Motor phase current sampling method and device, chip and motor controller

Abstract

The invention discloses a motor phase current sampling method and device, a chip and a motor controller, and the method comprises the steps: obtaining the duty ratio of a multi-phase bridge arm in a pulse modulation period; determining a to-be-sampled bridge arm according to the duty ratio; sampling a motor phase voltage corresponding to the to-be-sampled bridge arm in a target sampling time period corresponding to the to-be-sampled bridge arm, and determining a corresponding motor neutral point voltage; wherein the target sampling time period is a time period from the start of a dead zone corresponding to the to-be-sampled bridge arm to the completion of follow current; and determining a motor phase current corresponding to the to-be-sampled bridge arm according to the motor phase voltage corresponding to the to-be-sampled bridge arm and the corresponding motor neutral point voltage. According to the method, the sampling function of the motor phase current can be realized without phase shift and sampling point calculation, the algorithm is simple, harmonic waves are not generated, and the phase current sampling cost is relatively low.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular to a motor phase current sampling method and device, a chip, and a motor controller. Background Art

[0002] In the field of motor control, motor phase current has always been one of the important control parameters. During the operation of the motor, by monitoring the phase current signal of the motor, the load condition, speed, power, efficiency and other parameters of the motor can be understood, thereby realizing the control and protection of the motor. At present, the relevant technology usually adopts the single resistor sampling method to obtain the motor phase current. This method does not require the use of relatively expensive current sensors and has low hardware costs, so it is widely used. However, due to the complexity of the algorithm of the single resistor sampling method and the need to perform phase shifting and sampling point calculations during the sampling process of the phase current, this not only consumes a lot of computing resources, but also generates large harmonic noise and interferes with motor control, resulting in the high sampling cost of the motor phase current. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the first purpose of the present invention is to propose a motor phase current sampling method, which obtains the duty cycle of the multi-phase bridge arm in the motor controller in a pulse modulation cycle, and determines the bridge arm to be sampled according to the duty cycle, and then collects the motor phase voltage corresponding to the bridge arm to be sampled within the target sampling period corresponding to the bridge arm to be sampled, and determines the corresponding motor neutral point voltage, and finally determines the motor phase current corresponding to the bridge arm to be sampled according to the motor phase voltage and motor neutral point voltage corresponding to the bridge arm to be sampled, thereby realizing the sampling function of the motor phase current without the need for phase shifting and sampling point calculation, avoiding the problem of possible harmonic generation and interference with the motor operation, and the algorithm is simple and consumes less computing resources, thereby effectively reducing the phase current sampling cost of the motor.

[0004] A second objective of the present invention is to provide a motor phase current sampling device.

[0005] The third object of the present invention is to provide a chip.

[0006] A fourth objective of the present invention is to provide a motor controller.

[0007] A fifth object of the present invention is to provide an electrical device.

[0008] To achieve the above-mentioned purpose, an embodiment of the first aspect of the present invention proposes a motor phase current sampling method, which is applied to a motor controller, and the motor controller includes a multi-phase bridge arm. The method includes: obtaining the duty cycle of the multi-phase bridge arm in a pulse modulation cycle; determining the bridge arm to be sampled based on the duty cycle; within the target sampling period corresponding to the bridge arm to be sampled, sampling the motor phase voltage corresponding to the bridge arm to be sampled, and determining the corresponding motor neutral point voltage; wherein the target sampling period is the period from the start of the dead zone corresponding to the bridge arm to be sampled to the completion of the freewheeling; determining the motor phase current corresponding to the bridge arm to be sampled based on the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage.

[0009] According to the motor phase current sampling method of the embodiment of the present invention, the duty cycle of the multi-phase bridge arm in the motor controller is obtained in a pulse modulation cycle, and the bridge arm to be sampled is determined according to the duty cycle. Subsequently, within the target sampling period corresponding to the bridge arm to be sampled, the motor phase voltage corresponding to the bridge arm to be sampled is collected, and the corresponding motor neutral point voltage is determined. Finally, the motor phase current corresponding to the bridge arm to be sampled is determined according to the motor phase voltage and the motor neutral point voltage corresponding to the bridge arm to be sampled. In this way, the sampling function of the motor phase current is realized without the need for phase shifting and sampling point calculation, avoiding the problem of possible harmonic generation and interference with the motor operation. In addition, the algorithm is simple and consumes less computing resources, thereby effectively reducing the phase current sampling cost of the motor.

[0010] According to one embodiment of the present invention, the multi-phase bridge arm includes a three-phase bridge arm, the duty cycle includes a minimum duty cycle, an intermediate duty cycle and a maximum duty cycle, and the bridge arm to be sampled is determined according to the duty cycle, including: taking the bridge arm corresponding to the minimum duty cycle and the intermediate duty cycle as the bridge arm to be sampled.

[0011] According to one embodiment of the present invention, determining the corresponding motor neutral point voltage includes: when the bridge arm to be sampled is the bridge arm corresponding to the minimum duty cycle, the motor neutral point voltage is the DC bus voltage of the motor controller; when the bridge arm to be sampled is the bridge arm corresponding to the intermediate duty cycle, the motor neutral point voltage is half the DC bus voltage.

[0012] According to one embodiment of the present invention, the motor phase current corresponding to the bridge arm to be sampled is determined based on the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage, including: obtaining the voltage difference between the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage; obtaining the ratio of the voltage difference to the resistance of the motor winding corresponding to the bridge arm to be sampled, and obtaining the motor phase current corresponding to the bridge arm to be sampled.

[0013] According to one embodiment of the present invention, the method further includes: determining the direction of the motor phase current based on the voltage difference; wherein, when the difference is greater than zero, the motor phase current flows from the motor controller to the motor; when the difference is less than zero, the motor phase current flows from the motor to the motor controller.

[0014] According to one embodiment of the present invention, the target sampling period includes multiple target sampling periods, and within the target sampling period corresponding to the bridge arm to be sampled, the motor phase voltage corresponding to the bridge arm to be sampled is sampled, including: sampling in each target time period within at least one target sampling period to obtain at least one motor phase voltage sampling value corresponding to the bridge arm to be sampled; and determining the motor phase voltage corresponding to the bridge arm to be sampled based on at least one motor phase voltage sampling value.

[0015] According to one embodiment of the present invention, the motor phase voltage corresponding to the bridge arm to be sampled is determined based on at least one motor phase voltage sampling value, including: converting at least one motor phase voltage sampling value to obtain at least one motor phase voltage actual value; obtaining the average value of at least one motor phase voltage actual value to obtain the motor phase voltage corresponding to the bridge arm to be sampled.

[0016] According to one embodiment of the present invention, the method further includes: calculating the motor phase current corresponding to the remaining bridge arms based on the motor phase current corresponding to the bridge arm to be sampled; wherein the remaining bridge arms are the bridge arms in the multi-phase bridge arms except the bridge arm to be sampled.

[0017] To achieve the above-mentioned purpose, the second embodiment of the present invention proposes a motor phase current sampling device, which is applied to a motor controller, and the motor controller includes a multi-phase bridge arm. The device includes: a first acquisition module, which is used to obtain the duty cycle of the multi-phase bridge arm in a pulse modulation cycle; a first determination module, which is used to determine the bridge arm to be sampled according to the duty cycle; a second acquisition module, which is used to sample the motor phase voltage corresponding to the bridge arm to be sampled within the target sampling period corresponding to the bridge arm to be sampled, and determine the corresponding motor neutral point voltage; wherein the target sampling period is the period from the start of the dead zone corresponding to the bridge arm to be sampled to the completion of the freewheeling; the second determination module is used to determine the motor phase current corresponding to the bridge arm to be sampled based on the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage.

[0018] According to the motor phase current sampling device of the embodiment of the present invention, in one pulse modulation cycle, the duty cycle of the multi-phase bridge arm in the motor controller is obtained by using the first acquisition module, and the bridge arm to be sampled is determined according to the duty cycle by the first determination module. Subsequently, in the target sampling period corresponding to the bridge arm to be sampled, the motor phase voltage corresponding to the bridge arm to be sampled is collected by the second acquisition module, and the corresponding motor neutral point voltage is determined. Finally, the second determination module determines the motor phase current corresponding to the bridge arm to be sampled according to the motor phase voltage and the motor neutral point voltage corresponding to the bridge arm to be sampled. Thus, the sampling function of the motor phase current is realized without the need for phase shifting and sampling point calculation, thereby avoiding the problem of possible harmonic generation and interference with the motor operation. In addition, the algorithm is simple and consumes less computing resources, thereby effectively reducing the phase current sampling cost of the motor.

[0019] To achieve the above-mentioned object, a third embodiment of the present invention provides a chip including the aforementioned motor phase current sampling device.

[0020] According to the chip of the embodiment of the present invention, through the aforementioned motor phase current sampling device, the sampling function of the motor phase current can be realized without phase shifting and sampling point calculation, thereby avoiding the problem of harmonics generated by the motor controller due to phase current sampling. In addition, the algorithm is simple and the chip computing power requirements are low, thereby reducing the motor phase current sampling cost of the chip.

[0021] To achieve the above-mentioned objectives, a fourth embodiment of the present invention proposes a motor controller, including the aforementioned motor phase current sampling device, or the aforementioned chip.

[0022] According to the motor controller of the embodiment of the present invention, the aforementioned motor phase current sampling device or chip can realize the sampling function of the motor phase current without phase shifting, thereby avoiding the problem of harmonics generated by the motor controller due to phase current sampling, and the phase current sampling method is simple and easy to implement, thereby reducing the motor phase current sampling cost of the motor controller.

[0023] To achieve the above-mentioned purpose, a fifth embodiment of the present invention proposes an electrical device, including the aforementioned motor phase current sampling device, or the aforementioned chip, or the aforementioned motor controller.

[0024] According to the electrical equipment of the embodiment of the present invention, through the aforementioned motor phase current sampling device, or the aforementioned chip, or the aforementioned motor controller, the phase current sampling function of the motor in the electrical equipment can be realized without phase shifting, thereby avoiding the problem of harmonics generated by phase current sampling. In addition, the phase current sampling method is simple and easy to implement, thereby reducing the cost of motor phase current sampling of the electrical equipment.

[0025] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a structural diagram of a motor controller according to an embodiment of the present invention;

[0027] Figure 2 is a flow chart of a motor phase current sampling method according to an embodiment of the present invention;

[0028] Figure 3 Schematic diagram of the duty cycle of a multi-phase bridge arm in a single pulse modulation cycle according to an embodiment of the present invention;

[0029] Figure 4 is a circuit diagram of a single-ended sampling circuit according to an embodiment of the present invention;

[0030] Figure 5 2 is a schematic structural diagram of a motor phase current sampling device according to an embodiment of the present invention;

[0031] Figure 6 is a schematic structural diagram of a chip according to an embodiment of the present invention;

[0032] Figures 7a-7b is a schematic structural diagram of a motor controller according to some embodiments of the present invention;

[0033] Figures 8a to 8c Schematic diagram of the structure of electrical equipment according to some embodiments of the present invention. DETAILED DESCRIPTION

[0034] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0035] The following describes a motor phase current sampling method, a motor phase current sampling device, a chip, a motor controller, and an electrical device proposed in embodiments of the present invention with reference to the accompanying drawings.

[0036] It should be noted that the motor phase current sampling method of the embodiment of the present invention can be applied to a motor controller with a multi-phase bridge arm. Figure 1 The motor controller shown in FIG. 1 is used as an example to illustrate the motor phase current sampling method according to an embodiment of the present invention. Figure 1 As shown, the motor controller 100 includes three-phase bridge arms, namely a U-phase bridge arm, a W-phase bridge arm, and a V-phase bridge arm, which are connected to one end of the U-phase winding U, the W-phase winding W, and the V-phase winding V of the motor M. The other ends of the U-phase winding U, the W-phase winding W, and the V-phase winding V are connected and have a motor center point N. Each phase bridge arm includes an upper bridge arm and a lower bridge arm, and the upper bridge arms of the three-phase bridge arms are all connected to the DC bus power supply VBUS, and the lower bridge arms of the three-phase bridge arms are all grounded GND. The upper bridge arm also includes an upper bridge arm switch tube QU with a freewheeling diode in parallel, and the lower bridge arm also includes a lower bridge arm switch tube QD with a freewheeling diode in parallel.

[0037] Specifically, refer to Figure 1 As shown, the motor controller 100 constitutes a typical three-phase inverter circuit. By controlling the on-off of the six switching tubes in the three-phase bridge arm, the motor controller 100 can convert the DC power provided by the DC bus power supply VBUS into three-phase AC power, and then control the rotation of the motor M to realize the control function of the motor. The specific control logic is not expanded here.

[0038] Figure 2 is a flow chart of a motor phase current sampling method according to an embodiment of the present invention, referring to Figure 2 As shown, the method includes:

[0039] S11, obtaining the duty cycle of the multi-phase bridge arm in one pulse modulation cycle.

[0040] Specifically, pulse modulation is a voltage output modulation method of the motor controller, which can be divided into PWM (Pulse Width Modulation), PAM (Pulse Amplitude Modulation), etc. according to the changed pulse properties. Among them, the pulse modulation period refers to the carrier period of the pulse modulation method. Taking PWM modulation as an example, a pulse modulation period is Figure 3 The triangle wave period T0 to T1 is shown. In motor control, the duty cycle of each phase bridge arm will change in different pulse modulation cycles, and this change will cause the motor phase voltage and phase current corresponding to the multi-phase bridge arm to change. Therefore, the duty cycle of the multi-phase bridge arm in a pulse modulation cycle can be obtained as a basis for subsequently determining the bridge arm to be sampled. Among them, the duty cycle of the multi-phase bridge arm can be obtained in a variety of ways, such as by looking up a table, or by calculating and obtaining by phase voltage sampling and voltage vector decomposition, etc., which are not limited here.

[0041] S12, determining the bridge arm to be sampled according to the duty cycle.

[0042] Specifically, the bridge arm to be sampled refers to one or more bridge arms in the multi-phase bridge arm that can perform phase voltage sampling. Since the phase voltage of one or more phases may be negative when the motor is working normally, and the phase voltage sampling circuit is usually unable to sample negative voltage, if the phase voltage of the multi-phase winding is directly sampled, the phase voltage mismeasurement problem will occur. Therefore, the neutral point voltage of the motor in different time periods can be analyzed based on the duty cycle of the three-phase bridge arm, and then the bridge arm corresponding to the negative motor phase voltage may be determined based on the neutral point voltage of the motor, and the other bridge arms except this bridge arm are used as the bridge arms to be sampled to avoid possible phase voltage mismeasurement problems, thereby ensuring the accuracy of the phase current sampling method.

[0043] S13, within the target sampling period corresponding to the bridge arm to be sampled, sampling the motor phase voltage corresponding to the bridge arm to be sampled, and determining the corresponding motor neutral point voltage; wherein the target sampling period is the period from the start of the dead zone corresponding to the bridge arm to be sampled to the completion of freewheeling.

[0044] Specifically, the dead time refers to the off period artificially set when the upper and lower bridge switches of the single-phase bridge arm are switched on to avoid the problem of the upper and lower bridge switches being turned on at the same time, such as Figure 3 The periods t0 to t2 and t3 to t5 shown are the dead time of the U-phase bridge arm. After the dead time of each phase bridge arm begins, the freewheeling diode in that phase bridge arm will continue to flow to ensure stable operation of the motor. The target sampling period refers to the period from the start of the corresponding dead time to the completion of the freewheeling of the bridge arm to be sampled. For example, when the U-phase bridge arm is the bridge arm to be sampled, Figure 3 The periods t0-t1 and t3-t4 shown are the target sampling periods for the U-phase bridge arm. During these periods, since the freewheeling diode has not yet completed freewheeling, no freewheeling current is generated within it, and both the upper and lower bridge switches of the bridge arm to be sampled are off, the bridge arm to be sampled can be considered high-impedance. At this point, the phase current in the motor winding corresponding to the bridge arm to be sampled remains at the same level as before the dead time due to the inductance of the motor winding. Therefore, the motor phase voltage corresponding to the bridge arm to be sampled is generated by the phase current in the corresponding winding. Therefore, during the target sampling period corresponding to the bridge arm to be sampled, the motor phase voltage corresponding to the bridge arm to be sampled can be sampled, and the corresponding motor neutral point voltage can be determined to determine the motor phase current in the bridge arm to be sampled. The motor neutral point voltage can be determined based on the connections within the motor controller during the target sampling period.

[0045] In some embodiments, the multi-phase bridge arm includes a three-phase bridge arm, the duty cycle includes a minimum duty cycle, an intermediate duty cycle and a maximum duty cycle, and the bridge arm to be sampled is determined according to the duty cycle, including: taking the bridge arm corresponding to the minimum duty cycle and the intermediate duty cycle as the bridge arm to be sampled.

[0046] Furthermore, the corresponding motor neutral point voltage is determined, including: when the bridge arm to be sampled is the bridge arm corresponding to the minimum duty cycle, the motor neutral point voltage is the DC bus voltage of the motor controller; when the bridge arm to be sampled is the bridge arm corresponding to the intermediate duty cycle, the motor neutral point voltage is half the DC bus voltage.

[0047] Specifically, in a three-phase motor, the neutral point voltage of the motor can be determined by analyzing the connection relationship of the three-phase bridge arms in different time periods. Figure 1In the three-phase motor shown, when the upper switching transistors in all three bridge arms are conducting, the motor's neutral point is connected to the DC bus power supply through the three-phase windings, and the motor's neutral point voltage equals the DC bus voltage. When the upper switching transistors in two of the three bridge arms are conducting and the lower switching transistor in one bridge arm is conducting, the motor's neutral point is connected to the DC bus power supply through the two windings corresponding to the upper switching transistors in the bridge arms and is also connected to ground through the winding corresponding to the lower switching transistor in the bridge arm. Since the internal resistance of the three motor windings is the same, according to the voltage divider principle, the motor's neutral point voltage is equal to two-thirds of the DC bus voltage. When the upper switching tube in one of the three-phase bridge arms is turned on and the lower switching tubes in two of the three-phase bridge arms are turned on, the motor's neutral point is connected to the DC bus power supply through the winding corresponding to the upper switching tube in the bridge arm and is also connected to ground through the windings corresponding to the lower switching tubes in the bridge arm. Based on the voltage divider principle, the motor's neutral point voltage is equal to one-third of the DC bus voltage. When all three-phase bridge arms have the lower switching tubes turned on, the motor's neutral point is grounded through the three-phase windings, and the motor's neutral point voltage is equal to 0.

[0048] In the embodiment of the present invention, the neutral point voltage of the motor can be determined based on the connection relationship analysis of the bridge arm to be sampled in the motor controller during the target sampling period. When the bridge arm corresponding to the minimum duty cycle is the bridge arm to be sampled, for example Figure 3 When the U-phase bridge arm shown is the bridge arm to be sampled, during the target sampling period of the U-phase bridge arm, the upper and lower bridge switches of the U-phase bridge arm are both turned off, and the upper bridge switches of the V-phase bridge arm and the W-phase bridge arm are turned on. Since the freewheeling diode in the U-phase bridge arm does not freewheel during the target sampling period, the U-phase bridge arm can be regarded as a high-resistance state. Therefore, the neutral point of the motor can be connected to the DC bus power supply through the V-phase winding and the W-phase winding. Therefore, at this time, the neutral point voltage of the motor is the DC bus voltage of the motor controller.

[0049] When the bridge arm corresponding to the middle duty cycle is the bridge arm to be sampled, for example Figure 3 In the example shown, when the V-phase bridge arm is the bridge arm to be sampled, during the target sampling period of the V-phase bridge arm, both the upper and lower bridge switches of the V-phase bridge arm are off, the lower bridge switch of the U-phase bridge arm is on, and the upper bridge switch of the W-phase bridge arm is on. At this point, the V-phase bridge arm can be considered to be in a high-impedance state. Therefore, the DC bus power supply is grounded through the W-phase winding, the motor neutral point, and the U-phase winding. According to the voltage divider principle, the motor neutral point voltage is half the DC bus voltage.

[0050] When the bridge arm corresponding to the maximum duty cycle is the bridge arm to be sampled, for example Figure 3When the W-phase bridge arm shown is the bridge arm to be sampled, during the target sampling period of the W-phase bridge arm, the upper and lower bridge switches of the W-phase bridge arm are both turned off, while the lower bridge switches of the U-phase bridge arm and the V-phase bridge arm are turned on. At this time, the neutral point of the motor is grounded through the U-phase winding and the V-phase winding, and the neutral point voltage of the motor is 0. Therefore, during the target sampling period of the W-phase bridge arm, if the direction of the motor phase current is from the motor to the motor controller, the motor phase voltage corresponding to the W-phase bridge arm is negative, which will cause the aforementioned phase voltage mismeasurement problem. Therefore, when determining the bridge arm to be sampled based on the duty cycle, the bridge arm corresponding to the minimum duty cycle and the intermediate duty cycle can be used as the bridge arm to be sampled to avoid the phase voltage mismeasurement problem. This achieves the function of determining the motor neutral point voltage corresponding to the bridge arm to be sampled during the target sampling period.

[0051] S14, determining the motor phase current corresponding to the bridge arm to be sampled according to the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage.

[0052] Specifically, the motor phase current corresponding to the bridge arm to be sampled can be determined by Ohm's law based on the motor phase voltage corresponding to the bridge arm to be sampled, the corresponding motor neutral point voltage and the resistance of the motor winding corresponding to the bridge arm to be sampled, so as to realize the function of determining the motor phase current of the bridge arm to be sampled.

[0053] In the current sampling method of related technologies, such as single-resistor sampling, not only is it necessary to set up a sampling resistor and a corresponding op amp circuit, but it is also necessary to determine the phase shift method and calculate the corresponding sampling points based on the duty cycle of the multi-phase bridge arm in each pulse modulation cycle, which will increase the computing resource consumption of phase current sampling. At the same time, phase shifting will also generate harmonic noise and affect motor operation. When the single-resistor sampling method is applied, the motor controller may require an additional denoising unit to remove the harmonic effects brought by the single-resistor sampling. Therefore, the phase current sampling cost brought by the single-resistor sampling method is relatively high. In addition, due to the relevant requirements for the duty cycle size, the single-resistor sampling method cannot be applied to low-speed and light-load scenarios, and its applicability is relatively poor.

[0054] The phase current sampling method of the embodiment of the present invention not only utilizes the existing phase voltage sampling circuit, eliminating the need for additional hardware circuits, but also eliminates the need for phase shifting and sampling point calculations. The algorithm is relatively simple, consumes little computing resources, and avoids the potential generation of harmonics that interfere with motor operation, thereby effectively reducing the cost of motor phase current sampling. Furthermore, the phase current sampling method of the embodiment of the present invention performs sampling within the dead time, with no rigid requirements for duty cycle. Therefore, it can be applied in low-speed and light-load scenarios, thus offering an advantage in applicability.

[0055] In some embodiments, the motor phase current corresponding to the bridge arm to be sampled is determined based on the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage, including: obtaining the voltage difference between the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage; obtaining the ratio of the voltage difference to the resistance of the motor winding corresponding to the bridge arm to be sampled, and obtaining the motor phase current corresponding to the bridge arm to be sampled.

[0056] Specifically, when the motor phase current corresponding to the bridge arm to be sampled flows from the motor controller to the motor, the motor phase voltage corresponding to the bridge arm to be sampled in the target sampling period can be expressed as the following formula (1):

[0057] U1=U2+I*R (1)

[0058] Among them, U1 is the motor phase voltage corresponding to the bridge arm to be sampled, U2 is the motor neutral point voltage, I is the motor phase current corresponding to the bridge arm to be sampled, and R is the resistance of the motor winding corresponding to the bridge arm to be sampled.

[0059] When the direction corresponding to the bridge arm to be sampled is from the motor to the motor controller, the motor phase voltage corresponding to the bridge arm to be sampled in the target sampling period can be expressed as the following formula (2):

[0060] U1=U2-I*R (2)

[0061] The various marks have the same meaning as those in the aforementioned formula (1), and are not described here in detail. From the above formulas (1) and (2), it can be seen that when the motor phase voltage corresponding to the bridge arm to be sampled is obtained by sampling and the motor neutral point voltage is determined, the voltage difference between the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage can be first obtained. This voltage difference is the voltage difference generated by the phase current in the motor winding corresponding to the bridge arm to be sampled. Subsequently, the ratio of the voltage difference to the resistance of the motor winding corresponding to the bridge arm to be sampled is calculated. This ratio is the motor phase current corresponding to the bridge arm to be sampled.

[0062] Optionally, the method further includes: determining the direction of the motor phase current according to the voltage difference. As can be seen from the above formulas (1) and (2), the direction of the corresponding motor phase current can be determined based on the voltage difference between the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage. When the voltage difference is greater than zero, the motor phase voltage corresponding to the bridge arm to be sampled is greater than the corresponding motor neutral point voltage, which conforms to the above formula (1). Then, the direction of the motor phase current is from the motor controller to the motor. When the voltage difference is less than zero, the motor phase voltage corresponding to the bridge arm to be sampled is less than the corresponding motor neutral point voltage, which conforms to the above formula (2). Then, the direction of the motor phase current is from the motor to the motor controller. Thus, the function of determining the direction and magnitude of the motor phase current corresponding to the bridge arm to be sampled based on the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage is realized.

[0063] In some embodiments, the target sampling period includes multiple target sampling periods, and within the target sampling period corresponding to the bridge arm to be sampled, the motor phase voltage corresponding to the bridge arm to be sampled is sampled, including: sampling in each target time period within at least one target sampling period to obtain at least one motor phase voltage sampling value corresponding to the bridge arm to be sampled; determining the motor phase voltage corresponding to the bridge arm to be sampled based on at least one motor phase voltage sampling value.

[0064] Furthermore, the motor phase voltage corresponding to the bridge arm to be sampled is determined based on at least one motor phase voltage sampling value, including: converting at least one motor phase voltage sampling value to obtain at least one motor phase voltage actual value; obtaining the average value of at least one motor phase voltage actual value to obtain the motor phase voltage corresponding to the bridge arm to be sampled.

[0065] Specifically, refer to Figure 3 As shown, there is a target sampling period within each dead time of the bridge arm to be sampled. Therefore, one or more samplings can be performed within each target time period within one or more target sampling periods to obtain one or more motor phase voltage sample values. The more motor phase voltage sample values obtained, the higher the accuracy of the final motor phase voltage determination. The specific number of sampling times can be determined based on actual needs and the duration of the target sampling period.

[0066] After obtaining one or more motor phase voltage sample values, at least one motor phase voltage sample value can be first converted into the corresponding actual motor phase voltage value based on the sampling method. For example, if the motor phase voltage sample values are obtained using a voltage division method, the motor phase voltage sample value can be converted into the actual motor phase voltage value based on the voltage division ratio. Subsequently, the motor phase voltage corresponding to the bridge arm to be sampled can be obtained by averaging or other methods. The motor phase voltage determined by this multiple sampling and averaging method has higher accuracy.

[0067] It should be noted that one or more actual values of the motor phase voltage may also be processed in other ways to obtain the motor phase voltage corresponding to the bridge arm to be sampled, such as interpolation method, etc., which is not specifically limited here.

[0068] Optionally, the motor phase voltage can be sampled by Figure 4 The single-ended sampling circuit and ADC (Analog to Digital Converter) shown in the figure are determined by referring to Figure 4 As shown, the single-ended voltage sampling circuit 200 may include three identical single-ended sampling sub-circuits 210. The three sampling terminals of the single-ended sampling sub-circuit 210 are respectively connected to the JU, JW, and JV nodes of the motor controller 100, wherein the JU, JW, and JV nodes are the output terminals of the corresponding phase AC power of the motor controller 100, and the three sampling points (Vbemf_U, Vbemf_V, Vbemf_W) of the single-ended sampling circuit 210 are respectively connected to the three phase voltage sampling terminals of the ADC. The three single-ended sampling sub-circuits 210 have the same circuit structure. Taking the single-ended sampling sub-circuit 210 of the U-phase bridge arm as an example, the circuit 210 includes first to third resistors R1-R3 and a capacitor C. One end of the first resistor R1 is grounded to GND, and the other end of the first resistor R1 is connected to one end of the second resistor R2 and one end of the third resistor R3, respectively. The other end of the second resistor R2 is connected to the node JU as a sampling end. The other end of the third resistor R3 is connected to one end of the capacitor C and to the U-phase voltage sampling point Vbemf_U of the ADC. The other end of the capacitor C is grounded to GND. The circuit primarily collects the voltage of the upper or lower bridge arm of the U-phase bridge arm as the dead-zone voltage based on the voltage divider principle between the first resistor R1 and the second resistor R2. At the same time, the capacitor C has a voltage stabilizing function, and the third resistor R3 has a current limiting function to prevent excessive current in the single-ended voltage sampling circuit 200.

[0069] Optionally, since it takes a lot of time to obtain the average value through multiple sampling to improve the phase voltage sampling accuracy, a higher resolution ADC can be used to improve the sampling accuracy of the motor phase voltage. Figure 4 In the single-ended sampling circuit shown, a 12-bit ADC can meet the requirements of phase voltage sampling. To further improve the accuracy of motor phase voltage sampling, a 14-bit ADC can be used directly to obtain the phase voltage sampling value. Alternatively, the dead time can be increased and the ADC can be set to oversampling. A 13-bit ADC can be simulated by accumulating two consecutive samples, or a 14-bit ADC can be simulated by accumulating four samples. The specific ADC device selection method can be determined based on the actual cost and accuracy requirements, and is not restricted here.

[0070] In some embodiments, the method further includes: calculating the motor phase current corresponding to the remaining bridge arms based on the motor phase current corresponding to the bridge arm to be sampled; wherein the remaining bridge arms are the bridge arms in the multi-phase bridge arms except the bridge arm to be sampled.

[0071] Specifically, in one pulse modulation cycle, after the motor phase current corresponding to the bridge arm to be sampled is determined, the motor phase current corresponding to the remaining bridge arms can be determined according to Kirchhoff's law. For example, Figure 3 In the pulse modulation cycle shown, the U-phase bridge arm corresponding to the minimum duty cycle and the V-phase bridge arm corresponding to the intermediate duty cycle are the bridge arms to be sampled, and the W-phase bridge arm is the remaining bridge arm. At this time, the motor phase current corresponding to the W-phase bridge arm can be determined according to the following formula (3):

[0072] Ic=0-Ia-Ib (3)

[0073] Wherein, Ic is the motor phase current corresponding to the W-phase bridge arm, Ia is the motor phase current corresponding to the U-phase bridge arm, and Ib is the motor phase current corresponding to the V-phase bridge arm. Thus, the method of the embodiment of the present invention realizes the function of determining the three-phase current of the motor.

[0074] In summary, according to the motor phase current sampling method of an embodiment of the present invention, the duty cycle of the multi-phase bridge arm in the motor controller is obtained in a pulse modulation cycle, and the bridge arm to be sampled is determined according to the duty cycle. Subsequently, within the target sampling period corresponding to the bridge arm to be sampled, the motor phase voltage corresponding to the bridge arm to be sampled is collected, and the corresponding motor neutral point voltage is determined. Finally, the motor phase current corresponding to the bridge arm to be sampled is determined based on the motor phase voltage and the motor neutral point voltage corresponding to the bridge arm to be sampled. The sampling function of the motor phase current is realized without the need for phase shifting and sampling point calculation, avoiding the problem of possible harmonic generation and interference with the motor operation. The algorithm is simple and consumes less computing resources, thereby effectively reducing the phase current sampling cost of the motor.

[0075] Corresponding to the above embodiment, the present invention also provides a motor phase current sampling device, which is applied to Figure 1 The motor controller 100 shown in FIG. Figure 5 As shown, the apparatus 300 includes: a first acquisition module 310 , a first determination module 320 , a second acquisition module 330 and a second determination module 340 .

[0076] Among them, the first acquisition module 310 is used to obtain the duty cycle of the multi-phase bridge arm in a pulse modulation cycle; the first determination module 320 is used to determine the bridge arm to be sampled according to the duty cycle; the second acquisition module 330 is used to sample the motor phase voltage corresponding to the bridge arm to be sampled within the target sampling period corresponding to the bridge arm to be sampled, and determine the corresponding motor neutral point voltage; wherein the target sampling period is the period from the beginning of the dead zone corresponding to the bridge arm to be sampled to the completion of the freewheeling; the second determination module 340 is used to determine the motor phase current corresponding to the bridge arm to be sampled based on the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage.

[0077] According to one embodiment of the present invention, the multi-phase bridge arm includes a three-phase bridge arm, the duty cycle includes a minimum duty cycle, an intermediate duty cycle and a maximum duty cycle, and the first determination module 320 is further used to: use the bridge arm corresponding to the minimum duty cycle and the intermediate duty cycle as the bridge arm to be sampled.

[0078] According to one embodiment of the present invention, the second acquisition module 330 is also used to: when the bridge arm to be sampled is the bridge arm corresponding to the minimum duty cycle, determine that the neutral point voltage of the motor is the DC bus voltage of the motor controller; when the bridge arm to be sampled is the bridge arm corresponding to the intermediate duty cycle, determine that the neutral point voltage of the motor is half the DC bus voltage.

[0079] According to one embodiment of the present invention, the second determination module 340 is also used to: obtain the voltage difference between the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage; obtain the ratio of the voltage difference to the resistance of the motor winding corresponding to the bridge arm to be sampled, and obtain the motor phase current corresponding to the bridge arm to be sampled.

[0080] According to one embodiment of the present invention, the second determination module 340 is further used to: determine the direction of the motor phase current based on the voltage difference; wherein, when the difference is greater than zero, the motor phase current flows from the motor controller to the motor; when the difference is less than zero, the motor phase current flows from the motor to the motor controller.

[0081] According to one embodiment of the present invention, the target sampling period includes multiple periods, and the second acquisition module 330 is further used to: sample and obtain at least one motor phase voltage sampling value corresponding to the bridge arm to be sampled in each target time period within at least one target sampling period; and determine the motor phase voltage corresponding to the bridge arm to be sampled based on at least one motor phase voltage sampling value.

[0082] According to one embodiment of the present invention, the second acquisition module 330 is further used to: convert at least one motor phase voltage sampling value to obtain at least one motor phase voltage actual value; obtain the average value of at least one motor phase voltage actual value to obtain the motor phase voltage corresponding to the bridge arm to be sampled.

[0083] According to one embodiment of the present invention, the second determination module 340 is further used to: calculate the motor phase current corresponding to the remaining bridge arms based on the motor phase current corresponding to the bridge arm to be sampled; wherein the remaining bridge arms are the bridge arms in the multi-phase bridge arms except the bridge arm to be sampled.

[0084] It should be noted that, for the description of the motor phase current sampling device in this application, please refer to the aforementioned description of the motor phase current sampling method, which will not be repeated here.

[0085] According to the motor phase current sampling device of the embodiment of the present invention, in one pulse modulation cycle, the duty cycle of the multi-phase bridge arm in the motor controller is obtained by using the first acquisition module, and the bridge arm to be sampled is determined according to the duty cycle by the first determination module. Subsequently, in the target sampling period corresponding to the bridge arm to be sampled, the motor phase voltage corresponding to the bridge arm to be sampled is collected by the second acquisition module, and the corresponding motor neutral point voltage is determined. Finally, the second determination module determines the motor phase current corresponding to the bridge arm to be sampled according to the motor phase voltage and the motor neutral point voltage corresponding to the bridge arm to be sampled. Thus, the sampling function of the motor phase current is realized without the need for phase shifting and sampling point calculation, thereby avoiding the problem of possible harmonic generation and interference with the motor operation. In addition, the algorithm is simple and consumes less computing resources, thereby effectively reducing the phase current sampling cost of the motor.

[0086] Corresponding to the above embodiment, the embodiment of the present invention further provides a chip, referring to Figure 6 As shown, the chip 1000 includes the aforementioned motor phase current sampling device 300 .

[0087] The chip according to the embodiment of the present invention includes the motor phase current sampling device in the above embodiment. Here, the chip can be a chip for multiple purposes such as motor control, motor phase current sampling, and motor working status monitoring. These chips can implement the motor phase current sampling function through the above-mentioned motor phase current sampling device without phase shifting and sampling point calculation, thereby avoiding the problem of harmonics generated by phase current sampling in the motor controller. In addition, the algorithm is simple and the chip computing power requirements are low, thereby reducing the chip's motor phase current sampling cost.

[0088] Corresponding to the above embodiment, the embodiment of the present invention further provides a motor controller, referring to Figure 7a or Figure 7b As shown, the motor controller 2000 includes the aforementioned motor phase current sampling device 300 , or the aforementioned chip 1000 .

[0089] According to the motor controller of the embodiment of the present invention, the aforementioned motor phase current sampling device or chip can realize the sampling function of the motor phase current without phase shifting, thereby avoiding the problem of harmonics generated by the motor controller due to phase current sampling, and the phase current sampling method is simple and easy to implement, thereby reducing the motor phase current sampling cost of the motor controller.

[0090] Corresponding to the above embodiment, the embodiment of the present invention further provides an electrical device, referring to Figures 8a to 8c As shown, the electrical device 3000 includes the aforementioned motor phase current sampling device 300 , or the aforementioned chip 1000 , or the aforementioned motor controller 2000 .

[0091] An electrical device according to an embodiment of the present invention includes the motor phase current sampling device, chip, or motor controller described in any of the above embodiments. The electrical device may be an air conditioner, refrigerator, compressor, or other device. These electrical devices, through the aforementioned motor phase current sampling device, chip, or motor controller, can implement phase current sampling of the motor within the electrical device without phase shifting, thereby avoiding the problem of harmonics generated by phase current sampling. Furthermore, the phase current sampling method is simple and easy to implement, thereby reducing the cost of motor phase current sampling in the electrical device.

[0092] It should be noted that the logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic device), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable compact disc read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in another suitable manner if necessary, and then storing it in a computer memory.

[0093] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0094] Throughout this specification, references to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0095] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0096] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0097] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A motor phase current sampling method, characterized in that: Applied to a motor controller, the motor controller includes a multi-phase bridge arm, and the method includes: In one pulse modulation cycle, obtaining the duty cycle of the multi-phase bridge arm; Determining a bridge arm to be sampled according to the duty cycle; Within the target sampling period corresponding to the bridge arm to be sampled, the motor phase voltage corresponding to the bridge arm to be sampled is sampled, and the corresponding motor neutral point voltage is determined; wherein the target sampling period is the period from the start of the dead zone corresponding to the bridge arm to the completion of freewheeling; The motor phase current corresponding to the bridge arm to be sampled is determined according to the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage.

2. The method according to claim 1, characterized in that The multi-phase bridge arm includes a three-phase bridge arm, the duty cycle includes a minimum duty cycle, an intermediate duty cycle, and a maximum duty cycle, and determining the bridge arm to be sampled according to the duty cycle includes: The bridge arms corresponding to the minimum duty cycle and the intermediate duty cycle are used as the bridge arms to be sampled.

3. The method according to claim 2, characterized in that Determining the corresponding motor neutral point voltage includes: When the bridge arm to be sampled is the bridge arm corresponding to the minimum duty cycle, the neutral point voltage of the motor is the DC bus voltage of the motor controller; When the bridge arm to be sampled is the bridge arm corresponding to the intermediate duty cycle, the neutral point voltage of the motor is half of the DC bus voltage.

4. The method according to claim 1, wherein The determining, based on the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage, of the motor phase current corresponding to the bridge arm to be sampled includes: Obtaining a voltage difference between a motor phase voltage corresponding to the bridge arm to be sampled and a corresponding motor neutral point voltage; The ratio of the voltage difference to the resistance of the motor winding corresponding to the bridge arm to be sampled is obtained to obtain the motor phase current corresponding to the bridge arm to be sampled.

5. The method according to claim 4, characterized in that The method further comprises: The direction of the motor phase current is determined according to the voltage difference; wherein, When the difference is greater than zero, the motor phase current flows from the motor controller to the motor; When the difference is less than zero, the motor phase current flows from the motor to the motor controller.

6. The method according to claim 1, characterized in that The target sampling period includes a plurality of periods, and sampling the motor phase voltage corresponding to the bridge arm to be sampled within the target sampling period corresponding to the bridge arm to be sampled includes: Sampling in each target time period within at least one of the target sampling periods to obtain at least one motor phase voltage sampling value corresponding to the bridge arm to be sampled; The motor phase voltage corresponding to the bridge arm to be sampled is determined according to the at least one motor phase voltage sampling value.

7. The method according to claim 6, characterized in that The determining the motor phase voltage corresponding to the bridge arm to be sampled according to the at least one motor phase voltage sampling value includes: Converting the at least one motor phase voltage sampling value to obtain at least one motor phase voltage actual value; The average value of the at least one motor phase voltage actual value is obtained to obtain the motor phase voltage corresponding to the bridge arm to be sampled.

8. The method according to any one of claims 1 to 7, characterized in that The method further comprises: The motor phase currents corresponding to the remaining bridge arms are calculated based on the motor phase currents corresponding to the bridge arm to be sampled; wherein the remaining bridge arms are the bridge arms in the multi-phase bridge arms except the bridge arm to be sampled.

9. A motor phase current sampling device, characterized in that: Applied to a motor controller, the motor controller includes a multi-phase bridge arm, and the device includes: A first acquisition module is used to acquire the duty cycle of the multi-phase bridge arm in a pulse modulation cycle; A first determining module, configured to determine a bridge arm to be sampled according to the duty cycle; A second acquisition module is configured to sample the motor phase voltage corresponding to the bridge arm to be sampled and determine the corresponding motor neutral point voltage within a target sampling period corresponding to the bridge arm to be sampled; wherein the target sampling period is the period from the start of the dead zone corresponding to the bridge arm to be sampled to the completion of freewheeling; The second determining module is used to determine the motor phase current corresponding to the bridge arm to be sampled according to the motor phase voltage corresponding to the bridge arm to be sampled and the corresponding motor neutral point voltage.

10. A chip, characterized in that: It comprises the motor phase current sampling device according to claim 9.

11. A motor controller, characterized in that: It comprises the motor phase current sampling device according to claim 9, or the chip according to claim 10.

12. An electrical device, characterized in that: It comprises the motor phase current sampling device according to claim 9, or the chip according to claim 10, or the motor controller according to claim 11.

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