Current acquisition device and method

Abstract

The application discloses a current collection device and method, and belongs to the technical field of current collection. The technical problem to be solved by the application is how to improve the accuracy of current collection while guaranteeing the reliability of motor operation. The technical scheme is as follows: the device comprises an MCU, a U phase, a V phase and a W phase, the MCU is electrically connected with the U phase, the V phase and the W phase respectively, the U phase, the V phase and the W phase are respectively provided with a circuit collection unit one, a current collection unit two, an operational amplifier unit one and an operational amplifier module two, the current collection unit one is electrically connected with the operational amplifier unit one, the MCU converts the current values collected by the current collection unit one and the current collection unit two into real current values through the gain multiples and the voltage division coefficients of the corresponding operational amplifier unit one and the operational amplifier unit two, compares the current difference values of each phase, obtains the current value of the phase with the maximum current difference value, obtains the ideal current value by using the data of the other two phases, and estimates the maximum value of the current of the phase with the maximum current difference value at the current moment by using the weighted average method.

Description

Technical Field

[0001] This invention relates to the field of circuit data acquisition technology, specifically to a current acquisition device and method. Background Technology

[0002] The accuracy of phase current acquisition when driving a motor is crucial to the accuracy of FOC control. Currently, the common current acquisition method for high-power motors is to use Hall current transformers as hardware acquisition modules. For low-power motors, resistance sampling is generally used for current acquisition. Generally, the accuracy of small current is not a concern when controlling high-power motors. However, the accuracy of small current greatly affects the motor's motion performance when controlling low-power motors. When using resistance sampling, the current acquisition is unstable due to unstable bias voltage and MOS switching noise.

[0003] Therefore, how to improve the accuracy of current acquisition while ensuring the reliability of motor operation is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] The technical objective of this invention is to provide a current acquisition device and method to address the problem of improving the accuracy of current acquisition while ensuring the reliability of motor operation.

[0005] The technical objective of this invention is achieved as follows: a current acquisition device includes an MCU, a U-phase, a V-phase, and a W-phase. The MCU is electrically connected to the U-phase, V-phase, and W-phase respectively. The U-phase, V-phase, and W-phase are respectively equipped with a circuit acquisition unit one, a current acquisition unit two, an operational amplifier unit one, and an operational amplifier module two. The current acquisition unit one is electrically connected to the operational amplifier unit one; the current acquisition unit two is electrically connected to the operational amplifier unit two. The MCU converts the current values ​​acquired from the current acquisition units one and two into actual current values ​​through the gain factor and voltage division factor of the corresponding operational amplifier units one and two, respectively. By comparing the current difference of each phase, the current value of the phase with the largest current difference is obtained. The ideal current value is obtained using the data of the other two phases. Finally, the maximum value of the current of the phase with the largest current difference at the current moment is estimated by a weighted average method.

[0006] Preferably, the current acquisition unit one uses the low end of the resistor to sample the phase current; the operational amplifier unit one provides bias voltage, amplification and filtering for the current acquisition unit one.

[0007] Preferably, the second current acquisition unit uses a Hall sensor to sample the phase current; the second operational amplifier unit provides filtering and voltage division for the current sampling unit.

[0008] More preferably, when the circuit acquisition unit one or the current acquisition unit two acquires the current, the situation is as follows:

[0009] ① When the current value is less than the set threshold, the current is defined as a small current, and the current is collected by the first acquisition unit when the current is small;

[0010] ② When the current value is not less than the set threshold, the current is defined as a large current, and the current is collected by the second acquisition unit when the current is large.

[0011] More preferably, for small currents, the formula for predicting the maximum value of the phase current with the largest current difference at the current moment using the weighted average method is as follows:

[0012]

[0013] Among them, I a This is the calculated value of the U-phase current; The actual current value of the resistance sampling sensor; I b I is the phase V current value; c K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; ...2 is the weighting factor for phase W; K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; K2 is the weighting

[0014] More preferably, for high currents, the formula for predicting the maximum value of the phase current with the largest current difference at the current moment using the weighted average method is as follows:

[0015]

[0016] Among them, I a This is the calculated value of the U-phase current; The actual current value of the Hall current sampling sensor; I b I is the phase V current value; c K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; ...2 is the weighting factor for phase W; K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; K2 is the weighting

[0017] A current acquisition method is proposed. In this method, the MCU converts the current values ​​acquired from current acquisition unit 1 and current acquisition unit 2 into actual current values ​​through the gain factor and voltage division factor of the corresponding operational amplifier unit 1 and operational amplifier unit 2, respectively. By comparing the current difference of each phase, the current value of the phase with the largest current difference is obtained. The ideal current value is obtained using the data of the other two phases. Finally, the maximum value of the current of the phase with the largest current difference at the current moment is estimated by the weighted average method.

[0018] As a preferred method, the specific details are as follows:

[0019] Collect two current values ​​for the same phase;

[0020] Compare the difference between the two current values ​​of each phase, and find the phase with the largest difference in current values;

[0021] Determine if the current value is greater than the set threshold:

[0022] If so, then the high current weighted average algorithm shall be used;

[0023] If not, then the small current weighted average algorithm will be used.

[0024] More preferably, the formula for the high-current weighted average algorithm is as follows:

[0025]

[0026] Among them, I a This is the calculated value of the U-phase current; The actual current value of the resistance sampling sensor; I b I is the phase V current value; c K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; ...2 is the weighting factor for phase W; K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; K2 is the weighting

[0027] More preferably, the formula for the small current weighted average algorithm is as follows:

[0028]

[0029] Among them, I a This is the calculated value of the U-phase current; The actual current value of the Hall current sampling sensor; I b I is the phase V current value; c K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; ...2 is the weighting factor for phase W; K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; K2 is the weighting

[0030] The current acquisition device and method of the present invention have the following advantages:

[0031] (i) This invention can further improve the accuracy of current acquisition through a weighted average algorithm;

[0032] (ii) The present invention deploys current acquisition unit one and current acquisition unit two in phases U, V and W respectively. Even if the current acquisition of one phase fails, the current acquisition unit one and current acquisition unit two of the other two phases can still work normally, so that the motor can run normally and increase the stability of motor operation.

[0033] (III) Since the sampling resistor and Hall current sensor have different accuracies at low and high currents, the current value obtained by the resistor sampling is more reliable at low currents. At high currents, the current value obtained by the resistor sampling may be inaccurate due to uncertain factors such as temperature and dust, so the current value obtained by the Hall sensor sampling is more reliable. This invention deploys current acquisition unit one and current acquisition unit two in phases U, V and W respectively. The current acquired by current acquisition unit one is used at low currents, and the current acquired by current acquisition unit two is used at high currents, which greatly improves the accuracy of current acquisition.

[0034] (iv) This invention provides a simple and efficient current acquisition method, which also has the advantages of accuracy, speed and anti-interference.

[0035] Therefore, this invention has the characteristics of reasonable design, simple structure, small size, convenient use and multiple uses, and thus has great value for promotion and use. Attached Figure Description

[0036] The invention will be further described below with reference to the accompanying drawings.

[0037] Appendix Figure 1 This is a schematic diagram of the current acquisition device.

[0038] Appendix Figure 2 This is a flowchart of the current acquisition method. Detailed Implementation

[0039] The current acquisition device and method of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Example 1:

[0041] As attached Figure 1 As shown, this embodiment provides a current acquisition device, the structure of which includes an MCU, U phase, V phase and W phase. The MCU is electrically connected to the U phase, V phase and W phase respectively. The U phase, V phase and W phase are respectively deployed with a circuit acquisition unit 1, a current acquisition unit 2, an operational amplifier unit 1 and an operational amplifier module 2. The current acquisition unit 1 is electrically connected to the operational amplifier unit 1; the current acquisition unit 2 is electrically connected to the operational amplifier unit 2. The MCU converts the current values ​​acquired from the current acquisition unit 1 and the current acquisition unit 2 into actual current values ​​through the gain factor and voltage division factor of the corresponding operational amplifier unit 1 and operational amplifier unit 2, respectively. By comparing the current difference of each phase, the current value of the phase with the largest current difference is obtained. The ideal current value is obtained using the data of the other two phases. Then, the maximum value of the current of the phase with the largest current difference at the current moment is estimated by the weighted average method.

[0042] In this embodiment, the current acquisition unit 1 samples the phase current using the low end of a resistor; the operational amplifier unit 1 provides bias voltage, amplification, and filtering for the current acquisition unit 1.

[0043] In this embodiment, the second current acquisition unit uses a Hall sensor to sample the phase current; the second operational amplifier unit provides filtering and voltage division for the current sampling unit.

[0044] In this embodiment, when circuit acquisition unit one or current acquisition unit two acquires current, the situation is as follows:

[0045] ① When the current value is less than the set threshold, the current is defined as a small current, and the current is collected by the first acquisition unit when the current is small;

[0046] ② When the current value is not less than the set threshold, the current is defined as a large current, and the current is collected by the second acquisition unit when the current is large.

[0047] In this embodiment, when the current is small, the formula for predicting the maximum value of the phase current with the largest current difference at the current moment using the weighted average method is as follows:

[0048]

[0049] Among them, I a This is the calculated value of the U-phase current; The actual current value of the resistance sampling sensor; I b I is the phase V current value; c K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; ...2 is the weighting factor for phase W; K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; K2 is the weighting

[0050] In this embodiment, when the current is large, the formula for predicting the maximum value of the phase current with the largest current difference at the current moment using the weighted average method is as follows:

[0051]

[0052] Among them, I a This is the calculated value of the U-phase current; The actual current value of the Hall current sampling sensor; I b I is the phase V current value; c K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; ...2 is the weighting factor for phase W; K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; K2 is the weighting

[0053] Example 2:

[0054] This embodiment provides a current acquisition method. The method involves the MCU converting the current values ​​acquired from current acquisition unit one and current acquisition unit two into actual current values ​​through the gain factor and voltage division factor of the corresponding operational amplifier unit one and operational amplifier unit two, respectively. By comparing the current difference of each phase, the current value of the phase with the largest current difference is obtained. The ideal current value is obtained using the data of the other two phases. Finally, the maximum value of the current of the phase with the largest current difference at the current moment is estimated by the weighted average method.

[0055] As attached Figure 2 As shown, the method is as follows:

[0056] S1. Collect two current values ​​for the same phase;

[0057] S2. Compare the difference between the two current values ​​of each phase and find the phase with the largest difference in current values.

[0058] S3. Determine if the current value is greater than the set threshold:

[0059] ① If so, then the large current weighted average algorithm shall be adopted;

[0060] ② If not, then the small current weighted average algorithm shall be used.

[0061] The formula for the high-current weighted average algorithm in this embodiment is as follows:

[0062]

[0063] Among them, I a This is the calculated value of the U-phase current; The actual current value of the resistance sampling sensor; I b I is the phase V current value; c K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; ...2 is the weighting factor for phase W; K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; K2 is the weighting

[0064] The formula for the small current weighted average algorithm in this embodiment is as follows:

[0065]

[0066] Among them, I a This is the calculated value of the U-phase current; The actual current value of the Hall current sampling sensor; I b I is the phase V current value; c K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; ...2 is the weighting factor for phase W; K1 is the weighting factor for phase W; K2 is the weighting factor for phase W; K2 is the weighting

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A current acquisition device, characterized in that, The device includes an MCU, U-phase, V-phase, and W-phase. The MCU is electrically connected to U-phase, V-phase, and W-phase respectively. Current acquisition unit 1, current acquisition unit 2, operational amplifier unit 1, and operational amplifier unit 2 are deployed in U-phase, V-phase, and W-phase respectively. Current acquisition unit 1 is electrically connected to operational amplifier unit 1; current acquisition unit 2 is electrically connected to operational amplifier unit 2. The MCU converts the current values ​​acquired from current acquisition unit 1 and current acquisition unit 2 into actual current values ​​through the corresponding gain factor and voltage division factor of operational amplifier unit 1 and operational amplifier unit 2 respectively. By comparing the current difference between the two current values ​​of each phase, the current value of the phase with the largest current difference is obtained. The ideal current value is obtained using the data of the other two phases. Finally, the maximum value of the current of the phase with the largest current difference at the current moment is estimated by weighted average method. Determine if the current value is less than the set threshold: If so, then the small current weighted average method shall be used; If not, then the large current weighted average method shall be used; For low current, the formula for predicting the maximum value of the phase current with the largest current difference at the current moment using the weighted average method is as follows: ; in, This is the calculated value of the U-phase current; The actual current value of the resistance sampling sensor; This represents the V-phase current value. This refers to the W-phase current value. This is the weighting factor, with a value of 0.65; The weighting factor is 0.35; the current acquisition unit uses a resistance sampling sensor to acquire the actual current value. For high current applications, the formula for predicting the maximum value of the phase current with the largest current difference at the current moment using the weighted average method is as follows: ; in, This is the calculated value of the U-phase current; The actual current value of the Hall current sampling sensor; This represents the V-phase current value. This refers to the W-phase current value. This is the weighting factor, with a value of 0.65; The weighting coefficient is 0.35; the second current acquisition unit uses a Hall current sampling sensor to acquire the actual current value.

2. The current acquisition device according to claim 1, characterized in that, The operational amplifier unit one provides bias voltage, amplification, and filtering for the current acquisition unit one.

3. The current acquisition device according to claim 1, characterized in that, The second operational amplifier unit provides filtering and voltage division for the current sampling unit.

4. A current acquisition method, characterized in that, This method involves the MCU converting the current values ​​collected from current acquisition unit one and current acquisition unit two into actual current values ​​using the corresponding gain factors and voltage divider factors of operational amplifier units one and two, respectively. It then compares the current difference between the two current values ​​for each phase to obtain the current value of the phase with the largest current difference. Using data from the other two phases, it obtains the ideal current value and finally estimates the maximum value of the current in the phase with the largest current difference at the current moment using a weighted average method. The details are as follows: Collect two current values ​​for the same phase; Compare the difference between the two current values ​​of each phase, and find the phase with the largest difference in current values; Determine if the current value is less than the set threshold: If so, then the small current weighted average method shall be used; If not, then the large current weighted average method shall be used; For low current, the formula for predicting the maximum value of the phase current with the largest current difference at the current moment using the weighted average method is as follows: ; in, This is the calculated value of the U-phase current; The actual current value of the resistance sampling sensor; This represents the V-phase current value. This refers to the W-phase current value. This is the weighting factor, with a value of 0.65; The weighting factor is 0.35; the current acquisition unit uses a resistance sampling sensor to acquire the actual current value. For high current applications, the formula for predicting the maximum value of the phase current with the largest current difference at the current moment using the weighted average method is as follows: ; in, This is the calculated value of the U-phase current; The actual current value of the Hall current sampling sensor; This represents the V-phase current value. This refers to the W-phase current value. This is the weighting factor, with a value of 0.65; The weighting coefficient is 0.35; the second current acquisition unit uses a Hall current sampling sensor to acquire the actual current value.

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