Method and apparatus for reconfiguring the three-phase current of an electric motor

Abstract

This disclosure relates to a method and apparatus for reconstructing the three-phase current of a motor, wherein the method includes constructing a sawtooth wave as a first carrier wave with respect to a first phase of the motor; shifting the first carrier wave by a target phase to generate second carrier waves with respect to a second and third phase of the motor; generating phase voltages corresponding to the three phases based on the magnitude relationship between the modulation waves of the three phases of the motor and the carrier waves of the corresponding phases; determining a first sampling window based on the phase voltages corresponding to the three phases; and determining the second and third phase currents at the first sampling window, and reconstructing the first phase current based on the second and third phase currents. This scheme can accurately reconstruct the three-phase current of the motor.

Description

Technical Field

[0001] The embodiments of this disclosure generally relate to the field of motor control technology, and more specifically to a method and apparatus for reconfiguring the three-phase current of a motor. Background Technology

[0002] In the FOC (Field-Oriented Control) algorithm, accurately acquiring the three-phase current of the motor is crucial for achieving high-precision coordinate transformation of the motor. To reconstruct the motor's three-phase current, sampling of the three-phase current can be performed. However, in some cases, an excessively narrow effective current sampling window can cause current reconstruction distortion, leading to insufficient accuracy in three-phase current reconstruction and limiting voltage utilization and the motor's high-speed performance. Summary of the Invention

[0003] To address the aforementioned problems, this disclosure provides a method and apparatus for reconstructing the three-phase current of a motor, which can accurately reconstruct the three-phase current of the motor.

[0004] According to a first aspect of this disclosure, a method for reconstructing three-phase currents of an electric motor is provided. The method includes: constructing a sawtooth wave as a first carrier wave with respect to a first phase of the motor; shifting the first carrier wave by a target phase to generate second carrier waves with respect to a second and third phase of the motor; generating phase voltages corresponding to the three phases based on the magnitude relationship between the modulation waves of the three phases of the motor and the carrier waves of the corresponding phases; determining a first sampling window based on the phase voltages corresponding to the three phases; and determining the second and third phase currents at the first sampling window, and reconstructing the first phase current based on the second and third phase currents.

[0005] In some embodiments, determining the first sampling window based on the phase voltages corresponding to the three phases includes: configuring the phase voltages corresponding to the three phases such that the upper bridge of the first phase of the motor inverter is turned on, and the lower bridge of the second and third phases of the motor inverter is turned on, as the first sampling window.

[0006] In some embodiments, the magnitude of the target phase is positively correlated with the period of the first carrier.

[0007] In some embodiments, constructing a sawtooth wave includes: performing a cyclic count based on a target limit value to construct the sawtooth wave, the target limit value being related to the period of a first carrier wave.

[0008] In some embodiments, the modulation wave of the three phases of the motor is calculated based on the current reference value, current feedback value and electrical angle value of the motor.

[0009] In some embodiments, performing cyclic counting based on a target limit value to construct a sawtooth wave includes any one of the following: cyclic counting upwards between a first value and a target limit value; and cyclic counting downwards between a target limit value and a first value, where the first value is less than the target limit value.

[0010] In some embodiments, reconstructing the first phase current based on the second phase current and the third phase current includes: reconstructing the first phase current based on Kirchhoff's current law, using the second phase current and the third phase current.

[0011] According to a second aspect of this disclosure, an apparatus for reconstructing the three-phase current of a motor is provided. The apparatus includes: a first sampling resistor connected in series with the lower bridge of a second phase of an inverter of the motor; a second sampling resistor connected in series with the lower bridge of a third phase of the inverter of the motor; and a control unit electrically connected to the first and second sampling resistors, the control unit being configured to determine the second-phase current at a first sampling window based on a sampling voltage with respect to the first sampling resistor and to determine the third-phase current based on a sampling voltage with respect to the second sampling resistor, and to reconstruct the first-phase current of the motor according to the method of the first aspect of this disclosure.

[0012] In some embodiments, the control unit includes a counting unit configured to perform cyclic counting based on a target limit value to construct a sawtooth wave, the target limit value being related to the period of a first carrier wave.

[0013] In some embodiments, the device further includes a modulation wave determination unit configured to calculate a modulation wave for the three phases of the motor based on a current reference value, a current feedback value, and an electrical angle value.

[0014] According to the technical solution of this disclosure, a sawtooth wave is constructed as a first carrier wave for the first phase of the motor; the first carrier wave is phase-shifted by a target phase to generate second carrier waves for the second and third phases of the motor; based on the magnitude relationship between the modulation waves of the three phases of the motor and the carrier waves of the corresponding phases, phase voltages corresponding to the three phases are generated; a first sampling window is determined based on the phase voltages corresponding to the three phases; and the second and third phase currents are determined at the first sampling window, and the first phase current is reconstructed based on the second and third phase currents. By utilizing the phase difference between the second and first carrier waves and determining the first sampling window based on the phase voltages corresponding to the three phases, stable sampling of the phase currents (e.g., the second and third phase currents) can be achieved, thereby providing accuracy in reconstructing the three-phase currents.

[0015] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0016] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements.

[0017] Figure 1 A schematic diagram of an apparatus for reconfiguring the three-phase current of a motor, according to an embodiment of the present disclosure, is shown.

[0018] Figure 2 A schematic diagram of a first waveform of the modulated wave and the carrier wave according to an embodiment of the present disclosure is shown.

[0019] Figure 3 A second waveform diagram of the modulated wave and carrier wave according to an embodiment of the present disclosure is shown.

[0020] Figure 4 A flowchart of a method for reconfiguring the three-phase current of a motor, according to an embodiment of this disclosure, is shown.

[0021] Figure 5 A schematic block diagram of an example electronic device is shown, illustrating a method for processing a target object that can be used to implement embodiments of the present disclosure.

[0022] Figure 6 A third waveform diagram of the modulated wave and carrier wave of an embodiment of this disclosure is shown. Detailed Implementation

[0023] The exemplary embodiments of this disclosure are described below with reference to the accompanying drawings, including various details of the embodiments to aid understanding, and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this disclosure. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0024] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0025] As described earlier, in the FOC (Field Oriented Control) algorithm, accurately acquiring the three-phase current of the motor is crucial for achieving high-precision coordinate transformation of the motor. To reconstruct the motor's three-phase current, sampling of the three-phase current can be performed. In some cases, an excessively narrow effective current sampling window can cause current reconstruction distortion, leading to insufficient accuracy in three-phase current reconstruction and limiting voltage utilization and the motor's high-speed performance.

[0026] In summary, the shortcomings of traditional three-phase current reconstruction for motors are that the effective current sampling window is too narrow, which can cause current reconstruction distortion and result in insufficient accuracy of three-phase current reconstruction.

[0027] To at least partially address one or more of the aforementioned problems and other potential issues, exemplary embodiments of this disclosure propose a method and apparatus for reconstructing the three-phase current of a motor. In this scheme, a sawtooth wave is constructed as a first carrier wave for the first phase of the motor; the first carrier wave is phase-shifted by a target phase to generate second carrier waves for the second and third phases of the motor; phase voltages corresponding to the three phases are generated based on the magnitude relationship between the modulation waves of the three phases and the carrier waves of the corresponding phases; a first sampling window is determined based on the phase voltages corresponding to the three phases; and the second and third phase currents are determined at the first sampling window, and the first phase current is reconstructed based on the second and third phase currents. By utilizing the phase difference between the second and first carrier waves and determining the first sampling window based on the phase voltages corresponding to the three phases, stable sampling of the phase currents (e.g., the second and third phase currents) can be achieved, thereby providing accuracy in reconstructing the three-phase current.

[0028] The following description, in conjunction with the accompanying drawings, describes the embodiments of this disclosure.

[0029] The solutions of the embodiments disclosed herein are applicable, for example, to drive systems of AC motors such as permanent magnet synchronous motors and brushless DC motors that employ vector control (such as field-oriented control, FOC), especially to cost-sensitive, space-constrained scenarios requiring high-precision current feedback, such as electric drive systems for new energy vehicles, industrial servo drives, variable frequency motors for home appliances (such as air conditioner compressors and washing machine motors), robot joint motors, and power tools.

[0030] Figure 1A schematic diagram of a device 200 for reconfiguring the three-phase current of a motor, according to an embodiment of this disclosure, is shown. The motor 102 is electrically connected, for example, to an inverter 104. The inverter 104, for example, consists of a half-bridge module composed of six MOSFETs (Insulated Gate Field Effect Transistors), which generates corresponding output signals through complementary switching, for example, to control the speed of the motor 102. The inverter 104 includes, for example, a first MOSFET 141, a second MOSFET 142, a third MOSFET 143, a fourth MOSFET 144, a fifth MOSFET 145, and a sixth MOSFET 146. The first MOSFET 141 and the second MOSFET 142 respectively constitute the upper and lower bridges of the first phase; the third MOSFET 143 and the fourth MOSFET 144 respectively constitute the upper and lower bridges of the second phase; and the fifth MOSFET 145 and the sixth MOSFET 146 respectively constitute the upper and lower bridges of the third phase. The first phase of the motor 102 is, for example, the U phase; the second phase of the motor 102 is, for example, the V phase; and the third phase of the motor 102 is, for example, the W phase. It should be understood that in some embodiments, the V phase or W phase of the motor 102 may also be used as the first phase.

[0031] Device 200 includes, for example, a control unit 202, a first sampling resistor R1, and a second sampling resistor R2. The first sampling resistor R1 is connected in series with the lower bridge of the second phase of the motor inverter, and the second sampling resistor R2 is connected in series with the lower bridge of the third phase of the motor inverter. For example, one end of the first sampling resistor R1 is electrically connected to the emitter of the fourth MOSFET 144, and the other end of the first sampling resistor R1 is grounded; one end of the second sampling resistor R2 is electrically connected to the emitter of the sixth MOSFET 146, and the other end of the second sampling resistor R2 is grounded.

[0032] The device 200 may also include, for example, a sampling unit for sampling the sampling voltages output by the first sampling resistor R1 and the second sampling resistor R2, so that the control unit 202 determines the second phase current based on the sampling voltage with respect to the first sampling resistor and determines the third phase current based on the sampling voltage with respect to the second sampling resistor at the first sampling window.

[0033] The sampling unit includes, for example, a first sampling unit 221 and a second sampling unit 222. The first sampling unit 221 is electrically connected to a first sampling resistor R1 and is used to detect the first sampling voltage of the first sampling resistor R1. It should be understood that the first sampling voltage is related to the second phase current. The second sampling unit 222 is electrically connected to a second sampling resistor R2 and is used to detect the second sampling voltage of the second sampling resistor R2. It should be understood that the second sampling voltage is related to the third phase current. The control unit 202 receives the first sampling voltage and determines the second phase current (e.g., Iv) based on the first sampling voltage; the control unit 202 receives the second sampling voltage and determines the third phase current (e.g., Iw) based on the second sampling voltage. The control unit 202 reconstructs the first phase current based on the second phase current and the third phase current. For example, the control unit 202 reconstructs the first phase current based on the second phase current and the third phase current according to Kirchhoff's current law. For example, Kirchhoff's current law can be characterized by the following formula (1):

[0034] Iu + Iv + Iw = 0 (1)

[0035] Figure 2 A schematic diagram of a first waveform of the modulated wave and the carrier wave according to an embodiment of the present disclosure is shown. Figure 3 A second waveform diagram of the modulated wave and carrier wave according to an embodiment of the present disclosure is shown.

[0036] Control unit 202, for example, constructs a sawtooth wave as the first carrier wave (e.g., U_C) for the first phase of motor 102.

[0037] The control unit 202 performs cyclic counting based on a target limit value to construct a sawtooth wave, the target limit value being related to the period of the first carrier wave. The control unit 202 includes, for example, a first counting unit that performs cyclic counting based on the target limit value to construct the sawtooth wave.

[0038] Reference Figure 2In some embodiments, the first counting unit of the control unit 202 cyclically counts downwards between a target limit value and a first value, where the first value is less than the target limit value. For example, at time T0, the count value corresponding to the first counting unit is set to the target limit value. Then, the first counting unit counts downwards according to a predetermined clock, i.e., the count value of the first counting unit gradually decreases. For example, at time T1, the count value corresponding to the first counting unit is decreased to the first value (i.e., the minimum count value). Time T1 is, for example, earlier than time T2, and the time that time T1 is earlier than time T2 corresponds to a clock cycle corresponding to a predetermined clock. Then, at the next clock cycle of time T1 (i.e., time T2), the count value corresponding to the first counting unit is again set to the target limit value. The first counting unit cyclically counts in this manner. The count value of the first counting unit is used to generate a sawtooth wave, which is, for example, a first carrier wave (e.g., U_C) with respect to the first phase of the motor 102. In some embodiments, the count value output by the first counting unit is, for example, formed into a sawtooth wave after passing through a DAC (digital-to-analog converter). It should be understood that the period of the first carrier U_C is determined by the target limit value, the first value, and the period of the predetermined clock (related to the frequency of the counting clock). In some embodiments, the clock period corresponding to the predetermined clock is, for example, 0.1ms, which corresponds to a frequency of 10kHz.

[0039] Then, the control unit 202 shifts the first carrier U_C phase to the target phase to generate a second carrier with respect to the second and third phases of the motor 102.

[0040] In some embodiments, the magnitude of the target phase is positively correlated with the period of the first carrier. For example, the larger the period of the first carrier, the larger the target phase.

[0041] In some implementations, the ratio between the magnitude of the target phase and the period of the first carrier is, for example, within a predetermined range.

[0042] In some embodiments, the control unit 202 further includes, for example, a phase counter and a second counting unit. The phase shift of the corresponding target phase can be achieved by counting with the phase counter. For example, when the count value corresponding to the first counting unit is set to the target limit value, the phase counter starts counting from an initial value (e.g., 0). When the phase counter counts to the target phase value, the count value corresponding to the second counting unit is set to the target limit value, and counting begins downwards according to a predetermined clock, i.e., the count value of the second counting unit gradually decreases. After the count value corresponding to the second counting unit is decreased to a first value (i.e., the minimum count value), the count value corresponding to the second counting unit is set to the target limit value again, and the second counting unit counts cyclically in this manner. The count value of the second counting unit is used to generate a sawtooth wave, which serves, for example, as a second carrier wave (e.g., V_C and W_C) for the second and third phases of the motor 102. In some embodiments, the count value output by the second counting unit is, for example, generated by a DAC (digital-to-analog converter) to form the sawtooth wave.

[0043] Then, the control unit 202 generates the phase voltages corresponding to the three phases based on the magnitude relationship between the modulation waves of the three phases of the motor 102 and the carrier waves of the corresponding phases.

[0044] The three-phase modulation waves of the motor 102 include, for example, a first-phase modulation wave (e.g., U_M), a second-phase modulation wave (e.g., V_M), and a third-phase modulation wave (e.g., W_M). The three-phase modulation waves of the motor 102 are calculated based on current reference values, current feedback values, and electrical angle values ​​related to the motor 102. It should be understood that the three-phase modulation waves of the motor 102 exhibit, for example, sinusoidal characteristics. In some embodiments, the period of the three-phase modulation waves of the motor 102 is, for example, 20 ms (milliseconds), corresponding to a frequency of 50 Hz (Hertz).

[0045] The control unit 202 may also include, for example, a first comparator. The non-inverting input of the first comparator is used to receive a first carrier wave (e.g., U_C), the inverting input is used to receive a first-phase modulated wave (e.g., U_M), and the output is used to output a first-phase voltage (e.g., CTR_U) for controlling the complementary switching of the upper and lower bridges of the first phase. For example, when the first-phase voltage (e.g., CTR_U) is at a high level, the upper bridge of the first phase (e.g., the first MOSFET 141) is turned on, and the lower bridge of the first phase (e.g., the second MOSFET 142) is turned off.

[0046] Similarly, the control unit 202 also includes, for example, a second comparator. The non-inverting input of the second comparator is used to receive a second carrier wave (e.g., represented by V_C), the inverting input is used to receive a second-phase modulated wave (e.g., V_M), and the output is used to output a second-phase voltage (e.g., CTR_V) for controlling the complementary switching of the upper and lower bridges of the second phase. For example, when the second-phase voltage (e.g., CTR_V) is high, the upper bridge of the second phase (e.g., the third MOSFET 143) is turned on, and the lower bridge of the second phase (e.g., the fourth MOSFET 144) is turned off.

[0047] The control unit 202 further includes, for example, a third comparator. The non-inverting input of the third comparator is used to receive a second carrier wave (e.g., represented by W_C), the inverting input is used to receive a third-phase modulated wave (e.g., W_M), and the output is used to output a third-phase voltage (e.g., CTR_W) for controlling the complementary switching of the upper and lower bridges of the third phase. For example, when the third-phase voltage (e.g., CTR_W) is high, the upper bridge of the third phase (e.g., the fifth MOSFET 145) is turned on, and the lower bridge of the third phase (e.g., the sixth MOSFET 146) is turned off.

[0048] It is worth noting that, for ease of understanding, Figure 2 as well as Figure 3 The second carrier wave is illustrated as V_C corresponding to the second phase and W_C corresponding to the third phase, respectively, to facilitate illustrating the relationship between the second phase voltage CTR_V and V_C with respect to the second phase modulation wave V_M, and the relationship between the third phase voltage CTR_W and W_C with respect to the third phase modulation wave W_M. In actual implementation, the second carrier wave can be represented by the same signal, which is transmitted to the second comparator and the third comparator for comparison with the second phase modulation wave V_M and the third phase modulation wave W_M, respectively.

[0049] Next, the control unit 202 determines the first sampling window SW based on the phase voltages corresponding to the three phases of the motor 102.

[0050] The determination of the first sampling window based on the phase voltages of the three phases includes: configuring the phase voltages of the three phases such that the upper bridge of the first phase of the motor inverter is turned on, and the lower bridge of the second and third phases of the motor inverter is turned on, as the first sampling window.

[0051] For example, in the time window corresponding to the time interval SW, the phase voltages of the three phases are configured to enable the upper bridge of the first phase of the motor inverter to conduct, and to enable the lower bridge of the second and third phases of the motor inverter to conduct. Therefore, the time window corresponding to the time interval SW is used as the first sampling window SW.

[0052] It is worth noting that the first sampling window can be determined using logic circuits (such as combinational logic circuits and sequential logic circuits) based on the phase voltages of the three phases (e.g., the first phase voltage CTR_U, the second phase voltage CTR_V, and the third phase voltage CTR_W). For example, the first sampling window corresponds to the time window when the first phase voltage CTR_U is in the first state (e.g., a high-level state, meaning the upper bridge of the first phase of the motor inverter is turned on and the lower bridge of the first phase is turned off), and the second phase voltage CTR_V and the third phase voltage CTR_W are both in the second state (e.g., a low-level state, meaning the lower bridges of the second and third phases of the motor inverter are turned on and the upper bridges of the second and third phases are turned off).

[0053] Next, the control unit 202 determines the second phase current and the third phase current at the first sampling window, and reconstructs the first phase current based on the second phase current and the third phase current.

[0054] For example, the sampling unit samples the sampling voltages output by the first sampling resistor R1 and the second sampling resistor R2 at the first sampling window, so that the control unit 202 determines the second phase current based on the sampling voltage with respect to the first sampling resistor and determines the third phase current based on the sampling voltage with respect to the second sampling resistor at the first sampling window.

[0055] For example, the first sampling unit 221 is electrically connected to the first sampling resistor R1 and is used to detect the first sampling voltage of the first sampling resistor R1. It should be understood that the first sampling voltage is related to the second phase current. The second sampling unit 222 is electrically connected to the second sampling resistor R2 and is used to detect the second sampling voltage of the second sampling resistor R2. It should be understood that the second sampling voltage is related to the third phase current.

[0056] The control unit 202 acquires the first sampling voltage detected by the first sampling unit 221 and the second sampling voltage detected by the second sampling unit 222 at the first sampling window, and determines the second phase current based on the first sampling voltage and the first sampling resistor R1, and determines the third phase current based on the second sampling voltage and the second sampling resistor R2. It is worth noting that the control unit 202 can acquire the first sampling voltage detected by the first sampling unit 221 and the second sampling voltage detected by the second sampling unit 222 at appropriate sampling times within the first sampling window SW, in order to obtain stable sampling voltage values.

[0057] It is worth noting that using the same sampling window to sample the currents of two phases can save sampling time and improve the efficiency of reconstructing the three-phase current. Furthermore, it facilitates the coordinated setting of the target phase to form a reasonable duration corresponding to the first sampling window (or the ratio of the duration of the first sampling window to the period corresponding to the first phase voltage CTR_U), thereby enabling stable sampling of the second and third phase currents and thus providing accuracy in reconstructing the three-phase current.

[0058] It should be understood that the magnitude of the target phase shift of the second carrier relative to the first carrier can be adjusted, for example, by using the magnitude of the set target phase value.

[0059] In some embodiments, the ratio between the magnitude of the target phase and the period of the first carrier is, for example, within a predetermined proportional range. For instance, the ratio between the magnitude of the target phase and the period of the first carrier can be adjusted by adjusting the target phase value so that the ratio is within a predetermined proportional range, thereby facilitating stable sampling of the second and third phase currents and providing accuracy in reconstructing the three-phase currents.

[0060] In some embodiments, the device 200 further includes a modulation wave determination unit (not shown) configured to calculate a modulation wave for the three phases of the motor based on a current reference value, a current feedback value, and an electrical angle value.

[0061] Reference Figure 3In some embodiments, the first counting unit of the control unit 202 cyclically counts upwards between a first value and a target limit value, where the first value is less than the target limit value. For example, at time T0, the count value corresponding to the first counting unit is set to the first value (i.e., the minimum count value). Then, the first counting unit counts downwards according to a predetermined clock, i.e., the count value of the first counting unit gradually increases. For example, at time T1, the count value corresponding to the first counting unit is increased to the target limit value. Time T1 is, for example, earlier than time T2, and the time that time T1 is earlier than time T2 corresponds to a clock cycle corresponding to a predetermined clock. Then, at the next clock cycle of time T1 (i.e., time T2), the count value corresponding to the first counting unit is again set to the first value. The first counting unit cyclically counts in this manner. The count value of the first counting unit is used to generate a sawtooth wave, which is, for example, a first carrier wave (e.g., U_C) with respect to the first phase of the motor 102. In some embodiments, the count value output by the first counting unit is, for example, formed into a sawtooth wave after passing through a DAC (digital-to-analog converter). It should be understood that the period of the first carrier U_C is determined by the target limit value, the first value, and the period of the predetermined clock (related to the frequency of the counting clock). In some embodiments, the clock period corresponding to the predetermined clock is, for example, 0.1ms, which corresponds to a frequency of 10kHz.

[0062] In some embodiments, when the count value corresponding to the first counting unit is set to a first value (i.e., the minimum count value), the phase counter starts counting from an initial value (e.g., 0). When the phase counter counts to a phase target value, the count value corresponding to the second counting unit is set to the first value (i.e., the minimum count value), and starts counting upwards according to a predetermined clock, i.e., the count value of the second counting unit gradually increases. After the count value corresponding to the second counting unit increases to the target limit value, the count value corresponding to the second counting unit is set to the first value again, and the second counting unit counts cyclically in this manner. The count value of the second counting unit is used to generate a sawtooth wave, which is, for example, a second carrier wave (e.g., V_C and W_C) for the second and third phases of the motor 102. In some embodiments, the count value output by the second counting unit is, for example, generated by a DAC (digital-to-analog converter) to form a sawtooth wave.

[0063] The control unit 202 may also include, for example, a first comparator. The inverting input of the first comparator is used to receive a first carrier wave (e.g., U_C), the non-inverting input is used to receive a first-phase modulated wave (e.g., U_M), and the output is used to output a first-phase voltage (e.g., CTR_U) for controlling the complementary switching of the upper and lower bridges of the first phase. For example, when the first-phase voltage (e.g., CTR_U) is at a high level, the upper bridge of the first phase (e.g., the first MOSFET 141) is turned on, and the lower bridge of the first phase (e.g., the second MOSFET 142) is turned off.

[0064] Similarly, the control unit 202 may also include, for example, a second comparator. The inverting input of the second comparator is used to receive a second carrier wave (e.g., V_C and W_C), the non-inverting input is used to receive a second-phase modulated wave (e.g., V_M), and the output is used to output a second-phase voltage (e.g., CTR_V) for controlling the complementary switching of the upper and lower bridges of the second phase. For example, when the second-phase voltage (e.g., CTR_V) is high, the upper bridge of the second phase (e.g., the third MOSFET 143) is turned on, and the lower bridge of the second phase (e.g., the fourth MOSFET 144) is turned off.

[0065] The control unit 202 further includes, for example, a third comparator. The inverting input of the third comparator is used to receive a second carrier wave (e.g., V_C and W_C), the non-inverting input is used to receive a third-phase modulated wave (e.g., W_M), and the output is used to output a third-phase voltage (e.g., CTR_W) for controlling the complementary switching of the upper and lower bridges of the third phase. For example, when the third-phase voltage (e.g., CTR_W) is high, the upper bridge of the third phase (e.g., the fifth MOSFET 145) is turned on, and the lower bridge of the third phase (e.g., the sixth MOSFET 146) is turned off.

[0066] In some embodiments, the V phase of the motor 102 can be used as the first phase, and the U phase and W phase can be used as the second and third phases, respectively. In other embodiments, the W phase of the motor 102 can be used as the first phase, and the U phase and V phase can be used as the second and third phases, respectively. It should be understood that in the corresponding scheme, the first sampling resistor R1 is connected in series with the lower bridge of the second phase of the motor inverter, and the second sampling resistor R2 is connected in series with the lower bridge of the third phase of the motor inverter.

[0067] Figure 6 A third waveform diagram of the modulation wave and carrier wave according to an embodiment of this disclosure is shown. For example, the W phase of the motor 102 is used as the first phase, and the U and V phases are used as the second and third phases, respectively. Regarding... Figure 6 This can be understood by referring to the previous explanation, and will not be repeated here.

[0068] Figure 4 A flowchart of a method 300 for reconfiguring the three-phase current of a motor according to an embodiment of the present disclosure is shown. It should be understood that method 300 may also include other steps. Method 300 may be performed, for example, at control unit 202 or at electronic device 600.

[0069] At step 302, a sawtooth wave is constructed as the first carrier wave with respect to the first phase of the motor.

[0070] At step 304, the first carrier phase is shifted to the target phase to generate a second carrier with respect to the second and third phases of the motor.

[0071] At step 306, the phase voltages corresponding to the three phases are generated based on the magnitude relationship between the modulation waves of the three phases of the motor and the carrier waves of the corresponding phases.

[0072] At step 308, the first sampling window is determined based on the phase voltages corresponding to the three phases respectively;

[0073] In step 310, the second phase current and the third phase current are determined at the first sampling window, and the first phase current is reconstructed based on the second phase current and the third phase current.

[0074] For details on the specific implementation of method 300, please refer to the previous description of device 200.

[0075] At step 302, control unit 202 performs cyclic counting based on a target limit value to construct a sawtooth wave, the target limit value being related to the period of the first carrier wave. Control unit 202 includes, for example, a first counting unit that performs cyclic counting based on the target limit value to construct the sawtooth wave.

[0076] Reference Figure 2In some embodiments, the first counting unit of the control unit 202 cyclically counts downwards between a target limit value and a first value, where the first value is less than the target limit value. For example, at time T0, the count value corresponding to the first counting unit is set to the target limit value. Then, the first counting unit counts downwards according to a predetermined clock, i.e., the count value of the first counting unit gradually decreases. For example, at time T1, the count value corresponding to the first counting unit is decreased to the first value (i.e., the minimum count value). Time T1 is, for example, earlier than time T2, and the time that time T1 is earlier than time T2 corresponds to a clock cycle corresponding to a predetermined clock. Then, at the next clock cycle of time T1 (i.e., time T2), the count value corresponding to the first counting unit is again set to the target limit value. The first counting unit cyclically counts in this manner. The count value of the first counting unit is used to generate a sawtooth wave, which is, for example, a first carrier wave (e.g., U_C) with respect to the first phase of the motor 102. In some embodiments, the count value output by the first counting unit is, for example, formed into a sawtooth wave after passing through a DAC (digital-to-analog converter). It should be understood that the period of the first carrier U_C is determined by the target limit value, the first value, and the period of the predetermined clock (related to the frequency of the counting clock). In some embodiments, the clock period corresponding to the predetermined clock is, for example, 0.1ms, which corresponds to a frequency of 10kHz.

[0077] At step 304, the control unit 202 shifts the first carrier U_C phase to the target phase to generate a second carrier with respect to the second and third phases of the motor 102.

[0078] In some embodiments, the magnitude of the target phase is positively correlated with the period of the first carrier. For example, the larger the period of the first carrier, the larger the target phase.

[0079] In some implementations, the ratio between the magnitude of the target phase and the period of the first carrier is, for example, within a predetermined range.

[0080] In some embodiments, the control unit 202 further includes, for example, a phase counter and a second counting unit. The phase shift of the corresponding target phase can be achieved by counting with the phase counter. For example, when the count value corresponding to the first counting unit is set to the target limit value, the phase counter starts counting from an initial value (e.g., 0). When the phase counter counts to the target phase value, the count value corresponding to the second counting unit is set to the target limit value, and counting begins downwards according to a predetermined clock, i.e., the count value of the second counting unit gradually decreases. After the count value corresponding to the second counting unit is decreased to a first value (i.e., the minimum count value), the count value corresponding to the second counting unit is set to the target limit value again, and the second counting unit counts cyclically in this manner. The count value of the second counting unit is used to generate a sawtooth wave, which serves, for example, as a second carrier wave (e.g., V_C and W_C) for the second and third phases of the motor 102. In some embodiments, the count value output by the second counting unit is, for example, generated by a DAC (digital-to-analog converter) to form the sawtooth wave.

[0081] Then, at step 306, the control unit 202 generates the phase voltages corresponding to the three phases based on the magnitude relationship between the modulation waves of the three phases of the motor 102 and the carrier waves of the corresponding phases.

[0082] The three-phase modulation waves of the motor 102 include, for example, a first-phase modulation wave (e.g., U_M), a second-phase modulation wave (e.g., V_M), and a third-phase modulation wave (e.g., W_M). The three-phase modulation waves of the motor 102 are calculated based on current reference values, current feedback values, and electrical angle values ​​related to the motor 102. It should be understood that the three-phase modulation waves of the motor 102 exhibit, for example, sinusoidal characteristics. In some embodiments, the period of the three-phase modulation waves of the motor 102 is, for example, 20 ms (milliseconds), corresponding to a frequency of 50 Hz (Hertz).

[0083] The control unit 202 may also include, for example, a first comparator. The non-inverting input of the first comparator is used to receive a first carrier wave (e.g., U_C), the inverting input is used to receive a first-phase modulated wave (e.g., U_M), and the output is used to output a first-phase voltage (e.g., CTR_U) for controlling the complementary switching of the upper and lower bridges of the first phase. For example, when the first-phase voltage (e.g., CTR_U) is at a high level, the upper bridge of the first phase (e.g., the first MOSFET 141) is turned on, and the lower bridge of the first phase (e.g., the second MOSFET 142) is turned off.

[0084] Similarly, the control unit 202 also includes, for example, a second comparator. The non-inverting input of the second comparator is used to receive a second carrier wave (e.g., represented by V_C), the inverting input is used to receive a second-phase modulated wave (e.g., V_M), and the output is used to output a second-phase voltage (e.g., CTR_V) for controlling the complementary switching of the upper and lower bridges of the second phase. For example, when the second-phase voltage (e.g., CTR_V) is high, the upper bridge of the second phase (e.g., the third MOSFET 143) is turned on, and the lower bridge of the second phase (e.g., the fourth MOSFET 144) is turned off.

[0085] The control unit 202 further includes, for example, a third comparator. The non-inverting input of the third comparator is used to receive a second carrier wave (e.g., represented by W_C), the inverting input is used to receive a third-phase modulated wave (e.g., W_M), and the output is used to output a third-phase voltage (e.g., CTR_W) for controlling the complementary switching of the upper and lower bridges of the third phase. For example, when the third-phase voltage (e.g., CTR_W) is high, the upper bridge of the third phase (e.g., the fifth MOSFET 145) is turned on, and the lower bridge of the third phase (e.g., the sixth MOSFET 146) is turned off.

[0086] It is worth noting that, for ease of understanding, Figure 2 as well as Figure 3 The second carrier wave is illustrated as V_C corresponding to the second phase and W_C corresponding to the third phase, respectively, to facilitate illustrating the relationship between the second phase voltage CTR_V and V_C with respect to the second phase modulation wave V_M, and the relationship between the third phase voltage CTR_W and W_C with respect to the third phase modulation wave W_M. In actual implementation, the second carrier wave can be represented by the same signal, which is transmitted to the second comparator and the third comparator for comparison with the second phase modulation wave V_M and the third phase modulation wave W_M, respectively.

[0087] Next, in step 308, the control unit 202 determines the first sampling window SW based on the phase voltages corresponding to the three phases of the motor 102.

[0088] The determination of the first sampling window based on the phase voltages of the three phases includes: configuring the phase voltages of the three phases such that the upper bridge of the first phase of the motor inverter is turned on, and the lower bridge of the second and third phases of the motor inverter is turned on, as the first sampling window.

[0089] For example, in the time window corresponding to the time interval SW, the phase voltages of the three phases are configured to enable the upper bridge of the first phase of the motor inverter to conduct, and to enable the lower bridge of the second and third phases of the motor inverter to conduct. Therefore, the time window corresponding to the time interval SW is used as the first sampling window SW.

[0090] It is worth noting that the first sampling window can be determined using logic circuits (such as combinational logic circuits and sequential logic circuits) based on the phase voltages of the three phases (e.g., the first phase voltage CTR_U, the second phase voltage CTR_V, and the third phase voltage CTR_W). For example, the first sampling window corresponds to the time window when the first phase voltage CTR_U is in the first state (e.g., a high-level state, meaning the upper bridge of the first phase of the motor inverter is turned on and the lower bridge of the first phase is turned off), and the second phase voltage CTR_V and the third phase voltage CTR_W are both in the second state (e.g., a low-level state, meaning the lower bridges of the second and third phases of the motor inverter are turned on and the upper bridges of the second and third phases are turned off).

[0091] Next, in step 310, the control unit 202 determines the second phase current and the third phase current at the first sampling window, and reconstructs the first phase current based on the second phase current and the third phase current.

[0092] For example, the sampling unit samples the sampling voltages output by the first sampling resistor R1 and the second sampling resistor R2 at the first sampling window, so that the control unit 202 determines the second phase current based on the sampling voltage with respect to the first sampling resistor and determines the third phase current based on the sampling voltage with respect to the second sampling resistor at the first sampling window.

[0093] For example, the first sampling unit 221 is electrically connected to the first sampling resistor R1 and is used to detect the first sampling voltage of the first sampling resistor R1. It should be understood that the first sampling voltage is related to the second phase current. The second sampling unit 222 is electrically connected to the second sampling resistor R2 and is used to detect the second sampling voltage of the second sampling resistor R2. It should be understood that the second sampling voltage is related to the third phase current.

[0094] The control unit 202 acquires the first sampling voltage detected by the first sampling unit 221 and the second sampling voltage detected by the second sampling unit 222 at the first sampling window, and determines the second phase current based on the first sampling voltage and the first sampling resistor R1, and determines the third phase current based on the second sampling voltage and the second sampling resistor R2. It is worth noting that the control unit 202 can acquire the first sampling voltage detected by the first sampling unit 221 and the second sampling voltage detected by the second sampling unit 222 at appropriate sampling times within the first sampling window SW, in order to obtain stable sampling voltage values.

[0095] It is worth noting that using the same sampling window to sample the currents of two phases can save sampling time and improve the efficiency of reconstructing the three-phase current. Furthermore, it facilitates the coordinated setting of the target phase to form a reasonable duration corresponding to the first sampling window (or the ratio of the duration of the first sampling window to the period corresponding to the first phase voltage CTR_U), thereby enabling stable sampling of the second and third phase currents and thus providing accuracy in reconstructing the three-phase current.

[0096] For example, control unit 202 reconstructs the first phase current based on Kirchhoff's current law, using the second-phase current and the third-phase current. Kirchhoff's current law can be represented by the following formula:

[0097] Iu + Iv + Iw = 0

[0098] It should be understood that the magnitude of the target phase shift of the second carrier relative to the first carrier can be adjusted, for example, by using the magnitude of the set target phase value.

[0099] In some embodiments, the ratio between the magnitude of the target phase and the period of the first carrier is, for example, within a predetermined proportional range. For instance, the ratio between the magnitude of the target phase and the period of the first carrier can be adjusted by adjusting the target phase value so that the ratio is within a predetermined proportional range, thereby facilitating stable sampling of the second and third phase currents and providing accuracy in reconstructing the three-phase currents.

[0100] In some embodiments, the device 200 further includes a modulation wave determination unit (not shown) configured to calculate a modulation wave for the three phases of the motor based on a current reference value, a current feedback value, and an electrical angle value.

[0101] Reference Figure 3In some embodiments, at step 302, the first counting unit of the control unit 202 cyclically counts upwards between a first value and a target limit value, where the first value is less than the target limit value. For example, at time T0, the count value corresponding to the first counting unit is set to the first value (i.e., the minimum count value). Then, the first counting unit counts downwards according to a predetermined clock, i.e., the count value of the first counting unit gradually increases. For example, at time T1, the count value corresponding to the first counting unit is increased to the target limit value. Time T1 is, for example, earlier than time T2, and the time that time T1 is earlier than time T2 corresponds to a clock cycle corresponding to a predetermined clock. Then, at the next clock cycle of time T1 (i.e., time T2), the count value corresponding to the first counting unit is again set to the first value. The first counting unit cyclically counts in this manner. The count value of the first counting unit is used to generate a sawtooth wave, which is, for example, a first carrier wave (e.g., U_C) with respect to the first phase of the motor 102. In some embodiments, the count value output by the first counting unit is, for example, formed into a sawtooth wave after passing through a DAC (digital-to-analog converter). It should be understood that the period of the first carrier U_C is determined by the target limit value, the first value, and the period of the predetermined clock (related to the frequency of the counting clock). In some embodiments, the clock period corresponding to the predetermined clock is, for example, 0.1ms, which corresponds to a frequency of 10kHz.

[0102] In some embodiments, when the count value corresponding to the first counting unit is set to a first value (i.e., the minimum count value), the phase counter starts counting from an initial value (e.g., 0). When the phase counter counts to a phase target value, the count value corresponding to the second counting unit is set to the first value (i.e., the minimum count value), and starts counting upwards according to a predetermined clock, i.e., the count value of the second counting unit gradually increases. After the count value corresponding to the second counting unit increases to the target limit value, the count value corresponding to the second counting unit is set to the first value again, and the second counting unit counts cyclically in this manner. The count value of the second counting unit is used to generate a sawtooth wave, which is, for example, a second carrier wave (e.g., V_C and W_C) for the second and third phases of the motor 102. In some embodiments, the count value output by the second counting unit is, for example, generated by a DAC (digital-to-analog converter) to form a sawtooth wave.

[0103] The control unit 202 may also include, for example, a first comparator. The inverting input of the first comparator is used to receive a first carrier wave (e.g., U_C), the non-inverting input is used to receive a first-phase modulated wave (e.g., U_M), and the output is used to output a first-phase voltage (e.g., CTR_U) for controlling the complementary switching of the upper and lower bridges of the first phase. For example, when the first-phase voltage (e.g., CTR_U) is at a high level, the upper bridge of the first phase (e.g., the first MOSFET 141) is turned on, and the lower bridge of the first phase (e.g., the second MOSFET 142) is turned off.

[0104] Similarly, the control unit 202 may also include, for example, a second comparator. The inverting input of the second comparator is used to receive a second carrier wave (e.g., V_C and W_C), the non-inverting input is used to receive a second-phase modulated wave (e.g., V_M), and the output is used to output a second-phase voltage (e.g., CTR_V) for controlling the complementary switching of the upper and lower bridges of the second phase. For example, when the second-phase voltage (e.g., CTR_V) is high, the upper bridge of the second phase (e.g., the third MOSFET 143) is turned on, and the lower bridge of the second phase (e.g., the fourth MOSFET 144) is turned off.

[0105] The control unit 202 further includes, for example, a third comparator. The inverting input of the third comparator is used to receive a second carrier wave (e.g., V_C and W_C), the non-inverting input is used to receive a third-phase modulated wave (e.g., W_M), and the output is used to output a third-phase voltage (e.g., CTR_W) for controlling the complementary switching of the upper and lower bridges of the third phase. For example, when the third-phase voltage (e.g., CTR_W) is high, the upper bridge of the third phase (e.g., the fifth MOSFET 145) is turned on, and the lower bridge of the third phase (e.g., the sixth MOSFET 146) is turned off.

[0106] in, Figure 5 A schematic block diagram of an example electronic device 600 for processing a target object, which can be used to implement embodiments of the present disclosure, is shown. As shown, the electronic device 600 includes a central processing unit (i.e., CPU 601), which can perform various appropriate actions and processes according to computer program instructions stored in read-only memory (i.e., ROM 602) or loaded from storage unit 608 into random access memory (i.e., RAM 603). Various programs and data required for the operation of the electronic device 600 may also be stored in RAM 603. The CPU 601, ROM 602, and RAM 603 are interconnected via bus 604. Input / output interfaces (i.e., I / O interfaces 605) are also connected to bus 604.

[0107] Multiple components in electronic device 600 are connected to I / O interface 605, including: input unit 606, such as keyboard, mouse, microphone, etc.; output unit 607, such as various types of displays, speakers, etc.; storage unit 608, such as disk, optical disk, etc.; and communication unit 609, such as network card, modem, wireless transceiver, etc. Communication unit 609 allows electronic device 600 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0108] The various processes and procedures described above, such as method 500, can be executed by CPU 601. For example, in some embodiments, method 500 can be implemented as a computer software program tangibly contained in a machine-readable medium, such as storage unit 608. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 600 via ROM 602 and / or communication unit 609. When the computer program is loaded into RAM 603 and executed by CPU 601, one or more actions of method 500 described above can be performed.

[0109] This disclosure relates to methods, apparatus, systems, electronic devices, computer-readable storage media, and / or computer program products. A computer program product may include computer-readable program instructions for performing various aspects of this disclosure.

[0110] In some embodiments, the method 500 described above can be implemented as a computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for performing various aspects of this disclosure.

[0111] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0112] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge computing devices. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to computer-readable storage media within the respective computing / processing device.

[0113] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0114] Various aspects of this disclosure are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer-readable program instructions.

[0115] These computer-readable program instructions can be provided to a processing unit of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that, when executed by the processing unit of the computer or other programmable data processing apparatus, they create means for implementing the functions / actions specified in one or more blocks of the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium that causes a computer, programmable data processing apparatus, and / or other device to operate in a particular manner. Thus, the computer-readable medium storing the instructions comprises an article of manufacture that includes instructions for implementing aspects of the functions / actions specified in one or more blocks of the flowchart and / or block diagram.

[0116] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the instructions executed on the computer, other programmable data processing apparatus, or other device to perform the functions / actions specified in one or more boxes of a flowchart and / or block diagram.

[0117] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of an instruction, which contains one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0118] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

[0119] The above are merely optional embodiments of this disclosure and are not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A method for reconstructing three-phase currents of an electrical machine, characterized in that, The method comprises: constructing a sawtooth wave as a first carrier wave for a first phase of the motor; phase-shifting the first carrier wave by a target phase to generate a second carrier wave for a second phase and a third phase of the motor; generating a corresponding phase voltage for each of the three phases of the motor according to a magnitude relationship between a modulation wave for the three phases of the motor and the corresponding carrier wave; determining a first sampling window according to the corresponding phase voltage for each of the three phases; and determining a second phase current and a third phase current at the first sampling window, and reconstructing a first phase current according to the second phase current and the third phase current. The determining of the first sampling window according to the corresponding phase voltage for each of the three phases comprises: configuring the corresponding phase voltage for each of the three phases such that a time window corresponding to a time when an upper bridge of a first phase of an inverter of the motor is turned on and a lower bridge of a second phase and a third phase of the inverter of the motor is turned on is the first sampling window. The determining of the first sampling window according to the corresponding phase voltage for each of the three phases comprises: determining the second phase current according to a sampling voltage for a first sampling resistor and determining the third phase current according to a sampling voltage for a second sampling resistor at the first sampling window, wherein the first sampling resistor is connected in series with the lower bridge of the second phase of the inverter of the motor, and the second sampling resistor is connected in series with the lower bridge of the third phase of the inverter of the motor.

2. The method of claim 1, wherein, The magnitude of the target phase is positively correlated with the period of the first carrier wave.

3. The method of claim 1, wherein, The constructing of the sawtooth wave comprises: counting up to a target limit value to construct the sawtooth wave, the target limit value being related to the period of the first carrier wave.

4. The method of claim 1, wherein, The modulation wave for the three phases of the motor is calculated according to a current reference value, a current feedback value and an electrical angle value of the motor.

5. The method of claim 3, wherein, The counting up to the target limit value to construct the sawtooth wave comprises any one of: counting up between a first value and the target limit value; and counting down between the target limit value and the first value, the first value being less than the target limit value. The reconstructing of the first phase current according to the second phase current and the third phase current comprises:

6. The method of claim 1, wherein, reconstructing the first phase current according to the second phase current and the third phase current based on Kirchhoff's current law. The apparatus comprises:

7. An apparatus for reconstructing three-phase currents of an electrical machine, characterized in that a first sampling resistor connected in series with a lower bridge of a second phase of an inverter of the motor; a second sampling resistor connected in series with a lower bridge of a third phase of the inverter of the motor; and a control unit electrically connected with the first sampling resistor and the second sampling resistor, the control unit being configured to reconstruct a first phase current of the motor according to the method of any one of claims 1 to 6. The control unit comprises:

8. The apparatus of claim 7, wherein, a counting unit configured to count up to a target limit value to construct a sawtooth wave, the target limit value being related to a period of a first carrier wave. The apparatus further comprises a modulation wave determination unit configured to calculate a modulation wave for three phases of the motor according to a current reference value, a current feedback value and an electrical angle value of the motor.

9. The apparatus of claim 7, wherein, ​

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