Motor current sampling method, device, motor control circuit and electrical equipment

Abstract

The present invention discloses a motor current sampling method, device, motor control circuit and electrical equipment. The motor current sampling method includes the following steps: obtaining the vector area where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system; determining whether the vector area where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system is in a preset sampling blind area; if it is determined to be in the preset sampling blind area, controlling the current sampling circuit to switch the current sampling state to a preset sampling state matching the preset sampling blind area, so that the current sampling circuit can perform sampling in the vector area where the SVPWM space voltage vector is located in the next control cycle; and, if it is determined not to be in the preset sampling blind area, controlling the current sampling circuit to maintain the current sampling state. The technical solution of the present invention can improve the control accuracy and stability of the SVPWM control scheme for the motor.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a motor current sampling method, a motor current sampling device, a motor control circuit and an electrical device. Background Art

[0002] At present, in the motor control algorithm, it is necessary to sample the motor current to improve the control accuracy. However, in the motor control algorithm using SVPWM, the current sampling circuit constructed based on the sampling resistor will have a sampling blind area, which will lead to a decrease in the control accuracy and stability of the motor. Summary of the invention

[0003] The main purpose of the present invention is to provide a motor current sampling method, aiming to solve the problem of low motor control accuracy and stability of the SVPWM control scheme.

[0004] To achieve the above object, the motor current sampling method proposed in the present invention is applied to a motor control circuit, wherein the motor control circuit includes a current sampling circuit for sampling a motor phase current, and the motor current sampling method includes the following steps:

[0005] Obtaining the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system;

[0006] Determine whether the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system is in a preset sampling blind area, wherein the preset sampling blind area is the sampling blind area in the vector region where the current sampling circuit is located in the two-phase stationary coordinate system under the current sampling state;

[0007] If it is determined that the current sampling circuit is in the preset sampling blind area, control the current sampling circuit to switch the current sampling state to a preset sampling state matching the preset sampling blind area, so that the current sampling circuit can perform sampling in the vector area where the SVPWM space voltage vector is located in the next control cycle; and

[0008] If it is determined that the current sampling circuit is not in the preset sampling blind area, the current sampling circuit is controlled to maintain the current sampling state.

[0009] Optionally, if it is determined that the current sampling circuit is in the preset sampling blind area, after the step of controlling the current sampling circuit to switch the current sampling state to a preset sampling state matching the preset sampling blind area so that the current sampling circuit can perform sampling in the vector area where the space voltage vector is located in the next control cycle, the method further includes:

[0010] Switching to a first preset current sampling algorithm that matches a preset sampling state, and after entering the next control cycle, controlling the sampling circuit to sample the phase current of the motor with the first preset current sampling algorithm;

[0011] Obtain current sampling results and control the motor operation according to the current sampling results;

[0012] Return to the step of obtaining the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system.

[0013] Optionally, after the step of controlling the current sampling circuit to maintain a current sampling state, the method further includes:

[0014] Maintaining the currently running current sampling algorithm, and after entering the next control cycle, continuing to control the sampling circuit to sample the phase current of the motor with the currently running current sampling algorithm;

[0015] Obtain sampling results and control the motor operation according to the sampling results;

[0016] Return to the step of obtaining the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system.

[0017] Optionally, the preset sampling state includes at least two of a single-resistance sampling state, a dual-resistance sampling state and a triple-resistance sampling state.

[0018] The present invention further provides a motor current sampling device, which is applied to a motor control circuit. The motor control circuit includes a current sampling circuit for sampling a motor phase current. The motor current sampling device includes:

[0019] Memory;

[0020] Processor; and

[0021] A motor current sampling program is stored in a memory and can be run on a processor. When the processor executes the motor current sampling program, the motor current sampling method described above is implemented.

[0022] The present invention further provides a motor control circuit, the motor control circuit comprising:

[0023] A current sampling circuit for sampling a motor phase current; and

[0024] As in the above-mentioned motor current sampling device, the motor current sampling device is electrically connected to the current sampling circuit.

[0025] Optionally, the motor control circuit further includes:

[0026] Busbar incoming terminal, used to access the voltage busbar;

[0027] A three-phase bridge arm circuit, each phase of the bridge arm circuit has a bridge arm switch, and a first end of each bridge arm switch is connected to the voltage bus;

[0028] The current sampling circuit comprises: a first resistor, a second resistor, a third resistor and a switch circuit, wherein the first end and the second end of the first resistor are respectively connected to the first end of the bridge arm switch of the bridge arm circuit of one phase and the voltage bus, the first end and the second end of the second resistor are respectively connected to the second end of the bridge arm switch of the bridge arm circuit of another phase and the voltage bus, and the third resistor is arranged between the bus inlet terminal and the three-phase bridge arm circuit

[0029] The first controlled end, the second controlled end, the third controlled end and the fourth controlled end of the switch circuit are respectively connected to the sampling device of the motor current, the first input end is connected to the first end of one of the first resistor and the second resistor, the second input end is connected to the second end of the third resistor, the third input end is connected to the second end of one of the first resistor and the second resistor, the fourth input end is connected to the first end of the third resistor, the fifth input end is connected to the first end of the other of the first resistor and the second resistor, the sixth input end is connected to the second end of the other of the first resistor and the second resistor, and the first output end, the second output end, the third output end and the fourth output end of the switch circuit are respectively connected to the sampling device of the motor current.

[0030] Optionally, the switch circuit comprises: the switch circuit comprises: a first switch device, a second switch device, a third switch device and a fourth switch device;

[0031] The controlled ends of the first switching device, the second switching device, the third switching device and the fourth switching device are respectively the first controlled end, the second controlled end, the third controlled end and the fourth controlled end of the switching circuit; the input ends of the first switching device, the second switching device, the third switching device and the fourth switching device are respectively the first input end, the second input end, the third input end and the fourth input end of the switching circuit; the output end of the first switching device is the first output end, the output end of the second switching device is connected to the output end of the first switching device, the output end of the third switching device is the second output end, the output end of the fourth switching device is connected to the output end of the third switching device, the fifth input end is connected to the third output end, and the sixth input end is connected to the fourth output end.

[0032] Optionally, the motor control circuit further includes:

[0033] A first operational amplifier circuit is provided between the first output terminal and the second output terminal and the motor current sampling device;

[0034] The second operational amplifier circuit is arranged between the third output terminal, the fourth output terminal and the motor current sampling device.

[0035] Optionally, when determining that the SVPWM space voltage vector in the next control cycle is in the preset sampling blind area, the motor current sampling device controls the second switching device and the fourth switching device to turn on, and controls the first switching device and the third switching device to turn off.

[0036] Optionally, when determining that the SVPWM space voltage vector in the next control cycle is not in the preset sampling blind area, the motor current sampling device controls the first switching device and the third switching device to turn on, and controls the second switching device and the fourth switching device to turn off.

[0037] The present invention also provides an electrical device, the electrical device comprising a motor and the motor control circuit as described above;

[0038] The motor control circuit is electrically connected to the motor.

[0039] The technical solution of the present invention obtains the vector area where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system, and determines whether the vector area where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system is in a preset sampling blind area, and the preset sampling blind area is the sampling blind area in the vector area where the current sampling circuit corresponds to in the two-phase stationary coordinate system under the current sampling state; if it is determined to be in the preset sampling blind area, the current sampling circuit is controlled to switch the current sampling state to a preset sampling state matching the preset sampling blind area, so that the current sampling circuit can perform sampling in the vector area where the SVPWM space voltage vector is located in the next control cycle; if it is determined not to be in the preset sampling blind area, the current sampling circuit is controlled to maintain the current sampling state. The motor current sampling method of the present invention pre-switches the sampling state of the current sampling circuit according to the preset sampling blind area in the next control cycle, so that the switched current sampling circuit can work normally in the next control cycle; this cycle is repeated, and the current sampling circuit can output the current sampling result to the sampling device during the entire control process of the motor, thereby avoiding the situation where the motor control fails or the system overcurrent protection cannot be triggered in time due to the inability to feedback the current sampling result, and significantly improves the control accuracy and stability of the SVPWM control scheme for the motor, thereby solving the problem of low motor control accuracy and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0041] Figure 1 A schematic diagram of a step flow chart of an embodiment of a motor current sampling method of the present invention;

[0042] Figure 2 A schematic diagram of the steps of another embodiment of the motor current sampling method of the present invention;

[0043] Figure 3 A schematic diagram of the hardware operating environment of an embodiment of a motor current sampling device of the present invention;

[0044] Figure 4 A schematic diagram of the circuit structure of an embodiment of a motor control circuit of the present invention;

[0045] Figure 5 for Figure 4 Schematic diagram of the equivalent circuit structure of the current sampling circuit in the dual-resistance sampling state;

[0046] Figure 6 for Figure 4 Schematic diagram of the equivalent circuit structure of the current sampling circuit in the single resistor sampling state;

[0047] Figure 7 It is a regional schematic diagram of a preset sampling blind area corresponding to a single-resistance sampling state and a dual-resistance sampling state in a two-phase stationary coordinate system in an embodiment of a motor control circuit of the present invention.

[0048] Description of Figure Numbers:

[0049]

[0050] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0053] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" 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.

[0054] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their 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 addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0055] The invention provides a motor current sampling method.

[0056] In the motor control algorithm, a current sampling circuit is usually used to sample the motor phase current, and the motor operating parameters such as motor speed, rotor position and current are obtained based on the sampling results, so as to further use the above-mentioned various motor operating parameters to feedback and adjust the motor working conditions. However, due to the characteristics of the SVPWM control scheme, the current sampling circuit built based on the sampling resistor has a sampling blind spot, so there is a situation where the motor control fails or the system overcurrent protection cannot be triggered in time due to the inability to feedback the current sampling results at certain times, resulting in a low level of motor control accuracy and stability.

[0057] Reference Figures 1 to 7 In one embodiment of the present invention, the motor current sampling method comprises the following steps:

[0058] Step S100, obtaining the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system;

[0059] The executor of the motor current sampling method of the present invention may be a motor current sampling device. To simplify the description, "sampling device" is used to represent "motor current sampling device" below. The sampling device can obtain the current sampling result in the current control cycle, and can calculate the three-phase current of the motor and the first coordinate corresponding to the three-phase current according to the current sampling result. The first coordinate is the three-phase rotating coordinate in the three-phase rotating coordinate system. The sampling device can also convert the first coordinate into the corresponding second coordinate. The second coordinate is the coordinate in the two-phase stationary coordinate system (i.e., the attached Figure 7 The two-phase stationary coordinates of the second coordinates in the two-phase stationary coordinate system are α and β coordinate systems. It can be understood that the vector relationship of the second coordinates in the two-phase stationary coordinate system is the SVPWM space voltage vector in the current control cycle. In this way, the sampling device can determine the vector region where the current SVPWM space voltage vector is located in the two-phase stationary coordinate system and the vector region where it will be located in the next control cycle according to the second coordinates and the pre-integrated SVPWM control algorithm.

[0060] Step S200, determining whether the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system is in a preset sampling blind area, the preset sampling blind area being the sampling blind area in the vector region where the current sampling circuit is located in the two-phase stationary coordinate system under the current sampling state;

[0061] Under the control of the sampling device, the current sampling circuit can be in different sampling states, such as: single resistor sampling state, dual resistor sampling state or three resistor sampling state. In certain control cycles in the SVPWM control algorithm, in the above three sampling states, the corresponding bridge arm switch in a certain phase is turned on for a short time, which makes the sampling window time of the phase current short. There is often a problem that the sampling is not completed but the sampling window time has passed, resulting in the existence of corresponding sampling blind areas in the above three sampling states. Since the prior art does not take the above problems into account, usually only a sampling circuit with any one of the above three sampling states is used to sample the phase current. In addition, in the SVPWM control algorithm, the on / off control of the bridge arm switch is essentially SVPWM spatial voltage vector control. Therefore, those skilled in the art can use the corresponding vector area in the two-phase stationary coordinate system to represent the sampling blind areas corresponding to the above three sampling states, and pre-store them in the sampling device as preset sampling blind areas. In the attached Figure 7 In, attached Figure 7 The preset sampling blind areas corresponding to the single-resistance sampling state and the dual-resistance sampling state in each control cycle are disclosed. In this step S200, the sampling device can determine whether the vector area where the SVPWM space voltage vector in the two-phase stationary coordinate system in the next control cycle is located is in the preset sampling blind area according to the current sampling state of the sampling circuit, and can further determine whether to switch the sampling state of the current sampling circuit according to the determination result.

[0062] If it is determined to be in the preset sampling blind area, step S400 is executed to control the current sampling circuit to switch the current sampling state to a preset sampling state matching the preset sampling blind area, so that the current sampling circuit can perform sampling in the vector area where the SVPWM space voltage vector is located in the next control cycle.

[0063] If the sampling device determines that it is in the preset sampling blind area, that is, the current sampling state of the current sampling circuit will have a sampling blind area in the next control cycle, then the sampling device controls the current sampling circuit to switch to other sampling states. It can be understood that since the sampling blind areas corresponding to the above three sampling states are different, that is, the preset sampling blind areas corresponding to the three sampling states are also different, the current sampling circuit after switching the sampling state can be in the next control cycle. It is not affected by the preset sampling blind area in the vector area, and the motor current can be sampled normally and the sampling result can be output to the sampling device. In other words, the preset sampling state can be any other sampling state except the current sampling state. Of course, those skilled in the art can make the current sampling circuit have more sampling states without creative work, and when the preset sampling blind areas corresponding to the multiple sampling states have intersections (overlaps), the sampling device can control the current sampling circuit to switch to any one of the multiple sampling states that is not affected by the preset sampling blind area in the next control cycle, for example, it can be switched to a sampling state that is not affected and has a higher sampling accuracy. It should be noted that the preset sampling blind area in the technical solution of the present application is a real-time concept, that is, when the current sampling circuit enters the next control cycle with the switched sampling state, the preset sampling blind area is the sampling blind area corresponding to the switched sampling state. In this way, even if there is a preset sampling blind area that affects the current current sampling circuit in each control cycle, the sampling device can dynamically adjust the sampling state of the current sampling circuit according to the preset sampling blind area in each control cycle, so that the current sampling circuit can normally sample the motor current in each control cycle, thereby solving the problem of low motor control accuracy and stability in the SVPWM control scheme.

[0064] If it is determined that the current sampling circuit is not in the preset sampling blind zone, step 500 is executed to control the current sampling circuit to maintain the current sampling state.

[0065] If the sampling device determines that it is not in the preset sampling blind area, that is, the current sampling state of the current sampling circuit is not affected by the sampling blind area that will appear in the next control cycle, even if it enters the next control cycle, the current sampling circuit can still sample the motor current normally and output the sampling result to the sampling device. At this time, the sampling device does not control the current sampling circuit to perform the switching action, so that the current sampling circuit maintains the current sampling state.

[0066] The technical solution of the present invention obtains the vector area where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system, and determines whether the vector area where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system is in a preset sampling blind area, and the preset sampling blind area is the sampling blind area in the vector area where the current sampling circuit corresponds to in the two-phase stationary coordinate system under the current sampling state; if it is determined to be in the preset sampling blind area, the current sampling circuit is controlled to switch the current sampling state to a preset sampling state matching the preset sampling blind area, so that the current sampling circuit can perform sampling in the vector area where the SVPWM space voltage vector is located in the next control cycle; if it is determined not to be in the preset sampling blind area, the current sampling circuit is controlled to maintain the current sampling state. The motor current sampling method of the present invention pre-switches the sampling state of the current sampling circuit according to the preset sampling blind area in the next control cycle, so that the switched current sampling circuit can work normally in the next control cycle; this cycle is repeated, and the current sampling circuit can output the current sampling result to the sampling device during the entire control process of the motor, thereby avoiding the situation where the motor control fails or the system overcurrent protection cannot be triggered in time due to the inability to feedback the current sampling result, and significantly improves the control accuracy and stability of the SVPWM control scheme for the motor, thereby solving the problem of low motor control accuracy and stability.

[0067] Reference Figures 1 to 7 In one embodiment of the present invention, after step S300, controlling the current sampling circuit to switch the current sampling state to a preset sampling state matching the preset sampling blind area so that the current sampling circuit can perform sampling in the vector area where the SVPWM space voltage vector is located in the next control cycle, the motor current sampling method further includes:

[0068] Step S310, switching to run a first preset current sampling algorithm that matches a preset sampling state, and after entering the next control cycle, controlling the sampling circuit to sample the phase current of the motor with the first preset current sampling algorithm;

[0069] Step S320, obtaining a current sampling result, and controlling the motor operation according to the current sampling result;

[0070] Step S330, return to execute step S100.

[0071] Since the current sampling circuit constructed based on the sampling resistor is a pure hardware circuit and does not have driving capability, the sampling device needs to run the corresponding current sampling algorithm to sample the motor current and output the current sampling result in the form of voltage to the ADC end of the sampling device, and the sampling device can reconstruct the phase current of the received current sampling structure. This application enables the sampling device to control the current sampling circuit to switch the sampling state after the current sampling circuit is controlled to switch the sampling state, and the current sampling algorithm running inside the sampling device is also synchronously switched to the first preset current sampling algorithm that matches the sampling state after switching, so that the first preset current sampling algorithm can be run after entering the next control cycle to control the operation of the switched current sampling circuit. It should be noted that the first preset current sampling algorithm in the technical solution of this application is also a real-time concept, which will not be elaborated here.

[0072] In this way, in the next control cycle, the sampling device can obtain the current sampling result of the current sampling circuit, and can reconstruct the phase current through the first preset current sampling algorithm and the current sampling result, and can further calculate the motor operating parameters such as motor speed, rotor position and current according to the reconstructed phase current. The sampling device can also compare the various motor operating parameters with the corresponding preset motor operating parameters, so as to control the working conditions of the three-phase bridge arm circuit according to the comparison results, so as to realize feedback adjustment of various motor operating parameters and return to execute step S100 at the same time to form a loop. Such a setting can avoid the situation where the phase current cannot be accurately sampled and reconstructed due to algorithm mismatch, and can effectively improve the accuracy of current sampling and phase current reconstruction.

[0073] Reference Figures 1 to 7 In one embodiment of the present invention, after step S400, controlling the current sampling circuit to maintain the current sampling state, the motor current sampling method further includes:

[0074] Step S410, maintaining the current sampling algorithm currently in operation, and after entering the next control cycle, continuing to control the sampling circuit to sample the phase current of the motor with the current sampling algorithm currently in operation;

[0075] Step S420, obtaining sampling results, and controlling the motor operation according to the sampling results;

[0076] Step S430, return to execute step 100.

[0077] It is understandable that when there is no need to switch the current sampling state, the sampling device does not need to switch the currently running current sampling algorithm. After entering the next control cycle, the sampling device can continue to control the operation of the current sampling circuit by continuously running the current sampling algorithm, and can continue to reconstruct the phase current according to the currently running current sampling algorithm and the current sampling result, and continue to implement feedback adjustment of various working parameters of the motor and return to execute step S100 at the same time to form a loop. It is understandable that in this embodiment, step S330 and step 430 can be the same step. Such a setting allows the sampling device to perform only multiple operations when it is determined that it is not in the preset sampling blind area of ​​the next control cycle, which can effectively reduce the program complexity of the sampling device.

[0078] Reference Figures 1 to 7 In one embodiment of the present invention, the preset sampling state includes at least two of a single-resistance sampling state, a dual-resistance sampling state, and a triple-resistance sampling state.

[0079] In this embodiment, since the preset sampling state requires at least two sampling states for switching, the above three sampling states can have four combinations, namely: single resistor sampling state and dual resistor sampling state, single resistor sampling state and three resistor sampling, dual resistor sampling state and three resistor sampling, and single resistor sampling state, dual resistor sampling state and three resistor sampling. In this way, the operator can select at least two of the three according to actual needs to implement the technical solution of the present invention, which is conducive to improving the scope of application of the technical solution of the present invention.

[0080] In addition, since the three sampling states each have their own advantages and disadvantages, for example: the sampling accuracy of the single-resistance sampling state is not high, and the corresponding current sampling algorithm is relatively complex, but the cost is low; the dual-resistance sampling state has a more obvious sampling blind spot, but the accuracy is higher; the three-resistance sampling state requires a higher hardware cost, but the accuracy is the highest. In another optional embodiment, the preset sampling state of the sampling circuit is configured as a single-resistance sampling state, and the current operating state is configured as a dual-resistance sampling state, so as to have a higher sampling accuracy while also having a lower design cost.

[0081] The present invention further provides a motor current sampling device, which is applied to a motor control circuit. The motor control circuit includes a current sampling circuit for sampling the motor phase current.

[0082] Reference Figure 3 In one embodiment of the present invention, the motor current sampling device includes:

[0083] Memory 101;

[0084] processor 102; and

[0085] The motor current sampling program is stored in the memory 101 and can be run on the processor. When the processor 102 executes the motor current sampling program, the above motor current sampling method is implemented.

[0086] In this embodiment, the memory 101 may be a high-speed RAM memory, or a stable memory (non-volatile memory), such as a disk memory, and the memory 101 may optionally be a storage device independent of the aforementioned control device; the processor 102 may be a CPU. The memory 101 and the processor 102 are connected by a communication bus 103, which may be a UART bus or an I2C bus.

[0087] The present invention also proposes a motor control circuit, which includes a current sampling circuit and a motor current sampling device. The specific structure of the motor current sampling device refers to the above-mentioned embodiment. Since the motor control circuit adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0088] The motor current sampling device is electrically connected to the current sampling circuit, and the current sampling circuit is used to sample the motor phase current and output the current sampling result to the motor current sampling device. In other words, the motor current sampling device can also be the main control device of the motor control circuit.

[0089] Reference Figures 1 to 7 In one embodiment of the present invention, the motor control circuit further includes:

[0090] Busbar incoming terminal, used to access the voltage busbar;

[0091] A three-phase bridge arm circuit 120, each phase bridge arm circuit has a bridge arm switch, and a first end of each bridge arm switch is connected to the voltage bus;

[0092] The current sampling circuit 110 includes: a first resistor R1, a second resistor R2, a third resistor R3 and a switch circuit 111, the first end of the first resistor R1 is connected to the first end of the bridge arm switch of any phase bridge arm circuit, the second end of the first resistor R1 is connected to the voltage bus, the first end of the second resistor R2 is connected to the first end of the bridge arm switch of any phase bridge arm circuit in the other two phases, the second end of the second resistor R2 is connected to the voltage bus, and the third resistor R3 is arranged between the bus input terminal and the three-phase bridge arm circuit 120.

[0093] The first controlled end, the second controlled end, the third controlled end and the fourth controlled end of the switch circuit 111 are respectively connected to the sampling device of the motor current, the first input end of the switch circuit 111 is connected to the first end of one of the first resistor R1 and the second resistor R2, the second input end of the switch circuit 111 is connected to the second end of the third resistor R3, the third input end of the switch circuit 111 is connected to the second end of one of the first resistor R1 and the second resistor R2, the fourth input end of the switch circuit 111 is connected to the first end of the third resistor R3, the fifth input end of the switch circuit 111 is connected to the first end of the other of the first resistor R1 and the second resistor R2, the sixth input end of the switch circuit 111 is connected to the second end of the other of the first resistor R1 and the second resistor R2, and the first output end, the second output end, the third output end and the fourth output end of the switch circuit 111 are respectively connected to the sampling device of the motor current.

[0094] The voltage busbar may be a positive voltage busbar VDC+ and a negative voltage busbar VDC-; the three-phase bridge arm circuit 120 may be a three-phase full-bridge inverter circuit, and the bridge arm switch of each phase bridge arm circuit may be divided into an upper bridge arm switch and a lower bridge arm switch, and the common point of each upper bridge arm switch and the lower bridge arm switch connected thereto is a phase output terminal of the three-phase bridge arm circuit 120, and the upper bridge arm switch and the lower bridge arm switch may be implemented by one or more combinations of switch devices such as MOS tubes, triodes, and IGBTs. The three-phase bridge arm circuit 120 is used to control the upper and lower bridge arm switches in each phase bridge arm circuit to be turned on or off in sequence according to a preset timing according to the multi-channel drive signal connected, so as to invert the DC voltage connected to the positive and negative voltage buses (VDC+ and VDC-) into a three-phase AC voltage, and then output it to the three-phase input terminal of the motor, thereby driving the motor to operate. It can be understood that the drive signal may be a PWM signal, and may be obtained by the output of the sampling device.

[0095] The first resistor R1, the second resistor R2 and the third resistor R3 are sampling resistors. Figure 4-Figure 6In the illustrated embodiment, the voltage bus is a negative voltage bus VDC-, and the bridge arm switch of each phase bridge arm circuit pair is a lower bridge arm switch. At this time, the first resistor R1 and the second resistor R2 are respectively arranged between the two lower bridge arm switches and the negative voltage bus VDC-, and the first end of the third resistor R3 can be connected to the negative bus inlet terminal, and the second end can be respectively connected to the second end of the first resistor R1 and the second resistor R2. Of course, the first resistor R1 and the second resistor R2 can also be arranged between the two upper bridge arm switches and the positive voltage bus VDC+, and the first end of the third resistor R3 can be connected to the positive bus inlet terminal VDC+. Of course, the number of the first resistor R1, the second resistor R2 and the third resistor can also be 2, so that the first resistor R1 and the second resistor R2 are arranged between the upper bridge arm switch and the positive voltage bus VDC+, and between the lower bridge arm switch and the negative voltage bus VDC- of any two-phase bridge arm circuit, and the third resistor R3 is arranged between the positive and negative bus inlet terminals and the three-phase bridge arm circuit 120.

[0096] The switch circuit 111 can control the corresponding input end of the 6 input ends to be connected with the corresponding output end of the 4 output ends according to the level signals received by the 4 controlled ends, so that the current sampling circuit 110 after connection can present a single resistor sampling state, a dual resistor sampling state or a three resistor sampling state. In other words, the motor current sampling device can switch the sampling state of the current sampling circuit 110 by controlling the 4 level signals output to the 4 controlled ends of the switch circuit 111.

[0097] Specifically, the sampling device can control the second switch device S2 and the fourth switch device S4 to be turned on, and the first switch device S1 and the third switch device S3 to be turned off, so that the current sampling circuit 110 is in a single resistor sampling state. Specifically, Figure 6 By controlling the first switch device S1 and the third switch device S3 to be turned on, and controlling the second switch device S2 and the fourth switch device S4 to be turned off, the current sampling circuit 110 is in a dual-resistance sampling state, which can be specifically as follows Figure 5 Of course, those skilled in the art also add a sampling resistor between the lower bridge arm switch of another phase bridge arm circuit and the negative voltage bus, and correspondingly add a switching device to realize the three-resistance sampling state switching of the current sampling circuit 110, which will not be elaborated here.

[0098] Optionally, the switch circuit 111 includes: a first switch device S1, a second switch device S2, a third switch device S3 and a fourth switch device S4;

[0099] The controlled ends of the first switch device S1, the second switch device S2, the third switch device S3 and the fourth switch device S4 are respectively the first controlled end, the second controlled end, the third controlled end and the fourth controlled end of the switch circuit 111; the input ends of the first switch device S1, the second switch device S2, the third switch device S3 and the fourth switch device S4 are respectively the first input end, the second input end, the third input end and the fourth input end of the switch circuit 111; the output end of the first switch device S1 is the first output end of the switch circuit 111; the output end of the second switch device S2 is connected to the output end of the first switch device S1; the output end of the third switch device S3 is the second output end of the switch circuit 111; the output end of the fourth switch device S4 is connected to the output end of the third switch device S3; the fifth input end is connected to the third output end; and the sixth input end is connected to the fourth output end.

[0100] The first switch device S1, the second switch device S2, the third switch device S3 and the fourth switch device S4 can all be implemented by one or more combinations of switch devices such as MOS tubes, triodes, IGBTs, optocouplers, relays, etc. The technical solution of the present invention uses four switch devices to respectively control the connection or disconnection of the four input terminals and the four output terminals of the switch circuit 111, and configures the fifth input terminal and the third output terminal and the sixth input terminal and the fourth output terminal to be in a normally-on state, which can effectively simplify the circuit structure of the switch circuit 111 and reduce the difficulty of program design in the sampling device, and can also effectively reduce the number of occupied ADC ports of the sampling device.

[0101] Reference Figures 1 to 7 , characterized in that the motor control circuit further comprises:

[0102] The first operational amplifier circuit 130 is provided between the first output terminal and the second output terminal of the switch circuit 111 and the motor current sampling device;

[0103] The second operational amplifier circuit 140 is disposed between the third output terminal and the fourth output terminal of the switch circuit 111 and the motor current sampling device.

[0104] In view of the problem of detection threshold of the ADC port of the sampling device, the present application is provided with a first operational amplifier circuit 130 and a first operational amplifier circuit 130. The first operational amplifier circuit 130 and the second operational amplifier circuit 140 can be implemented by an amplifier circuit composed of discrete devices such as an operational amplifier, a resistor, and a capacitor; or, an operational amplifier chip can also be used to implement it. The positive input terminal and the negative input terminal of the first operational amplifier circuit 130 are connected to the first output terminal and the second output terminal of the switch circuit 111 in a one-to-one correspondence, and the positive input terminal and the negative input terminal of the second operational amplifier circuit 140 are connected to the third output terminal and the fourth output terminal of the switch circuit 111 in a one-to-one correspondence. The first operational amplifier circuit 130 and the second operational amplifier circuit 140 are used to respectively perform operational amplification on the input signals connected to the positive input terminal and the negative input terminal of the sampling device, and then output two output signals to the ADC port of the sampling device for the ADC port of the sampling device to identify and receive. Such a setting can effectively improve the recognition and reception range of the ADC end of the sampling device, which is conducive to further improving the accuracy and stability of motor control.

[0105] The present invention also proposes an electrical device, which includes a motor and a motor control circuit. The specific structure of the motor control circuit refers to the above embodiment. Since the electrical device adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here. Among them, the motor control circuit is electrically connected to the motor, and the motor can be connected to the three-phase AC voltage output by the motor control circuit and operate. In addition, the electrical device can be a freezer, a refrigerator, an air conditioner, a water heater, etc., which will not be described here.

[0106] The above are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A motor current sampling method, applied to a motor control circuit, wherein the motor control circuit comprises a current sampling circuit for sampling a motor phase current, characterized in that: The motor current sampling method comprises the following steps: Obtaining the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system; Determine whether the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system is in a preset sampling blind area, wherein the preset sampling blind area is the sampling blind area in the vector region where the current sampling circuit is located in the two-phase stationary coordinate system under the current sampling state; If it is determined that the current sampling circuit is in the preset sampling blind area, control the current sampling circuit to switch the current sampling state to a preset sampling state matching the preset sampling blind area, so that the current sampling circuit can perform sampling in the vector area where the SVPWM space voltage vector is located in the next control cycle; and If it is determined that the current sampling circuit is not in the preset sampling blind area, the current sampling circuit is controlled to maintain the current sampling state.

2. The motor current sampling method according to claim 1, characterized in that: After the step of controlling the current sampling circuit to switch the current sampling state to a preset sampling state matching the preset sampling blind area if it is determined that the current sampling circuit is in the preset sampling blind area, so that the current sampling circuit can perform sampling in the vector area where the space voltage vector is located in the next control cycle, the method further includes: Switching to a first preset current sampling algorithm that matches a preset sampling state, and after entering the next control cycle, controlling the current sampling circuit to sample the phase current of the motor with the first preset current sampling algorithm; Obtain current sampling results and control the motor operation according to the current sampling results; Return to the step of obtaining the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system.

3. The motor current sampling method according to claim 1, characterized in that: After the step of controlling the current sampling circuit to maintain the current sampling state, the method further includes: Maintaining the currently running current sampling algorithm, and after entering the next control cycle, continuing to control the current sampling circuit to sample the phase current of the motor with the currently running current sampling algorithm; Obtain sampling results and control the motor operation according to the sampling results; Return to the step of obtaining the vector region where the SVPWM space voltage vector in the next control cycle is located in the two-phase stationary coordinate system.

4. The motor current sampling method according to any one of claims 1 to 3, characterized in that: The preset sampling state includes at least two of a single-resistance sampling state, a dual-resistance sampling state and a triple-resistance sampling state.

5. A motor current sampling device, applied to a motor control circuit, wherein the motor control circuit comprises a current sampling circuit for sampling a motor phase current, characterized in that: The motor current sampling device comprises: Memory; Processor; and A motor current sampling program is stored in a memory and can be run on a processor, and when the processor executes the motor current sampling program, the motor current sampling method according to any one of claims 1 to 4 is implemented.

6. A motor control circuit, characterized in that: The motor control circuit comprises: A current sampling circuit for sampling a motor phase current; and The motor current sampling device as claimed in claim 5, wherein the motor current sampling device is electrically connected to the current sampling circuit.

7. The motor control circuit according to claim 6, characterized in that: The motor control circuit further comprises: Busbar incoming terminal, used to access the voltage busbar; A three-phase bridge arm circuit, each phase of the bridge arm circuit has a bridge arm switch, and a first end of each bridge arm switch is connected to the voltage bus; The current sampling circuit comprises: a first resistor, a second resistor, a third resistor and a switch circuit, wherein the first end and the second end of the first resistor are respectively connected to the first end of the bridge arm switch of the bridge arm circuit of one phase and the voltage bus, the first end and the second end of the second resistor are respectively connected to the second end of the bridge arm switch of the bridge arm circuit of another phase and the voltage bus, and the third resistor is arranged between the bus inlet terminal and the three-phase bridge arm circuit The first controlled end, the second controlled end, the third controlled end and the fourth controlled end of the switch circuit are respectively connected to the sampling device of the motor current, the first input end of the switch circuit is connected to the first end of one of the first resistor and the second resistor, the second input end of the switch circuit is connected to the second end of the third resistor, the third input end of the switch circuit is connected to the second end of one of the first resistor and the second resistor, the fourth input end of the switch circuit is connected to the first end of the third resistor, the fifth input end of the switch circuit is connected to the first end of the other of the first resistor and the second resistor, the sixth input end of the switch circuit is connected to the second end of the other of the first resistor and the second resistor, and the first output end, the second output end, the third output end and the fourth output end of the switch circuit are respectively connected to the sampling device of the motor current.

8. The motor control circuit according to claim 7, characterized in that: The switch circuit comprises: a first switch device, a second switch device, a third switch device and a fourth switch device; The controlled ends of the first switching device, the second switching device, the third switching device and the fourth switching device are respectively the first controlled end, the second controlled end, the third controlled end and the fourth controlled end of the switching circuit; the input ends of the first switching device, the second switching device, the third switching device and the fourth switching device are respectively the first input end, the second input end, the third input end and the fourth input end of the switching circuit; the output end of the first switching device is the first output end, the output end of the second switching device is connected to the output end of the first switching device, the output end of the third switching device is the second output end, the output end of the fourth switching device is connected to the output end of the third switching device, the fifth input end is connected to the third output end, and the sixth input end is connected to the fourth output end.

9. The motor control circuit according to claim 7, characterized in that: The motor control circuit further comprises: A first operational amplifier circuit is provided between the first output terminal and the second output terminal and the motor current sampling device; The second operational amplifier circuit is arranged between the third output terminal, the fourth output terminal and the motor current sampling device.

10. The motor control circuit according to claim 8, characterized in that: When determining that the SVPWM space voltage vector in the next control cycle is in the preset sampling blind area, the motor current sampling device controls the second switching device and the fourth switching device to turn on, and controls the first switching device and the third switching device to turn off.

11. The motor control circuit according to claim 8, characterized in that: When determining that the SVPWM space voltage vector in the next control cycle is not in the preset sampling blind area, the motor current sampling device controls the first switching device and the third switching device to turn on, and controls the second switching device and the fourth switching device to turn off.

12. An electrical device, characterized in that: The electrical device comprises a motor and a motor control circuit as claimed in any one of claims 6 to 11; The motor control circuit is electrically connected to the motor.

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