Phase current sampling control circuit multiplexed for multiple motors

Abstract

The invention discloses a phase current sampling control circuit multiplexed for multiple motors. The phase current sampling control circuit comprises a three-bridge-arm driving circuit, a phase current switching circuit and a single-operational-amplifier sampling circuit. The phase current switching circuit is used for selecting three phase current transmission ends of one motor in the motor group to be respectively communicated with connecting nodes of one upper bridge arm and one lower bridge arm of the three-bridge arm driving circuit; the three-bridge-arm driving circuit is connected to the single-operational-amplifier sampling circuit through two ends of a sampling resistor in the three-bridge-arm driving circuit; each lower bridge arm in the three-bridge-arm driving circuit is connected to one end of the sampling resistor, so that the sampling resistor is used for sampling a phase current flowing out of the corresponding lower bridge arm at different moments and feeding back the phase current to the single-operational-amplifier sampling circuit; and the single operational amplifier sampling circuit is used for reducing an offset signal by connecting a resistor in series at the input end of the single operational amplifier sampling circuit when the phase current is input, and filtering the phase current through a built-in filter network.

Description

Technical Field

[0001] The present application relates to the technical field of motor current sampling, and in particular to a phase current sampling control circuit multiplexed for multiple motors. Background Art

[0002] In a motor control chip and a motor control circuit disclosed in a Chinese patent with patent application number CN202311200362.0, the motor control chip adjusts the main current generated by the three-phase inverter circuit in real time. The three-phase inverter circuit is used to generate the three-phase voltage required by the motor based on the state coding value to drive the motor to operate. The sampling resistor is connected to the three-phase inverter circuit so that the main current generated by the three-phase inverter circuit flows through the sampling resistor to form a single resistor sampling circuit.

[0003] In the existing technology, for a single resistor sampling circuit, different phase currents are obtained in a variety of ways. The first is to detect the phase current through a Hall sensor to estimate the current of each phase; the second is to connect a sampling resistor in series with each lower bridge arm of a power device such as an IGBT / MOSFET, and reproduce the current information of each phase through the voltage information of the sampling resistor. Although the first method has high accuracy, the circuit complexity is high, the volume is large, and the cost is high. Although the second method has low cost, the accuracy is not high.

[0004] If the current of each phase is sampled in a multi-motor drive scenario, as the number of motors increases, more MOS tubes and more operational amplifiers are added due to drive control needs. Therefore, the use of more devices will introduce more ripple voltage to reduce the sampling accuracy and increase the complexity and cost of the circuit. Summary of the invention

[0005] The present application discloses a phase current sampling control circuit reused for multiple motors, and the specific technical solutions involved are as follows: A phase current sampling control circuit for multiple motors, the phase current sampling control circuit comprising a three-bridge arm driving circuit, a phase current switching circuit and a single operational amplifier sampling circuit; the motor group comprises at least two motors; the phase current switching circuit is used to select three phase current transmission ends of one motor in the motor group to be respectively connected to the connection nodes of an upper bridge arm and a lower bridge arm of the three-bridge arm driving circuit, and each phase current transmission end of the same motor is used to transmit one phase current; the three-bridge arm driving circuit is connected to the single operational amplifier sampling circuit through the two ends of the sampling resistor inside it; each lower bridge arm in the three-bridge arm driving circuit is connected to one end of the sampling resistor, so that the sampling resistor is used to sample a phase current flowing out of the corresponding lower bridge arm at different times and feed it back to the single operational amplifier sampling circuit; the single operational amplifier sampling circuit is used to reduce the offset signal by connecting a resistor in series at its input end when inputting the one phase current, and also filter the one phase current through a built-in filtering network. The phase current sampling control circuit disclosed in the present application selects different motors and their sampling detection of each phase current to share the same three-bridge arm drive circuit (including the same sampling resistor) and the same single op amp sampling circuit structure, which is conducive to reducing the cost of multi-motor sampling drive circuits and improving the sampling accuracy of single-phase current. Compared with the multi-motor drive circuit framework disclosed in the prior art, in the single-phase current sampling scenario, the present application sets the circuit module with the selection and switching function between the three-bridge arm drive circuit and the motor group, selects the three-phase current of the motor currently required to be sampled through the phase current switching circuit, and connects it to the three-bridge arm drive circuit, and then feeds back to the sampling resistor phase by phase from the three-bridge arm drive circuit, and then samples to the single op amp sampling circuit through the sampling resistor, so as to obtain higher-precision single-phase current sampling results corresponding to the selected motor at different times.

[0006] Further, the phase current switching circuit includes a first switch, a second switch and a third switch, and the three phase current transmission ends of the motor are respectively a U-phase current transmission end, a V-phase current transmission end and a W-phase current transmission end; each single selection end of the phase current switching circuit is used to connect the three phase current transmission ends of each motor in the motor group, including: each single selection end of the first switch is connected to the U-phase current transmission end of each motor, each single selection end of the second switch is connected to the V-phase current transmission end of each motor, and each single selection end of the third switch is connected to the W-phase current transmission end of each motor; the first switch, the second switch and the third switch are used to simultaneously select the three phase current transmission ends of the same motor to transmit the corresponding phase current. Compared with the prior art, the present application adds three switches to select the three-phase current of different motors in the motor group, and cooperates with the three-bridge arm drive circuit to select the three-phase current of one of the motors to be transmitted by the phase current switching circuit.

[0007] Furthermore, the three-bridge-arm driving circuit includes three upper bridge arms and three lower bridge arms, the three upper bridge arms are respectively a first switch tube, a second switch tube and a third switch tube, the three lower bridge arms are respectively a fourth switch tube, a fifth switch tube and a sixth switch tube, the first transmission end of the first switch tube, the first transmission end of the second switch tube and the first transmission end of the third switch tube are all connected to the power supply; the second transmission end of the first switch tube and the first transmission end of the sixth switch tube are connected to the common selection end of the first switch, the second transmission end of the second switch tube and the first transmission end of the fifth switch tube are connected to the common selection end of the second switch, and the second transmission end of the third switch tube and the first transmission end of the fourth switch tube are connected to the common selection end of the third switch ; The common selection end of the first switch, the common selection end of the second switch and the common selection end of the third switch are used to switch and connect the corresponding single selection end under the triggering of the external selection signal, so as to output the current from the three-bridge arm driving circuit to the corresponding phase current transmission end of the motor, or output the corresponding phase current from the corresponding phase current transmission end of the motor to the three-bridge arm driving circuit; wherein, the connection node between the second transmission end of the first switch tube and the first transmission end of the sixth switch tube, the connection node between the second transmission end of the second switch tube and the first transmission end of the fifth switch tube, and the connection node between the second transmission end of the third switch tube and the first transmission end of the fourth switch tube are all connection nodes of each upper bridge arm and the corresponding lower bridge arm. In the case where multi-motor selection drive control is required, for example, when there are at least 2 motors that need to be driven and controlled, the aforementioned phase current sampling control circuit is adopted, and a total of 6 switch tubes and 3 switches are required to achieve it, which has the characteristics of low cost. By adjusting the duty cycle of the 6 switching tubes and the single selection end selected by the 3 switches, the currently selected motor and its three-phase current are selected and connected to the three-bridge arm drive circuit to obtain higher-precision single-phase current sampling results corresponding to the selected motor at different times.

[0008] Furthermore, the second transmission end of the sixth switch tube, the second transmission end of the fifth switch tube, and the second transmission end of the fourth switch tube are all connected to one end of the sampling resistor, and the two ends of the sampling resistor are connected to the single op amp sampling circuit, so that the voltage drop of the sampling resistor is fed back to a phase current flowing out of the corresponding lower bridge arm. Therefore, the present application realizes the feedback of phase current from the three-bridge arm driving circuit to the sampling resistor to form a current sampling object of the single op amp sampling circuit by turning on the corresponding switch tubes in the upper / lower bridge arm in the three-bridge arm driving circuit and turning off the remaining switch tubes.

[0009] Further, in the case where the first switch, the second switch and the third switch are used to simultaneously select the three phase current transmission ends of the same motor, the following conditions exist: when the first switch tube, the fourth switch tube and the fifth switch tube are all turned on and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current input to the U-phase current transmission end of the same motor, and is sampled as the U-phase current; when the first switch tube, the fourth switch tube and the second switch tube are all turned on and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current output from the W-phase current transmission end of the same motor, and is sampled as the negative value of the W-phase current; when the sixth switch tube, the second switch tube and the fourth switch tube are all turned on and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current output from the W-phase current transmission end of the same motor, and is sampled as the negative value of the W-phase current. The current inputted from the V-phase current transmission terminal of the motor is sampled as the V-phase current; when the sixth switch tube, the second switch tube and the third switch tube are all turned on and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current outputted from the U-phase current transmission terminal of the same motor, and is sampled as the negative value of the U-phase current; when the third switch tube, the fifth switch tube and the sixth switch tube are all turned on and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current inputted from the W-phase current transmission terminal of the same motor, and is sampled as the W-phase current; when the first switch tube, the third switch tube and the fifth switch tube are all turned on and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current outputted from the V-phase current transmission terminal of the same motor, and is sampled as the negative value of the V-phase current. In summary, the sampling and detection of each phase current in the selected single motor shares the same set of the three-bridge-arm drive circuit, and the corresponding switch tubes in each bridge arm of the three-bridge-arm drive circuit are alternately turned on and the remaining switch tubes are turned off, so that the three-phase current of the single motor is sampled on a single sampling resistor.

[0010] Furthermore, the sum of the current transmitted by the U-phase current transmission terminal of the same motor, the current transmitted by the V-phase current transmission terminal of the same motor, and the current transmitted by the W-phase current transmission terminal of the same motor is equal to zero. The magnitude of each phase current of the motor can be determined according to Kirchhoff's law.

[0011] Furthermore, the single op amp sampling circuit includes an operational amplifier, a first resistor and a second resistor; the positive input terminal and the negative input terminal of the operational amplifier are respectively used to connect the two ends of the sampling resistor; the positive input terminal of the operational amplifier is connected to one end of the first resistor, and the other end of the first resistor is grounded; the positive input terminal of the operational amplifier is connected to one end of the second resistor, and the other end of the second resistor is connected to the reference voltage. Therefore, the reference voltage is divided by the second resistor and the first resistor to provide a bias voltage, so that the input voltage is boosted to obtain a positive voltage, and the anti-interference ability of the output voltage of the operational amplifier can be improved to obtain a more stable signal.

[0012] Furthermore, a fourth resistor is connected between the positive input terminal of the operational amplifier and one end of the sampling resistor, and a fifth resistor is connected between the negative input terminal of the operational amplifier and the other end of the sampling resistor, and the resistance value of the fourth resistor is equal to the resistance value of the fifth resistor, so that when the operational amplifier samples the voltage drop across the sampling resistor, input impedance matching is established by introducing the fourth resistor and the fifth resistor. In this way, the input impedance of the operational amplifier can be matched, and the influence of the offset current and bias current of the operational amplifier can be minimized, so that the output phase current is more accurate.

[0013] Furthermore, the single op amp sampling circuit also includes a first capacitor, which is connected in parallel to both ends of the first resistor to filter the reference voltage; wherein the capacitance of the first capacitor is in the picofarad level, so as to achieve a fast response effect and achieve the purpose of real-time detection.

[0014] Furthermore, the single operational amplifier sampling circuit further includes a second capacitor and a third resistor, one end of the third resistor is connected to the output end of the operational amplifier, the other end of the third resistor is connected to one end of the second capacitor, and one end of the second capacitor is grounded, wherein the third resistor and the second capacitor form the filtering network, and the capacitance of the second capacitor is in the order of magnitude of microfarads. Thus, the high-frequency components in the phase current are filtered out, making the output signal of the operational amplifier more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic structural diagram of a phase current sampling control circuit for multiple motors is disclosed as an embodiment of the present application. DETAILED DESCRIPTION

[0016] In the following description, specific details are given to provide a thorough understanding of the embodiments. However, one of ordinary skill in the art will appreciate that the embodiments may be practiced without these specific details. For example, circuits may be shown in block diagrams so as not to obscure the embodiments in unnecessary detail. In other cases, well-known circuits, structures, and techniques may not be shown in detail in order not to obscure the embodiments.

[0017] In the description of this application, if it involves a description of orientation, for example, the orientation or position relationship indicated by "upper", "lower", "front", "back", "left", "right", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. If a technical feature is referred to as "set", "fixed", "connected", or "installed" on another technical feature, it can be directly set, fixed, or connected to the other technical feature, or it can be indirectly set, fixed, connected, or installed on the other technical feature.

[0018] In the description of this application, if "several" is involved, it means more than one; if "multiple" is involved, it means two or more; if "greater than", "less than", or "exceed" is involved, it should be understood as not including the number itself; if "above", "below", or "within" is involved, it should be understood as including the number itself. If "first", "second", etc. are involved, they should be understood as being used only to distinguish the names of the same or similar technical features, and should not be understood as implying / indicating the relative importance of the technical features, the number of the technical features, or the order of the technical features.

[0019] In order to improve the reuse rate of devices and ensure the sampling accuracy of each phase current of each motor, and avoid adding more MOS tube bridge arms and more operational amplifiers due to the requirements of multi-motor driving scenarios, the present application discloses a phase current sampling control circuit reused for multiple motors. The reuse of multiple motors here means that the phase current sampling control circuit can detect the phase currents of different motors at different times, and switch to detect different phase currents of different motors on the same set of operational amplifier structure and bridge arm structure (multiple motors share the same number of switch tubes on the bridge arm for drive sampling).

[0020] like Figure 1 As shown, the phase current sampling control circuit includes a three-bridge arm driving circuit, a phase current switching circuit and a single op amp sampling circuit; the phase current sampling control circuit is used to connect the motor group. The motor group includes at least two motors, such as Figure 1The motor M1 and motor M2 shown are both connected to the phase current sampling control circuit. The phase current switching circuit is used to select the three phase current transmission ends of a motor in the motor group to be connected to the connection nodes of an upper bridge arm and a lower bridge arm of the three-bridge arm driving circuit respectively, so that the three phase current transmission ends of each motor in the motor group can be connected to the three-bridge arm driving circuit through the phase current switching circuit; during a period of current action time, the phase current switching circuit selects the three phase current transmission ends U, V and W of the motor M1 in the motor group to be connected to the connection nodes of each upper bridge arm and the corresponding lower bridge arm of the three-bridge arm driving circuit respectively; during another period of current action time, the phase current switching circuit selects the three phase current transmission ends U, V and W of the motor M2 in the motor group to be connected to the connection nodes of each upper bridge arm and the corresponding lower bridge arm of the same three-bridge arm driving circuit respectively.

[0021] Each phase current transmission end of a motor is used to transmit a phase current. Three pairs of bridge arms are arranged in the three-bridge arm driving circuit. Each pair of bridge arms is provided with an upper bridge arm and a lower bridge arm, and a connection node of an upper bridge arm and a lower bridge arm is connected to the phase current switching circuit, such as Figure 1 As shown, the upper bridge arm and the lower bridge arm on the far left are switch tube NM1 and switch tube NM6 respectively, the upper bridge arm and the lower bridge arm in the middle are switch tube NM2 and switch tube NM5 respectively, and the upper bridge arm and the lower bridge arm on the far right are switch tube NM3 and switch tube NM4 respectively; a pair of bridge arms are used to provide a phase current to a phase current transmission end of a motor selected by the phase current switching circuit, or a phase current transmission end of a motor selected by the phase current switching circuit is used to output a phase current to a pair of bridge arms.

[0022] The three-arm driving circuit is connected to the single op amp sampling circuit through the two ends of the sampling resistor inside it; each lower bridge arm in the three-arm driving circuit is connected to one end of the sampling resistor, so that the sampling resistor is used to sample a phase current flowing out of the corresponding lower bridge arm at different times and feed it back to the single op amp sampling circuit. The sampling resistor is as follows: Figure 1 As shown by the resistor Rs. The present application sets the phase current switching circuit between the three-bridge arm drive circuit and the motor group. The motor group selects the three-phase current of the motor currently required to be sampled by selecting the phase current switching circuit and connects it to the three-bridge arm drive circuit. Then, the corresponding upper / lower bridge arms in the three-bridge arm drive circuit are turned on and the remaining switch tubes are turned off. Then, each phase current of the selected motor can reuse the three-bridge arm drive circuit. According to Kirchhoff's law, after the phase currents flowing into and out of the selected motor are collected in the sampling resistor Rs, it is equivalent to forming a single-phase current, and then sampled into a single operational amplifier structure of a single operational amplifier sampling circuit through the sampling resistor Rs. The operational amplifier structure is as shown in Figure 1 As shown in the operational amplifier A1, the single operational amplifier sampling circuit captures the single-phase current sampling result of a selected motor.

[0023] Based on this, a reusable operational amplifier circuit structure is disclosed, namely, a single operational amplifier sampling circuit; the single operational amplifier sampling circuit is used to reduce the offset signal by connecting a resistor in series at its input end when inputting the one phase current, and also filters the one phase current through a built-in filter network, so the single operational amplifier sampling circuit is a differential filter circuit structure composed of a single operational amplifier. Figure 1 As shown, the operational amplifier A1 provided in the single op amp sampling circuit can detect the current of the corresponding half-bridge arm or its sum by connecting the sampling resistor Rs in parallel, and reproduce it with the voltage drop of the sampling resistor Rs, and cooperate with the resistor connected to the positive input end of the operational amplifier for impedance matching to reduce the influence of the offset current, and also connect the filter network for filtering to reduce the influence of the ripple voltage, thereby forming a circuit device reuse mode for improving the phase current detection accuracy.

[0024] The phase current sampling control circuit disclosed in the present application selects different motors and their sampling detection of each phase current to share the same three-bridge arm drive circuit (including the same sampling resistor) and the same single op amp sampling circuit structure, which is conducive to reducing the cost of multi-motor sampling drive circuits and improving the sampling accuracy of single-phase current. Compared with the multi-motor drive circuit framework disclosed in the prior art, in the single-phase current sampling scenario, the present application sets the circuit module with the selection and switching function between the three-bridge arm drive circuit and the motor group, selects the three-phase current of the motor currently required to be sampled through the phase current switching circuit, and connects it to the three-bridge arm drive circuit, and then feeds back to the sampling resistor phase by phase from the three-bridge arm drive circuit, and then samples to the single op amp sampling circuit through the sampling resistor, so as to obtain higher-precision single-phase current sampling results corresponding to the selected motor at different times.

[0025] As an embodiment, the phase current switching circuit includes a first switch, a second switch and a third switch, such as Figure 1As shown, the phase current switching circuit shown in the figure is composed of a first switch MU1, a second switch MU2 and a third switch MU3, each switch is provided with at least two single selection terminals I0 and I1 to respectively connect the same type of phase current transmission terminals of each motor, and each switch is also provided with a common selection terminal M to connect to the connection node of an upper bridge arm and a lower bridge arm of the three-bridge arm drive circuit. The three phase current transmission terminals of the motor are respectively the U-phase current transmission terminal, the V-phase current transmission terminal and the W-phase current transmission terminal. The form in which the single selection terminals of the phase current switching circuit are respectively used to connect the three phase current transmission terminals of each motor in the motor group includes: the single selection terminals of the first switch are respectively connected to the U-phase current transmission terminal of each motor, the single selection terminals of the second switch are respectively connected to the V-phase current transmission terminal of each motor, and the single selection terminals of the third switch are respectively connected to the W-phase current transmission terminal of each motor; the first switch, the second switch and the third switch are used to simultaneously select the three phase current transmission terminals of the same motor to transmit the corresponding phase current. In some embodiments, such as Figure 1 As shown, the first switch MU1, the second switch MU2 and the third switch MU3 simultaneously select the U-phase current transmission end, the V-phase current transmission end and the W-phase current transmission end of the motor M1. The first switch MU1 selects the path between the common selection end M and the single selection end I0 under the configuration of the selection signal s1 to connect the U-phase current transmission end of the motor M1 with the three-bridge arm drive circuit and transmit the phase current between the U-phase current transmission end of the motor M1 and the three-bridge arm drive circuit. The second switch MU2 selects the path between the common selection end M and the single selection end I0 under the configuration of the selection signal s2 to connect the V-phase current transmission end of the motor M1 with the three-bridge arm drive circuit and transmit the phase current between the V-phase current transmission end of the motor M1 and the three-bridge arm drive circuit. The third switch MU3 selects the path between the common selection end M and the single selection end I0 under the configuration of the selection signal s3 to connect the W-phase current transmission end of the motor M1 with the three-bridge arm drive circuit and transmit the phase current between the W-phase current transmission end of the motor M1 and the three-bridge arm drive circuit. Compared with the prior art, the present application adds three switches to perform selection processing on the three-phase currents of different motors in the motor group, and cooperates with the three-arm bridge drive circuit, and the phase current switching circuit selects the three-phase current of one of the motors to be transmitted.

[0026] As an embodiment, the three-bridge-arm driving circuit includes three upper bridge arms and three lower bridge arms, the three upper bridge arms are respectively a first switch tube, a second switch tube and a third switch tube, the three lower bridge arms are respectively a fourth switch tube, a fifth switch tube and a sixth switch tube, the first transmission end of the first switch tube, the first transmission end of the second switch tube and the first transmission end of the third switch tube are all connected to the power supply; the second transmission end of the first switch tube and the first transmission end of the sixth switch tube are connected to the common selection end of the first switch, the second transmission end of the second switch tube and the first transmission end of the fifth switch tube are connected to the common selection end of the second switch, and the second transmission end of the third switch tube and the first transmission end of the fourth switch tube are connected to the common selection end of the third switch; the three-bridge-arm driving circuit includes three pairs of bridge arms, schematically, as shown Figure 1 As shown, the upper bridge arm of the left pair of bridge arms is the first switch tube NM1, the lower bridge arm of the left pair of bridge arms is the sixth switch tube NM6, the upper bridge arm of the middle pair of bridge arms is the second switch tube NM2, the lower bridge arm of the middle pair of bridge arms is the fifth switch tube NM5, the upper bridge arm of the right pair of bridge arms is the third switch tube NM3, and the lower bridge arm of the right pair of bridge arms is the fourth switch tube NM4, wherein the first transmission end of each switch tube is the drain end of the NMOS tube, the second transmission end of each switch tube is the source end of the NMOS tube, and the control signal received by the gate end of each switch tube is used to turn the switch tube on or off.

[0027] In this embodiment, the common selection end of the first switch, the common selection end of the second switch and the common selection end of the third switch are used to switch and connect the corresponding single selection ends under the triggering of an external selection signal, so as to output current from the three-bridge arm drive circuit to the corresponding phase current transmission end of the motor, or output the corresponding phase current from the corresponding phase current transmission end of the motor to the three-bridge arm drive circuit; for example, the first switch MU1 is triggered by the selection signal s1, and the second switch MU2 is triggered by the selection signal s2, and the third switch MU3 is triggered by the selection signal s3, the first switch MU1 selects the single selection end I0 and the common selection end M, and the second switch MU2 selects the single selection end I0 and the common selection end M, and the third switch MU3 selects the single selection end I0 and the common selection end M, then the U-phase current, the V-phase current and the W-phase current can be simultaneously transmitted between the three-bridge arm drive circuit and the motor M1 through the single selection end I0.

[0028] In this embodiment, the connection node between the second transmission end of the first switch tube and the first transmission end of the sixth switch tube, the connection node between the second transmission end of the second switch tube and the first transmission end of the fifth switch tube, and the connection node between the second transmission end of the third switch tube and the first transmission end of the fourth switch tube are all connection nodes between each upper bridge arm and the corresponding lower bridge arm. Schematically, as shown in Figure 1As shown, the connection node of the first switch tube NM1 and the sixth switch tube NM6 is connected to the common selection terminal M of the first switch MU1, and is dedicated to selecting the U-phase current transmitted by the U-phase current transmission terminal of the motor M1 or the motor M2 through the first switch MU1; the connection node of the second switch tube NM2 and the fifth switch tube NM5 is connected to the common selection terminal M of the second switch MU2, and is dedicated to selecting the V-phase current transmitted by the V-phase current transmission terminal of the motor M1 or the motor M2 through the second switch MU2; the connection node of the third switch tube NM3 and the fourth switch tube NM4 is connected to the common selection terminal M of the third switch MU3, and is dedicated to selecting the W-phase current transmitted by the W-phase current transmission terminal of the motor M1 or the motor M2 through the third switch MU3.

[0029] In situations where multiple motors need to be driven and controlled, for example, when there are at least two motors that need to be driven and controlled, the above-mentioned phase current sampling control circuit is used, which requires a total of 6 switch tubes and 3 switches to achieve low cost. By adjusting the duty cycle of the 6 switch tubes and the single selection end selected by the 3 switches, the currently selected motor and its three-phase current are connected to the three-bridge arm drive circuit to obtain higher-precision single-phase current sampling results corresponding to the selected motor at different times.

[0030] Based on the above embodiment, the second transmission end of the sixth switch tube, the second transmission end of the fifth switch tube and the second transmission end of the fourth switch tube are all connected to one end of the sampling resistor. Figure 1 It can be known that an equivalent current is collected to the sampling resistor Rs through the sixth switch tube NM6, the fifth switch tube NM5 and the fourth switch tube NM4 to form a phase current flowing through the sampling resistor Rs; wherein the sixth switch tube NM6, the fifth switch tube NM5 and the fourth switch tube NM4 all belong to the lower bridge arm of the three-bridge arm driving circuit.

[0031] It should be noted that in order to prevent the voltage across the sampling resistor from being too large and the sampling resistor has power limitations, the resistance of the sampling resistor is generally very small, so the voltage difference across it is also very small. If it is directly input into a microcontroller or processor unit, it needs to be connected to an op amp structure for amplification processing to facilitate identification.

[0032] The two ends of the sampling resistor are connected to a single op amp sampling circuit, so that the voltage drop of the sampling resistor is fed back to a phase current corresponding to the lower bridge arm, and the voltage drop of the sampling resistor is used as the current sampling object of the single op amp sampling circuit. Therefore, the present application realizes that the current is fed back from the three-bridge-arm driving circuit to the sampling resistor phase by phase to form the current sampling object of the single op amp sampling circuit by turning on the corresponding switch tubes in the upper / lower bridge arms in the three-bridge-arm driving circuit and turning off the other switch tubes.

[0033] As an embodiment, the first switch, the second switch and the third switch are used to simultaneously select the three phase current transmission ends of the same motor, specifically, when the first switch, the second switch and the third switch respectively select the three phase current transmission ends of the same motor to be connected to the connection nodes of the corresponding upper bridge arm and the corresponding lower bridge arm, combined with Figure 1 It can be seen that there exists: When the first switch tube, the fourth switch tube and the fifth switch tube are all turned on and the remaining switch tubes in the three-arm driving circuit are all turned off, the current flowing through the sampling resistor is equal to the current input to the U-phase current transmission end of the same motor, and the current is sampled as the U-phase current; corresponding to Figure 1 , the first switch tube NM1, the fourth switch tube NM4 and the fifth switch tube NM5 are all turned on, and the sixth switch tube NM6, the second switch tube NM2 and the third switch tube NM3 are all turned off. At this time, if the three phase current transmission ends of the motor M1 are selected to the three-bridge arm drive circuit by the phase current switching circuit, the V-phase current transmission end of the motor M1 outputs current to the fifth switch tube NM5 through the second switch MU2, and the W-phase current transmission end of the motor M1 outputs current to the fourth switch tube NM4 through the third switch MU3, and the power supply VDD is transmitted to the U-phase of the motor M1 through the first switch tube NM1 and the first switch MU1. The current is input to the current transmission end; the current flowing through the sampling resistor Rs is the result of the current output from the V-phase current transmission end of the motor M1 and the current output from the W-phase current transmission end (the sum of the currents at the common connection node of the sixth switch tube NM6, the fifth switch tube NM5 and the fourth switch tube NM4); based on Kirchhoff's law, it can be known that the sum of the current output from the V-phase current transmission end of the motor M1 and the current output from the W-phase current transmission end is equal to the current input to the U-phase current transmission end of the motor M1. Based on this, the single op amp sampling circuit reproduces the current transmitted by the U-phase current transmission end of the motor M1 through the voltage drop of the sampling resistor Rs.

[0034] When the first switch tube, the fourth switch tube and the second switch tube are all turned on, and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current output by the W-phase current transmission end of the same motor, and the sampling is the negative value of the W-phase current; corresponding to Figure 1, the first switch tube NM1, the fourth switch tube NM4 and the second switch tube NM2 are all turned on, and the sixth switch tube NM6, the fifth switch tube NM5 and the third switch tube NM3 are all turned off. At this time, if the three phase current transmission ends of the motor M1 are selected to the three-bridge arm drive circuit by the phase current switching circuit, the W-phase current transmission end of the motor M1 outputs current to the fourth switch tube NM4 through the third switch MU3, and the power supply VDD inputs current to the U-phase current transmission end of the motor M1 through the first switch tube NM1 and the first switch MU1, and the power supply VDD inputs current to the U-phase current transmission end of the motor M1 through the second switch tube NM2 and the second switch The device MU2 inputs current to the V-phase current transmission end of the motor M1, and the current flowing through the sampling resistor Rs is the W-phase current transmission end of the motor M1 outputs current to the fourth switch tube NM4 through the third switch MU3. Based on Kirchhoff's law, it can be known that the sum of the current input to the U-phase current transmission end of the motor M1 and the current input to the V-phase current transmission end is equal to the current output by the W-phase current transmission of the motor M1, and the current output by the W-phase current transmission of the motor M1 represents the negative value of the W-phase current; based on this, the single op amp sampling circuit reproduces the current transmitted by the W-phase current transmission end of the motor M1 through the voltage drop of the sampling resistor Rs.

[0035] When the sixth switch tube, the second switch tube and the fourth switch tube are all turned on and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current input to the V-phase current transmission end of the same motor, and the current is sampled as the V-phase current; corresponding to Figure 1 , the second switch tube NM2, the fourth switch tube NM4 and the sixth switch tube NM6 are all turned on, and the first switch tube NM1, the fifth switch tube NM5 and the third switch tube NM3 are all turned off. At this time, if the three phase current transmission ends of the motor M1 are selected to the three-bridge arm drive circuit by the phase current switching circuit, the U-phase current transmission end of the motor M1 outputs current to the sixth switch tube NM6 through the first switch MU1, and the W-phase current transmission end of the motor M1 outputs current to the fourth switch tube NM4 through the third switch MU3, and the power supply VDD is transmitted to the V-phase of the motor M1 through the second switch tube NM2 and the second switch MU2. The current is input to the current transmission end; the current flowing through the sampling resistor Rs is the result of the collection of the output current of the U-phase current transmission end and the current output from the W-phase current transmission end of the motor M1 (the sum of the currents at the common connection node of the sixth switch tube NM6, the fifth switch tube NM5 and the fourth switch tube NM4); based on Kirchhoff's law, it can be known that the sum of the current output from the U-phase current transmission end and the current output from the W-phase current transmission end of the motor M1 is equal to the current input to the V-phase current transmission end of the motor M1. Based on this, the single op amp sampling circuit reproduces the current transmitted by the V-phase current transmission end of the motor M1 through the voltage drop of the sampling resistor Rs.

[0036] When the sixth switch tube, the second switch tube and the third switch tube are all turned on, and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current output by the U-phase current transmission end of the same motor, and the sampling is the negative value of the U-phase current; corresponding to Figure 1 , the second switch tube NM2, the third switch tube NM3 and the sixth switch tube NM6 are all turned on, and the first switch tube NM1, the fourth switch tube NM4 and the fifth switch tube NM5 are all turned off. At this time, if the three phase current transmission ends of the motor M1 are selected to the three-bridge arm drive circuit by the phase current switching circuit, the U-phase current transmission end of the motor M1 outputs current to the sixth switch tube NM6 through the first switch MU1, and the power supply VDD inputs current to the W-phase current transmission end of the motor M1 through the third switch tube NM3 and the third switch MU3, and the power supply VDD is connected to the motor M1 through the second switch tube NM2 and the second switch. The device MU2 inputs current to the V-phase current transmission end of the motor M1, and the current flowing through the sampling resistor Rs is the U-phase current transmission end of the motor M1 outputs current to the sixth switch tube NM6 through the first switch MU1. Based on Kirchhoff's law, it can be known that the sum of the current input to the W-phase current transmission end of the motor M1 and the current input to the V-phase current transmission end is equal to the current output by the U-phase current transmission of the motor M1, and the current output by the U-phase current transmission of the motor M1 represents the negative value of the U-phase current; based on this, the single op amp sampling circuit reproduces the current transmitted by the U-phase current transmission end of the motor M1 through the voltage drop of the sampling resistor Rs.

[0037] When the third switch tube, the fifth switch tube and the sixth switch tube are all turned on and the remaining switch tubes in the three-bridge arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current input to the W-phase current transmission end of the same motor, and the current is sampled as the W-phase current; corresponding to Figure 1, the third switch tube NM3, the fifth switch tube NM5 and the sixth switch tube NM6 are all turned on, and the first switch tube NM1, the second switch tube NM2 and the fourth switch tube NM4 are all turned off. At this time, if the three phase current transmission ends of the motor M1 are selected to the three-bridge arm drive circuit by the phase current switching circuit, the U-phase current transmission end of the motor M1 outputs current to the sixth switch tube NM6 through the first switch MU1, and the V-phase current transmission end of the motor M1 outputs current to the fifth switch tube NM5 through the second switch MU2, and the power supply VDD is transmitted to the W-phase current transmission end of the motor M1 through the third switch tube NM3 and the third switch MU3. The current is input to the current transmission end; the current flowing through the sampling resistor Rs is the result of the collection of the output current of the U-phase current transmission end and the current output from the V-phase current transmission end of the motor M1 (the sum of the currents at the common connection node of the sixth switch tube NM6, the fifth switch tube NM5 and the fourth switch tube NM4); based on Kirchhoff's law, it can be known that the sum of the current output from the U-phase current transmission end and the current output from the V-phase current transmission end of the motor M1 is equal to the current input to the W-phase current transmission end of the motor M1. Based on this, the single op amp sampling circuit reproduces the current transmitted by the W-phase current transmission end of the motor M1 through the voltage drop of the sampling resistor Rs.

[0038] When the first switch tube, the third switch tube and the fifth switch tube are all turned on and the remaining switch tubes in the three-arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current output by the V-phase current transmission end of the same motor, and the current sampled is the negative value of the V-phase current. Figure 1 , the first switch tube NM1, the third switch tube NM3 and the fifth switch tube NM5 are all turned on, and the second switch tube NM2, the fourth switch tube NM4 and the sixth switch tube NM6 are all turned off. At this time, if the three phase current transmission ends of the motor M1 are selected to the three-bridge arm drive circuit by the phase current switching circuit, the V-phase current transmission end of the motor M1 outputs current to the fifth switch tube NM5 through the second switch MU2, and the power supply VDD inputs current to the W-phase current transmission end of the motor M1 through the third switch tube NM3 and the third switch MU3. The power supply VDD passes through the first switch tube NM1 and the first switch The device MU1 inputs current to the U-phase current transmission end of the motor M1, and the current flowing through the sampling resistor Rs is the current output by the U-phase current transmission end of the motor M1 to the sixth switch tube NM6 through the first switch MU1. Based on Kirchhoff's law, it can be known that the sum of the current input to the W-phase current transmission end of the motor M1 and the current input to the U-phase current transmission end is equal to the current output by the V-phase current transmission of the motor M1, and the current output by the V-phase current transmission of the motor M1 represents the negative value of the V-phase current; based on this, the single op amp sampling circuit reproduces the current transmitted by the V-phase current transmission end of the motor M1 through the voltage drop of the sampling resistor Rs.

[0039] In summary, the sampling and detection of each phase current in the selected single motor shares the same set of the three-bridge-arm drive circuit, and the corresponding switch tubes in each bridge arm of the three-bridge-arm drive circuit are alternately turned on and the remaining switch tubes are turned off, so that the three-phase current of the single motor is sampled on a single sampling resistor.

[0040] In the above embodiment, the sum of the current transmitted by the U-phase current transmission terminal of the same motor, the current transmitted by the V-phase current transmission terminal of the same motor, and the current transmitted by the W-phase current transmission terminal of the same motor is equal to zero, and the magnitude of each phase current of the motor can be determined based on Kirchhoff's law.

[0041] The current transmitted by a phase current transmission terminal is a current output or input by the phase current transmission terminal.

[0042] It should be noted that, in the same motor, the U-phase current transmission terminal, the V-phase current transmission terminal and the W-phase current transmission terminal are all connected to the same common node through resistance and / or inductance; when the current flows out from the common node, it is regarded as output from the corresponding phase current transmission terminal, and the output current is recorded as negative current; when the current flows into the common node, it is regarded as input to the corresponding phase current transmission terminal, and the input current is recorded as positive current; based on Kirchhoff's law, it can be seen that the sum of the current transmitted by the U-phase current transmission terminal, the current transmitted by the V-phase current transmission terminal and the current transmitted by the W-phase current transmission terminal at the common node is equal to zero.

[0043] Specifically, the sum of the current output by the U-phase current transmission terminal of the same motor, the current output by the V-phase current transmission terminal of the same motor, and the current input by the W-phase current transmission terminal of the same motor is equal to zero.

[0044] The sum of the current input to the U-phase current transmission terminal of the same motor, the current output from the V-phase current transmission terminal of the same motor, and the current input to the W-phase current transmission terminal of the same motor is equal to zero.

[0045] The sum of the current output by the U-phase current transmission terminal of the same motor, the current input by the V-phase current transmission terminal of the same motor, and the current input by the W-phase current transmission terminal of the same motor is equal to zero.

[0046] The sum of the current input to the U-phase current transmission terminal of the same motor, the current output from the V-phase current transmission terminal of the same motor, and the current output from the W-phase current transmission terminal of the same motor is equal to zero.

[0047] The sum of the current output by the U-phase current transmission terminal of the same motor, the current input by the V-phase current transmission terminal of the same motor, and the current output by the W-phase current transmission terminal of the same motor is equal to zero.

[0048] The sum of the current input to the U-phase current transmission terminal of the same motor, the current input to the V-phase current transmission terminal of the same motor, and the current output from the W-phase current transmission terminal of the same motor is equal to zero.

[0049] If two current samples are taken in one regulation cycle (the same sector), two phase currents can be obtained. If Kirchhoff's law is used, other phase currents can also be obtained. Therefore, other phase currents can be estimated based on the sum of the two phase currents.

[0050] As an embodiment, the single operational amplifier sampling circuit includes an operational amplifier, a first resistor and a second resistor; Figure 1 It can be seen that the positive input terminal + and the negative input terminal - of the operational amplifier are respectively used to connect the two ends of the sampling resistor Rs. Without considering the wire impedance, the sampling resistor can be regarded as being connected in parallel to the positive input terminal and the negative input terminal of the operational amplifier; when considering the wire impedance, there is a wire impedance between the two ends of the sampling resistor and the input terminal of the operational amplifier. The positive input terminal + of the operational amplifier A1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is grounded GND; the positive input terminal + of the operational amplifier A1 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to the reference voltage Vref. Since the voltage input to the positive input terminal of the operational amplifier may be positive or negative, if a negative voltage is input, the output of the operational amplifier will also be a negative voltage. Finally, the voltage output by the operational amplifier will be collected by the chip, and the chip cannot recognize the negative voltage. Therefore, the reference voltage is divided by the second resistor R2 and the first resistor R1 to provide a bias voltage, so that the input voltage is boosted to obtain a positive voltage, and the anti-interference ability of the output voltage of the operational amplifier can also be improved to obtain a more stable signal.

[0051] Preferably, the reference voltage is 3.3V. When the resistance value of the second resistor R2 is equal to the resistance value of the first resistor R1, the bias voltage of the positive input terminal of the input operational amplifier is 1.65V, and the maximum negative voltage of the input signal is -1.65V. Therefore, the resistance value of the second resistor R2 and the first resistor R1 can raise the negative voltage of the input signal to a positive voltage output.

[0052] As an example, see Figure 1 It can be seen that the fourth resistor R4 is connected between the positive input terminal + of the operational amplifier A1 and one end of the sampling resistor Rs, and the fifth resistor R5 is connected between the negative input terminal - of the operational amplifier A1 and the other end of the sampling resistor Rs. The resistance value of the fourth resistor R4 is equal to the resistance value of the fifth resistor R5. When the operational amplifier A1 samples the voltage drop across the sampling resistor Rs, the fourth resistor R4 and the fifth resistor R5 are introduced to establish input impedance matching. Figure 1 In the embodiment, the equivalent impedance introduced by the connecting line between the sampling resistor Rs and the positive and negative input terminals of the operational amplifier A1 is taken into account, the negative input terminal is connected to the equivalent resistor R5, and the positive input terminal is connected to the equivalent impedance R4. The resistance value of the fifth resistor R5 is equal to the resistance value of the fourth resistor R4, which can not only match the input impedance of the operational amplifier, but also minimize the influence of the offset current and bias current of the operational amplifier, so that the output phase current is more accurate.

[0053] As an example, Figure 1 As shown, the single operational amplifier sampling circuit also includes a first capacitor C1, which is connected in parallel to both ends of the first resistor R1 to filter the reference voltage; wherein the capacitance of the first capacitor C1 is in the order of picofarads. The first capacitor C1 is used to filter out the clutter carried by the voltage signal of the reference voltage and the sampling resistor Rs connected to the positive input terminal of the operational amplifier, and the capacitance of the first capacitor C1 is in the order of picofarads, which can achieve a fast response effect and achieve the purpose of real-time detection.

[0054] Based on the above embodiment, the single operational amplifier sampling circuit further includes a second capacitor and a third resistor, such as Figure 1 As shown, one end of the third resistor R3 is connected to the output end out of the operational amplifier A1, and the other end of the third resistor R3 is connected to one end of the second capacitor C2, and one end of the second capacitor C2 is grounded, so that the output end out of the operational amplifier A1 outputs the filtered phase current sampling signal, wherein the third resistor R3 and the second capacitor C2 form the filtering network, and the capacitance of the second capacitor C2 is in the microfarad level. Since the phase current has ripples, in order to eliminate the ripples in the phase current, the filtering network is used for filtering, the third resistor R3 is set to a resistor of Ω level, and the second capacitor C2 is a capacitor of uf level. The current output by the operational amplifier A1 has no ripples and a small delay, and is generally low-pass filtered to filter out the high-frequency components in the phase current, and the signal output by the output end out of the operational amplifier A1 is more stable.

[0055] Although the embodiments of the present application have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is limited by the attached claims and their equivalents. The above is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A phase current sampling control circuit for multiple motors, characterized in that: The phase current sampling control circuit includes a three-bridge arm driving circuit, a phase current switching circuit and a single operational amplifier sampling circuit; the motor group includes at least two motors; the phase current switching circuit is used to select three phase current transmission ends of a motor in the motor group to be connected to the connection nodes of an upper bridge arm and a lower bridge arm of the three-bridge arm driving circuit respectively, and each phase current transmission end of the same motor is used to transmit a phase current; The three-bridge-arm driving circuit is connected to the single op-amp sampling circuit through the two ends of the internal sampling resistor; Each lower bridge arm in the three-bridge arm driving circuit is connected to one end of a sampling resistor, so that the sampling resistor is used to sample a phase current flowing out of the corresponding lower bridge arm at different times and feed it back to the single operational amplifier sampling circuit; The single operational amplifier sampling circuit is used for reducing the offset signal by connecting a resistor in series at its input terminal when the one phase current is input, and filtering the one phase current through a built-in filtering network.

2. The phase current sampling control circuit according to claim 1, characterized in that: The phase current switching circuit includes a first switch, a second switch and a third switch, and the three phase current transmission ends of the motor are respectively a U-phase current transmission end, a V-phase current transmission end and a W-phase current transmission end; The single selection ends of the phase current switching circuit are respectively used to connect the three phase current transmission ends of each motor in the motor group, including: the single selection ends of the first switch are respectively connected to the U-phase current transmission end of each motor, the single selection ends of the second switch are respectively connected to the V-phase current transmission end of each motor, and the single selection ends of the third switch are respectively connected to the W-phase current transmission end of each motor; the first switch, the second switch and the third switch are used to simultaneously select the three phase current transmission ends of the same motor to transmit the corresponding phase current.

3. The phase current sampling control circuit according to claim 2, characterized in that: The three-bridge-arm driving circuit comprises three upper bridge arms and three lower bridge arms, the three upper bridge arms are respectively a first switch tube, a second switch tube and a third switch tube, the three lower bridge arms are respectively a fourth switch tube, a fifth switch tube and a sixth switch tube, and the first transmission end of the first switch tube, the first transmission end of the second switch tube and the first transmission end of the third switch tube are all connected to a power supply; The second transmission end of the first switch tube and the first transmission end of the sixth switch tube are connected to the common selection end of the first switch, the second transmission end of the second switch tube and the first transmission end of the fifth switch tube are connected to the common selection end of the second switch, and the second transmission end of the third switch tube and the first transmission end of the fourth switch tube are connected to the common selection end of the third switch; The common selection end of the first switch, the common selection end of the second switch and the common selection end of the third switch are used to switch and connect the corresponding single selection end under the triggering of the external selection signal, so as to output the current from the three-bridge arm driving circuit to the corresponding phase current transmission end of the motor, or output the corresponding phase current from the corresponding phase current transmission end of the motor to the three-bridge arm driving circuit; Among them, the connection node between the second transmission end of the first switch tube and the first transmission end of the sixth switch tube, the connection node between the second transmission end of the second switch tube and the first transmission end of the fifth switch tube, and the connection node between the second transmission end of the third switch tube and the first transmission end of the fourth switch tube are all connection nodes between each upper bridge arm and the corresponding lower bridge arm.

4. The phase current sampling control circuit according to claim 3, characterized in that: The second transmission end of the sixth switch tube, the second transmission end of the fifth switch tube and the second transmission end of the fourth switch tube are all connected to one end of the sampling resistor, and the two ends of the sampling resistor are connected to the single op amp sampling circuit, so that the voltage drop feedback of the sampling resistor corresponds to a phase current flowing out of the lower bridge arm.

5. The phase current sampling control circuit according to claim 4, characterized in that: In the case where the first switch, the second switch and the third switch are used to simultaneously switch on the three phase current transmission terminals of the same motor, there are: When the first switch tube, the fourth switch tube and the fifth switch tube are all turned on and the remaining switch tubes in the three-bridge arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current input to the U-phase current transmission end of the same motor, and the current is sampled as the U-phase current; When the first switch tube, the fourth switch tube and the second switch tube are all turned on and the remaining switch tubes in the three-bridge arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current output by the W-phase current transmission end of the same motor, and the current sampled is the negative value of the W-phase current; When the sixth switch tube, the second switch tube and the fourth switch tube are all turned on and the remaining switch tubes in the three-bridge arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current input to the V-phase current transmission end of the same motor, and the current is sampled as the V-phase current; When the sixth switch tube, the second switch tube and the third switch tube are all turned on, and the remaining switch tubes in the three-bridge arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current output by the U-phase current transmission end of the same motor, and the current sampled is the negative value of the U-phase current; When the third switch tube, the fifth switch tube and the sixth switch tube are all turned on and the remaining switch tubes in the three-bridge arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current input to the W-phase current transmission end of the same motor, and the current is sampled as the W-phase current; When the first switch tube, the third switch tube and the fifth switch tube are all turned on and the remaining switch tubes in the three-bridge arm drive circuit are all turned off, the current flowing through the sampling resistor is equal to the current output by the V-phase current transmission end of the same motor, and the sampling is the negative value of the V-phase current.

6. The phase current sampling control circuit according to claim 5, characterized in that: The sum of the current transmitted by the U-phase current transmission terminal of the same motor, the current transmitted by the V-phase current transmission terminal of the same motor, and the current transmitted by the W-phase current transmission terminal of the same motor is equal to zero.

7. The phase current sampling control circuit according to claim 5, characterized in that: The single operational amplifier sampling circuit comprises an operational amplifier, a first resistor and a second resistor; The positive input terminal and the negative input terminal of the operational amplifier are respectively used to connect the two ends of the sampling resistor; The positive input terminal of the operational amplifier is connected to one end of the first resistor, and the other end of the first resistor is grounded; The positive input terminal of the operational amplifier is connected to one end of the second resistor, and the other end of the second resistor is connected to the reference voltage.

8. The phase current sampling control circuit according to claim 7, characterized in that: A fourth resistor is connected between the positive input terminal of the operational amplifier and one end of the sampling resistor, and a fifth resistor is connected between the negative input terminal of the operational amplifier and the other end of the sampling resistor. The resistance value of the fourth resistor is equal to the resistance value of the fifth resistor, so that when the operational amplifier samples the voltage drop across the sampling resistor, input impedance matching is established by introducing the fourth resistor and the fifth resistor.

9. The phase current sampling control circuit according to claim 7, characterized in that: The single operational amplifier sampling circuit further includes a first capacitor, which is connected in parallel to both ends of the first resistor to filter the reference voltage; wherein the capacitance of the first capacitor is in the order of magnitude of picofarads.

10. The phase current sampling control circuit according to claim 9, characterized in that: The single operational amplifier sampling circuit also includes a second capacitor and a third resistor, one end of the third resistor is connected to the output end of the operational amplifier, the other end of the third resistor is connected to one end of the second capacitor, and one end of the second capacitor is grounded, wherein the third resistor and the second capacitor constitute the filtering network, and the capacitance of the second capacitor is in the order of microfarad level.

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