Motor phase current sampling method and device, storage medium, chip and electrical equipment

Abstract

The invention discloses a motor phase current sampling method and device, a storage medium, a chip and electrical equipment, the method is applied to an inverter, the inverter comprises multiple phases of bridge arms, each phase of bridge arm comprises an upper bridge arm and a lower bridge arm, the upper bridge arm comprises an upper bridge arm switch tube connected in parallel with a fly-wheel diode, and the lower bridge arm comprises a lower bridge arm switch tube connected in parallel with a fly-wheel diode. The lower bridge arm comprises a lower bridge arm switch tube connected with a fly-wheel diode in parallel, the method comprises the following steps: obtaining an upper bridge arm current and a lower bridge arm current of a target bridge arm in a dead zone time, the upper bridge arm current being a current flowing through the fly-wheel diode of the upper bridge arm in the dead zone time, and the lower bridge arm current being a current flowing through the fly-wheel diode of the lower bridge arm in the dead zone time; the current of the lower bridge arm is the current flowing through a fly-wheel diode of the lower bridge arm in the dead time; and based on the upper bridge arm current and the lower bridge arm current, determining the phase current size and the phase current direction of the motor. Therefore, simplification of the motor phase current sampling method is realized, no phase shift is generated in the sampling process, and the influence on the motor is small, so that the convenience and applicability of the current sampling method can be improved.

Description

Technical Field

[0001] The present invention relates to the field of chip design, and in particular to a motor phase current sampling method and device, a storage medium, a chip, and electrical equipment for a vehicle. Background Art

[0002] Motor current sampling technology is a technology widely used in the field of industrial control and power electronics. It mainly monitors and analyzes the internal current of the motor in real time to achieve motor control, protection and fault diagnosis. At present, current sampling in related technologies usually adopts single resistor sampling, which has the advantage of low cost compared with the method of using sensors to obtain phase current.

[0003] The disadvantage of the above-mentioned related technologies is that the single resistor sampling method needs to update 8 duty cycle comparison values ​​in one carrier cycle, and needs to calculate the phase shift and sampling calculation points, which makes the method more complicated. Summary of the invention

[0004] 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, by obtaining the upper bridge arm current and the lower bridge arm current of the target bridge arm within the dead time of the target bridge arm, and then determining the magnitude and direction of the motor phase current, so that the phase current of the target bridge arm can be sampled without calculating the phase shift and sampling calculation point, thereby simplifying the motor phase current sampling method, and no phase shift will be generated during the sampling process, which has little impact on the motor, thereby improving the convenience and applicability of the current sampling method.

[0005] A second object of the present invention is to provide a computer-readable storage medium.

[0006] The third objective of the present invention is to provide a chip.

[0007] A fourth objective of the present invention is to provide a motor phase current sampling device.

[0008] A fifth object of the present invention is to provide an electrical device.

[0009] To achieve the above-mentioned purpose, the first aspect of the present invention proposes a motor phase current sampling method, which is applied to an inverter. The inverter includes a multi-phase bridge arm, each phase bridge arm includes an upper bridge arm and a lower bridge arm, the upper bridge arm includes an upper bridge arm switch tube with a freewheeling diode in parallel, and the lower bridge arm includes a lower bridge arm switch tube with a freewheeling diode in parallel. The method includes: obtaining the upper bridge arm current and the lower bridge arm current of the target bridge arm within the dead time, wherein the upper bridge arm current is the current flowing through the freewheeling diode of the upper bridge arm within the dead time, and the lower bridge arm current is the current flowing through the freewheeling diode of the lower bridge arm within the dead time; based on the upper bridge arm current and the lower bridge arm current, determining the phase current size and phase current direction of the motor.

[0010] According to the motor phase current sampling method of the embodiment of the present invention, the upper bridge arm current and the lower bridge arm current of the target bridge arm are obtained within the dead time of the target bridge arm, and then the phase current size and direction of the motor are determined based on this, so that the phase current of the target bridge arm can be sampled without calculating the phase shift and sampling calculation points, thereby simplifying the motor phase current sampling method, and no phase shift will be generated during the sampling process, which has little impact on the motor, thereby improving the convenience and applicability of the current sampling method.

[0011] According to one embodiment of the present invention, the magnitude and direction of the phase current of the motor are determined based on the upper bridge arm current and the lower bridge arm current, including: when the upper bridge arm current is greater than a preset current and the lower bridge arm current is less than or equal to the preset current, the magnitude of the phase current is determined to be the upper bridge arm current, and the direction of the phase current is a negative direction; when the lower bridge arm current is greater than the preset current and the upper bridge arm current is less than or equal to the preset current, the magnitude of the phase current is determined to be the lower bridge arm current, and the direction of the phase current is a positive direction; wherein the negative direction is the direction in which the phase current flows from the motor to the inverter, and the positive direction is the direction in which the phase current flows from the inverter to the motor.

[0012] According to an embodiment of the present invention, the method further comprises: determining the motor rotor position based on the phase current direction.

[0013] According to an embodiment of the present invention, determining the motor rotor position based on the phase current direction includes: determining the motor rotor position when the phase current direction switches from a positive direction to a negative direction, or from a negative direction to a positive direction.

[0014] According to one embodiment of the present invention, obtaining the upper bridge arm current of the target bridge arm within the dead time includes: obtaining the upper bridge arm voltage of the target bridge arm within the dead time and the DC bus voltage of the inverter, wherein the upper bridge arm voltage is obtained by sampling the voltage generated by the upper bridge arm current on the upper bridge arm through a single-ended voltage sampling circuit; determining the upper bridge arm current based on the upper bridge arm voltage, the DC bus voltage, the conduction voltage of the freewheeling diode of the upper bridge arm and the phase resistance of the motor.

[0015] According to one embodiment of the present invention, the upper bridge arm also includes an upper bridge arm sampling resistor to obtain the upper bridge arm current of the target bridge arm within the dead time, and also includes: determining the upper bridge arm current based on the upper bridge arm voltage, the DC bus voltage, the conduction voltage of the freewheeling diode of the upper bridge arm, the phase resistance of the motor and the resistance of the upper bridge arm sampling resistor.

[0016] According to one embodiment of the present invention, obtaining the lower bridge arm current of the target bridge arm includes: obtaining the lower bridge arm voltage of the target bridge arm within the dead time, wherein the lower bridge arm voltage is obtained by sampling the voltage generated by the lower bridge arm current on the lower bridge arm through a differential voltage sampling circuit; determining the lower bridge arm current based on the lower bridge arm voltage, the conduction voltage of the freewheeling diode of the lower bridge arm and the phase resistance of the motor.

[0017] According to one embodiment of the present invention, the lower bridge arm also includes a lower bridge arm sampling resistor to obtain the lower bridge arm current of the target bridge arm within the dead time, and also includes: determining the lower bridge arm current based on the lower bridge arm voltage, the conduction voltage of the freewheeling diode of the lower bridge arm, the phase resistance of the motor and the resistance of the lower bridge arm sampling resistor.

[0018] To achieve the above-mentioned object, the second aspect of the present invention proposes a computer-readable storage medium having a program stored thereon, which implements the aforementioned motor phase current sampling method when executed by a processor.

[0019] According to the computer-readable storage medium of an embodiment of the present invention, through the aforementioned motor phase current sampling method, the sampling function of the motor phase current can be realized more simply, and the sampling process will not affect the normal operation of the motor, thereby improving the convenience and applicability of the phase current sampling function.

[0020] To achieve the above objectives, the third aspect of the present invention proposes a chip, comprising: a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, the aforementioned motor phase current sampling method is implemented.

[0021] According to the chip of the embodiment of the present invention, the motor phase current sampling method mentioned above can more simply realize the sampling of the motor phase current, and the sampling process will not affect the normal operation of the motor, thereby improving the convenience and applicability of the chip.

[0022] To achieve the above-mentioned purpose, the fourth aspect of the present invention proposes a motor phase current sampling device, which is applied to an inverter. The inverter includes a multi-phase bridge arm, each phase bridge arm includes an upper bridge arm and a lower bridge arm, the upper bridge arm includes an upper bridge arm switch tube with a freewheeling diode in parallel, and the lower bridge arm includes a lower bridge arm switch tube with a freewheeling diode in parallel. The device includes: an acquisition module, used to obtain the upper bridge arm current and the lower bridge arm current of the target bridge arm during the dead time, wherein the upper bridge arm current is the current flowing through the freewheeling diode of the upper bridge arm during the dead time, and the lower bridge arm current is the current flowing through the freewheeling diode of the lower bridge arm during the dead time; a determination module, used to determine the phase current size and phase current direction of the motor based on the upper bridge arm current and the lower bridge arm current.

[0023] According to the motor phase current sampling device of the embodiment of the present invention, the upper bridge arm current and the lower bridge arm current of the target bridge arm are obtained by the acquisition module within the dead time of the target bridge arm, and the phase current size and direction of the motor are determined by the determination module, so that the phase current of the target bridge arm can be sampled without calculating the phase shift and the sampling calculation point, thereby simplifying the current sampling device, and no phase shift will be generated during the sampling process, which has little impact on the motor, thereby improving the convenience and applicability of the current sampling device.

[0024] To achieve the above-mentioned object, a fifth aspect of the present invention proposes an electrical device, including the aforementioned chip, or the aforementioned motor phase current sampling device.

[0025] According to the electrical equipment of the embodiment of the present invention, the sampling of the motor phase current can be realized more simply through the aforementioned chip or motor phase current sampling device, and the sampling process will not affect the normal operation of the motor, thereby optimizing the motor phase current sampling function.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a structural schematic diagram of an inverter according to an embodiment of the present invention;

[0028] Figure 2 is a flow chart of a motor phase current sampling method according to an embodiment of the present invention;

[0029] Figure 3 is a control timing diagram of a target bridge arm according to an embodiment of the present invention;

[0030] Figure 4a to Figure 4b A schematic diagram of the phase current direction of a target bridge arm according to some embodiments of the present invention;

[0031] Figure 5is a circuit diagram of a single-ended voltage sampling circuit according to an embodiment of the present invention;

[0032] Figure 6 is a circuit diagram of a differential voltage sampling circuit according to an embodiment of the present invention;

[0033] Figure 7 is a structural schematic diagram of an inverter according to another embodiment of the present invention;

[0034] Figure 8 A schematic diagram of a dead zone phase voltage and a phase current of an inverter according to an embodiment of the present invention;

[0035] Fig. 9 is a schematic structural diagram of a chip according to an embodiment of the present invention;

[0036] Fig.10 2 is a schematic diagram of the structure of a motor phase current sampling device according to an embodiment of the present invention;

[0037] Figure 11a to Figure 11b FIG. 1 is a schematic diagram of the structure of an electrical device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, 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 should not be construed as limiting the present invention.

[0039] The motor phase current sampling method and device, storage medium, chip, and electrical equipment proposed in the embodiments of the present invention are described below with reference to the accompanying drawings.

[0040] It should be noted that the motor phase current sampling method of the embodiment of the present invention can be applied to Figure 1 In the inverter shown, reference Figure 1 As shown, the inverter 100 includes a three-phase bridge arm, which is respectively a U-phase bridge arm, a W-phase bridge arm and a V-phase bridge arm, so as to be connected to the U-phase, W-phase and V-phase of the motor M. Each phase bridge arm includes an upper bridge arm and a lower bridge arm, and the upper bridge arm of the three-phase bridge arm is connected to the preset bus power supply VBUS, and the lower bridge arm of the three-phase bridge arm is grounded GND. The upper bridge arm also includes an upper bridge arm switch tube QU connected in parallel with a freewheeling diode, and the lower bridge arm also includes a lower bridge arm switch tube QD connected in parallel with a freewheeling diode. By controlling the on-off of the six switch tubes in the three-phase bridge arm, the inverter can convert the DC power provided by the preset bus power supply VBUS into three-phase AC power, and then control the rotation of the motor. The control logic can be a variety of control logics such as two-by-two conduction and three-by-three conduction. The specific control logic is not expanded here.

[0041] It should be noted that the motor phase current sampling method of the embodiment of the present invention can be applied to an inverter with multiple phase bridge arms. Figure 1 The inverter of the three-phase bridge arm shown is exemplary and is not intended to limit the present application.

[0042] Figure 2 FIG. 1 is a motor phase current sampling method according to an embodiment of the present invention. Figure 2 As shown, the method includes:

[0043] S11, obtaining the upper bridge arm current and the lower bridge arm current of the target bridge arm during the dead time, wherein the upper bridge arm current is the current flowing through the freewheeling diode of the upper bridge arm during the dead time, and the lower bridge arm current is the current flowing through the freewheeling diode of the lower bridge arm during the dead time.

[0044] Specifically, the target bridge arm can be any phase of the three-phase bridge arm of the inverter. The dead time of the target bridge arm refers to the time when the upper bridge switch tube and the lower bridge switch tube of the target bridge arm need to be switched on in the control process of the inverter, such as Figure 3 As shown, the dead time is a period of time artificially set to avoid damage to the inverter caused by the upper and lower bridge arms being turned on at the same time, such as Figure 3 The t0-t1 period and the t2-t3 period are shown. Subsequently, during the dead time, due to the existence of the freewheeling diodes in the upper bridge arm switch tube and the lower bridge arm switch tube of the target bridge arm, even if the upper bridge arm switch tube and the lower bridge arm switch tube are both turned off at this time, there is still a freewheeling circuit in the target bridge arm, so the corresponding upper bridge arm current or lower bridge arm current can be detected, and the upper bridge arm current or lower bridge arm current can be used as a basis for determining the motor phase current.

[0045] In some embodiments, obtaining the upper bridge arm current of the target bridge arm within the dead time in S11 includes: obtaining the upper bridge arm voltage of the target bridge arm within the dead time and the DC bus voltage of the inverter, wherein the upper bridge arm voltage is obtained by sampling the voltage generated by the upper bridge arm current on the upper bridge arm through a single-ended voltage sampling circuit; determining the upper bridge arm current based on the upper bridge arm voltage, the DC bus voltage, the conduction voltage of the freewheeling diode of the upper bridge arm and the phase resistance of the motor.

[0046] Specifically, refer to Figure 5 As shown, a single-ended voltage sampling circuit can be set at the connection point of the upper bridge arm and the lower bridge arm in the three-phase bridge arm of the inverter to obtain the upper bridge arm voltage of the target bridge arm. After the upper bridge arm voltage is determined, the upper bridge arm current can be determined according to the upper bridge arm voltage, the DC bus voltage, the conduction voltage of the freewheeling diode of the upper bridge arm and the phase resistance of the motor.

[0047] Optional, continue to refer to Figure 5As shown, the single-ended voltage sampling circuit 200 may include three identical single-ended sampling sub-circuits 210, and the sampling ends of the single-ended sampling sub-circuits 210 are respectively connected to the JU, JW, and JV nodes of the inverter 100, wherein the reference Figure 5 As shown, the JU, JW, and JV nodes are the output ends of the corresponding phase AC power of the inverter, respectively. Taking the single-ended sampling sub-circuit 210 of the U-phase bridge arm as an example, the circuit 210 includes a first resistor to a third resistor R1~R3 ​​and a capacitor C, wherein one end of the first resistor R1 is grounded 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 serves as the voltage sampling point Vbemf of the single-ended voltage sampling circuit 200, and the other end of the capacitor C is grounded GND. The circuit mainly collects the upper bridge arm voltage of the U-phase bridge arm according to the voltage division principle of the first resistor R1 and the second resistor R2. At the same time, the capacitor C has a voltage stabilizing effect, and the third resistor R3 has a current limiting effect to avoid excessive current in the single-ended voltage sampling circuit 200.

[0048] When the single-ended voltage sampling circuit is Figure 5 As shown, the process of obtaining the upper arm current of the target bridge arm of the inverter is as follows: When the U-phase bridge arm is the target bridge arm, and there is current in the upper arm of the U-phase bridge arm, the current direction at this time is as follows: Figure 4a As shown, according to the voltage division principle, the following formula (1) can be obtained:

[0049] Vbemf=VU*R1 / (R2+R2) (1)

[0050] Wherein, Vbemf is the voltage collected by the single-ended voltage sampling circuit, VU is the upper bridge arm voltage, R1 is the resistance value of the first resistor, and R2 is the resistance value of the second resistor. The upper bridge arm voltage of the U-phase bridge arm at this time can be obtained by the above formula (1).

[0051] It should be noted that the upper bridge arm current of the target bridge arm can also be obtained through other single-ended voltage sampling circuits. Figure 5 The single-ended voltage sampling circuit shown is exemplary and is not intended to limit the present application.

[0052] In some embodiments, the upper bridge arm also includes an upper bridge arm sampling resistor to obtain the upper bridge arm current of the target bridge arm within the dead time, and also includes: determining the upper bridge arm current based on the upper bridge arm voltage, the DC bus voltage, the conduction voltage of the freewheeling diode of the upper bridge arm, the phase resistance of the motor and the resistance of the upper bridge arm sampling resistor.

[0053] Specifically, refer to Figure 5As shown, a sampling resistor RC can be set on each upper bridge arm of the three-phase bridge arm, and the voltage across the upper bridge arm sampling resistor can be obtained according to the obtained upper bridge arm voltage, so as to determine the upper bridge arm current of the target bridge arm within the dead time. This method can more simply obtain the upper bridge arm current. The specific process is as follows: After obtaining the upper bridge arm voltage, according to the voltage division principle, the following formula (2) can be obtained:

[0054] VU=Vbus+Vd+Vsample (2)

[0055] Among them, VU is the upper bridge arm voltage, which has been Figure 5 The single-ended voltage sampling circuit shown in the figure is obtained, Vbus is the DC bus voltage of the inverter, which can be obtained through real-time detection; Vd is the diode conduction voltage, which can be obtained by obtaining the diode parameters; Vsample is the voltage corresponding to the phase resistance of the motor and the upper bridge arm sampling resistance. It can be seen from the above that after determining the upper bridge arm voltage VU, the DC bus voltage Vbus and the diode conduction voltage Vd, Vsample can be obtained according to the above formula (2). Subsequently, the upper bridge arm current of the target bridge arm in the dead time can be obtained by combining the resistance value of the sampling resistor and the phase resistance value of the motor.

[0056] It should be noted that when the target bridge arm is the V-phase bridge arm or the W-phase bridge arm, the process of obtaining the upper bridge arm current of the target bridge arm is similar to the above-mentioned process of obtaining the upper bridge arm current of the U-phase bridge arm, and will not be repeated here.

[0057] In some embodiments, obtaining the lower bridge arm current of the target bridge arm within the dead time in S11 includes: obtaining the lower bridge arm voltage of the target bridge arm within the dead time, wherein the lower bridge arm voltage is obtained by sampling the voltage generated by the lower bridge arm current on the lower bridge arm through a differential voltage sampling circuit; determining the lower bridge arm current based on the lower bridge arm voltage, the conduction voltage of the freewheeling diode of the lower bridge arm and the phase resistance of the motor.

[0058] Furthermore, the lower bridge arm also includes a lower bridge arm sampling resistor to obtain the lower bridge arm current of the target bridge arm within the dead time, and also includes: determining the lower bridge arm current based on the lower bridge arm voltage, the conduction voltage of the freewheeling diode of the lower bridge arm, the phase resistance of the motor and the resistance of the lower bridge arm sampling resistor.

[0059] Specifically, refer to Figure 5 As shown in FIG. 1 , the lower bridge arm current of the target bridge arm during the dead time can also be obtained by setting a sampling resistor RC in the lower bridge arm and collecting the lower bridge arm voltage and then calculating. The difference is that, assuming that the target bridge arm is the U-phase bridge arm, during the dead time, when there is current in the lower bridge arm, the current direction at this time is as follows: Figure 4b As shown, since the anode of the freewheeling diode of the lower bridge arm switch tube is grounded, the following formula (3) can be obtained:

[0060] VU=0-Vd-Vsample (3)

[0061] Among them, VU is the upper bridge arm voltage, Vd is the diode conduction voltage, and Vsample is the voltage corresponding to the phase resistance of the motor and the upper bridge arm sampling resistance. It can be seen from formula (3) that if the voltage is obtained by a single-ended voltage sampling circuit, the obtained voltage is a negative value, and because the value of the lower bridge arm voltage is small, the value obtained by the single-ended voltage sampling circuit may have insufficient accuracy. Therefore, the single-ended voltage sampling circuit cannot be used to obtain the lower bridge arm voltage. At this time, a differential sampling circuit can be used to sample the two ends of the lower bridge arm. The voltages obtained at both ends are the lower bridge arm voltage. Subsequently, Vsample can be obtained based on the above formula (3). Combined with the resistance value of the lower bridge arm sampling resistor and the phase resistance value of the motor, the lower bridge arm current can be determined.

[0062] Optionally, the differential sampling circuit of each phase bridge arm in the inverter can be as follows: Figure 6 As shown, reference Figure 5 and Figure 6 As shown, the differential sampling circuit 300 may include an MCU (Microcontroller Unit), a first differential resistor RF1 and a second differential resistor RF2, a first differential capacitor CF1 and a second differential capacitor CF2, wherein the negative input terminal of the MCU is connected to one of the output nodes (JU, JV, JW) of the alternating current of the inverter 100 through the first resistor RB1, and the negative input terminal of the MCU is also connected to the ground GND through the first differential capacitor CF1; the positive input terminal of the MCU is also connected to the common ground terminal K of the inverter 100 through the second differential resistor RF2, and the negative input terminal of the MCU is also connected to the ground GND through the second differential capacitor CF2.

[0063] Specifically, the MCU is mainly used to calculate the difference between the voltages collected at the positive input terminal and the negative input terminal and output it. Therefore, the differential sampling circuit 300 can realize the function of collecting the voltage of the lower bridge arm of the target bridge arm through the internal MCU; at the same time, the first differential resistor RF1 and the second differential resistor RF2 in the differential sampling circuit 300 mainly play the role of current limiting, and the first differential capacitor CF1 and the second differential capacitor CF2 mainly play the role of voltage stabilization. The specific principle will not be expanded here.

[0064] Optional, reference Figure 7As shown, sampling resistors can be set only in the upper bridge arm and the lower bridge arm of two phases in the three-phase bridge arm of the inverter, and corresponding single-ended sampling circuits and differential sampling circuits can be configured. For example, sampling resistors and corresponding sampling circuits are set only in the U-phase and V-phase bridge arms in the inverter. At this time, assuming that the W-phase is the target bridge arm, the phase current of the W-phase can be calculated by 0-U-phase phase current-V-phase phase current, and the magnitude and direction of the W-phase current can also be obtained, thereby reducing the setting of one sampling resistor and the corresponding single-ended voltage sampling circuit and differential sampling circuit, thereby effectively reducing the hardware cost of the inverter.

[0065] S12, determining the phase current magnitude and phase current direction of the motor based on the upper bridge arm current and the lower bridge arm current.

[0066] In some embodiments, S12 determines the phase current magnitude and phase current direction of the motor based on the upper bridge arm current and the lower bridge arm current, including: when the upper bridge arm current is greater than a preset current and the lower bridge arm current is less than or equal to the preset current, determining the phase current magnitude to be the upper bridge arm current, and the phase current direction to be a negative direction; when the lower bridge arm current is greater than a preset current and the upper bridge arm current is less than or equal to the preset current, determining the phase current magnitude to be the lower bridge arm current, and the phase current direction to be a positive direction; wherein, the negative direction is the direction in which the phase current flows from the motor into the inverter, and the positive direction is the direction in which the phase current flows from the inverter into the motor.

[0067] Specifically, the preset current is used to distinguish whether the upper bridge arm current and the lower bridge arm current are greater than zero. Since the upper bridge arm switch tube and the lower bridge arm switch tube in the target bridge arm are about to be turned on and switched during the dead time of the target bridge arm, one of the upper bridge arm current and the lower bridge arm current of the target bridge arm must be greater than the preset current and the other is less than the preset current. Taking the U-phase bridge arm as the target bridge arm as an example, when the upper bridge arm current of the U-phase bridge arm is obtained through a single-ended voltage sampling circuit, and the lower bridge arm current of the U-phase bridge arm is obtained through a differential sampling circuit, when the upper bridge arm current is greater than the preset current, the lower bridge arm current must be less than the preset current. At this time, the upper bridge arm current is the phase current of the U-phase of the motor. At the same time, the current direction of the inverter is as follows: Figure 4a As shown, it can be determined that the phase current direction is negative, that is, the phase current flows from the motor to the inverter; when the lower bridge arm current is greater than the preset current and the upper bridge arm current is less than the preset current, the lower bridge arm current is the U-phase phase current of the motor, and the current direction of the inverter is as shown Figure 4b As shown, at this time it can be determined that the phase current direction of the motor is positive, that is, the phase current flows from the inverter into the motor.

[0068] In the control cycle of the motor, it is necessary to frequently switch the upper and lower bridge arms of the target bridge arm to realize phase change. For example, when the motor is controlled by a three-three conduction method, a phase change is required every 60° in the motor. Each time the upper and lower bridge arms are switched on, the phase current direction and magnitude of the target bridge arm at this time can be determined within the dead time by the above method, thereby providing data support for motor control. Compared with the single-resistance current sampling method in the related art, the current sampling method of the embodiment of the present invention has no duty cycle limitation, so there is no need to calculate the phase shift and sampling calculation point, nor is there a need to update the duty cycle comparison value in each carrier cycle. The calculation method is simpler and requires less computing power. At the same time, the current sampling method of the embodiment of the present invention does not require phase shifting, so it will not It generates harmonic vibrations, but has little impact on the operation of the motor, so it can be used in places with higher requirements on motor control performance. In addition, the single-resistance sampling method can only detect the single-phase current value in the three-phase motor, and cannot detect the load imbalance of the motor. The current sampling method of the present application is aimed at the target bridge arm in the dead time. For example, when the motor is controlled by sampling the three-three conduction method, the three bridge arms can all be the target bridge arms, so the imbalance of the phase current of the motor can be detected according to the phase current size and direction of the three bridge arms. In addition, the phase current sampling method of the embodiment of the present invention can be applied to the chip, so when the chip is designed, the phase current sampling method of the embodiment of the present invention can be used to enable the chip to achieve the sampling function of the motor phase current at a lower cost.

[0069] In the above embodiment, the upper bridge arm current and the lower bridge arm current of the target bridge arm are obtained within the dead time of the target bridge arm, and then the phase current size and direction of the motor are determined based on this, thereby simplifying the motor phase current sampling method, and no phase shift will occur during the sampling process, which has little impact on the motor. The motor phase current imbalance phenomenon can also be detected, thereby improving the convenience and applicability of the current sampling method.

[0070] In some embodiments, the method further includes determining a rotor position of the motor based on the phase current direction.

[0071] Furthermore, based on the phase current direction, the motor rotor position is determined, including: when the phase current direction switches from a positive direction to a negative direction, or from a negative direction to a positive direction, the motor rotor position is determined.

[0072] Specifically, when the motor is controlled by a three-phase conduction method, the three-phase current of the motor and the generated dead zone phase voltage can be expressed as follows: Figure 8 As shown, Figure 8Taking the U phase shown in the figure as an example, when the dead zone phase voltage of the U phase bridge arm switches between high level and low level, it means that the bridge arm switch tube of the phase bridge arm is switched, so that the motor is switched. During the switching, the phase current of the U phase bridge arm passes through the zero point. In the control logic of the motor, the motor rotor position corresponding to the zero point of the phase current of the three-phase bridge arm is determined. For example, refer to Figure 8 As shown, six commutations are required in one control cycle of the inverter, one every 60°. At this time, the two zero crossings corresponding to the U-phase current are the second and fifth, respectively. The corresponding motor rotor positions should be 60° and 240°. Figure 8 It can be seen that the motor rotor position corresponding to the falling edge of the U-phase dead zone phase voltage is 60°, and the rotor position corresponding to the rising edge of the U-phase dead zone phase voltage is 240°, and the motor rotor positions of the remaining phases are similar. It can be seen that the motor rotor position corresponding to the rising and falling edges of the dead zone phase voltage of the U-phase bridge arm is determined.

[0073] In one control cycle of the motor, that is, Figure 8 In the range of 0° to 360° shown in the figure, the phase voltage of the U-phase bridge arm has undergone two high-low level switchings, and the falling edge or rising edge of the switching is the dead time. During the dead time, when the dead phase voltage of the U-phase bridge arm switches from a high level to a low level, the freewheeling current in the U-phase of the motor will be Figure 4a The direction shown becomes Figure 4b The direction shown is switched from positive to negative. Therefore, if the phase current direction of the U-phase bridge arm is detected to switch to the negative direction during actual operation, it means that the motor commutation time has arrived. Figure 8 The falling edge position of the U-phase dead zone phase voltage is shown in FIG. 1 ; similarly, when the phase current direction of the U-phase bridge arm is detected to switch from the negative direction to the positive direction during actual operation, it indicates that the motor commutation time has arrived. Figure 8 The rising edge position of the U-phase dead zone phase voltage is shown in FIG. 1 , and it can be seen from the above that the motor rotor position corresponding to the rising edge and falling edge of the dead zone phase voltage of the U-phase bridge arm is determined. Therefore, after determining whether the motor dead zone phase voltage is at the rising edge or the falling edge at this time, the motor rotor position at this time can be obtained by looking up a table or the like. Thus, the function of determining the motor rotor position according to the phase current direction is realized, thereby expanding the function of the current sampling method.

[0074] At the same time, compared to the traditional method of using sliding film and Lomborg sensorless observer to obtain the motor rotor position, the motor rotor position acquisition method of the embodiment of the present invention does not need to measure the inductance and resistance of the motor and the flux parameters, and can reduce the computing power requirements of the MCU, does not require complex arctan and sin and cos operations, does not require floating-point data, and has low requirements for chips. Therefore, it has the advantages of simple control logic, high reliability and low error. Compared with other related technologies that use sensors (such as Hall sensors, magnetic encoders) to obtain the motor rotor position, the motor rotor position acquisition method of the embodiment of the present invention has the advantage of low cost.

[0075] It should be noted that, since the current sampling method of the embodiment of the present invention only works within the dead time of the inverter, the corresponding sampling frequency can be set based on the dead time of the inverter. Figure 8 When the three-three conduction mode is used for control, each phase bridge arm performs two phase changes in a single control cycle. Therefore, the sampling frequency can be set to twice the control frequency. For example, when the control frequency of the inverter is 16KHZ, the sampling frequency of the current sampling method in the embodiment of the present invention can be 32KHZ, which can achieve the effect of determining the phase current size and direction of the motor and the corresponding rotor position within the dead time.

[0076] In summary, according to the current sampling method of the embodiment of the present invention, by obtaining the upper bridge arm current and the lower bridge arm current of the target bridge arm within the dead time of the target bridge arm, and then determining the phase current size and direction of the motor, the motor phase current sampling method is simplified, and no phase shift will occur during the sampling process, which has little impact on the motor, and the phase current imbalance of the motor can also be detected; at the same time, the specific position of the motor rotor can also be determined based on the determined phase current direction, thereby improving the convenience, applicability and functionality of the current sampling method.

[0077] Corresponding to the above embodiment, an embodiment of the present invention further provides a computer-readable storage medium on which a program is stored. When the program is executed by a processor, the above motor phase current sampling method is implemented.

[0078] According to the computer-readable storage medium of the embodiment of the present invention, through the above-mentioned motor phase current sampling method, the sampling function of the motor phase current can be realized more simply, and the sampling process will not affect the normal operation of the motor. At the same time, the motor phase current imbalance phenomenon and the position of the motor rotor can be detected, thereby improving the convenience, applicability and functionality of the phase current sampling function.

[0079] Corresponding to the above embodiment, the embodiment of the present invention further provides a chip, referring to Fig. 9As shown, the chip 400 includes: a memory 410, a processor 420, and a program stored in the memory 410 and executable on the processor. When the processor 420 executes the program, the aforementioned motor phase current sampling method is implemented.

[0080] According to the chip of the embodiment of the present invention, through the above-mentioned motor phase current sampling method, the sampling of the motor phase current can be realized more simply, and the sampling process will not affect the normal operation of the motor. At the same time, the motor phase current imbalance phenomenon and the position of the motor rotor can be detected, thereby improving the convenience, applicability and functionality of the chip.

[0081] Corresponding to the above embodiment, the present invention also provides a motor phase current sampling device, which is applied to Figure 1 The inverter 100 shown in FIG. Figure 1 As shown, the inverter 100 includes a multi-phase bridge arm (U, V, W), each phase bridge arm includes an upper bridge arm and a lower bridge arm, the upper bridge arm includes an upper bridge arm switch tube connected in parallel with a freewheeling diode, and the lower bridge arm includes a lower bridge arm switch tube connected in parallel with a freewheeling diode, Fig.10 As shown, the device 500 includes: an acquisition module 510 and a determination module 520.

[0082] Among them, the acquisition module 510 is used to obtain the upper bridge arm current and the lower bridge arm current of the target bridge arm within the dead time, wherein the upper bridge arm current is the current of the freewheeling diode flowing through the upper bridge arm within the dead time, and the lower bridge arm current is the current of the freewheeling diode flowing through the lower bridge arm within the dead time; the determination module 520 is used to determine the phase current size and phase current direction of the motor based on the upper bridge arm current and the lower bridge arm current.

[0083] According to one embodiment of the present invention, the determination module 520 is also used for: when the upper bridge arm current is greater than the preset current and the lower bridge arm current is less than or equal to the preset current, determining that the phase current is the upper bridge arm current and the phase current is in the negative direction; when the lower bridge arm current is greater than the preset current and the upper bridge arm current is less than or equal to the preset current, determining that the phase current is the lower bridge arm current and the phase current is in the positive direction; wherein, the negative direction is the direction in which the phase current flows from the motor to the inverter, and the positive direction is the direction in which the phase current flows from the inverter to the motor.

[0084] According to an embodiment of the present invention, the determination module 520 is further configured to determine the motor rotor position based on the phase current direction.

[0085] According to an embodiment of the present invention, the determination module 520 is further configured to determine the motor rotor position when the phase current direction switches from a positive direction to a negative direction, or from a negative direction to a positive direction.

[0086] According to one embodiment of the present invention, the acquisition module 510 is also used to: obtain the upper bridge arm voltage of the target bridge arm within the dead time and the DC bus voltage of the inverter, wherein the upper bridge arm voltage is obtained by sampling the voltage generated by the upper bridge arm current on the upper bridge arm through a single-ended voltage sampling circuit; determine the upper bridge arm current based on the upper bridge arm voltage, the DC bus voltage, the conduction voltage of the freewheeling diode of the upper bridge arm and the phase resistance of the motor.

[0087] According to one embodiment of the present invention, the upper bridge arm also includes an upper bridge arm sampling resistor, and the acquisition module 510 is also used to determine the upper bridge arm current based on the upper bridge arm voltage, the DC bus voltage, the conduction voltage of the freewheeling diode of the upper bridge arm, the phase resistance of the motor and the resistance of the upper bridge arm sampling resistor.

[0088] According to one embodiment of the present invention, the acquisition module 510 is also used to: obtain the lower bridge arm voltage of the target bridge arm within the dead time, wherein the lower bridge arm voltage is obtained by sampling the voltage generated by the lower bridge arm current on the lower bridge arm through a differential voltage sampling circuit; determine the lower bridge arm current based on the lower bridge arm voltage, the conduction voltage of the freewheeling diode of the lower bridge arm and the phase resistance of the motor.

[0089] According to one embodiment of the present invention, the lower bridge arm also includes a lower bridge arm sampling resistor, and the acquisition module 510 is also used to determine the lower bridge arm current based on the lower bridge arm voltage, the conduction voltage of the freewheeling diode of the lower bridge arm, the phase resistance of the motor and the resistance of the lower bridge arm sampling resistor.

[0090] It should be noted that for the description related to the motor phase current sampling device in this application, please refer to the description of the motor phase current sampling method in this application, and the details will not be repeated here.

[0091] According to the motor phase current sampling device of the embodiment of the present invention, the upper bridge arm current and the lower bridge arm current of the target bridge arm are obtained by the acquisition module within the dead time of the target bridge arm, and the phase current size and direction of the motor are determined by the determination module, thereby simplifying the current sampling method, and no phase shift will be generated during the sampling process, which has little impact on the motor, and the phase current imbalance of the motor can also be detected; at the same time, the specific position of the motor rotor can also be determined based on the determined phase current size and direction, thereby improving the convenience, applicability and functionality of the current sampling device.

[0092] Corresponding to the above embodiment, the embodiment of the present invention further provides an electrical device, referring to Figure 11a to Figure 11b As shown, the electrical device 1000 includes the aforementioned chip 400 , or the aforementioned motor phase current sampling device 500 .

[0093] The electrical equipment according to the embodiments of the present invention comprises the chip or the motor phase current sampling device in any of the above embodiments, wherein the electrical equipment may be various equipment such as air conditioners, refrigerators, compressors, etc. These electrical equipment can more simply implement the sampling of the motor phase current through the aforementioned chip or the motor phase current sampling device, and the sampling process will not affect the normal operation of the motor. At the same time, the motor phase current imbalance phenomenon and the position of the motor rotor can also be detected, thereby optimizing the motor phase current collection function.

[0094] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, 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 in other suitable ways if necessary, and then stored in a computer memory.

[0095] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0096] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0097] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0098] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0099] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A motor phase current sampling method, characterized in that: Applied to an inverter, the inverter includes a multi-phase bridge arm, each phase bridge arm includes an upper bridge arm and a lower bridge arm, the upper bridge arm includes an upper bridge arm switch tube connected in parallel with a freewheeling diode, the lower bridge arm includes a lower bridge arm switch tube connected in parallel with a freewheeling diode, and the method includes: Obtaining an upper bridge arm current and a lower bridge arm current of a target bridge arm within a dead time, wherein the upper bridge arm current is a current flowing through a freewheeling diode of the upper bridge arm within the dead time, and the lower bridge arm current is a current flowing through a freewheeling diode of the lower bridge arm within the dead time; Based on the upper bridge arm current and the lower bridge arm current, the phase current magnitude and the phase current direction of the motor are determined.

2. The method according to claim 1, characterized in that The determining the phase current magnitude and the phase current direction of the motor based on the upper bridge arm current and the lower bridge arm current includes: When the upper bridge arm current is greater than a preset current and the lower bridge arm current is less than or equal to the preset current, determining that the magnitude of the phase current is the upper bridge arm current and the direction of the phase current is a negative direction; When the lower bridge arm current is greater than the preset current and the upper bridge arm current is less than or equal to the preset current, determining that the magnitude of the phase current is the lower bridge arm current and the direction of the phase current is a positive direction; The negative direction is the direction in which the phase current flows from the motor into the inverter, and the positive direction is the direction in which the phase current flows from the inverter into the motor.

3. The method according to claim 2, characterized in that The method further comprises: Based on the phase current directions, the motor rotor position is determined.

4. The method according to claim 3, characterized in that: The step of determining the motor rotor position based on the phase current direction includes: When the direction of the phase current switches from the positive direction to the negative direction, or switches from the negative direction to the positive direction, the motor rotor position is determined.

5. The method according to any one of claims 1 to 4, characterized in that: Get the upper arm current of the target bridge arm during the dead time, including: Obtaining an upper bridge arm voltage of the target bridge arm within the dead time and a DC bus voltage of the inverter, wherein the upper bridge arm voltage is obtained by sampling a voltage generated by the upper bridge arm current on the upper bridge arm through a single-ended voltage sampling circuit; The upper bridge arm current is determined based on the upper bridge arm voltage, the DC bus voltage, the conduction voltage of the freewheeling diode of the upper bridge arm and the phase resistance of the motor.

6. The method according to claim 5, characterized in that The upper bridge arm further includes an upper bridge arm sampling resistor, and the method of obtaining the upper bridge arm current of the target bridge arm within the dead time also includes: The upper bridge arm current is determined based on the upper bridge arm voltage, the DC bus voltage, the on-voltage of the freewheeling diode of the upper bridge arm, the phase resistance of the motor and the resistance of the upper bridge arm sampling resistor.

7. The method according to any one of claims 1 to 4, characterized in that: Get the lower arm current of the target bridge arm during the dead time, including: Acquire the lower bridge arm voltage of the target bridge arm within the dead time, wherein the lower bridge arm voltage is obtained by sampling the voltage generated by the lower bridge arm current on the lower bridge arm through a differential voltage sampling circuit; The lower bridge arm current is determined based on the lower bridge arm voltage, the conduction voltage of the freewheeling diode of the lower bridge arm and the phase resistance of the motor.

8. The method according to claim 7, characterized in that The lower bridge arm further includes a lower bridge arm sampling resistor, and the step of obtaining the lower bridge arm current of the target bridge arm within the dead time further includes: The lower bridge arm current is determined based on the lower bridge arm voltage, the conduction voltage of the freewheeling diode of the lower bridge arm, the phase resistance of the motor and the resistance of the lower bridge arm sampling resistor.

9. A computer-readable storage medium, characterized in that: A program is stored thereon, and when the program is executed by a processor, the motor phase current sampling method according to any one of claims 1-8 is implemented.

10. A chip, characterized in that: include: A memory, a processor, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, the motor phase current sampling method according to any one of claims 1 to 8 is implemented.

11. A motor phase current sampling device, characterized in that: Applied to an inverter, the inverter includes a multi-phase bridge arm, each phase bridge arm includes an upper bridge arm and a lower bridge arm, the upper bridge arm includes an upper bridge arm switch tube connected in parallel with a freewheeling diode, the lower bridge arm includes a lower bridge arm switch tube connected in parallel with a freewheeling diode, and the device includes: An acquisition module, used to acquire an upper bridge arm current and a lower bridge arm current of a target bridge arm within a dead time, wherein the upper bridge arm current is a current flowing through a freewheeling diode of the upper bridge arm within the dead time, and the lower bridge arm current is a current flowing through a freewheeling diode of the lower bridge arm within the dead time; A determination module is used to determine the phase current magnitude and phase current direction of the motor based on the upper bridge arm current and the lower bridge arm current.

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

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