Method and device for checking phase sequence of three-phase asynchronous motor

Abstract

The invention relates to the technical field of phase sequence inspection of three-phase asynchronous motors, and is a method and device for implementing phase sequence inspection of three-phase asynchronous motors. The device comprises a collection unit for collecting line voltage and a sine waveform of a three-phase power supply input; a calculation unit for calculating the line voltage to obtain an integral calculation result; a judgment unit for judging whether the integral calculation result is greater than or equal to a standard threshold value; a response unit for responding if yes, the phase sequence is correct, that is, the A, B, and C phases of the three-phase power supply are connected in sequence; and responding if no, the phase sequence is wrong. According to the invention, only when the phase sequence is connected in sequence, the integral calculation result is greater than or equal to the threshold value of the reference phase sequence, and if the phase sequence is not connected in sequence, the integral calculation result is less than the threshold value of the reference phase sequence, thereby achieving the purpose of phase sequence inspection through the characteristics of different phase sequence access modes, and using the reference phase sequence threshold value for judgment, the fault tolerance rate is high, and the problem of motor reversal and damage when the three-phase power supply is connected in sequence is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of three-phase asynchronous motor phase sequence inspection, and in particular to a method and device for implementing three-phase asynchronous motor phase sequence inspection. Background Art

[0002] The three-phase asynchronous motor is mainly driven by three-phase alternating current. The phase sequence of three-phase alternating current is the phase sequence of three-phase alternating current. The three-phase sequence of three-phase alternating current A, B, and C rotates clockwise, and the phase difference is 120°. When the phase sequence of three-phase electricity is connected incorrectly, the motor may be reversed or even damaged.

[0003] There are two basic methods for judging the phase sequence of three-phase electricity: one is to connect an unbalanced load, and the voltage on each phase load will be unbalanced due to its different impedance, so the phase sequence can be judged. The other is to use the characteristic of 120° phase difference of three-phase electricity, perform pulse conversion at the zero-crossing point of each phase voltage through hardware circuit, and then judge the timing of the three pulses through the single-chip microcomputer to detect the phase sequence. Summary of the invention

[0004] The present invention provides a method and device for checking the phase sequence of a three-phase asynchronous motor, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problem that the existing three-phase asynchronous motor is prone to motor reversal or even damage when the phase sequence of the three-phase power supply is connected incorrectly.

[0005] To solve the above problem, one of the technical solutions of the present invention is implemented in the following way: a method for checking the phase sequence of a three-phase asynchronous motor comprises the following steps:

[0006] Collect the line voltage and sinusoidal waveform of three-phase power input;

[0007] Calculate the line voltage and obtain the integral calculation result;

[0008] Determine whether the integral calculation result is greater than or equal to the standard threshold;

[0009] If the response is yes, the phase sequence is correct, that is, the three-phase power supply A, B, and C phases are connected in sequence;

[0010] If the response is no, the phase sequence is wrong, that is, the three-phase power supply A, B, and C are connected in phase swap.

[0011] The above phase sequence is correct as follows:

[0012] ,

[0013] in, is the sine wave angle corresponding to the sampling point, Lim is the judgment threshold corresponding to the reference phase sequence; The angle of the sine wave is The line voltage of phase AB at ; The angle of the sine wave is The line voltage of phase BC at time ; The angle of the sine wave is [ The line voltage of phase BC at .

[0014] The judgment conditions for the above phase sequence error are:

[0015] ,

[0016] in, is the sine wave angle corresponding to the sampling point, Lim is the judgment threshold corresponding to the reference phase sequence; The angle of the sine wave is The line voltage of the AC phase at ; The angle of the sine wave is The line voltage of CB phase at time ; The angle of the sine wave is The line voltage of CB phase at .

[0017] The second technical solution of the present invention is realized by the following method: a device for realizing phase sequence inspection of a three-phase asynchronous motor, comprising a three-phase power supply, a collection unit, a calculation unit, a judgment unit, and a response unit;

[0018] A collection unit collects the line voltage and sinusoidal waveform of the three-phase power input;

[0019] A calculation unit calculates the line voltage to obtain an integral calculation result;

[0020] A judgment unit, judging whether the integral calculation result is greater than or equal to a standard threshold;

[0021] The response unit responds with "yes", then the phase sequence is correct, that is, the three-phase power supply A, B, and C phases are connected in sequence; the response unit responds with "no", then the phase sequence is wrong, that is, the three-phase power supply A, B, and C phases are connected in phase swapping.

[0022] The acquisition unit comprises a first acquisition circuit and a second acquisition circuit, and the first acquisition circuit and the second acquisition circuit are respectively connected between two phases of a three-phase power supply.

[0023] The above also includes an output module and a phase-changing module. The output module is used to control the output of the three-phase power supply; the phase-changing module is used to change the phase of the three-phase power supply.

[0024] The present invention has the advantage that only when the phase sequence is connected sequentially, the integral calculation result is greater than or equal to the threshold value of the reference phase sequence. If the phase sequence is not connected sequentially, the integral calculation result is less than the threshold value of the reference phase sequence. Thus, the purpose of phase sequence checking is achieved through the characteristics of different phase sequence connection modes, and the reference phase sequence threshold is used for judgment, with high fault tolerance, thus avoiding the problem of motor reversal and damage when the three-phase asynchronous motor is connected in phase sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0026] Figure 1 This is a flow chart of the method of Example 1 of the present invention.

[0027] Figure 2 This is a three-phase electrical phase sequence determination diagram in Example 1 of the present invention.

[0028] Figure 3 This is a phase sequence diagram when the three-phase power supply is connected sequentially in Example 1 of the present invention.

[0029] Figure 4 This is a phase sequence diagram when the three-phase power supply is connected in phase switching in Example 1 of the present invention.

[0030] Figure 5 Schematic diagram of the circuit structure in Example 3 of the present invention. DETAILED DESCRIPTION

[0031] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0032] Example 1: Figure 1 As shown, the embodiment of the present invention discloses a method for implementing phase sequence checking of a three-phase asynchronous motor, comprising the following steps:

[0033] S101, collecting the line voltage and sinusoidal waveform of the three-phase power input;

[0034] S102, calculating the line voltage to obtain an integral calculation result;

[0035] S103, determining whether the integral calculation result is greater than or equal to a standard threshold;

[0036] S104, if the response is yes, the phase sequence is correct, that is, the three-phase power supply A, B, and C phases are connected in sequence;

[0037] S105, if the response is no, then the phase sequence is wrong, that is, the three-phase power supply A, B, and C are connected in phase swap.

[0038] For the input three-phase power supply, only two line voltages and sine waveforms are collected. If the three-phase power supply is connected in sequence, the line voltage collected is UAB , U BC , the phase sequence rotates clockwise; if the three-phase power supply B and C phases are connected in phase, the line voltage collected is U AC , U CB , the phase sequence rotates counterclockwise, and U BC with U CB Between AC with U CA The phase angle difference is 180°.

[0039] Among them, the basis for judging the phase sequence is as follows: Figure 2 As shown in the figure, it can be seen that the three-phase power line voltage U AB , U BC , U CA There is a 120° difference between them. When phases B and C are swapped, the actual original U AB The line voltage collected at the collection point is U AC , original U BC The line voltage collected at the collection point is U CB , and U AC with U CA There is a 180° difference between them, U BC with U CB There is a difference of 180° between them.

[0040] The collected line voltage is calculated, and the integral calculation result is used instead of the judgment of the 120° angle, and compared with the standard threshold (where the marked threshold is set manually, and the empirical value of the test is selected, and the reference range is: marked threshold ±5) to achieve the purpose of phase sequence inspection. Specifically:

[0041] 1. When the three-phase power supply is connected in the order of A, B, and C, such as Figure 3 As shown, the conditions for judging the correct phase sequence are:

[0042] ,

[0043] in, is the sine wave angle corresponding to the sampling point, Lim is the judgment threshold corresponding to the reference phase sequence; The angle of the sine wave is The line voltage of phase AB at ; The angle of the sine wave is The line voltage of phase BC at time ; The angle of the sine wave is The line voltage of phase BC at .

[0044] 2. When the three-phase power supply B and C phases are connected in phase, the voltage actually collected at the original collection point is as follows: Figure 4 As shown, the conditions for judging the correct phase sequence at this time, that is, the conditions for judging the wrong phase sequence when the three-phase power supply is connected in sequence are:

[0045] ,

[0046] in, is the sine wave angle corresponding to the sampling point, Lim is the judgment threshold corresponding to the reference phase sequence; The angle of the sine wave is The line voltage of the AC phase at ; The angle of the sine wave is The line voltage of CB phase at time ; The angle of the sine wave is The line voltage of CB phase at .

[0047] In summary, according to the above judgment method, the present invention only has the phase sequence connected sequentially, the integral calculation result is greater than or equal to the threshold of the reference phase sequence, if the phase sequence is not connected sequentially, the integral calculation result is less than the threshold of the reference phase sequence, thereby achieving the purpose of phase sequence inspection through the characteristics of different phase sequence access methods, and using the reference phase sequence threshold for judgment, with high fault tolerance, avoiding the problem of motor reversal and damage when the three-phase asynchronous motor is connected in phase sequence.

[0048] Embodiment 2: The embodiment of the present invention discloses a method for checking the phase sequence of a three-phase asynchronous motor, wherein the judgment condition for a correct phase sequence is:

[0049] ,

[0050] in, is the sine wave angle corresponding to the sampling point, Lim is the judgment threshold corresponding to the reference phase sequence; The angle of the sine wave is The line voltage of phase AB at ; The angle of the sine wave is The line voltage of phase BC at time ; The angle of the sine wave is The line voltage of phase BC at .

[0051] The judgment conditions for phase sequence error are:

[0052] ,

[0053] in, is the sine wave angle corresponding to the sampling point, Lim is the judgment threshold corresponding to the reference phase sequence; The angle of the sine wave is The line voltage of the AC phase at ; The angle of the sine wave is The line voltage of CB phase at time ; The angle of the sine wave is The line voltage of CB phase at .

[0054] Example 3: Figure 5 As shown, an embodiment of the present invention discloses a device for implementing phase sequence checking of a three-phase asynchronous motor, including a three-phase power supply, a collection unit, a calculation unit, a judgment unit, and a response unit;

[0055] A collection unit collects the line voltage and sinusoidal waveform of the three-phase power input;

[0056] A calculation unit calculates the line voltage to obtain an integral calculation result;

[0057] A judgment unit, judging whether the integral calculation result is greater than or equal to a standard threshold;

[0058] The response unit responds with "yes", then the phase sequence is correct, that is, the three-phase power supply A, B, and C phases are connected in sequence; the response unit responds with "no", then the phase sequence is wrong, that is, the three-phase power supply A, B, and C phases are connected in phase swapping.

[0059] The acquisition unit includes a first acquisition circuit and a second acquisition circuit, and the first acquisition circuit and the second acquisition circuit are respectively connected between two phases of a three-phase power supply.

[0060] It also includes an output module and a phase-changing module. The output module is used to control the output of the three-phase power supply; the phase-changing module is used to change the phase of the three-phase power supply.

[0061] Among them, the three-phase power supply is used to drive the rotation of the three-phase asynchronous motor; the phase change module is used for phase sequence switching when the three-phase asynchronous motor is installed forward and reverse.

[0062] The three-phase sequence of the three-phase action power supply can be A, B, C or C, B, A, and the phase sequence identification is not limited to U AB with U BC , which can be determined by any two-phase line voltage.

Claims

1. A method for checking the phase sequence of a three-phase asynchronous motor, characterized in that: The following steps are involved: Collect the line voltage and sinusoidal waveform of three-phase power input; Calculate the line voltage and obtain the integral calculation result; Determine whether the integral calculation result is greater than or equal to the standard threshold; If the response is yes, the phase sequence is correct, that is, the three-phase power supply A, B, and C phases are connected in sequence; If the response is no, the phase sequence is wrong, that is, the three-phase power supply A, B, and C are connected in phase swap; The conditions for determining the correct phase sequence are: ， in, is the sine wave angle corresponding to the sampling point, Lim is the judgment threshold corresponding to the reference phase sequence; The angle of the sine wave is The line voltage of AB phase at ; The angle of the sine wave is The line voltage of phase BC at time ; The angle of the sine wave is The line voltage of BC phase at time ; When the three-phase power supply B and C phases are connected in phase, the judgment condition of phase sequence error is: ， in, is the sine wave angle corresponding to the sampling point, Lim is the judgment threshold corresponding to the reference phase sequence; The angle of the sine wave is The line voltage of the AC phase at ; The angle of the sine wave is The line voltage of CB phase at time ; The angle of the sine wave is The line voltage of CB phase at time ; It also includes a three-phase power supply, a collection unit, a calculation unit, a judgment unit, and a response unit; A collection unit collects the line voltage and sinusoidal waveform of the three-phase power input; A calculation unit calculates the line voltage to obtain an integral calculation result; A judgment unit, judging whether the integral calculation result is greater than or equal to a standard threshold; The response unit responds yes, then the phase sequence is correct, that is, the three-phase power supply A, B, and C phases are connected in sequence; if the response is no, then the phase sequence is wrong, that is, the three-phase power supply A, B, and C phases are connected in phase swap; The acquisition unit includes a first acquisition circuit and a second acquisition circuit, and the first acquisition circuit and the second acquisition circuit are respectively connected between two phases of a three-phase power supply; It also includes an output module and a phase-changing module. The output module is used to control the output of the three-phase power supply; the phase-changing module is used to change the phase of the three-phase power supply.

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