Current sampling control method of electric drive system, motor drive system and vehicle

Abstract

The current sampling control method of the electric drive system, the motor drive system and the vehicle provided by the application are related to the motor drive technology field, and aim to realize the optimization of the full-speed domain accurate control of the motor and the optimization of the functional safety index while simplifying the current sampling circuit. The method comprises the following steps: acquiring the real-time rotating speed of the motor; when the real-time rotating speed is less than or equal to a preset rotating speed threshold, controlling the switching switch group to sequentially turn on each phase current sensor to the signal processing circuit in a control period, performing time domain synchronous correction on the acquired phase current sensing signals, obtaining a first target phase current, and controlling the motor to operate based on the first target phase current; when the real-time rotating speed is greater than the preset rotating speed threshold, controlling the switching switch group to turn on the bus current sensor to the signal processing circuit, obtaining a second target phase current based on the acquired bus current sensing signal corresponding to the bus current sensor, and controlling the motor to operate based on the second target phase current.

Description

Technical Field

[0001] This application relates to the field of motor drive technology, specifically to a current sampling control method for electric drive systems, motor drive systems, and vehicles. Background Technology

[0002] With the evolution of vehicle architecture towards domain-centralized systems and the development of high-voltage and intelligent technologies, the functional safety requirements for electric drive systems are becoming increasingly stringent. Motor output torque is directly proportional to winding current, and accurate current acquisition is a prerequisite for precise torque control. Current current sampling schemes mostly involve simultaneously acquiring three-phase current or acquiring two-phase current to calculate the third phase. Simultaneous three-phase acquisition circuitry is complex and costly; two-phase acquisition, however, suffers from reduced reliability because it cannot utilize the zero sum of the three-phase currents for verification. Furthermore, to meet functional safety requirements, existing technologies typically employ redundant designs or add monitoring loops, further increasing the number of components and system cost. Therefore, there is an urgent need for a current sampling scheme that can simplify hardware while maintaining full-speed domain control accuracy and functional safety indicators. Summary of the Invention

[0003] In view of the shortcomings of the above-mentioned related technologies, the purpose of this application is to provide a current sampling control method for an electric drive system, a motor drive system and a vehicle, which aims to achieve both simplified current sampling circuit and optimization of motor full-speed-range precise control and functional safety indicators.

[0004] In a first aspect, embodiments of this application provide a current sampling control method for an electric drive system. This method is applied to a motor drive system, which includes: multiple current detection sensors, a switching group, a signal processing circuit, and a motor. The multiple current detection sensors include multiple phase current sensors for detecting the current in the multi-phase windings of the motor, and a bus current sensor for detecting the DC bus current. The switching group is connected between the multiple current detection sensors and the signal processing circuit, and is used to simultaneously select one current sensing signal from the multiple current detection sensors to the signal processing circuit. The signal processing circuit is used to process the current transmitted to the signal processing circuit. The method involves processing the sensor signals. The process includes: acquiring the real-time speed of the motor; when the real-time speed is less than or equal to a preset speed threshold, controlling the switching group to sequentially connect each phase current sensor to the signal processing circuit within a control cycle, and performing time-domain synchronous correction on the acquired phase current sensing signals to obtain a first target phase current, thereby controlling the motor operation based on the first target phase current; when the real-time speed is greater than the preset speed threshold, controlling the switching group to connect the bus current sensor to the signal processing circuit, and obtaining a second target phase current based on the acquired bus current sensing signal corresponding to the bus current sensor, thereby controlling the motor operation based on the second target phase current.

[0005] This solution switches the sampling path based on the real-time speed of the motor. Only a single current sensor is connected to the signal processing circuit at any given time, avoiding the risks of signal crosstalk, channel interference, and synchronous failures in multiple acquisition circuits caused by parallel acquisition of multiple signals. This improves the hardware safety and signal acquisition reliability of the current sampling stage. At low speeds, it sequentially acquires the current of each phase and performs time-domain synchronous correction to accurately reconstruct the independent phase current, improving low-speed torque control accuracy and reducing torque ripple. At high speeds, it only acquires the bus current to reconstruct the phase current, significantly reducing the amount of switching and correction calculations within a cycle, improving control real-time performance, and adapting to high-speed, high-frequency control requirements. Furthermore, the single-channel time-division multiplexing architecture eliminates multiple independent signal processing circuits, reducing hardware cost and size. The single-channel acquisition mode simplifies the sampling fault diagnosis logic, facilitating rapid identification of sensor and switch path anomalies, further enhancing the operational safety of the electric drive system, and balancing sampling accuracy, control real-time performance, hardware cost, and overall machine operational safety across the entire speed range.

[0006] In one possible embodiment, time-domain synchronous correction is performed on the acquired phase current sensing signals to obtain a first target phase current. This includes: using the sampling time of any one of the multiple phase current sensors as a reference time, determining the sampling time difference of the remaining phase current sensors relative to the reference time; calculating the phase compensation angle corresponding to each phase current sensor based on the current angular velocity of the motor and each sampling time difference; and correcting the time-division acquired phase current sensing signals to the same reference time based on each phase compensation angle through vector rotation transformation to obtain the first target phase current. The vector rotation transformation is used to convert the time-domain deviation corresponding to the phase compensation angle into an angular correction amount of the phase current sensing signal in a rotating coordinate system, so that the time-division acquired phase current sensing signals are equivalent to synchronous sampling values ​​at the same time when vector synthesis is performed.

[0007] Based on the aforementioned technical means, this embodiment, under low-speed operating conditions, uses the sampling time of one phase as a reference to calculate the phase compensation angle of each phase based on the difference between the angular velocity and the sampling time for the time-division multiplexing current sensing signals of each phase. Through vector rotation transformation, the asynchronously sampled three-phase currents are corrected to the same reference time. This method eliminates the sampling time difference error introduced by time-division multiplexing, making the corrected three-phase current equivalent to the synchronously sampled value at the same moment. This ensures the accuracy of current vector synthesis under low-speed operating conditions, improves the accuracy of low-speed torque control, reduces torque ripple, and avoids the unobservable zone problem caused by insufficient effective vector action time in the low-speed region, a problem inherent in single-current sensor reconstruction schemes.

[0008] In one embodiment, obtaining a second target phase current based on the bus current sensing signal corresponding to the acquired bus current sensor includes: sampling the bus current sensing signal during different effective voltage vectors within a control cycle to obtain at least two bus current values; determining the phase current associated with each bus current value according to a preset correspondence between the space voltage vector and the phase current; and calculating the second target phase current based on the constraint that the sum of the phase currents is zero.

[0009] Based on the aforementioned technical means, this embodiment samples the bus current during different effective voltage vectors under high-speed operating conditions. Combining this with a preset mapping relationship between the space voltage vector and phase currents, the three-phase current is reconstructed using the constraint that the sum of the phase currents is zero. In this method, the switching group is fixed to conduct the bus current sensor, eliminating the need for channel switching, thus removing the time delay introduced by switch switching. The sampling and calculation response speed is fast, adapting to high-speed, high-frequency control requirements. Furthermore, only one bus current sensor is needed to acquire the three-phase current, reducing the amount of switching and correction calculations within the cycle and improving the real-time performance of the control.

[0010] In some embodiments, the method further includes: when the real-time rotational speed is within a preset transition range near a preset rotational speed threshold, verifying the second target phase current using the first target phase current, or verifying the first target phase current using the second target phase current, to diagnose non-failure drift faults of the current sensor.

[0011] Based on the aforementioned technical means, this embodiment utilizes the characteristic that both current sampling modes can output valid results within the transition range. Through cross-validation, it achieves online diagnosis of non-failure drift faults of current sensors without adding additional hardware. Non-failure drift faults refer to situations where the sensor is not completely faulty, but the output value continuously deviates from the true value. Such faults do not immediately trigger protection shutdown, but their long-term existence will affect control accuracy and functional safety. Dual-mode cross-validation can promptly identify such hidden faults, improving the system's fault detection coverage and helping to meet higher levels of functional safety requirements.

[0012] In an exemplary embodiment, controlling the switching switch group to sequentially turn on each phase current sensor to the signal processing circuit within a control cycle includes: sending selection signals to the switching switch group in a preset order at different time periods within a control cycle, so that each phase current sensor is connected to the signal processing circuit in a time-sharing manner within the same control cycle; wherein, the preset order includes: sequentially sending a first selection signal, a second selection signal, and a third selection signal, which respectively turn on the first phase current sensor, the second phase current sensor, and the third phase current sensor, and there is a preset time interval between two adjacent selection signals.

[0013] Based on the aforementioned technical means, this embodiment uses time-division multiplexing signals with a preset sequence and fixed time intervals to sequentially connect the three-phase current sensors to the signal processing circuit under low-speed operating conditions. The preset time interval between two adjacent gating signals is greater than the time required for signal stabilization, ensuring that the signal is sufficiently stable at each sampling time and avoiding the impact of transient interference during channel switching on sampling accuracy. Simultaneously, the fixed sampling sequence provides a definite time difference parameter for subsequent time-domain synchronous correction, simplifying the compensation algorithm.

[0014] In an exemplary embodiment, controlling the switching group to connect the bus current sensor to the signal processing circuit includes: sending a fixed gating signal to the switching group so that the bus current sensor is continuously connected to the signal processing circuit; the fixed gating signal is used to keep the switching channel of the corresponding bus current sensor in the switching group in the on state and the switching channels of the other corresponding phase current sensors in the off state during the continuous period when the real-time speed is greater than a preset speed threshold.

[0015] Based on the aforementioned technical means, this embodiment continuously connects the bus current sensor to the signal processing circuit under high-speed operating conditions through a fixed gating signal, while keeping the switching channels of the other phase current sensors disconnected. The switching group no longer performs channel switching, eliminating the time delay and switching noise introduced by switching at the source. The signal transmission path is fixed, and the sampling timing is stable, which is beneficial for achieving fast and continuous current sampling under high-speed and high-frequency operating conditions, meeting the requirements of high-speed motor control for sampling frequency and response speed.

[0016] In an exemplary embodiment, the method further includes: at any given time, only one current sensing signal from the plurality of current sensing sensors is selected to the signal processing circuit.

[0017] Based on the aforementioned technical means, this embodiment ensures that only one current sensing signal is selected for the signal processing circuit at any given time by switching the switch group. This avoids signal crosstalk and channel interference problems that may occur when multiple sensor signals are accessed in parallel from the architectural level. Simultaneously, single-channel signal selection means that the subsequent signal processing circuit only needs to process one signal at a time. This provides an architectural basis for multiple sensors to share the same signal processing circuit, eliminating the need for multiple independent signal processing circuits, reducing hardware cost and size, simplifying sampling fault diagnosis logic, and facilitating rapid identification of sensor and switch path anomalies.

[0018] In an exemplary embodiment, the signal processing circuit includes multiple components; the method further includes: obtaining the single-point failure rate of each component in the signal processing circuit, and summing them to obtain the total single-point failure rate of the signal processing circuit; wherein, the number of components included in the signal processing circuit shared by multiple current detection sensors is less than the total number of components required when each current detection sensor is configured with its own independent signal processing circuit, thereby reducing the total single-point failure rate.

[0019] Based on the aforementioned technical means, this embodiment reduces the number of components in the signal processing circuit from multiple sets to a single set by time-division multiplexing multiple sensor signals. In functional safety analysis, each component is considered a potential source of failure. Reducing the number of components directly means reducing the number of single-point failure sources, and consequently lowering the overall single-point failure rate. This method of reducing failure rate through a simplified architecture improves single-point failure and latent failure indicators while reducing the probability of random hardware failure. It optimizes functional safety indicators by subtracting components, balancing hardware cost reduction with improved system security.

[0020] Secondly, this application provides a motor drive system, the motor drive system including: a controller, the controller being used to execute the method described in the first aspect above.

[0021] Thirdly, this application provides a vehicle, including: a body and the electric motor drive system described in the second aspect above.

[0022] Fourthly, this application provides an electronic device comprising: a processor and a memory; the memory storing processor-executable instructions. When the processor is configured to execute the instructions, the electronic device causes the method described in the first aspect to be implemented.

[0023] Fifthly, this application provides a computer-readable storage medium storing computer program instructions that, when executed by a processor, implement the method described in the first aspect.

[0024] In a sixth aspect, this application provides a computer program product including computer program instructions that, when executed by a processor, implement the method described in the first aspect.

[0025] It should be noted that the technical effects of any of the implementation methods in aspects two through six can be found in the technical effects of the corresponding implementation method in aspect one, and will not be repeated here.

[0026] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application will be described below.

[0028] Figure 1 A schematic diagram of the composition of a motor drive system provided in this application; Figure 2 A motor control circuit diagram provided in this application; Figure 3 A flowchart illustrating a current sampling control method for an electric drive system provided in this application; Figure 4 A flowchart illustrating a time-domain synchronization correction method provided in this application; Figure 5 A flowchart illustrating a bus current reconfiguration method provided in this application; Figure 6 A flowchart illustrating a current sampling control method for an electric drive system provided in this application; Figure 7 This application provides a schematic diagram of a component failure mode classification and failure rate calculation process; Figure 8 This is a schematic diagram of the composition of an electronic device provided in this application. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0030] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0031] In this application, the terms "exemplarily" or "for example" are used to indicate that something is being described as an example, illustration, or illustration. Any embodiment or design described as "exemplarily" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0032] In the embodiments of this application, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0033] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0034] In related technologies, current sampling in electric drive systems typically employs either simultaneous acquisition of three-phase current or acquisition of two-phase current to calculate the third phase. Simultaneous three-phase acquisition requires independent signal processing circuitry for each phase, resulting in a large number of components and high hardware costs. While two-phase acquisition reduces some components, it cannot utilize the zero sum of the three-phase currents for verification, leading to insufficient reliability. To meet functional safety requirements, existing solutions often reduce the risk of single-point failures by adding redundant designs or monitoring loops, further increasing the number of components. Since each component is a potential source of failure, the increased number of components leads to a higher single-point failure rate, making it even more difficult to meet functional safety standards. Therefore, existing technologies struggle to balance hardware cost, full-speed-domain control accuracy, and functional safety requirements.

[0035] Based on this, this application provides a current sampling control method for an electric drive system. This method switches the sampling path by real-time motor speed, and only a single current sensor is connected to the signal processing circuit at any given time throughout the entire process. This avoids the risks of signal crosstalk, channel interference, and synchronous failure of multiple acquisition circuits caused by parallel acquisition of multiple signals, thereby improving the hardware safety and signal acquisition reliability of the current sampling stage. At low speeds, the current of each phase is collected in sequence and time-domain synchronous correction is performed to accurately restore the independent phase current, improve the accuracy of low-speed torque control, and reduce torque ripple. At high speeds, only the bus current is collected to reconstruct the phase current, which greatly reduces the amount of switching and correction calculations within the cycle, improves the real-time control performance, and adapts to the high-speed and high-frequency control requirements. Moreover, the single-channel time-division multiplexing architecture eliminates multiple sets of independent signal processing circuits, reducing hardware cost and size. At the same time, the single-channel acquisition mode simplifies the sampling fault diagnosis logic, making it easier to quickly identify sensor and switch path abnormalities, further enhancing the operational safety performance of the electric drive system, and taking into account the sampling accuracy, control real-time performance, hardware cost, and overall machine operational safety across the entire speed range.

[0036] The embodiments of this application are described below with reference to the accompanying drawings.

[0037] The current sampling control method for the electric drive system provided in this application can be applied to the controller corresponding to the electric motor drive system in a vehicle. The vehicle can be, but is not limited to, a pure electric vehicle (PEV / BEV), a hybrid electric vehicle (HEV), a range-extended electric vehicle (REEV), a plug-in hybrid electric vehicle (PHEV), or a new energy vehicle. In one implementation, the electric motor drive system can be fixed to the vehicle body.

[0038] Please see Figure 1 , Figure 1 The present application provides a schematic diagram of the composition of a motor drive system, which includes: multiple current detection sensors 101, a switching switch group 102, a signal processing circuit 103, a motor 104, and a controller 105.

[0039] As one possible implementation method, such as Figure 1 As shown, the output terminals of multiple current sensing sensors 101 are respectively connected to multiple input terminals of a switching group 102; the output terminal of the switching group 102 is connected to the input terminal of a signal processing circuit 103; the output terminal of the signal processing circuit 103 is connected to the input terminal of a controller 105; the control signal output terminal of the controller 105 is connected to the control terminal of the switching group 102, used to send a selection signal to the switching group 102; the drive signal output terminal of the controller 105 is connected to the control terminal of a motor 104, used to drive the motor 104 to run. The switching group 102 simultaneously selects one current sensing signal from the multiple current sensing sensors 101 and sends it to the signal processing circuit 103. The signal processing circuit 103 processes the current sensing signal connected to its input terminal and outputs it to the controller 105.

[0040] The plurality of current detection sensors 101 include a plurality of phase current sensors and a bus current sensor. In this embodiment, the plurality of current detection sensors 101 include a plurality of phase current sensors for detecting the multi-phase winding current of a motor, and a bus current sensor for detecting the DC bus current.

[0041] Among them, multiple phase current sensors include: U-phase current sensor 1011, V-phase current sensor 1012, and W-phase current sensor 1013.

[0042] The U-phase current sensor 1011 is installed on the power supply line of the U-phase winding of the motor 104 to detect the current value of the U-phase winding. The U-phase current sensor 1011 can be a Hall current sensor, a current transformer, or a sampling resistor-type current detection circuit. As one possible implementation, the U-phase current sensor 1011 converts the U-phase current into a voltage signal and outputs it to the switching switch group 102 to provide U-phase current feedback for motor control.

[0043] The V-phase current sensor 1012 is installed on the power supply line of the V-phase winding of the motor 104 to detect the current value of the V-phase winding. The V-phase current sensor 1012 can be a Hall current sensor, a current transformer, or a sampling resistor-type current detection circuit. As one possible implementation, the V-phase current sensor 1012 converts the V-phase current into a voltage signal and outputs it to the switching switch group 102 to provide V-phase current feedback for motor control.

[0044] The W-phase current sensor 1013 is installed on the W-phase winding power supply line of the motor 104 to detect the current value of the W-phase winding. The W-phase current sensor 1013 can be a Hall current sensor, a current transformer, or a sampling resistor-type current detection circuit. As one possible implementation, the W-phase current sensor 1013 converts the W-phase current into a voltage signal and outputs it to the switching switch group 102 to provide W-phase current feedback for motor control.

[0045] The bus current sensor 1014 is connected in series in the DC bus circuit, specifically on the positive or negative line of the DC bus, to detect the total current value on the DC bus. The bus current sensor 1014 can be a Hall current sensor, a current transformer, or a sampling resistor-type current detection circuit. As one possible implementation, the bus current sensor 1014 converts the bus current into a voltage signal and outputs it to the switching group 102 for reconstructing the three-phase current in high-speed mode.

[0046] As one possible implementation, the multiple phase current sensors include a U-phase current sensor 1011, a V-phase current sensor 1012, and a W-phase current sensor 1013; the number of bus current sensors 1014 is one, which is connected in series in the DC bus circuit; the switching switch group 102 includes at least four independently controllable switching channels, the input terminal of each switching channel is coupled to the corresponding current detection sensor 101, and the output terminals of each switching channel are connected in parallel and then connected to the signal processing circuit 103.

[0047] In this embodiment, the switching switch group 102 is connected between multiple current detection sensors 101 and the signal processing circuit 103, and is used to select one of the multiple current sensing signals output by the multiple current detection sensors 101 to the signal processing circuit 103 at the same time.

[0048] The switching group 102 includes multiple independently controllable switching channels. The input terminal of each switching channel is coupled to a corresponding current detection sensor, and the output terminals of each switching channel are connected in parallel and then connected to the signal processing circuit 103. The switching group 102 can be an analog switch array, a multiplexer (MUX), a relay array, or a MOSFET switch array.

[0049] In one possible implementation, the switching group 102 is a four-channel analog switch, including four input terminals and one output terminal. The four input terminals are respectively coupled to the signal output terminals of the U-phase current sensor 1011, V-phase current sensor 1012, W-phase current sensor 1013, and bus current sensor 1014. The output terminal is connected to the signal processing circuit 103. The switching group 102 receives the selection signal sent by the controller 105 through its control terminal, and selects only one of the four channels at any given time, that is, only one current sensing signal is transmitted to the output terminal, while the other three signals are blocked, thereby realizing the time-division multiplexing of multiple current sensing signals using the same signal processing circuit 103.

[0050] In this embodiment of the application, the input terminal of the signal processing circuit 103 is connected to the output terminal of the switching switch group 102, and is used to process the current sensing signal input after being selected by the switching switch group 102.

[0051] In one possible implementation, the signal processing circuit 103 is used to filter and amplify the current sensing signal input to its input terminal. In one implementation, the signal processing circuit 103 includes a filter circuit 1031 and an operational amplifier circuit 1032. The filter circuit 1031 is used to filter out high-frequency noise and interference components in the current sensing signal; the operational amplifier circuit 1032 is used to amplify the filtered current sensing signal to the voltage amplitude range required by the analog-to-digital converter.

[0052] In one possible implementation, the filter circuit 1031 is an RC low-pass filter circuit, and the operational amplifier circuit 1032 is a differential amplifier circuit. The output of the signal processing circuit 103 is connected to the analog-to-digital converter input pin of the controller 105.

[0053] It should be understood that since the switching switch group 102 selects only one current sensing signal to the signal processing circuit 103 at any given time, the signal processing circuit 103 processes only one current sensing signal at any given time. There is no need to configure a separate signal processing circuit for each sensor, which greatly reduces the number of components required for the signal processing circuit.

[0054] The controller 105 is connected to the switching switch group 102 and the signal processing circuit 103 respectively. The controller 105 can be a microcontroller (MCU), a digital signal processor (DSP), a field-programmable gate array (FPGA), or an application-specific integrated circuit (ASIC).

[0055] In one possible implementation, the controller 105 is a microcontroller with an integrated analog-to-digital converter for converting the analog current signal output by the signal processing circuit 103 into a digital current value. The controller 105 is also used to send a gating signal to the switching switch group 102 to control the conduction and cutoff of each switch channel in the switching switch group 102, thereby determining which current sensing signal is selected to the signal processing circuit 103. The controller 105 is also used to execute the current sampling control method of any of the following method embodiments.

[0056] In one possible implementation, the output terminals of multiple current sensing sensors 101 (including U-phase current sensor 1011, V-phase current sensor 1012, W-phase current sensor 1013, and bus current sensor 1014) are respectively connected to multiple input terminals of the switching switch group 102; the output terminal of the switching switch group 102 is connected to the input terminal of the signal processing circuit 103; the output terminal of the signal processing circuit 103 is connected to the input terminal of the controller 105; the control signal output terminal of the controller 105 is connected to the control terminal of the switching switch group 102, for sending a selection signal to the switching switch group 102; the drive signal output terminal of the controller 105 is connected to the control terminal of the motor 104, for driving the motor 104 to run. The switching switch group 102 simultaneously selects one current sensing signal output from the multiple current sensing sensors 101 to the signal processing circuit 103. The signal processing circuit 103 filters and amplifies the selected current sensing signal before outputting it to the controller 105.

[0057] In one possible implementation, the controller 105 acquires the real-time speed of the motor 104. When the real-time speed is less than or equal to a preset speed threshold, the controller 105 sends a polling selection signal to the switching switch group 102, controlling the switching switch group 102 to sequentially select the U-phase current sensing signal output by the U-phase current sensor 1011, the V-phase current sensing signal output by the V-phase current sensor 1012, and the W-phase current sensing signal output by the W-phase current sensor 1013 to the signal processing circuit 103 within one control cycle, thereby acquiring the current sensing signals of each phase in a time-division manner. Time-domain synchronous correction is performed on the acquired phase current sensing signals to obtain the first target phase current, and the motor 104 is controlled to run based on the first target phase current. When the real-time speed is greater than the preset speed threshold, the controller 105 sends a fixed selection signal to the switching switch group 102, and controls the switching switch group 102 to continuously select the bus current sensing signal output by the bus current sensor 1014 to the signal processing circuit 103 to obtain the bus current sensing signal. The second target phase current is reconstructed based on the bus current sensing signal, and the motor 104 is controlled to run based on the second target phase current.

[0058] As one possible embodiment, the motor drive system also includes a signal conversion module. The signal conversion module is connected between the signal processing circuit and the controller, and is used to convert the analog current signal output by the signal processing circuit into a digital signal, and then transmit the digital signal to the controller for calculation and analysis. As one possible implementation, the signal conversion module is an analog-to-digital converter (ADC), which can be integrated inside the controller or installed independently outside the controller.

[0059] It should be understood that Figure 1 The structure shown is for illustrative purposes only; in actual implementation, some modules can be added or removed as needed. Figure 1 The connections between modules indicate signal flow or control relationships, not restrictions on physical wiring. Figure 1 The present application also provides a current sampling control method for the electric drive system shown in the motor drive system, as detailed in the following description of the method embodiments.

[0060] Next, to further illustrate the specific connection positions of the multiple current detection sensors 101 in the motor drive circuit of this application, please refer to the following references. Figure 2 , Figure 2 This application provides a motor control circuit diagram to exemplify the specific connection positions of multiple current detection sensors 101 in a three-phase motor drive circuit. Figure 1 The U-phase current sensor 1011, V-phase current sensor 1012, W-phase current sensor 1013, and bus current sensor 1014 shown are related to... Figure 2 The corresponding sensors shown form a complete signal link through a one-to-one connection.

[0061] like Figure 2 As shown, the motor control circuit includes: DC bus positive terminal VCC, DC bus negative terminal GND, bus current sensor 1014, three-phase inverter bridge 106, U-phase current sensor 1011, V-phase current sensor 1012, W-phase current sensor 1013, and motor 104.

[0062] The bus current sensor 1014 is connected in series in the DC bus circuit (specifically, it can be set on the positive VCC side or the negative GND side of the DC bus) to detect the total current on the DC bus and output a bus current sensing signal. The signal output terminal of the bus current sensor 1014 is connected to... Figure 1 The corresponding input terminal of the switching group 102. As one possible implementation, the bus current sensor 1014 can be a Hall current sensor, a current transformer, or a sampling resistor current detection circuit, which converts the bus current into a voltage signal and outputs it to the switching group 102.

[0063] The three-phase inverter bridge 106 includes an upper bridge arm switch 1061 for phase A, an upper bridge arm switch 1062 for phase B, an upper bridge arm switch 1063 for phase C, a lower bridge arm switch 1064 for phase A, a lower bridge arm switch 1065 for phase B, and a lower bridge arm switch 1066 for phase C. These six switches form a three-phase full-bridge inverter circuit used to drive the motor 104. The gates of each switch are connected to... Figure 1 The PWM drive signal output terminal of the controller 105 is turned on or off under the control of the controller 105.

[0064] The U-phase current sensor 1011 is installed on the line between the A-phase lower bridge arm switch 1064 and the U-phase winding of the motor 104. It is used to detect the current in the U-phase winding and output a U-phase current sensing signal. The signal output terminal of the U-phase current sensor 1011 is connected to... Figure 1 The corresponding input terminal of the switching group 102. The V-phase current sensor 1012 is installed on the line between the B-phase lower bridge arm switch 1065 and the V-phase winding of the motor 104, used to detect the current in the V-phase winding and output a V-phase current sensing signal. The signal output terminal of the V-phase current sensor 1012 is connected to... Figure 1 The corresponding input terminal of the switching group 102. The W-phase current sensor 1013 is installed on the line between the C-phase lower bridge arm switch 1066 and the W-phase winding of the motor 104, used to detect the current in the W-phase winding and output a W-phase current sensing signal. The signal output terminal of the W-phase current sensor 1013 is connected to... Figure 1 The corresponding input terminal of the switching switch group 102 in the middle.

[0065] In conclusion, Figure 1 and Figure 2 Each sensor is matched one-to-one with its corresponding sensor number. Figure 1 The U-phase current sensor 1011, V-phase current sensor 1012, W-phase current sensor 1013, and bus current sensor 1014 shown are related to... Figure 2 The sensors at the corresponding positions are the same device. Figure 1 The signal connection relationships between each sensor and the switching group 102, the signal processing circuit 103, and the controller 105 are shown from the perspective of system functional modules. Figure 2 This further demonstrates the specific connection positions of each current sensing sensor in the three-phase inverter circuit from the perspective of motor drive circuit topology.

[0066] Figure 2 The U-phase current sensor 1011, V-phase current sensor 1012, and W-phase current sensor 1013 are respectively disposed between the lower bridge arm of the corresponding phase and the motor winding, which is only one embodiment of this application. In practical applications, the three-phase current sensors can also be disposed between the upper bridge arm and the motor winding, or connected in series at any position in the winding circuit of each phase, as long as they can detect the current of the corresponding phase winding. This application does not make any specific limitation in this regard.

[0067] It should be noted that the embodiments of this application Figure 1 and Figure 2 The illustrated structure does not constitute a specific limitation on the motor drive system. The system may include more or fewer components than illustrated, or combine or separate certain components, or employ different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of both.

[0068] Please see Figure 3 This is a flowchart illustrating a current sampling control method for an electric drive system provided in this application, applied to the controller of the aforementioned motor drive system. The current sampling control method for the electric drive system includes: S301, Obtain the real-time speed of the motor.

[0069] As one possible implementation, the real-time speed of the motor can be obtained using a speed sensor. The speed sensor can be any one of a rotary transformer, Hall effect sensor, photoelectric encoder, or magnetic encoder. In one implementation, the controller receives the speed pulse signal or analog signal output from the speed sensor, and obtains the real-time speed value of the motor after signal processing and calculation.

[0070] Based on S301, obtaining the real-time operating status of the motor can provide a basis for subsequent judgment on which current sampling mode should be selected for the current operating condition.

[0071] S302. When the real-time speed is less than or equal to the preset speed threshold, the control switching switch group sequentially turns on each phase current sensor to the signal processing circuit within one control cycle, and performs time-domain synchronous correction on the acquired phase current sensing signals to obtain the first target phase current, so as to control the motor operation based on the first target phase current.

[0072] The preset speed threshold can be 30% of the motor's rated speed. It should be understood that this value is merely illustrative and can be adaptively adjusted according to the motor type, load characteristics, and control accuracy requirements in actual applications. For example, it can be set within the range of 20% to 40% of the rated speed; this application does not specifically limit this. One implementation method involves determining the preset speed threshold based on the motor's rated speed parameters and actual test calibration results, such that below this threshold, the accuracy of time-sharing polling acquisition is better than the accuracy of bus current reconstruction, and above this threshold, the accuracy of bus current reconstruction is better than the accuracy of time-sharing polling acquisition.

[0073] It should be understood that the fundamental principle behind how an electric motor can achieve motion control through current lies in the interaction between the magnetic field generated by the permanent magnets of the motor rotor and the current flowing through the stator windings, producing electromagnetic torque that drives the rotor to rotate. Specifically, when three-phase sinusoidal current is sequentially applied to the U-phase, V-phase, and W-phase windings of the motor, a rotating magnetic field is formed inside the motor. This rotating magnetic field interacts with the rotor's permanent magnet magnetic field to generate driving torque, causing the rotor to rotate synchronously with the rotating magnetic field. Therefore, by real-time acquisition of the amplitude, phase, and frequency of the current in each phase winding, the current state of the internal magnetic field of the motor can be accurately determined, thereby achieving precise control of the motor's speed and torque.

[0074] The first target phase current refers to the synchronous three-phase current value obtained by time-division polling and time-domain synchronous correction when the real-time speed is less than or equal to the preset speed threshold. It is used to replace the real synchronous sampling value for motor control under this operating condition.

[0075] As one possible implementation, controlling the switching switch group to sequentially turn on each phase current sensor to the signal processing circuit within a control cycle includes: sending selection signals to the switching switch group in a preset order at different time periods within a control cycle, so that each phase current sensor is connected to the signal processing circuit in a time-sharing manner within the same control cycle.

[0076] The preset sequence includes: sending a first gating signal, a second gating signal, and a third gating signal in sequence, which respectively turn on the first phase current sensor, the second phase current sensor, and the third phase current sensor, and there is a preset time interval between two adjacent gating signals.

[0077] The first, second, and third gating signals are channel selection control signals sent by the controller to the switching group, used to sequentially activate the switching channels of the corresponding three phase current sensors in the switching group. When the first gating signal is valid, the first phase current sensor is activated to the signal processing circuit; when the second gating signal is valid, the second phase current sensor is activated; and when the third gating signal is valid, the third phase current sensor is activated. The three gating signals are valid in a time-sharing manner within the same control cycle and do not overlap.

[0078] The first-phase current sensor, second-phase current sensor, and third-phase current sensor correspond to the U-phase current sensor, V-phase current sensor, and W-phase current sensor of the motor, respectively. It should be noted that the designations "first," "second," and "third" in this application are only used to distinguish current sensors of different phases and do not limit their specific correspondence. As one possible implementation, the first-phase current sensor is a U-phase current sensor, the second-phase current sensor is a V-phase current sensor, and the third-phase current sensor is a W-phase current sensor. As another possible implementation, the first-phase current sensor is a V-phase current sensor, the second-phase current sensor is a U-phase current sensor, and the third-phase current sensor is a W-phase current sensor. It should be understood that the numbering order of the three-phase current sensors can be adjusted according to actual control requirements, and this application does not specifically limit this.

[0079] As one possible implementation, in different time periods of a control cycle, selection signals are sequentially sent to the switching group in a preset order, so that the current sensors of each phase within the same control cycle are connected to the signal processing circuit in a time-sharing manner, including: At the start of the control cycle, a first gating signal is sent to the switching switch group to activate the first phase current sensor and collect the first phase current sensing signal. After a preset time interval, the first gating signal is deactivated, and a second gating signal is sent to the switching switch group to activate the second phase current sensor and collect the second phase current sensing signal. After another preset time interval, the second gating signal is deactivated, and a third gating signal is sent to the switching switch group to activate the third phase current sensor and collect the third phase current sensing signal.

[0080] The preset time interval is greater than the time required for the current sensing signal to establish a stable output in the signal processing circuit, so as to ensure that the signal is stable at each sampling time.

[0081] It should be understood that during the time-division acquisition process described above, the three-phase current sensing signals are not acquired at the same time, and there is a fixed sampling time difference between them. This time difference has little impact on control accuracy when the motor is running at low speed, but it is still necessary to correct the three-phase signals to the same reference time through subsequent time-domain synchronization correction in order to eliminate residual errors.

[0082] As one possible implementation method, please refer to Figure 4 As shown, Figure 4 This is a flowchart illustrating a time-domain synchronization correction method provided in this application. The method involves performing time-domain synchronization correction on the acquired phase current sensing signals to obtain the first target phase current, including: S401. Using the sampling time of any one of the multiple phase current sensors as a reference time, determine the sampling time difference of the other phase current sensors relative to the reference time.

[0083] One implementation method involves using the sampling time of any one of the multiple phase current sensors as a reference time to determine the sampling time difference of the remaining phase current sensors relative to the reference time. This includes: using the sampling time of the first phase current sensor among the multiple phase current sensors as the reference time, the sampling time difference of the second phase current sensor relative to the reference time is Δt, and the sampling time difference of the third phase current sensor relative to the reference time is 2Δt.

[0084] For example, if the preset time interval between two adjacent gating signals is 2μs, then the sampling time of the first phase current sensor is taken as the reference time t0, the sampling time of the second phase current sensor is t0+2μs, and the sampling time of the third phase current sensor is t0+4μs. The sampling time difference of the second phase current sensor relative to the reference time is Δt=2μs, and the sampling time difference of the third phase current sensor relative to the reference time is 2Δt=4μs.

[0085] For example, using the sampling time of the U-phase current sensor as a reference time, a first time difference between the sampling times of the V-phase current sensor and the U-phase current sensor, and a second time difference between the sampling times of the W-phase current sensor and the U-phase current sensor are determined. Since the switching group sequentially selects the current sensors of each phase in a preset order of U-phase → V-phase → W-phase within one control cycle, the sampling time difference is equal to an integer multiple of the preset time interval between two adjacent selection signals. For example, if the preset time interval between two adjacent selection signals is Δt, and there is one selection switch between U-phase and V-phase, then the first time difference is Δt; if there are two selection switches between U-phase and W-phase, then the second time difference is 2Δt.

[0086] Based on S401, the time deviation between the current sensing signals of each phase was determined, providing a basis for subsequent phase compensation calculations.

[0087] S402. Calculate the phase compensation angle corresponding to each phase current sensor based on the current angular velocity of the motor and the sampling time difference.

[0088] In one implementation, the current angular velocity of the motor is positively correlated with its real-time rotational speed. For example, the relationship between the current angular velocity and the real-time rotational speed is: ω = 2πn / 60, where ω is the angular velocity and n is the current real-time rotational speed. The current angular velocity can be calculated from the real-time rotational speed obtained from S301. Since one mechanical cycle corresponds to one electrical cycle, the relationship between the electrical angular velocity and the mechanical angular velocity is ω_e = p × ω_m, where p is the number of pole pairs of the motor. In this application, "current angular velocity" can refer to the electrical angular velocity, i.e., the angular velocity used in field-oriented control and vector rotation transformation.

[0089] One implementation involves calculating the phase compensation angle corresponding to each phase current sensor based on the current angular velocity of the motor and the sampling time difference, including: taking the first phase current sensor as a reference, its phase compensation angle is 0; the phase compensation angle corresponding to the second phase current sensor is Δθ2=ω×Δt; and the phase compensation angle corresponding to the third phase current sensor is Δθ3=ω×2Δt.

[0090] For example, if the current angular velocity of the motor ω = 100 rad / s and the sampling time difference Δt = 2 μs, then the phase compensation angle Δθ2 of the second phase current sensor = 100 × 0.000002 = 0.0002 rad, and the phase compensation angle Δθ3 of the third phase current sensor = 100 × 0.000004 = 0.0004 rad. It should be understood that the above values ​​are merely illustrative examples for ease of understanding. In actual applications, the specific values ​​of the sampling time difference and phase compensation angle depend on the preset time interval and the motor speed, and this application does not impose specific limitations on them.

[0091] It should be understood that by calculating the phase compensation angle based on the current angular velocity and the sampling time difference, the phase deviation introduced by time-division acquisition can be accurately quantified, providing an accurate compensation amount for subsequent vector rotation transformation.

[0092] S403. Through vector rotation transformation, based on each phase compensation angle, the phase current sensing signals acquired in time division are corrected to the same reference time to obtain the first target phase current.

[0093] Among them, the vector rotation transformation is used to convert the time-domain deviation corresponding to the phase compensation angle into the angle correction amount of the phase current sensing signal in the rotating coordinate system, so that the phase current sensing signals acquired in time division are equivalent to the synchronous sampling values ​​at the same moment when vector synthesis is performed.

[0094] It should be understood that the three-phase current values ​​acquired in time-division multiplexing are obtained at different times, and their phase relationship deviates from the true phase relationship at the same moment due to the time difference. By rotating each phase current value in the opposite direction in the current vector rotating coordinate system according to its corresponding phase compensation angle, they can be corrected to the same reference time.

[0095] One implementation method involves using vector rotation transformation to correct the phase current sensing signals acquired in a time-division manner to the same reference time based on each phase compensation angle, thereby obtaining the first target phase current. This includes: converting the three-phase current sensing signals acquired in a time-division manner to a stationary coordinate system via Clark transformation, and then to a rotating coordinate system via Park transformation; in the rotating coordinate system, correcting the second-phase current sensing signals and the third-phase current sensing signals according to their corresponding phase compensation angles; and performing inverse Park transformation and inverse Clark transformation on the corrected signals to obtain the three-phase current values ​​corrected to the same reference time, which is the first target phase current.

[0096] The Clark transform is a mathematical transformation that converts three-phase current signals in a three-phase stationary coordinate system (abc coordinate system) into two-phase orthogonal current signals in a two-phase stationary coordinate system (αβ coordinate system). After the Clark transform, the three-phase currents Ia, Ib, and Ic yield two orthogonal components, Iα and Iβ.

[0097] Park transformation refers to the mathematical transformation that converts a current signal in a two-phase stationary coordinate system (αβ coordinate system) into a current signal in a two-phase rotating coordinate system (dq coordinate system). The rotating coordinate system rotates synchronously with the motor rotor, and the AC current signal in the dq coordinate system is converted into a DC signal, which facilitates angle correction.

[0098] For example, taking the sampling time t0 of the first-phase current sensor as the reference time, the sampling time of the second-phase current sensor is t0 + Δt, and the sampling time of the third-phase current sensor is t0 + 2Δt. The three-phase time-division current signals are obtained by Clark transform to Iα and Iβ, and then by Park transform to Id and Iq. In the dq coordinate system, the second-phase current signal has an electrical angle lag of Δθ2 = ω × Δt due to the sampling lag of Δt. The dq component of the second-phase current signal is corrected by reverse rotation according to the phase compensation angle Δθ2. The third-phase current signal has an electrical angle lag of Δθ3 = ω × 2Δt due to the sampling lag of 2Δt. The dq component of the third-phase current signal is corrected by reverse rotation according to the phase compensation angle Δθ3. The first-phase current signal is used as a reference and does not require compensation. After compensation, the three-phase signals in the dq coordinate system are equivalent to the synchronous sampling values ​​at the same time t0. After Park inverse transform and Clark inverse transform, the corrected three-phase current values ​​are obtained, which are the first target phase currents.

[0099] Based on S403, the time difference of time-division sampling is converted into an angle correction in a rotating coordinate system through vector rotation transformation, which eliminates the phase error introduced by time-division polling acquisition, so that the three-phase current signal sampled asynchronously is equivalent to the synchronous sampling result at the same time after correction.

[0100] Based on S401 to S403, by determining the sampling time difference, calculating the phase compensation angle, and performing vector rotation transformation correction, the asynchronous three-phase current signal acquired in time division is corrected to the synchronous equivalent value. This solves the problem of current vector synthesis deviation caused by different sampling times in polling acquisition and ensures the current control accuracy under low-speed conditions.

[0101] Based on S302, the three-phase current is obtained by combining time-division polling acquisition with time-domain synchronous correction when the motor is running at low speed. The real current value of each phase winding is directly acquired, avoiding the problem of unobservable area caused by insufficient effective vector action time in the low-speed region of the single current sensor reconstruction scheme. At the same time, the time delay of time-division sampling is eliminated by the compensation algorithm, realizing accurate current control under low-speed conditions.

[0102] S303. When the real-time speed is greater than the preset speed threshold, the control switching group will turn on the bus current sensor to the signal processing circuit. Based on the bus current sensing signal corresponding to the acquired bus current sensor, the second target phase current is obtained, and the motor operation is controlled based on the second target phase current.

[0103] The preset speed threshold can be 30% of the motor's rated speed. This value is for illustrative purposes only, and in actual applications, it can be adaptively adjusted according to the motor type, load characteristics, and control accuracy requirements. For example, it can be set within the range of 20% to 40% of the rated speed, and this application does not specifically limit it in this regard. In one implementation, the preset speed threshold can be determined based on a combination of the motor's rated speed and the minimum speed boundary of the observable range of the single-resistor reconfiguration scheme.

[0104] It should be understood that above the preset speed threshold, the effective voltage vector's duration is sufficient to meet the minimum sampling time requirement, and the single-resistor reconstruction scheme can accurately reconstruct the three-phase current. Therefore, it is possible to switch to high-speed mode to improve the sampling response speed.

[0105] The second target phase current is obtained in high-speed mode (real-time speed greater than a preset speed threshold). This is achieved by switching the bus current sensor signal from the bus current sensor to the signal processing circuit via a switching group. After acquiring the bus current sensor signal, the circuit combines the current SVPWM sector information and the preset correspondence between the space voltage vector and the phase current to calculate the equivalent three-phase current value of each phase winding's real-time current. Since only the bus current is collected in high-speed mode, a reconstruction algorithm is needed to extract the phase current information from the bus current; therefore, it is called the "second" target phase current, to distinguish it from the first target phase current obtained by directly collecting the three-phase current and then performing time-domain synchronous correction in low-speed mode.

[0106] As one possible implementation, controlling the switching group to connect the bus current sensor to the signal processing circuit includes: sending a fixed selection signal to the switching group so that the bus current sensor is continuously connected to the signal processing circuit.

[0107] The fixed strobe signal is used to keep the switching channel of the corresponding bus current sensor in the switching switch group in the on state and the switching channels of the other corresponding phase current sensors in the off state during the continuous period when the real-time speed is greater than the preset speed threshold.

[0108] For example, when the controller determines that the real-time speed is greater than a preset speed threshold, it continuously sends the corresponding bus current sensor channel selection signal to the switching group. The bus current sensing signal output by the bus current sensor enters the signal processing circuit through the switching group, and is sent to the controller after filtering and amplification. During this process, the corresponding switching channels of the three phase current sensors (U-phase, V-phase, and W-phase) remain open, and the switching group does not perform channel switching to eliminate the time delay caused by switching.

[0109] It should be understood that "connecting the sensor to the signal processing circuit" in this application means selecting the signal output channel of the corresponding sensor through a switching group, so that the current sensing signal output by the sensor can be transmitted to the signal processing circuit. The sensor itself is always in a continuous working state, and its power supply is provided independently by the system power supply and is not controlled by the switching group.

[0110] As one possible implementation method, please refer to Figure 5 , Figure 5 This is a flowchart illustrating a bus current reconstruction method provided in this application. Based on the bus current sensing signal corresponding to the acquired bus current sensor, a second target phase current is obtained, including: S501. Within one control cycle, the bus current sensing signal is sampled during different effective voltage vectors to obtain at least two bus current values.

[0111] As one possible implementation, based on the current space vector pulse width modulation (SVPWM) sector, two effective voltage vectors corresponding to the sector are selected, and the bus current sensing signal is sampled at the midpoint of the period of each effective vector to obtain the first bus current value and the second bus current value.

[0112] It should be understood that, since the effective voltage vector has a limited period of stability, the sampling time should be set near the midpoint of the effective vector's effective range to avoid the oscillation range (dead time, current settling time) generated during switch switching, and to ensure that the sampled bus current value is stable.

[0113] In this context, SVPWM (Space Vector Pulse Width Modulation) sectors are used. In motor drives, the six switches of a three-phase inverter bridge generate eight basic voltage vectors through different conduction combinations. These include six active vectors: V1 (100), V2 (110), V3 (010), V4 (011), V5 (001), and V6 (101), as well as two zero vectors: V0 (000) and V7 (111). The six active vectors divide a 360° electrical angle plane into six sectors, each occupying 60° of the electrical angle, sequentially referred to as sectors I through VI. Refer to Table 1 below for the active vectors.

[0114] One implementation involves determining the sector in which the target voltage vector is located based on its phase angle, selecting two adjacent effective vectors and a zero vector in that sector, and synthesizing the target voltage vector by adjusting their respective duty cycles, thereby driving the motor to rotate.

[0115] One implementation involves different effective vector combinations corresponding to different sectors. For example, the effective vectors for sector I are V4 (100) and V6 (110), and the effective vectors for sector II are V6 (110) and V2 (010), and so on. The controller samples the bus current at the midpoint of the corresponding effective vector's action period based on the current sector. Combining this with a pre-stored vector-phase current mapping, the currents of each phase can be reconstructed from the bus current.

[0116] For example, if the current space voltage vector is located in sector I, the corresponding effective vectors are V4 (100) and V6 (110). Idc1 is obtained by sampling at the midpoint during the action of V4, and Idc2 is obtained by sampling at the midpoint during the action of V6. The effective vectors can be referred to in Table 1 below.

[0117] Based on S501, the bus current is sampled under different switching states to obtain the bus current values ​​associated with different phase currents, providing a data basis for subsequent phase current calculation.

[0118] S502. Based on the preset correspondence between the space voltage vector and the phase current, determine the phase current associated with each bus current value.

[0119] As one possible implementation, the controller has a pre-stored table (or mapping table) showing the correspondence between space voltage vectors and phase currents. This table records the relationship between the DC bus current and each phase current under different effective voltage vectors. When the controller obtains the bus current value, it looks up the table to determine the phase current associated with that bus current value, based on the type of effective voltage vector at the current sampling time, and which phase current is positive or negative when the bus current value is equal to it.

[0120] For example, continuing from the example in S501, the first bus current value Idc1 is sampled during the action of vector V1 (100). According to the preset correspondence between space voltage vector and phase current, the DC bus current Idc under vector V1 (100) is +Ia (i.e., the U-phase current), so Idc1 is the U-phase current value. The second bus current value Idc2 is sampled during the action of vector V2 (110). According to this correspondence, the DC bus current Idc under vector V2 (110) is -Ic (i.e., the negative value of the W-phase current), so Idc2 is the negative value of the W-phase current, and the W-phase current value is -Idc2. Thus, by sampling twice and combining the vector-phase current correspondence, the two phase current values, U-phase and W-phase, can be obtained.

[0121] One implementation method, the preset correspondence between space voltage vector and phase current is shown in Table 1 below: Table 1

[0122] It should be understood that the upper arm conducting phases A, B, and C and the lower arm conducting phases A, B, and C in Table 1 are related to... Figure 2 Each switch in the three-phase inverter bridge 106 shown corresponds to a single switch.

[0123] Specifically, the conducting phase A of the upper bridge arm corresponds to Figure 2 Phase A upper arm switch 1061 is on; phase B of upper arm is on, corresponding to phase B upper arm switch 1062; phase C of upper arm is on, corresponding to phase C upper arm switch 1063. Phase A of lower arm is on, corresponding to phase A lower arm switch 1064; phase B of lower arm is on, corresponding to phase B lower arm switch 1065; phase C of lower arm is on, corresponding to phase C lower arm switch 1066.

[0124] Taking the zero vector V0(000) as an example, in Table 1, the conducting phase of the upper bridge arm is "none," and the conducting phases of the lower bridge arm are A, B, and C. Combined with... Figure 2 That is, the lower bridge arm switches 1064 (phase A), 1065 (phase B), and 1066 (phase C) are turned on, while all three upper bridge arm switches are turned off. At this time, the DC bus does not form a current loop, and the current Idc on the DC bus is 0.

[0125] Taking zero vector V7(111) as an example, in Table 1, the conducting phases of the upper bridge arm are A, B, and C, and the conducting phase of the lower bridge arm is "none". Combined with... Figure 2 That is, the upper bridge arm switch 1061 of phase A, the upper bridge arm switch 1062 of phase B, and the upper bridge arm switch 1063 of phase C are turned on, and all three lower bridge arm switches are turned off. At this time, the DC bus does not form a current loop, and the current Idc on the DC bus is 0.

[0126] Taking the effective vector V1(100) as an example, in Table 1, the conducting phase of the upper bridge arm is A, and the conducting phases of the lower bridge arm are B and C. Combined with... Figure 2 That is, the upper bridge arm switch 1061 of phase A is turned on, and the lower bridge arm switches 1065 and 1066 of phase B and C are turned on. At this time, the current flows from the positive terminal VCC of the DC bus into the U-phase winding of the motor through the upper bridge arm switch 1061 of phase A, and then flows out from the V-phase and W-phase windings respectively, and merges into the negative terminal GND of the DC bus through the lower bridge arm switches 1065 of phase B and 1066 of phase C. Under this current loop, the current Idc on the DC bus is equal to the current flowing into the U-phase winding + Ia.

[0127] Taking the effective vector V2(110) as an example, in Table 1, the conducting phases of the upper arm are A and B, and the conducting phase of the lower arm is C. Combined with... Figure 2 That is, the upper bridge arm switches 1061 and 1062 of phase A and phase B are turned on, and the lower bridge arm switch 1066 of phase C is turned on. At this time, the current flows from the positive terminal VCC of the DC bus into the U-phase and V-phase windings through the upper bridge arm switches 1061 and 1062 of phase A and phase B respectively, and then flows out from the W-phase winding, converging into the negative terminal GND of the DC bus through the lower bridge arm switch 1066 of phase C. Under this current loop, the current Idc on the DC bus is equal to the current flowing out of the W-phase winding, i.e., -Ic.

[0128] Taking the effective vector V3(010) as an example, in Table 1, the conducting phase of the upper bridge arm is B, and the conducting phases of the lower bridge arm are A and C. Combined with... Figure 2 That is, the upper bridge arm switch 1062 of phase B is turned on, and the lower bridge arm switches 1064 of phase A and 1066 of phase C are turned on. At this time, the current flows from the positive terminal VCC of the DC bus into the V phase winding of the motor through the upper bridge arm switch 1062 of phase B, and then flows out from the U phase and W phase windings respectively, and merges into the negative terminal GND of the DC bus through the lower bridge arm switches 1064 of phase A and 1066 of phase C. Under this current loop, the current Idc on the DC bus is equal to the current flowing into the V phase winding + Ib.

[0129] Taking the effective vector V4(011) as an example, in Table 1, the conducting phases of the upper arm are B and C, and the conducting phase of the lower arm is A. Combined with... Figure 2 That is, the upper bridge arm switch 1062 of phase B and the upper bridge arm switch 1063 of phase C are turned on, and the lower bridge arm switch 1064 of phase A is turned on. At this time, the current flows from the positive terminal VCC of the DC bus into the V-phase and W-phase windings through the upper bridge arm switches 1062 of phase B and 1063 of phase C respectively, and then flows out from the U-phase winding, converging into the negative terminal GND of the DC bus through the lower bridge arm switch 1064 of phase A. Under this current loop, the current Idc on the DC bus is equal to the current flowing out of the U-phase winding, i.e., -Ia.

[0130] Taking the effective vector V5(001) as an example, in Table 1, the conducting phase of the upper arm is C, and the conducting phases of the lower arm are A and B. Combined with... Figure 2 That is, the upper bridge arm switch 1063 of phase C is turned on, and the lower bridge arm switches 1064 of phase A and 1065 of phase B are turned on. At this time, the current flows from the positive terminal VCC of the DC bus into the W phase winding of the motor through the upper bridge arm switch 1063 of phase C, and then flows out from the U phase and V phase windings respectively, and merges into the negative terminal GND of the DC bus through the lower bridge arm switches 1064 of phase A and 1065 of phase B. Under this current loop, the current Idc on the DC bus is equal to the current flowing into the W phase winding + Ic.

[0131] Taking the effective vector V6(101) as an example, in Table 1, the conducting phases of the upper arm are A and C, and the conducting phase of the lower arm is B. Combined with... Figure 2 That is, the upper bridge arm switch 1061 of phase A and the upper bridge arm switch 1063 of phase C are turned on, and the lower bridge arm switch 1065 of phase B is turned on. At this time, the current flows from the positive terminal VCC of the DC bus into the U-phase and W-phase windings through the upper bridge arm switches 1061 of phase A and 1063 of phase C respectively, and then flows out from the V-phase winding, converging into the negative terminal GND of the DC bus through the lower bridge arm switch 1065 of phase B. Under this current loop, the current Idc on the DC bus is equal to the current flowing out of the V-phase winding, i.e., -Ib.

[0132] In summary, among the eight basic voltage vectors, the DC bus current is zero under the two zero vectors V0 (000) and V7 (111); under the six effective vectors V1 to V6, the DC bus current is equal to the positive or negative value of the corresponding conducting phase current, respectively. Based on the above correspondence, by sampling the bus current value during the action of different effective vectors in high-speed mode, the corresponding phase current can be determined according to the mapping relationship in Table 1, and thus the complete three-phase current information can be reconstructed.

[0133] S503. Based on the constraint that the sum of the phase currents is zero, the second target phase current is calculated.

[0134] In one implementation, when the three-phase windings are connected in a star configuration, the sum of the three-phase currents is always zero, i.e., Ia + Ib + Ic = 0. Using this constraint, the third-phase current can be directly calculated based on the two-phase currents obtained through S502.

[0135] For example, following the example of S502, having obtained the U-phase current Ia and the W-phase current Ic, the V-phase current Ib = -(Ia + Ic). Thus, the three-phase currents Ia, Ib, and Ic are all solved, yielding the second target phase current.

[0136] Based on S501 to S503, by combining two bus current samplings with a preset mapping relationship and the constraint that the sum of the three-phase currents is zero, the three-phase current can be completely reconstructed using only one bus current sensor. In this method, the switching group keeps the bus current sensor in constant operation, eliminating the need for channel switching, thus eliminating the time delay introduced by switch switching and realizing rapid current acquisition and precise motor control under high-speed conditions.

[0137] In summary, based on S301-S303, this application achieves a balance between low-speed accuracy and high-speed response across the entire speed range by adaptively switching the current acquisition strategy according to real-time speed—polling to acquire the current of each phase and performing time-domain synchronous correction at low speeds, and sampling the bus current at a single point and reconstructing the three-phase current at high speeds. Simultaneously, both modes utilize a switching group to time-division multiplex the multiplexed sensor signals using the same signal processing circuit, thus simplifying the hardware architecture and optimizing functional safety performance.

[0138] In summary, for example, please refer to Figure 6 , Figure 6 This is a flowchart illustrating a current sampling control method for an electric drive system provided in this application. This process is the complete execution flow of the current sampling control method for an electric drive system. Specifically, it includes: after the process starts, the real-time speed of the motor is obtained through the speed sensor and the current operating condition is determined; when the real-time speed is less than or equal to the preset speed threshold, it is determined to be a low-speed operating condition. The three-phase current is collected sequentially in a time-division sampling manner within a single PWM cycle. This time-division sampling method introduces a fixed sampling time difference Δt. Then, the corresponding phase compensation angle is calculated by combining the current angular velocity of the motor with the sampling time difference. The three-phase currents collected at different times are corrected to the same reference time through vector rotation transformation to obtain the first target phase current; when the real-time speed is greater than the preset speed threshold, it is determined to be a high-speed operating condition. Within a single PWM cycle, based on the current space vector sector, the midpoint time of two different effective voltage vector action intervals is selected to complete two bus current samplings. Then, combined with the preset mapping relationship between the sector and the phase current, the complete three-phase current is reconstructed from the two sets of bus current sampling values ​​through table lookup and logical operation to obtain the second target phase current; after obtaining the target phase current through low-speed correction or high-speed reconstruction, the motor closed-loop control in the full speed domain is completed based on this current, and the process ends.

[0139] As one possible implementation, the method further includes: when the real-time rotational speed is within a preset transition range near a preset rotational speed threshold, verifying the second target phase current using the first target phase current, or verifying the first target phase current using the second target phase current, to diagnose non-failure drift faults of the current sensor.

[0140] The preset transition range refers to a speed range centered on a preset speed threshold, such as within ±5% of the preset speed threshold. Within this range, the motor speed approaches the switching boundary between the two current sampling modes, and both time-division polling acquisition and bus current reconstruction can output valid phase current results, providing conditions for dual-mode mutual detection.

[0141] One implementation method involves using a first target phase current to verify a second target phase current, including: simultaneously or alternately performing current sampling in low-speed mode and high-speed mode within a transition interval to obtain the first target phase current and the second target phase current, respectively; calculating the current difference between the two in each phase; and determining that the corresponding phase current sensor or bus current sensor has a non-failure drift fault when the current difference of one or more phases exceeds a preset verification threshold.

[0142] One implementation method involves using a second target phase current to verify a first target phase current, including: using the second target phase current reconstructed from the bus current as a reference, comparing the first target phase current, which is collected by time-division polling and then synchronously corrected in the time domain, with the second target phase current; and when the deviation between the two exceeds a preset verification threshold, determining that the phase current sensor in the time-division polling acquisition channel has a non-failure drift fault.

[0143] Non-failure drift faults refer to situations where the current sensor does not completely fail (e.g., open circuit or short circuit), but its output value exhibits a persistent offset error relative to the true value. Such faults do not immediately cause system shutdown, but they reduce the accuracy of current acquisition, and their long-term persistence may affect motor control performance and functional safety. Common non-failure drift faults include sensor temperature drift, aging drift, and gain deviation.

[0144] In this embodiment, by taking advantage of the fact that both current sampling modes can output valid results within the transition range, online diagnosis of non-failure drift faults of the current sensor is achieved through cross-validation without adding additional hardware, thereby improving the fault detection coverage and functional safety level of the system.

[0145] As one possible implementation, the method further includes: at any given time, only one current sensing signal from the multiple current sensing sensors is selected to the signal processing circuit.

[0146] One implementation involves keeping the bus current sensor disconnected via a switching group when the real-time speed is less than or equal to a preset speed threshold; and keeping each phase current sensor disconnected via a switching group when the real-time speed is greater than the preset speed threshold. This ensures that at any given time, only one current sensing signal from the multiple current sensors is selected for the signal processing circuit, while the rest are disconnected.

[0147] In this embodiment, by ensuring that only one current sensing signal is selected at any given time, signal crosstalk caused by multiple sensor signals being simultaneously accessed by the signal processing circuit is avoided, thus guaranteeing sampling accuracy. Simultaneously, this architecture allows multiple current sensing sensors to share the same signal processing circuit, reducing the number of components in the signal processing chain from multiple sets to one, decreasing the number of single-point failure sources, and resulting in a lower single-point failure rate in functional safety analysis, thus optimizing functional safety indicators.

[0148] As one possible implementation, the signal processing circuit includes multiple components; the method further includes: obtaining the single-point failure rate of each component in the signal processing circuit, and summing them to obtain the total single-point failure rate of the signal processing circuit; wherein, the number of components included in the signal processing circuit shared by multiple current detection sensors is less than the total number of components required when each current detection sensor is configured with its own independent signal processing circuit, thereby reducing the total single-point failure rate.

[0149] It should be understood that in this application, the switching group only connects one current sensing sensor to the signal processing circuit at any given time. Multiple current sensing sensors share the same signal processing circuit in a time-sharing manner, eliminating the need for a separate signal processing circuit for each sensor. In traditional solutions, each sensor is configured with an independent signal processing circuit, requiring four circuits for four sensors. Each circuit includes multiple components such as operational amplifiers, filter resistors, and filter capacitors. This solution simplifies these four circuits into one, significantly reducing the number of components in the signal processing circuit. In functional safety analysis, each component is considered a potential source of failure. Reducing the number of components means a corresponding reduction in the number of single-point failure sources. After summing the single-point failure rates of each component, the overall single-point failure rate of the signal processing circuit decreases accordingly. This method of reducing failure rate by simplifying the hardware architecture, contrary to the traditional approach of increasing redundancy to improve safety, is the core logic behind this solution's optimization of functional safety indicators.

[0150] The signal processing circuit is a circuit for processing inputs from multiple current sensing sensors; the method further includes: determining the single-point failure rate of the signal processing circuit based on the failure modes and failure rates of each component in the signal processing circuit; wherein, the number of components included in the signal processing circuit is less than the total number of components required when each current sensing sensor is configured with its own independent signal processing circuit, thus reducing the single-point failure rate.

[0151] In this application, since the switching group selects multiple current sensing sensors to the same signal processing circuit in a time-division manner, the original architecture that required a separate signal processing circuit for each current sensing sensor is simplified to only one signal processing circuit, and the number of channels of the signal processing circuit is reduced from multiple to one.

[0152] In one implementation, the signal processing circuit includes operational amplifiers, resistors, capacitors, and filtering devices. Since only one signal processing circuit is needed, the number of these components is reduced from multiple sets to one, resulting in a significant reduction in the total number of components.

[0153] Single-point failure rate refers to the failure rate at which the failure of a single component directly leads to the loss of system function. When the number of components decreases, the probability that the failure of any component in the system will result in the loss of signal processing function also decreases. With the unit failure rate of components remaining constant, the fewer the number of components, the lower the overall single-point failure rate. Therefore, this application reduces the single-point failure rate by simplifying the number of components in the signal processing circuit, which is beneficial to achieving the single-point failure target in functional safety indicators.

[0154] It should be understood that in functional safety standards, a single point of failure refers to a failure in a system where the failure of a single hardware component can lead to a breach of safety objectives. The single point of failure rate is one of the important parameters for assessing system safety. By reducing the number of components, the number of potential single point of failure points in the system is reduced, thereby lowering the single point of failure rate and improving the system's functional safety level. This application achieves time-division multiplexing of multiple sensor signals to a single signal processing circuit by switching switch groups. While ensuring the integrity of the current sampling function, it reduces the number of components in the signal processing circuit, thus optimizing the single point of failure rate index.

[0155] The current sampling control method provided in this application optimizes functional safety indicators by simplifying the hardware architecture.

[0156] As one possible implementation method, this application establishes a correlation between hardware architecture simplification and functional safety indicators based on the core requirements of electric drive functional safety: torque safety and high-voltage safety. The motor output torque is directly proportional to the winding current; precise current control is a prerequisite for accurate torque output, and the reliability of the current sampling module directly affects the functional safety level. Functional safety levels are divided into four levels: A, B, C, and D, namely the automotive safety integrity level (ASIL). Different levels must meet three corresponding metrics: the single-point fault metric (SPFM), the latent fault metric (LFM), and the probabilistic metric for random hardware failures (PMHF).

[0157] Among them, SPFM reflects the system's robustness to single-point failures and residual failures; LFM reflects the system's robustness to latent failures; and PMHF assesses the probability that random failure of hardware components will lead to a violation of safety objectives. The more complex the system architecture and the more components, the more difficult it is to achieve the above functional safety indicators.

[0158] For example, for the ASILC level, SPFM is required to be greater than 97%, LFM greater than 80%, and PMHF less than 10 to the power of -7 per hour; for the ASILD level, SPFM is required to be greater than 99%, LFM greater than 90%, and PMHF less than 10 to the power of -8 per hour. In traditional schemes where four current sensing sensors are configured with independent signal processing circuits, the signal processing link contains a large number of components. Each signal processing circuit requires independent operational amplifiers, resistors, capacitors, filters, etc., resulting in a large number of components across all four circuits. This leads to high single-point failure rates, residual failure rates, and latent failure rates, increasing the difficulty of meeting high ASIL level requirements. This application uses a switching group to time-division multiplex the four sensing signals using the same signal processing circuit, significantly reducing the number of components in the signal processing circuit. This reduces the aforementioned three types of failure rates at the hardware architecture level, resulting in positive optimization of SPFM, LFM, and PMHF, making it easier to meet high ASIL level requirements.

[0159] As one possible implementation, this application classifies the failure modes of each component in the signal processing circuit through failure modes effect and diagnostic analysis (FMEDA), and quantifies the single-point failure rate based on the classification results.

[0160] The component failure modes include: safety-irrelevant failures, indicating that the failure is unrelated to functional safety; safety-related failures, indicating that the failure is related to functional safety; safety failures, indicating that although the failure is related to functional safety, its occurrence will not lead to a violation of safety objectives; single-point failures, indicating that there is no safety mechanism covering the failure, and the failure of a certain point directly leads to a violation of safety objectives; residual failures, indicating that although there is a safety mechanism, it is not covered, and still leads to a violation of safety objectives; multi-point detectable failures, indicating multi-point failures that can be diagnosed; and multi-point undetectable failures, i.e., latent failures, indicating multi-point failures that cannot be diagnosed.

[0161] In one implementation, during FMEDA calculation, all components undergo a logical judgment process: First, it is determined whether the component is a safety-related hardware element. If not, it is classified as a safety-irrelevant fault; if so, it is classified as a safety-related fault and further judged. Without considering safety mechanisms, it is determined whether the safety objective is violated. If not, it is classified as a safety fault; if it is violated, it is determined whether there is a safety mechanism covering it. If not, it is classified as a single point fault; if so, it is classified as a residual fault. Then, it is further determined whether the failure of the component together with another component causes a violation of the safety objective, in order to distinguish between multi-point detectable faults and latent faults.

[0162] For example, consider a sampling resistor in a signal processing circuit. This resistor is located in the current sampling loop and is a safety-related hardware element, so it is initially classified as a safety-related fault. Without considering safety mechanisms, if this resistor is open-circuited, the current signal will be lost, the controller will be unable to obtain accurate current information, leading to torque runaway and violating safety objectives. Therefore, it proceeds to the next step. If there is no independent safety mechanism in the signal processing circuit for the resistor's failure, the resistor's failure is classified as a single-point fault. If a safety mechanism exists but cannot completely cover the failure, it is classified as a residual fault. If the resistor's failure occurs simultaneously with the failure of another component (such as operational amplifier drift) and the system cannot detect it, it is further classified as a latent fault. By performing the above judgment on each component in the signal processing circuit, the failure rates of similar faults are summarized to obtain the total failure rate of various types of faults, including single-point fault failure rate, residual fault failure rate, and latent fault failure rate.

[0163] As one possible implementation, this application, based on FMEDA quantitative analysis results, reduces the single-point failure rate, residual failure rate, and latent failure rate by simplifying the number of components in the signal processing circuit, thereby optimizing the three functional safety indicators: SPFM, LFM, and PMHF. Based on the various failure rates obtained from FMEDA, the following three functional safety indicator calculation formulas are used for quantitative evaluation: The single point of failure index is calculated using the formula SPFM=1-(λ_SPF+λ_RF) / λ_SR, where λ_SPF is the single point of failure rate, λ_RF is the residual failure rate, and λ_SR is the total failure rate of safety-related failures. The latent fault index is calculated using the formula LFM=1-λ_MPF_L / (λ_SR-λ_SPF-λ_RF), where λ_MPF_L is the latent fault failure rate. The random hardware failure rate is calculated using the formula PMHF=λ_SPF+λ_RF+λ_MPF_L×λ_MPF_D×T_lifetime, where λ_MPF_D is the multi-point detectable failure rate and T_lifetime is the vehicle's lifespan.

[0164] In this application, the switching group selects multiple current sensing sensors to the same signal processing circuit in a time-division manner. This simplifies the architecture, which previously required a separate signal processing circuit for each current sensing sensor, to a single circuit, reducing the number of components from multiple sets to one. This reduction in the number of components directly lowers λ_SPF, λ_RF, and λ_MPF_L: Firstly, each component in the signal processing chain can become a source of single-point failure; reducing the number of components causes a simultaneous decrease in λ_SPF and λ_RF. According to the SPFM formula, a decrease in the sum of λ_SPF and λ_RF increases the SPFM value. Secondly, multi-point failures involve combined failures between two or more components; reducing the number of components results in a quadratic decrease in the number of combinations, thus significantly reducing λ_MPF_L. According to the LFM formula, a decrease in λ_MPF_L increases the LFM value. Simultaneously, according to the PMHF formula, the simultaneous decrease in λ_SPF, λ_RF, and λ_MPF_L lowers the PMHF value.

[0165] For example, assuming each signal processing circuit contains one operational amplifier, 10 resistors, and 8 capacitors, the traditional solution requires four signal processing circuits when the four current sensing sensors are configured independently, totaling four operational amplifiers, 40 resistors, and 32 capacitors, for a total of 76 components. This application uses a switching group to time-division multiplex the four signals using the same signal processing circuit, requiring only one operational amplifier, 10 resistors, 8 capacitors, and a few components of the switching group itself, such as one four-channel analog switch chip. The total number of components in the signal processing link is reduced from 76 to approximately 19, a reduction of about 75%. In FMEDA quantitative analysis, the reduction in components leads to a simultaneous decrease in λ_SPF, λ_RF, and λ_MPF_L, a corresponding increase in SPFM and LFM, and a simultaneous decrease in PMHF. This positive optimization of the above three indicators makes it easier for the system to achieve higher ASIL level requirements under the same safety mechanism configuration.

[0166] The above-described implementation methods work together to form the complete technical logic chain of this application: "hardware simplification → reduction in the number of components → reduction in FMEDA failure rate → simultaneous optimization of three functional safety indicators: SPFM / LFM / PMHF". By switching the switch group to achieve time-division multiplexing of multiple sensor signals to a single signal processing circuit, this application simplifies the hardware architecture and reduces hardware costs. At the level of quantitative functional safety analysis, it simultaneously reduces the single-point failure rate, residual failure rate, and latent failure rate. After substituting into the calculation formulas for SPFM, LFM, and PMHF, SPFM and LFM increase, PMHF decreases, and all three functional safety indicators are positively optimized. This achieves a unity between simplified hardware architecture and improved functional safety performance, providing technical support at the hardware architecture level for electric drive systems to meet higher ASIL level requirements.

[0167] As one possible implementation, all components in the electric drive system can undergo the aforementioned safety function tests. This application does not impose any specific limitations.

[0168] In summary, for example, please refer to Figure 7 , Figure 7 This application provides a schematic diagram of a component failure mode classification and failure rate calculation process. The flowchart is used to classify and calculate the failure rate of various types of faults based on the component's basic failure rate λ. Specifically, it includes: The process starts by inputting the component failure rate λ. First, it determines whether the component is a safety-related hardware element. If not, it is classified as a safety-irrelevant fault, with a corresponding failure rate λ_NSR=λ. If it is, it is classified as a safety-related fault, with a corresponding failure rate λ_SR=λ. Next, it determines whether the fault would violate safety objectives without considering safety mechanisms. If not, it is directly identified as a safety fault, with a failure rate λ_S=λ. If it does, it further determines whether a safety mechanism with coverage of F1 exists. If no safety mechanism exists, it is classified as a single-point fault, with a failure rate λ_SPF=λ. If a safety mechanism exists, the residual failure rate λ_RF=λ×(1) is calculated. F1); Subsequently, for the two branches of single-point failure and residual failure, it is determined whether the failure will jointly cause a violation of the safety target with the failure of another component. If so, it is further determined whether there is a latent failure protection safety mechanism with coverage of F2. If such a mechanism exists, the failure rate of two-point detectable faults λ_MPF_D=λ×F1×F2 and the failure rate of latent faults λ_MPF_L2=λ×F1×(1) are calculated respectively. F2).

[0169] After the step of "classifying it as a safety-related fault, with a corresponding failure rate λ_SR=λ", it is determined whether it will cause a violation of the safety objective together with the failure of another component. If so, it is determined whether there is a safety mechanism to prevent latent failures. If so, the latent failure rate λ_MPF_L1=λ×(1 F2).

[0170] After both of the above steps are completed, the latent fault failure rates λ_MPF_L1 and λ_MPF_L2 are added together to obtain the total latent fault failure rate λ_MPF_L.

[0171] It should be understood that the failure rate λ refers to the probability of a single hardware component failing per unit time, usually expressed as FIT (Failure In Time, i.e., every 10... 9 The failure rate is measured in hours (number of failures per hour). In functional safety analysis, each component is assigned a base failure rate λ, which can be obtained from industry standard databases (such as IEC 62380, SN 29500, etc.) based on factors such as component type, operating conditions, temperature, and stress. Figure 7 The classification process shown takes the basic failure rate λ of each component as input. Based on the functional role of the component in the circuit, whether it belongs to safety-related hardware elements, whether it is covered by safety mechanisms, and whether it involves multi-point fault combinations, λ is decomposed into failure rate components of different fault categories. Finally, the total failure rate of various types of faults such as λ_SPF, λ_RF, and λ_MPF_L is obtained, which provides a data foundation for the subsequent quantitative calculation of the three functional safety indicators SPFM, LFM, and PMHF.

[0172] The foregoing mainly describes the solutions provided by the embodiments of this application from a methodological perspective. To achieve the above functions, the electronic device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, based on the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0173] like Figure 8 As shown, the electronic device 800 provided in this application includes, but is not limited to, a processor 801 and a memory 802.

[0174] The memory 802 described above is used to store the executable instructions of the processor 801. It is understood that the processor 801 is configured to execute instructions to implement the methods in the above embodiments.

[0175] It should be noted that those skilled in the art will understand that Figure 8 The electronic device structure shown does not constitute a limitation on electronic device 800; electronic device may include, but is not limited to, other electronic devices. Figure 8 This may indicate more or fewer components, or a combination of certain components, or a different arrangement of components.

[0176] The processor 801 is the control center of the electronic device 800. It connects various parts of the electronic device via various interfaces and lines. By running or executing software programs and / or modules stored in the memory 802, and by calling data stored in the memory 802, it performs various functions and processes data of the electronic device 800, thereby providing overall monitoring of the electronic device 800. The processor 801 may include one or more processing units. Optionally, the processor 801 may integrate an application processor and a modem processor. The application processor mainly handles the operating system, user interface, and applications, while the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into the processor 801.

[0177] The memory 802 can be used to store software programs and various data. The memory 802 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs required by at least one functional module (such as a determination unit, processing unit, etc.), etc. Furthermore, the memory 802 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0178] In an exemplary embodiment, a computer-readable storage medium including instructions is also provided, such as a memory 802 including instructions, which can be executed by a processor 801 of an electronic device 800 to implement the methods in the above embodiments.

[0179] Optionally, the computer-readable storage medium may be a non-transitory computer-readable storage medium, such as a read-only memory (ROM), random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device.

[0180] In an exemplary embodiment, this application also provides a computer program product including one or more instructions, which can be executed by the processor 801 of the electronic device 800 to perform the methods described above.

[0181] It should be noted that when one or more instructions in the computer-readable storage medium or computer program product are executed by the processor of an electronic device, they implement the various processes of the above method embodiments and achieve the same technical effect as the above method. To avoid repetition, they will not be described again here.

[0182] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0183] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another apparatus, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0184] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0185] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0186] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, essentially, or the parts that contribute to related technologies, or all or part of the technical solutions, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0187] The above embodiments are merely preferred embodiments provided to fully illustrate this application, and the scope of protection of this application is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on this application are all within the scope of protection of this application.

Claims

1. A current sampling control method for an electric drive system, characterized in that, This invention relates to a motor drive system, comprising: multiple current detection sensors, a switching group, a signal processing circuit, and a motor; wherein the multiple current detection sensors include multiple phase current sensors for detecting the current of the multi-phase windings of the motor, and a bus current sensor for detecting the DC bus current; the switching group is connected between the multiple current detection sensors and the signal processing circuit, and is used to select one current sensing signal from the multiple current detection sensors to the signal processing circuit at the same time; the signal processing circuit is used to process the current sensing signal connected to the signal processing circuit. The method includes: Obtain the real-time speed of the motor; When the real-time speed is less than or equal to a preset speed threshold, the switching switch group is controlled to sequentially turn on each phase current sensor to the signal processing circuit within a control cycle, and time-domain synchronous correction is performed on each acquired phase current sensing signal to obtain a first target phase current, so as to control the motor operation based on the first target phase current; When the real-time speed is greater than the preset speed threshold, the switching switch group is controlled to turn on the bus current sensor to the signal processing circuit. Based on the bus current sensing signal corresponding to the acquired bus current sensor, the second target phase current is obtained, and the motor is controlled to run based on the second target phase current.

2. The method according to claim 1, characterized in that, The step of performing time-domain synchronous correction on the acquired phase current sensing signals to obtain the first target phase current includes: Using the sampling time of any one of the multiple phase current sensors as a reference time, the sampling time difference of the other phase current sensors relative to the reference time is determined; Based on the current angular velocity of the motor and the sampling time difference, calculate the phase compensation angle corresponding to each phase current sensor; By using vector rotation transformation, based on the phase compensation angles, the phase current sensing signals acquired in time division are corrected to the same reference time to obtain the first target phase current; wherein, the vector rotation transformation is used to convert the time domain deviation corresponding to the phase compensation angle into the angle correction amount of the phase current sensing signal in the rotating coordinate system, so that the phase current sensing signals acquired in time division are equivalent to the synchronous sampling values ​​at the same time when vector synthesis is performed.

3. The method according to claim 1, characterized in that, The step of obtaining the second target phase current based on the bus current sensing signal corresponding to the acquired bus current sensor includes: Within one control cycle, the bus current sensing signal is sampled during different effective voltage vectors to obtain at least two bus current values. Based on the preset correspondence between the space voltage vector and the phase current, the phase current associated with each of the bus current values ​​is determined; Based on the constraint that the sum of the phase currents is zero, the second target phase current is calculated.

4. The method according to claim 1, characterized in that, The method further includes: When the real-time rotational speed is within a preset transition range near the preset rotational speed threshold, the second target phase current is verified using the first target phase current, or the first target phase current is verified using the second target phase current, in order to diagnose the non-failure drift fault of the current sensor.

5. The method according to claim 1, characterized in that, The method of controlling the switching group to sequentially turn on each of the phase current sensors to the signal processing circuit within one control cycle includes: During different time periods of the control cycle, selection signals are sent sequentially to the switching switch group in a preset order, so that each phase current sensor in the same control cycle is connected to the signal processing circuit in a time-sharing manner; wherein, the preset order includes: sending a first selection signal, a second selection signal and a third selection signal in sequence, respectively turning on the first phase current sensor, the second phase current sensor and the third phase current sensor, and there is a preset time interval between two adjacent selection signals.

6. The method according to claim 1, characterized in that, The control of the switching switch group to connect the bus current sensor to the signal processing circuit includes: A fixed strobe signal is sent to the switching switch group, so that the bus current sensor is continuously connected to the signal processing circuit; the fixed strobe signal is used to keep the switch channel corresponding to the bus current sensor in the switching switch group in the on state and the switch channels corresponding to each phase current sensor in the off state during the continuous period when the real-time speed is greater than the preset speed threshold.

7. The method according to claim 1, characterized in that, The method further includes: at any given time, only one current sensing signal from the plurality of current sensing sensors is selected to the signal processing circuit.

8. The method according to claim 1, characterized in that, The signal processing circuit includes multiple components; The method further includes: The single-point failure rate of each component in the signal processing circuit is obtained, and the total single-point failure rate of the signal processing circuit is obtained by summing them up. The number of components in the signal processing circuit shared by the multiple current detection sensors is less than the total number of components required when each current detection sensor is configured with its own independent signal processing circuit, thereby reducing the total single-point failure rate.

9. A motor drive system, characterized in that, The motor drive system includes a controller for performing the method as described in any one of claims 1 to 8.

10. A vehicle, characterized in that, The vehicle includes a body and an electric motor drive system as described in claim 9.

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