary embodiment, controller 14 regulates the operation of AC motor 42 at least in part based on the torque provided by AC motor 42. In a non-limiting example, controller 14 executes a closed-loop control algorithm to regulate the voltage, current, frequency, phase angle, etc., of the inverter 40 output to AC motor 42 at least in part based on the torque provided by AC motor 42. For example, controller 14 may execute a closed-loop control algorithm configured to maintain the torque provided by AC motor 42 at a given setpoint. It should be understood that various additional and / or alternative control actions based on the torque provided by AC motor 42 are within the scope of this disclosure, including, for example, diagnostic actions, data collection / crowdsourcing actions, information display actions (e.g., providing information about the torque provided by AC motor 42 to the occupants of vehicle 12), etc. After block 122, method 100 enters a standby state at block 118.

[0090] In an exemplary embodiment, controller 14 repeatedly exits standby state 118 and restarts method 100 at block 102. In a non-limiting example, controller 14 exits standby state 118 and restarts method 100 on a timer, for example, every 300 milliseconds.

[0091] The systems 10a, 10b, and method 100 of this disclosure offer several advantages. By using systems 10a, 10b, and method 100, a third current in the third AC motor conductor 48c is determined without requiring a third current sensor, thereby reducing weight, resource usage, and component count. Furthermore, the influence of common-mode current is considered when determining the third current, thereby improving the accuracy of current determination and thus allowing for more precise control of the AC motor 42. Additionally, the identification of isolation faults and other diagnostic tasks can be performed based on the common-mode current determined using systems 10a, 10b, and method 100 to control the AC motor 42.

[0092] The description in this disclosure is exemplary in nature only, and variations thereof without departing from the spirit of this disclosure are intended to be within the scope of this disclosure. Such variations should not be considered as departing from the scheme and scope of this disclosure.

Claims

1. A method for determining a DC current supplied to an AC motor, the method comprising: Measure the first current in the first AC motor conductor; Measure the second current in the second AC motor conductor; Determine the common-mode current in the AC system, including the inverter and the AC motor; The third current in the third AC motor conductor is determined at least in part based on the first current, the second current, and the common-mode current; as well as The DC current is determined at least in part based on the first current, the second current, and the third current.

2. The method according to claim 1, wherein, Determining the common-mode current further includes: Measure the magnetic field induced in a common-mode choke that is electromagnetically communicating with two or more conductors of the AC system; and The common-mode current is determined at least in part based on the magnetic field.

3. The method according to claim 2, wherein, Measuring the magnetic field induced in the common-mode choke also includes: The magnetic field induced in the common-mode choke is measured, wherein the common-mode choke is in electromagnetic communication with the first AC motor conductor, the second AC motor conductor, and the third AC motor conductor.

4. The method according to claim 2, wherein, Measuring the magnetic field induced in the common-mode choke also includes: The magnetic field induced in the common-mode choke is measured, wherein the common-mode choke is in electromagnetic communication with the first DC conductor and the second DC conductor of the inverter.

5. The method according to claim 2, wherein, Measuring the magnetic field induced in the common-mode choke also includes: The magnetic field induced in the common-mode choke is measured using a sensing coil electromagnetically coupled to the common-mode choke, wherein the voltage induced across the sensing coil is proportional to the rate of change of the magnetic field.

6. The method according to claim 5, wherein, Determining the common-mode current further includes: Measure the voltage across the shunt resistor connected in parallel with the sensing coil; and The common-mode current is determined, wherein the common-mode current is proportional to the voltage across the shunt resistor.

7. The method according to claim 5, wherein, Determining the common-mode current further includes: The common-mode current is determined, wherein the common-mode current is proportional to the integral of the voltage induced across the sensing coil over time.

8. The method according to claim 2, wherein, Measuring the magnetic field induced in the common-mode choke also includes: The magnetic field induced in the common-mode choke is measured using a point field detector that is in electromagnetic communication with the common-mode choke.

9. The method according to claim 2, wherein, Determining the common-mode current further includes: The common-mode current is filtered using a low-pass filter to extract the basic motor speed-related component of the common-mode current.

10. The method according to claim 1, wherein, Determining the third current also includes: The third current is determined using the following formula: I3=-[(I1)+(I2)+(3*I CM )] Wherein, I3 is the third current, I1 is the first current, I2 is the second current, and I... CM The common-mode current is denoted as .

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