Current detection device and method of motor

Abstract

The invention discloses a current detection device and method for a motor. The current detection device comprises a sampling module, an amplification module and a control module, the sampling module is used for sampling the current of the motor; the amplification module comprises an adjusting unit and an operational amplifier, the input end of the adjusting unit is connected with the sampling module, the output end of the adjusting unit is connected with the input end of the operational amplifier, and the output end of the operational amplifier is connected with the control module; and the control module is used for controlling the adjusting unit to enable the adjusting unit to output different resistance values. The amplification factor of the amplification module is controlled and adjusted through the control module, precise detection of the motor current is completed, the detection range of the motor sampling current can be expanded, and the detection precision when the motor sampling current is small can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of current detection, and in particular to a current detection device and method for a motor. Background Art

[0002] At present, when using sensorless FOC to control the operation of a brushless DC motor, it is necessary to obtain the three-phase current of the motor and calculate the position and speed of the motor rotation based on the three-phase current. The higher the accuracy of the motor current sampling, the more accurate the calculated position and speed of the motor, and the more stable the motor rotation.

[0003] The common method to obtain the motor current is to use a sampling resistor, and then obtain the voltage difference across the sampling resistor, and obtain the motor current according to the current I = voltage U / resistance R. Because the sampling resistor is generally small, the voltage across the sampling resistor is also very low, and generally needs to be amplified by an op amp and then connected to the MCU's ADC for sampling.

[0004] Common sampling methods include single resistor sampling, double resistor sampling, and three resistor sampling. Figures 1a to 1c The schematic diagrams of the circuits correspond to single-resistance, dual-resistance, and triple-resistance sampling respectively. The brushless DC motor has three wires, corresponding to the U phase, V phase, and W phase of the motor respectively. The amplification factor of the op amp in this sampling method is fixed, for example, the amplification factor of the op amp is fixed at 3 times or 4 times. The amplification factor remains unchanged during the operation of the motor, regardless of whether the motor rotates fast or slow.

[0005] When the motor output torque remains unchanged, the magnitude of the motor current is related to the speed. The faster the motor rotates, the greater the motor current. The sampling circuit of a general current detection device has a fixed amplification factor and can only detect currents within a certain range and then convert them into corresponding voltage signals. For some products with large motor speed changes, when the motor speed changes in a large range, the current will also change in a large range. This current detection device is not conducive to the stability of motor current detection.

[0006] Therefore, there is an urgent need to provide a current detection device and method for a motor to solve the problem. Summary of the invention

[0007] Based on this, the object of the present invention is to provide a motor current detection device and method with adjustable operational amplifier circuit gain, which can effectively detect the motor current when the motor speed changes greatly.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a current detection device for a motor, which includes a sampling module, an amplification module and a control module; the sampling module is used to sample the current of the motor; the amplification module includes an adjustment unit and an operational amplifier, the input end of the adjustment unit is connected to the sampling module, the output end of the adjustment unit is connected to the input end of the operational amplifier, and the output end of the operational amplifier is connected to the control module; the control module is used to control the adjustment unit so that the adjustment unit outputs different resistance values.

[0009] In one embodiment, the adjustment unit includes a control unit and a first adjustment resistor unit and / or a second adjustment resistor unit, the first adjustment resistor unit and / or the second adjustment resistor unit are connected to the input end of the operational amplifier, the first adjustment resistor unit includes a resistor combination of at least two resistance values ​​and / or the second adjustment resistor unit includes a resistor combination of at least two resistance values, and the control unit is used to adjust the output resistance value of the first adjustment resistor unit and / or the output resistance value of the second adjustment resistor unit.

[0010] In one embodiment, the first adjusting resistance unit includes a first resistor connected to the first output terminal of the control unit, a second resistor connected to the first input terminal of the control unit, and a third resistor connected to the second input terminal of the control unit, the first resistor is at the non-inverting input terminal of the operational amplifier, one end of the second resistor and one end of the third resistor are both connected to the sampling module, and the control unit controls the connection status between the second resistor and the third resistor and the first resistor respectively.

[0011] In one embodiment, the first adjusting resistance unit further includes a tenth resistor connected to the fifth input terminal of the control unit, one end of the tenth resistor is connected to the sampling module, and the control unit controls the connection status between the second resistor, the third resistor and the tenth resistor and the first resistor respectively.

[0012] In one embodiment, the first adjusting resistance unit also includes a twelfth resistor connected to the seventh input terminal of the control unit, one end of the twelfth resistor is connected to the sampling module, and the control unit controls the connection status between the second resistor, the third resistor, the tenth resistor and the twelfth resistor and the first resistor respectively.

[0013] In one embodiment, the resistance of the first resistor is zero.

[0014] In one embodiment, the second adjusting resistance unit includes a fourth resistor connected to the second output terminal of the control unit, a fifth resistor connected to the third input terminal of the control unit, and a sixth resistor connected to the fourth input terminal of the control unit, the fourth resistor is located at the inverting input terminal of the operational amplifier, one end of the fifth resistor and one end of the sixth resistor are both connected to the sampling module, and the control unit controls the connection status between the fifth resistor and the sixth resistor and the fourth resistor respectively.

[0015] In one embodiment, the second adjusting resistance unit further includes an eleventh resistor connected to the sixth input terminal of the control unit, one end of the eleventh resistor is connected to the sampling module, and the control unit controls the connection status between the fifth resistor, the sixth resistor and the eleventh resistor and the fourth resistor respectively.

[0016] In one embodiment, the second adjusting resistance unit further includes a thirteenth resistor connected to the eighth input terminal of the control unit, one end of the thirteenth resistor is connected to the sampling module, and the control unit controls the connection status between the fifth resistor, the sixth resistor, the eleventh resistor and the thirteenth resistor and the fourth resistor respectively.

[0017] In one embodiment, the resistance of the fourth resistor is zero.

[0018] In summary, the present invention provides a motor current detection device and method that controls and adjusts the amplification factor of the amplification module through the control module, thereby completing the precise detection of the motor current, which can expand the detection range of the motor sampling current and the detection accuracy when the motor sampling current is relatively small. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figures 1a to 1c They are circuit schematic diagrams of single-resistance, double-resistance and three-resistance sampling corresponding to an existing motor current detection device;

[0020] Figure 2 A circuit principle block diagram of a current detection device for a motor disclosed in the present invention;

[0021] Figure 3 A circuit schematic diagram of a current detection device for a first motor disclosed in the present invention;

[0022] Figure 4 It is a circuit principle diagram when the first resistor and the third resistor in the current detection device of the first motor disclosed in the present invention are zero;

[0023] Figure 5 A circuit schematic diagram of a second type of current detection device for a motor disclosed in the present invention;

[0024] Figure 6 It is a circuit principle diagram when the first resistor and the third resistor in the current detection device of the second motor disclosed in the present invention are zero;

[0025] Figure 7 A circuit schematic diagram of a third type of current detection device for a motor disclosed in the present invention;

[0026] Figure 8 It is a circuit principle diagram when the first resistor and the third resistor in the current detection device of the third motor disclosed in the present invention are zero;

[0027] Fig. 9 It is a flow chart of a current detection method for a motor disclosed in the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] See also Figures 2 to 8A current detection device for a motor of the present invention includes a sampling module 100, an amplifying module 200 and a control module 300. The sampling module 100 is used to sample the current of the motor and obtain a current sampling signal of the motor. The sampling module 100 includes a sampling resistor, which is connected to a current sampling end of the motor. Specifically, the motor is generally driven and controlled by an IPM driving module. The IPM module has a specific pin connected to the sampling resistor, which can be used as a current sampling end of the motor for sampling the motor phase current.

[0032] The amplification module 200 includes an adjustment unit 210 and an operational amplifier 220, wherein the input end of the adjustment unit 210 is connected to the sampling module 100, the output end of the adjustment unit 210 is connected to the input end of the operational amplifier 220, the control end of the adjustment unit 210 is connected to the control module 300, and the output end of the operational amplifier 220 is connected to the control module 300; wherein the adjustment unit 210 is used to output different resistance values ​​to adjust the resistance size at the input end of the operational amplifier 220; specifically, the adjustment unit 210 is used to output different resistance values ​​to adjust the resistance size at the non-phase input end and / or the inverting input end of the operational amplifier 220.

[0033] The control module 300 is used to control the regulating unit 210 through the control end of the regulating unit 210, and to change the internal on-off state of the input end of the regulating unit 210 and the output end of the regulating unit 210 so that the regulating unit 210 outputs different resistance values, thereby realizing the adjustment of the resistance at the input end of the operational amplifier 220; specifically, the control module 300 is also used to receive the amplified current sampling signal of the motor when connected to the output end of the operational amplifier 220, and perform signal conversion processing, such as analog-to-digital conversion processing, to obtain the current sampling value of the motor; the resistance at the positive input end and / or the negative input end of the operational amplifier 220 can affect the amplification factor of the operational amplifier 220, and the present invention is based on changing the resistance at the positive input end and / or the negative input end of the operational amplifier 220 so that The amplification factor of the operational amplifier 220 can be adjusted, and then the adjustment unit 210 outputs different resistance values ​​to adjust the resistance size at the non-phase input terminal and / or the inverting input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220. Therefore, when the motor speed changes greatly, a suitable resistor is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplifier module 200 uses different amplification factors to detect the motor current; that is, when the motor speed is relatively high, the current sampling value of the motor is relatively large. At this time, the amplification factor of the operational amplifier 220 needs to be relatively small to achieve accurate measurement of the motor current; when the motor speed is relatively low, the current sampling value of the motor is relatively small. At this time, the amplification factor of the operational amplifier 220 needs to be relatively large, so as to facilitate the accurate measurement of the motor current.

[0034] See also Figure 2In one embodiment, the adjustment unit 210 includes a control unit U33 and a first adjustment resistor unit 211 and / or a second adjustment resistor unit 212. The first adjustment resistor unit 211 and / or the second adjustment resistor unit 212 are connected to the input end of the operational amplifier 220. The first adjustment resistor unit 211 includes a resistor combination of at least two resistance values, and the second adjustment resistor unit 212 includes a resistor combination of at least two resistance values. The control unit U33 is used to adjust the output resistance value of the first adjustment resistor unit 211 and the output resistance value of the second adjustment resistor unit 212, so that the output resistance value of the first adjustment resistor unit 211 corresponds to the different resistance combinations in the first adjustment resistor unit 211 as needed, and the output resistance value of the second adjustment resistor unit 212 corresponds to the second adjustment resistor as needed. The output end of the control unit U33 is connected to the input end of the operational amplifier 220, and the control end of the control unit U33 corresponds to the control end of the adjustment unit 210. Specifically, the control end of the control unit U33 is connected to the control module 300. After the control end of the control unit U33 receives the control signal of the control module 300, the control unit U33 controls the first adjustment resistor unit 211 and the second adjustment resistor unit 212 to adjust the output resistance value of the first adjustment resistor unit 211 and the output resistance value of the second adjustment resistor unit 212. The control unit U33 can adjust the output resistance value of the first adjustment resistor unit 211 and the output resistance value of the second adjustment resistor unit 212 in a manner commonly used by technicians in the present technical field, which need not be elaborated here.

[0035] See also Figure 3In one embodiment, the first regulating resistor unit 211 includes a first resistor R75 connected to the first output terminal of the control unit U33, a second resistor R80 connected to the first input terminal of the control unit U33, and a third resistor R82 connected to the second input terminal of the control unit U33. The first resistor R75 is located at the positive phase input terminal of the operational amplifier 220, one end of the second resistor R80 and one end of the third resistor R82 are both connected to the sampling module 100, and the first control terminal of the control unit U33 is connected to the control module 300. Specifically, one end of the second resistor R80 and one end of the third resistor R82 are both connected to one end of the sampling resistor, that is, the second resistor R The I_U end corresponding to one end of the third resistor R82 and one end of the second resistor R80 is connected to the first end of the sampling resistor, the other end of the second resistor R80 is connected to the twelfth pin of the control unit U33, the other end of the third resistor R82 is connected to the fourteenth pin of the control unit U33, one end of the first resistor R75 is connected to the thirteenth pin of the control unit U33, the other end of the first resistor R75 is connected to the positive input end of the operational amplifier 220, the ninth pin of the control unit U33 is connected to the control module 300, the control module 300 sends a control signal to the control unit U33 through the ninth pin, the control unit U33 controls the connection status between the second resistor R80 and the third resistor R82 and the first resistor R75 respectively, and then controls the output resistance value of the first regulating resistor unit 211, when the control unit U33 controls the twelfth pin to be turned on with the thirteenth pin , the output resistance value of the first regulating resistor unit 211 is the sum of the resistance values ​​of the second resistor R80 and the first resistor R75; when the control unit U33 controls the fourteenth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the sum of the resistance values ​​of the third resistor R82 and the first resistor R75; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistor is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplifier module 200 uses different amplification factors to detect the motor current.

[0036] See also Figure 4, further, when the resistance value of the first resistor R75 is zero, the equivalent resistance unit corresponding to the first adjusting resistance unit 211 includes a second resistor R80 connected to the first input end of the control unit U33 and a third resistor R82 connected to the second input end of the control unit U33, the first output end of the control unit U33 is connected to the positive phase input end of the operational amplifier 220, one end of the second resistor R80 and one end of the third resistor R82 are both connected to the sampling module 100, specifically, one end of the second resistor R80 and one end of the third resistor R82 are both connected to the first end of the sampling resistor; the other end of the second resistor R80 is connected to the twelfth pin of the control unit U33, the other end of the third resistor R82 is connected to the fourteenth pin of the control unit U33, the thirteenth pin of the control unit U33 is connected to the positive phase input end of the operational amplifier 220, and the control unit U33 controls the second resistor R80 and the third resistor R82 to be connected to the first output end of the control unit U33 respectively. The connection state between the two pins is determined, and the output resistance value of the first regulating resistor unit 211 is controlled. When the control unit U33 controls the twelfth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the resistance value of the second resistor R80; when the control unit U33 controls the fourteenth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the resistance value of the third resistor R82; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistance is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplification module 200 uses different amplification factors to detect the motor current.

[0037] See also Figure 3In one embodiment, the second regulating resistor unit 212 includes a fourth resistor R76 connected to the second output terminal of the control unit U33, a fifth resistor R77 connected to the third input terminal of the control unit U33, and a sixth resistor R78 connected to the fourth input terminal of the control unit U33. The fourth resistor R76 is located at the inverting input terminal of the operational amplifier 220, and one end of the fifth resistor R77 and one end of the sixth resistor R78 are both connected to the sampling module 100, that is, the I_DC terminal corresponding to one end of the fifth resistor R77 and one end of the sixth resistor R78 is connected to the second end of the sampling resistor. The second control end of the control unit U33 is connected to the control module 300. Specifically, one end of the fifth resistor R77 and one end of the sixth resistor R78 are both connected to the second end of the sampling resistor, the other end of the fifth resistor R77 is connected to the first pin of the control unit U33, the other end of the sixth resistor R78 is connected to the fifth pin of the control unit U33, one end of the fourth resistor R76 is connected to the third pin of the control unit U33, the other end of the fourth resistor R76 is connected to the inverting input end of the operational amplifier 220, the tenth pin of the control unit U33 is connected to the control module 300, and the control module 300 is connected through The tenth pin sends a control signal to the control unit U33, and the control unit U33 controls the connection status between the fifth resistor R77 and the sixth resistor R78 and the fourth resistor R76 respectively, thereby controlling the output resistance value of the second regulating resistor unit 212. When the control unit U33 controls the first pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the sum of the resistance values ​​of the fifth resistor R77 and the fourth resistor R76; when the control unit U33 controls the fifth pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the sum of the resistance values ​​of the sixth resistor R78 and the fifth resistor R76. The present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220. When the motor speed changes greatly, a suitable resistance is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplifier module 200 uses different amplification factors to detect the motor current.

[0038] See also Figure 4, further, when the resistance value of the fourth resistor R76 is zero, the equivalent resistance unit corresponding to the second adjustment resistance unit 212 includes a fifth resistor R77 connected to the third input terminal of the control unit U33 and a sixth resistor R78 connected to the fourth input terminal of the control unit U33, the second output terminal of the control unit U33 is connected to the inverting input terminal of the operational amplifier 220, one end of the fifth resistor R77 and one end of the sixth resistor R78 are both connected to the sampling module 100, specifically, one end of the fifth resistor R77 and one end of the sixth resistor R78 are both connected to the second end of the sampling resistor; the other end of the fifth resistor R77 is connected to the first pin of the control unit U33, the other end of the sixth resistor R78 is connected to the fifth pin of the control unit U33, the third pin of the control unit U33 is connected to the inverting input terminal of the operational amplifier 220, and the control unit U33 controls the fifth resistor R77 and the sixth resistor R78 to be respectively connected to the second output terminal of the control unit U33 The connection state between them is determined, and the output resistance value of the second regulating resistor unit 212 is controlled. When the control unit U33 controls the first pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the resistance value of the fifth resistor R77; when the control unit U33 controls the fifth pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the resistance value of the sixth resistor R78; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistance is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplification module 200 uses different amplification factors to detect the motor current.

[0039] See also Figures 3 to 8 In one embodiment, the non-inverting input terminal of the operational amplifier 220 is also connected to a seventh resistor R83 and an eighth resistor R81, wherein one end of the seventh resistor R83 is grounded, one end of the eighth resistor R81 is connected to a reference voltage of 3.3V, and a ninth resistor R79 is connected between the inverting input terminal of the operational amplifier 220 and the output terminal of the operational amplifier 220; the above connection relationship is combined with the first adjustment resistor unit 211 connected to the non-inverting input terminal of the operational amplifier 220 and the second adjustment resistor unit 212 connected to the inverting input terminal of the operational amplifier 220 to jointly realize the effect of the amplification module 200 amplifying the sampling resistor voltage, thereby completing the purpose of detecting the motor current.

[0040] In one embodiment, the chip model used by the control unit U33 is 74HC4052, and the chip model used by the control module 300 is V32L168x.

[0041] In this embodiment, the first adjusting resistor unit 211 or the second adjusting resistor unit 212 can be used alone or in combination with another adjusting resistor unit. Taking the first adjusting resistor unit 211 as an example, the input resistance value of the inverting input terminal of the operational amplifier 220 needs to remain unchanged, that is, the output resistance value of the second adjusting resistor unit 212 satisfies: the sum of the resistance values ​​of the fifth resistor R77 and the fourth resistor R76 is equal to the sum of the resistance values ​​of the sixth resistor R78 and the fourth resistor R76; at this time, the resistance design of the second adjusting resistor unit 212 has the following ways: the fifth resistor R77 and the sixth resistor R78 have the same resistance value and the resistance value is not zero, and the fourth resistor R76 is not zero; the fifth resistor R77 and the sixth resistor R78 have the same resistance value and the resistance value is not zero, and the fourth resistor R76 is zero; the fifth resistor R77 and the sixth resistor R78 have zero resistance values, and the fourth resistor R76 is not zero.

[0042] Taking the second adjusting resistor unit 212 as an example, the input resistance value of the non-inverting input terminal of the operational amplifier 220 needs to remain unchanged, that is, the output resistance value of the first adjusting resistor unit 211 satisfies: the sum of the resistance values ​​of the second resistor R80 and the first resistor R75 is equal to the sum of the resistance values ​​of the third resistor R82 and the first resistor R75; at this time, the resistance design of the first adjusting resistor unit 211 exists in the following ways: the second resistor R80 and the third resistor R82 have the same resistance value and the resistance value is not zero, and the first resistor R75 is not zero; the second resistor R80 and the third resistor R82 have the same resistance value and the resistance value is not zero, and the first resistor R75 is zero; the second resistor R80 and the third resistor R82 have zero resistance values, and the first resistor R75 is not zero.

[0043] Taking the combined application of the first regulating resistor unit 211 and the second regulating resistor unit 212 as an example, the control unit U33 needs to synchronously adjust the output resistance value of the first regulating resistor unit 211 and the output resistance value of the second regulating resistor unit 212, that is, the control module 300 sends a control signal to the control unit U33 through the ninth pin and the tenth pin. When the control unit U33 controls the twelfth pin and the thirteenth pin to be turned on, the first pin and the third pin are turned on, and the output resistance value of the first regulating resistor unit 211 is the sum of the resistance values ​​of the second resistor R80 and the first resistor R75, and the output resistance value of the second regulating resistor unit 212 is the sum of the resistance values ​​of the fifth resistor R77 and the fourth resistor R76; when the control unit U33 controls the fourteenth pin and the thirteenth pin to be turned on, the fifth pin and the third pin are turned on, and the output resistance value of the first regulating resistor unit 211 is the sum of the resistance values ​​of the third resistor R82 and the first resistor R75, and the output resistance value of the second regulating resistor unit 212 is the sum of the resistance values ​​of the sixth resistor R78 and The sum of the resistance values ​​of the fourth resistor R76; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance values ​​at the non-phase input terminal and the inverting input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance value at the non-phase input terminal of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistor is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplification module 200 uses different amplification factors to detect the motor current; wherein, when the first adjustment resistor unit 211 and the second adjustment resistor unit 212 are used in combination, it is necessary to ensure that the first amplification factor of the amplification unit composed of resistors R75, R79, R83, R76, R80, R77 and the operational amplifier 220 and the second amplification factor of the amplification unit composed of resistors R75, R79, R83, R76, R82, R78 and the operational amplifier 220 are different.

[0044] See also Figure 5, further, the first regulating resistor unit 211 also includes a tenth resistor R86 connected to the fifth input terminal of the control unit U33, one end of the tenth resistor R86 is connected to the sampling module 100, specifically, one end of the tenth resistor R86 is connected to one end of the sampling resistor, that is, the I_U end corresponding to one end of the tenth resistor R86 is connected to the first end of the sampling resistor, and the other end of the tenth resistor R86 is connected to the fifteenth pin of the control unit U33, the control module 300 sends a control signal to the control unit U33 through the ninth pin, and the control unit U33 controls the connection status between the second resistor R80, the third resistor R82 and the tenth resistor R86 and the first resistor R75 respectively, thereby adjusting the output resistance value of the first regulating resistor unit 211. Control, when the control unit U33 controls the fifteenth pin and the thirteenth pin to be turned on, the output resistance value of the first adjusting resistor unit 211 is the sum of the resistance values ​​of the tenth resistor R86 and the first resistor R75; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistor is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplifier module 200 uses different amplification factors to detect the motor current.

[0045] Please continue reading Figure 5The second regulating resistor unit 212 also includes an eleventh resistor R94 connected to the sixth input terminal of the control unit U33. One end of the eleventh resistor R94 is connected to the sampling module 100, that is, the I_DC terminal corresponding to one end of the eleventh resistor R94 is connected to the second end of the sampling resistor. Specifically, one end of the eleventh resistor R94 is connected to the second end of the sampling resistor, and the other end of the eleventh resistor R94 is connected to the second pin of the control unit U33. The control module 300 sends a control signal to the control unit U33 through the tenth pin. The control unit U33 controls the connection states between the fifth resistor R77, the sixth resistor R78 and the eleventh resistor R94 and the fourth resistor R76 respectively, thereby adjusting the output resistance value of the second regulating resistor unit 212. When the control unit U33 controls the second pin and the third pin to be turned on, the output resistance value of the first adjusting resistor unit 211 is the sum of the resistance values ​​of the eleventh resistor R94 and the fourth resistor R76; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistor is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplifier module 200 uses different amplification factors to detect the motor current.

[0046] When the first regulating resistor unit 211 and the second regulating resistor unit 212 are used in combination, the control unit U33 needs to synchronously adjust the output resistance value of the first regulating resistor unit 211 and the output resistance value of the second regulating resistor unit 212, that is, when the control unit U33 controls the fifteenth pin and the thirteenth pin to be turned on, the second pin and the third pin are turned on, the output resistance value of the first regulating resistor unit 211 is the sum of the resistance values ​​of the tenth resistor R86 and the first resistor R75, and the output resistance value of the second regulating resistor unit 212 is the sum of the resistance values ​​of the eleventh resistor R94 and the fourth resistor R76; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance value at the positive input terminal and the negative input terminal of the operational amplifier 220, and then controls the operational amplifier 220 by adjusting the resistance value at the positive input terminal. The amplification factor of the amplifier 220 is controlled by selecting a suitable resistor at the input end of the operational amplifier 220 to control the amplification factor of the operational amplifier 220 when the motor speed changes greatly, so that the adaptive amplification module 200 uses different amplification factors to detect the motor current; wherein, when the first adjustment resistor unit 211 and the second adjustment resistor unit 212 are used in combination, it is necessary to ensure that the first amplification factor of the amplification unit composed of resistors R75, R79, R83, R76, R80, R77 and the operational amplifier 220, the second amplification factor of the amplification unit composed of resistors R75, R79, R83, R76, R82, R78 and the operational amplifier 220, and the third amplification factor of the amplification unit composed of resistors R75, R79, R83, R76, R96, R94 and the operational amplifier 220 are different.

[0047] See also Figure 6In a special case, when the resistance value of the first resistor R75 is zero, the equivalent resistance unit corresponding to the first adjustment resistance unit 211 includes a second resistor R80 connected to the first input terminal of the control unit U33, a third resistor R82 connected to the second input terminal of the control unit U33, and a tenth resistor R86 connected to the fifth input terminal of the control unit U33. The first output terminal of the control unit U33 is connected to the positive phase input terminal of the operational amplifier 220, and one end of the second resistor R80, one end of the third resistor R82, and one end of the tenth resistor R86 are all connected to the sampling module 100. Specifically, one end of the second resistor R80, one end of the third resistor R82 and one end of the tenth resistor R86 are all connected to one end of the sampling resistor; the other end of the second resistor R80 is connected to the twelfth pin of the control unit U33, the other end of the third resistor R82 is connected to the fourteenth pin of the control unit U33, the other end of the tenth resistor R86 is connected to the fifteenth pin of the control unit U33, the thirteenth pin of the control unit U33 is connected to the non-inverting input terminal of the operational amplifier 220, and the control unit U33 controls the second resistor R80, the third resistor R82 and the tenth resistor R86 to be connected to the control unit U33 respectively. The control unit U33 controls the connection state between the first output end of the first regulating resistor unit 211, and then controls the output resistance value of the first regulating resistor unit 211. When the control unit U33 controls the twelfth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the resistance value of the second resistor R80; when the control unit U33 controls the fourteenth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the resistance value of the third resistor R82; when the control unit U33 controls the fifteenth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the resistance value of the third resistor R82. The output resistance value is the resistance value of the tenth resistor R86; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistor is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplifier module 200 uses different amplification factors to detect the motor current.

[0048] When the resistance value of the fourth resistor R76 is zero, the equivalent resistor unit corresponding to the second adjusting resistor unit 212 includes a fifth resistor R77 connected to the third input terminal of the control unit U33, a sixth resistor R78 connected to the fourth input terminal of the control unit U33, and an eleventh resistor R94 connected to the sixth input terminal of the control unit U33. The second output terminal of the control unit U33 is connected to the inverting input terminal of the operational amplifier 220, and one end of the fifth resistor R77, one end of the sixth resistor R78, and one end of the eleventh resistor R94 are all connected to the sampling module 100. In the embodiment, one end of the fifth resistor R77, one end of the sixth resistor R78 and one end of the eleventh resistor R94 are all connected to one end of the sampling resistor; the other end of the fifth resistor R77 is connected to the first pin of the control unit U33, the other end of the sixth resistor R78 is connected to the fifth pin of the control unit U33, the other end of the eleventh resistor R94 is connected to the second pin of the control unit U33, the third pin of the control unit U33 is connected to the inverting input terminal of the operational amplifier 220, and the control unit U33 controls the fifth resistor R77, the sixth resistor R78 and the eleventh resistor R94 to be connected to the control unit U33 respectively. The connection state between the first and second output ends of the unit U33 is controlled, and the output resistance value of the second regulating resistor unit 212 is controlled. When the control unit U33 controls the first pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the resistance value of the fifth resistor R77; when the control unit U33 controls the fifth pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the resistance value of the sixth resistor R78; when the control unit U33 controls the second pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the resistance value of the eleventh resistor R94; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input end of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input end of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistance is selected at the input end of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplification module 200 uses different amplification factors to detect the motor current.

[0049] See also Figure 7, further, taking the amplification module 200 provided with 4 kinds of amplification factors as an example, the first adjustment resistance unit 211 also includes a twelfth resistor 97 connected to the seventh input terminal of the control unit U33, one end of the twelfth resistor 97 is connected to the sampling module 100, that is, the I_U terminal corresponding to one end of the twelfth resistor R97 is connected to the first end of the sampling resistor, specifically, one end of the twelfth resistor 97 is connected to the first end of the sampling resistor, and the other end of the twelfth resistor 97 is connected to the eleventh pin of the control unit U33, the control module 300 sends a control signal to the control unit U33 through the ninth pin, and the control unit U33 controls the connection states between the second resistor R80, the third resistor R82, the tenth resistor R86 and the twelfth resistor 97 and the first resistor R75 respectively, thereby adjusting the first adjustment resistance unit 211. The output resistance value of the first adjusting resistance unit 211 is controlled. When the control unit U33 controls the eleventh pin and the thirteenth pin to be turned on, the output resistance value of the first adjusting resistance unit 211 is the sum of the resistance values ​​of the twelfth resistor 97 and the first resistor R75. The present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220. Therefore, when the motor speed changes greatly, a suitable resistance is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplifier module 200 uses different amplification factors to detect the motor current.

[0050] Please continue reading Figure 7The second regulating resistor unit 212 also includes a thirteenth resistor 95 connected to the eighth input terminal of the control unit U33, one end of the thirteenth resistor 95 is connected to the sampling module 100, that is, the I_DC terminal corresponding to one end of the thirteenth resistor 95 is connected to the second end of the sampling resistor, specifically, one end of the thirteenth resistor 95 is connected to the second end of the sampling resistor, and the other end of the thirteenth resistor 95 is connected to the fourth pin of the control unit U33, the control module 300 sends a control signal to the control unit U33 through the tenth pin, and the control unit U33 controls the connection states between the fifth resistor R77, the sixth resistor R78, the eleventh resistor R94 and the thirteenth resistor 95 and the fourth resistor R76 respectively, thereby adjusting the output voltage of the second regulating resistor unit 212. The resistance value is controlled. When the control unit U33 controls the fourth pin and the third pin to be turned on, the output resistance value of the first adjusting resistance unit 211 is the sum of the resistance values ​​of the thirteenth resistor 95 and the fourth resistor R76. The present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220. In the case where the motor speed changes greatly, a suitable resistance is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplifier module 200 uses different amplification factors to detect the motor current.

[0051] When the first regulating resistor unit 211 and the second regulating resistor unit 212 are used in combination, the control unit U33 needs to synchronously adjust the output resistance value of the first regulating resistor unit 211 and the output resistance value of the second regulating resistor unit 212, that is, the control module 300 sends a control signal to the control unit U33 through the ninth pin and the tenth pin. When the control unit U33 controls the eleventh pin and the thirteenth pin to be turned on, the fourth pin and the third pin are turned on, and the output resistance value of the first regulating resistor unit 211 is the sum of the resistance values ​​of the twelfth resistor 97 and the first resistor R75, and the output resistance value of the second regulating resistor unit 212 is the sum of the resistance values ​​of the thirteenth resistor 95 and the fourth resistor R76; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance value at the positive input terminal and the negative input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance value at the positive input terminal of the operational amplifier 220. number, so that when the motor speed changes greatly, a suitable resistor is selected at the input end of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplification module 200 uses different amplification factors to detect the motor current; wherein, when the first adjustment resistor unit 211 and the second adjustment resistor unit 212 are used in combination, it is necessary to ensure that the first amplification factor of the amplification unit composed of resistors R75, R79, R83, R76, R80, R77 and the operational amplifier 220, the second amplification factor of the amplification unit composed of resistors R75, R79, R83, R76, R82, R78 and the operational amplifier 220, the third amplification factor of the amplification unit composed of resistors R75, R79, R83, R76, R96, R94 and the operational amplifier 220, and the fourth amplification factor of the amplification unit composed of resistors R75, R79, R83, R76, R97, R95 and the operational amplifier 220 are different.

[0052] See also Figure 8In a special case, when the resistance value of the first resistor R75 is zero, the equivalent resistance unit corresponding to the first adjustment resistance unit 211 includes a second resistor R80 connected to the first input terminal of the control unit U33, a third resistor R82 connected to the second input terminal of the control unit U33, a tenth resistor R86 connected to the fifth input terminal of the control unit U33, and a twelfth resistor 97 connected to the seventh input terminal of the control unit U33. The first output terminal of the control unit U33 is connected to the positive phase input terminal of the operational amplifier 220, and one end of the second resistor R80, one end of the third resistor R82, one end of the tenth resistor R86, and one end of the twelfth resistor 97 are all connected to the sampling module 100. Specifically, one end of the second resistor R80, one end of the third resistor R82, one end of the tenth resistor R86 and one end of the twelfth resistor 97 are all connected to one end of the sampling resistor; the other end of the second resistor R80 is connected to the twelfth pin of the control unit U33, the other end of the third resistor R82 is connected to the fourteenth pin of the control unit U33, the other end of the tenth resistor R86 is connected to the fifteenth pin of the control unit U33, the other end of the twelfth resistor 97 is connected to the eleventh pin of the control unit U33, and the thirteenth pin of the control unit U33 is connected to the non-inverting input terminal of the operational amplifier 220. The control unit U33 controls the second resistor R80, the third resistor R82, the tenth resistor R86 and The connection state between the twelfth resistor 97 and the first output end of the control unit U33 is respectively controlled, and the output resistance value of the first regulating resistor unit 211 is further controlled. When the control unit U33 controls the twelfth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the resistance value of the second resistor R80; when the control unit U33 controls the fourteenth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the resistance value of the third resistor R82; when the control unit U33 controls the fifteenth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the resistance value of the tenth resistor R86; when the control unit U33 controls the fifteenth pin and the thirteenth pin to be turned on, the output resistance value of the first regulating resistor unit 211 is the resistance value of the tenth resistor R86; When U33 controls the eleventh pin and the thirteenth pin to be turned on, the output resistance value of the first adjusting resistor unit 211 is the resistance value of the twelfth resistor 97; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the non-phase input terminal of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistor is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplifier module 200 uses different amplification factors to detect the motor current.

[0053] When the resistance value of the fourth resistor R76 is zero, the equivalent resistor unit corresponding to the second adjustment resistor unit 212 includes a fifth resistor R77 connected to the third input terminal of the control unit U33, a sixth resistor R78 connected to the fourth input terminal of the control unit U33, an eleventh resistor R94 connected to the sixth input terminal of the control unit U33, and a thirteenth resistor 95 connected to the eighth input terminal of the control unit U33. The second output terminal of the control unit U33 is connected to the inverting input terminal of the operational amplifier 220, and one end of the fifth resistor R77, one end of the sixth resistor R78, one end of the eleventh resistor R94, and one end of the thirteenth resistor 95 are all connected to the sampling module 100. Specifically, one end of the fifth resistor R77, one end of the sixth resistor R78, one end of the eleventh resistor R94 and one end of the thirteenth resistor 95 are all connected to one end of the sampling resistor; the other end of the fifth resistor R77 is connected to the first pin of the control unit U33, the other end of the sixth resistor R78 is connected to the fifth pin of the control unit U33, the other end of the eleventh resistor R94 is connected to the second pin of the control unit U33, the other end of the thirteenth resistor 95 is connected to the fourth pin of the control unit U33, the third pin of the control unit U33 is connected to the inverting input terminal of the operational amplifier 220, and the control unit U33 controls the fifth resistor R77, the sixth resistor R78, the eleventh resistor R94 and the thirteenth resistor 95 are respectively connected to the second output end of the control unit U33, thereby controlling the output resistance value of the second regulating resistor unit 212. When the control unit U33 controls the first pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the resistance value of the fifth resistor R77; when the control unit U33 controls the fifth pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the resistance value of the sixth resistor R78; when the control unit U33 controls the second pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the resistance value of the eleventh resistor R94; when the control unit U33 controls the second pin and the third pin to be turned on, the output resistance value of the second regulating resistor unit 212 is the resistance value of the eleventh resistor R94; When the fourth pin 33 controls the connection with the third pin, the output resistance value of the second adjusting resistor unit 212 is the resistance value of the thirteenth resistor 95; the present invention adjusts the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220, and then controls the amplification factor of the operational amplifier 220 by adjusting the resistance at the inverting input terminal of the operational amplifier 220, so that when the motor speed changes greatly, a suitable resistor is selected at the input terminal of the operational amplifier 220 to control the amplification factor of the operational amplifier 220, so that the adaptive amplification module 200 adopts different amplification factors to detect the motor current.

[0054] According to the above-mentioned current detection device of a motor of the present invention, the present invention provides a current detection method of a motor, and the sampling module, amplification module and control module involved in the method can be the same as the technical features described in the above-mentioned embodiment of the current detection device of the motor, and can produce the same technical effects. The current detection method of the motor of the present invention controls and adjusts the amplification factor of the amplification module through the control module, thereby completing the accurate detection of the motor current, which can expand the detection range of the motor sampling current and the detection accuracy when the motor sampling current is relatively small; specifically, by setting amplification modules with different amplification factors, when the motor speed is relatively high, the current sampling value of the motor is relatively large, and at this time, the amplification factor of the amplification module needs to be relatively small, and when the motor speed is relatively low, the current sampling value of the motor is relatively small, and at this time, the amplification factor of the amplification module needs to be relatively large, so as to facilitate the accurate measurement of the motor current.

[0055] Considering that when using the current detection circuit to detect the current of the motor, it is limited by the chip port voltage of the control module, and there are problems such as the detection range is not wide enough or the detection accuracy is insufficient when the sampling current is small, resulting in a large detection error. For example: the chip port voltage of the control module usually cannot exceed 3.3V or 5V. The current detection device converts the current signal into a sampling voltage signal through a sampling resistor, and then amplifies the sampling voltage signal through the amplifier module for detection at the chip port of the control module. For example, when the fixed amplification factor of the amplifier module is 10 and the chip port voltage of the control module is limited to 5V, the maximum sampling voltage signal can only reach 0.5V. For example: the voltage at the sampling point of a normal current detection circuit is very small, and generally an increase of such as Figures 3 to 8 The eighth resistor R81 in the circuit is pulled up to a bias power supply, so that the input-output formula of the operational amplifier 220 is Uo=AUi+B, where Uo is the output, Ui is the input, A is the amplification factor, and B is a constant.

[0056] Fig. 9 is a flow chart of a method for detecting a current of a motor provided by an embodiment of the present invention. Fig. 9 As shown, the motor current detection method includes steps S110 to S140, which are specifically as follows:

[0057] Step S110, obtaining current sampling signals corresponding to the U phase, V phase, and W phase of the motor; sampling the current of the motor through the sampling module to obtain current sampling signals corresponding to the U phase, V phase, and W phase of the motor, specifically, as follows Figure 1cAs shown, taking the commonly used single-resistance sampling method as an example, the sampling module 100 includes a U-phase sampling unit, a V-phase sampling unit and a W-phase sampling unit. Each sampling unit is provided with a sampling resistor to be respectively connected to the sampling ends of the three-phase current of the motor: U-phase current, V-phase current, and W-phase current, so that the sampling module can obtain the sampling signals of the currents corresponding to the U-phase, V-phase, and W-phase of the motor.

[0058] Step S120, obtaining the amplified current sampling signals corresponding to the U phase, V phase, and W phase of the motor; amplifying the current sampling signals of the motor by the amplification factor set by the amplification module itself to obtain the amplified current sampling signals of the motor; Figure 7 Taking the current detection device of the corresponding motor as an example, the amplification module is provided with 4 different gears of amplification factors, which are the first amplification factor of the fourth gear, the second amplification factor of the third gear, the third amplification factor of the second gear and the fourth amplification factor of the first gear from high to low. The amplification factors of the first amplification factor, the second amplification factor, the third amplification factor and the fourth amplification factor decrease in sequence. In the initial state, the first amplification factor can be preset to amplify the current sampling signal of the motor to obtain the amplified current sampling signal of the motor; alternatively, in the initial state, the second amplification factor, the third amplification factor or the fourth amplification factor can be preset as needed to amplify the current sampling signal of the motor to obtain the amplified current sampling signal of the motor.

[0059] Specifically, the U phase, V phase, and W phase of the motor each output a motor current sampling signal, and are respectively amplified by the amplification module to obtain the amplified current sampling signals of the motor corresponding to the U phase, V phase, and W phase of the motor.

[0060] Since the amplification module matches different amplification factors as needed to amplify the output current sampling signals of the U-phase, V-phase and W-phase of the motor, it can be simply implemented by using an amplification module combining an adjustment unit and an operational amplifier. The control module only needs to control the output of the adjustment unit to output different resistance values ​​to change the resistance of the input end of the operational amplifier, thereby adjusting the amplification factor of the amplification module, effectively reducing the design area of ​​the PCB, and can effectively adapt to products with a smaller PCB design area.

[0061] Step S130, obtaining the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor; after the control module receives the amplified current sampling signal of the motor output by the amplification module, it performs signal conversion processing to obtain the current sampling value of the motor.

[0062] Specifically, after the amplified current sampling signals of the motor corresponding to the U phase, V phase and W phase of the motor are received by the control module, signal conversion processing is performed to obtain the corresponding current sampling values ​​of the U phase, V phase and W phase of the motor.

[0063] Step S140, determine whether the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is within the preset range threshold. If so, keep the amplification factor of the current sampling signal of the motor unchanged; if not, when the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is less than the preset minimum threshold, increase the amplification factor of the current sampling signal of the motor by one level; when the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is greater than the preset maximum threshold, reduce the amplification factor of the current sampling signal of the motor by one level; preset a preset range threshold, the preset range threshold includes a preset maximum threshold and a preset minimum threshold, the preset maximum threshold is greater than the preset minimum threshold, that is, the preset range threshold = [preset minimum threshold, preset maximum threshold].

[0064] Since the current sampling values ​​corresponding to the motor U phase, V phase, and W phase are different in magnitude at the same time, if the current sampling value of one of the phase currents of the motor is sampled alone, selecting different phase currents will produce different motor current judgment results, which is not enough to judge the overall current output state of the motor and easily leads to misjudgment problems; while by detecting the three phase currents of the motor at the same time and performing square sum processing on the current sampling values ​​corresponding to each phase current, the overall current output state of the motor is within a stable range of values, so the three-phase current of the motor is detected at the same time and the square sum of the three-phase current is compared with the preset range threshold, so that the control module can more accurately control the motor operation process.

[0065] In addition, the current detection method of the motor of the present invention utilizes an adjustment unit with an adjustable resistance value output to change the resistance value of the input end of the operational amplifier. Taking the commonly used single resistor sampling method as an example, in order to achieve the effect of amplifying the current sampling signals of the U phase, V phase, and W phase of the motor, it is necessary to match an amplification module separately for the current sampling signals corresponding to the U phase, V phase, and W phase of the motor; when it is necessary to change the amplification factor of the amplification module, it is only necessary to change the output resistance value of the adjustment unit, and there is no need to add other amplification modules for the current sampling signals corresponding to the U phase, V phase, and W phase of the motor to perform amplification processing, which effectively saves the number of current sampling times and the current sampling time, and is more suitable for the current detection effect of motors with higher speeds.

[0066] Specifically, when the motor starts to start, the control unit first controls the amplification module to amplify the current sampling signals corresponding to the U phase, V phase, and W phase of the motor with the first amplification factor corresponding to the fourth gear, and after the control module receives the amplified current sampling signals corresponding to the U phase, V phase, and W phase of the motor output by the amplification module, it performs signal conversion processing to obtain the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor, and squares the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor respectively and adds them to obtain the square sum result of the current sampling values, and compares the square sum result with the preset range threshold. If the square sum result If the sum of squares is within the preset range threshold, the amplification module continues to amplify the current sampling signals corresponding to the U phase, V phase, and W phase of the motor with the first amplification factor; if the sum of squares result is not within the preset range threshold, there are two possibilities for the sum of squares result. When the sum of squares result is greater than the preset maximum threshold, the motor speed is in a relatively high state, and the control module is required to control the adjustment of the amplification factor of the amplification module so that the amplification factor of the amplification module is lowered by one level; when the sum of squares result is less than the preset minimum threshold, the motor speed is in a relatively low state, and the control module is required to control the adjustment of the amplification factor of the amplification module so that the amplification factor of the amplification module is increased by one level.

[0067] When the motor is working, if the current current sampling signals corresponding to the U phase, V phase and W phase of the motor are amplified respectively with the first amplification factor corresponding to the fourth gear, when the control module obtains that the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase and W phase of the motor is less than the preset minimum threshold value, the speed of the motor is in a relatively low state, then it is necessary to further increase the amplification factor of the amplification module, but at this time, since the amplification factor of the amplification module is already in the highest gear, the control module controls the adjustment of the amplification factor of the amplification module to not change; if the current current sampling signals corresponding to the U phase, V phase and W phase of the motor are amplified respectively with the fourth amplification factor corresponding to the first gear, when the control module obtains that the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase and W phase of the motor is greater than the preset maximum threshold value, the speed of the motor is in a relatively high state, then it is necessary to further lower the amplification factor of the amplification module, but at this time, since the amplification factor of the amplification module is already in the lowest gear, the control module controls the adjustment of the amplification factor of the amplification module to not change.

[0068] Furthermore, the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is not within the preset range threshold. When the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is less than the preset minimum threshold, it is determined whether the amplification factor of the current amplification module is in the highest gear. If so, the amplification factor of the current sampling signal of the motor is kept unchanged; if not, the amplification factor of the current sampling signal of the motor is increased by one gear; the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is not within the preset range threshold. When the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is greater than the preset maximum threshold, it is determined whether the amplification factor of the current amplification module is in the lowest gear. If so, the amplification factor of the current sampling signal of the motor is kept unchanged; if not, the amplification factor of the current sampling signal of the motor is reduced by one gear.

[0069] In summary, the present invention provides a motor current detection device and method that controls and adjusts the amplification factor of the amplification module through the control module, thereby completing the precise detection of the motor current, which can expand the detection range of the motor sampling current and the detection accuracy when the motor sampling current is relatively small.

[0070] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A current detection device for a motor, characterized in that: It includes a sampling module, an amplification module and a control module; The sampling module is used to sample the current of the motor; The amplification module includes an adjustment unit and an operational amplifier, the input end of the adjustment unit is connected to the sampling module, the output end of the adjustment unit is connected to the input end of the operational amplifier, and the output end of the operational amplifier is connected to the control module; The control module is used to control the adjustment unit so that the adjustment unit outputs different resistance values.

2. The current detection device for a motor according to claim 1, characterized in that: The adjustment unit includes a control unit and a first adjustment resistor unit and / or a second adjustment resistor unit, the first adjustment resistor unit and / or the second adjustment resistor unit are connected to the input end of the operational amplifier, the first adjustment resistor unit includes a resistor combination of at least two resistance values ​​and / or the second adjustment resistor unit includes a resistor combination of at least two resistance values, and the control unit is used to adjust the output resistance value of the first adjustment resistor unit and / or the output resistance value of the second adjustment resistor unit.

3. The current detection device for a motor according to claim 2, characterized in that: The first adjusting resistance unit includes a first resistor connected to the first output end of the control unit, a second resistor connected to the first input end of the control unit, and a third resistor connected to the second input end of the control unit. The first resistor is located at the non-inverting input end of the operational amplifier, one end of the second resistor and one end of the third resistor are both connected to the sampling module, and the control unit controls the connection status between the second resistor and the third resistor and the first resistor respectively.

4. The current detection device for a motor according to claim 3, characterized in that: The first regulating resistor unit also includes a tenth resistor connected to the fifth input terminal of the control unit, one end of the tenth resistor is connected to the sampling module, and the control unit controls the connection status between the second resistor, the third resistor and the tenth resistor and the first resistor respectively.

5. The current detection device for a motor according to claim 4, characterized in that: The first regulating resistor unit also includes a twelfth resistor connected to the seventh input terminal of the control unit, one end of the twelfth resistor is connected to the sampling module, and the control unit controls the connection status between the second resistor, the third resistor, the tenth resistor and the twelfth resistor and the first resistor respectively.

6. The current detection device for a motor according to claim 2, characterized in that: The second regulating resistor unit includes a fourth resistor connected to the second output terminal of the control unit, a fifth resistor connected to the third input terminal of the control unit, and a sixth resistor connected to the fourth input terminal of the control unit, the fourth resistor is located at the inverting input terminal of the operational amplifier, one end of the fifth resistor and one end of the sixth resistor are both connected to the sampling module, and the control unit controls the connection status between the fifth resistor and the sixth resistor and the fourth resistor respectively.

7. The current detection device for a motor according to claim 6, characterized in that: The second regulating resistor unit also includes an eleventh resistor connected to the sixth input terminal of the control unit, one end of the eleventh resistor is connected to the sampling module, and the control unit controls the connection status between the fifth resistor, the sixth resistor and the eleventh resistor and the fourth resistor respectively.

8. The current detection device for a motor according to claim 7, characterized in that: The second regulating resistor unit also includes a thirteenth resistor connected to the eighth input terminal of the control unit, one end of the thirteenth resistor is connected to the sampling module, and the control unit controls the connection status between the fifth resistor, the sixth resistor, the eleventh resistor and the thirteenth resistor and the fourth resistor respectively.

9. A method for detecting current of a motor, characterized in that: The steps include: Obtain current sampling signals corresponding to the U phase, V phase, and W phase of the motor; Obtaining amplified current sampling signals corresponding to the U phase, V phase, and W phase of the motor; Obtain current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor; Determine whether the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is within a preset range threshold. If so, keep the amplification factor of the current sampling signal of the motor unchanged; if not, when the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is less than the preset minimum threshold, increase the amplification factor of the current sampling signal of the motor by one level; when the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is greater than the preset maximum threshold, reduce the amplification factor of the current sampling signal of the motor by one level.

10. The method for detecting current of a motor according to claim 9, characterized in that: The sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is not within the preset range threshold. When the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is less than the preset minimum threshold, it is determined whether the amplification factor of the current amplification module is in the highest gear. If so, the amplification factor of the current sampling signal of the motor is kept unchanged; if not, the amplification factor of the current sampling signal of the motor is increased by one gear; when the sum of the squares of the current sampling values ​​corresponding to the U phase, V phase, and W phase of the motor is greater than the preset maximum threshold, it is determined whether the amplification factor of the current amplification module is in the lowest gear. If so, the amplification factor of the current sampling signal of the motor is kept unchanged; if not, the amplification factor of the current sampling signal of the motor is reduced by one gear.

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