Pre-protection motor control method
By simplifying the pre-protection motor control circuit and signal detection method, the problems of complexity and inaccuracy of existing motor pre-protection schemes are solved, enabling safe motor start-up and fault detection, and reducing hardware costs and data processing load.
Patent Information
- Application Number
- CN202511129881.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-13
- Publication Date
- 2025-11-14
AI Technical Summary
Existing motor pre-protection schemes are complex, resulting in high hardware costs and inaccurate predictions, which can easily lead to pre-protection failure. Furthermore, they rely heavily on microcontrollers for data processing, which can affect the continuous use of the motor.
A simple pre-protection motor control circuit is adopted. The pre-detection circuit is connected to the terminal of the controller and the three-phase motor. The coil status is detected by using high-frequency pulse signals and feedback signals. Combined with signal cyclic acquisition and data processing, the judgment of coil short circuit and open circuit is realized.
It simplifies the motor control circuit structure, improves the accuracy and reliability of pre-protection, avoids faulty operation, reduces hardware costs and complexity, and ensures safe motor startup.
Smart Images
Figure CN120955558A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of motor control, and specifically to a pre-protection motor control circuit and method. Background Technology
[0002] If a high-power water pump (motor) has problems such as short circuit, phase loss, open circuit, or coil abnormality, it can lead to bigger problems, including affecting the power grid, damaging the water pump and surrounding property, and even causing major safety issues.
[0003] Existing motor pre-protection schemes employ complex hardware circuits, increasing hardware costs and lacking accuracy in predicting motor protection, thus easily leading to pre-protection failure. Furthermore, traditional motor control circuits rely on microcontrollers, such as single-chip microcomputers, which sample and process detection data. Due to the complexity and large data processing volume of existing pre-protection schemes, the computational load on the unprocessor is significantly increased, making such schemes unsuitable for continuous use. Summary of the Invention
[0004] In order to solve the technical problems and shortcomings in the prior art, the present invention provides a pre-protection motor control circuit and method, which can overcome the technical problem of how to implement safety pre-protection operation in motor control in the prior art, and can perform pre-detection on the motor before starting the motor to avoid running with faults.
[0005] To achieve the above and other related objectives, the present invention adopts the following technical solution:
[0006] A pre-protected motor control method includes a controller, a relay module, a three-phase motor, and a motor control circuit. The controller is connected to the three-phase terminals of the three-phase motor (U, V, and W) through the motor control circuit. Three pre-detection circuits are connected between the controller and the three-phase terminals of the three-phase motor. Each pre-detection circuit includes a signal injection terminal and a signal sampling terminal. The signal injection terminal is provided with a high-frequency pulse signal or a low signal by the controller, and the signal sampling terminal provides a feedback signal to the controller. The relay module controls the connection and disconnection between the three-phase terminals and the pre-detection circuits.
[0007] When the signal injection terminal of one of the pre-detection circuits is set to a high-frequency pulse signal input, and the signal injection terminals of the other two pre-detection circuits are set to a low level, the feedback signals from the signal sampling terminals of the other two pre-detection circuits are provided to the controller as a basis for judgment. The controller cycles through the setting of the signal injection terminals of the three pre-detection circuits and cycles through the acquisition of signals from the signal sampling terminals.
[0008] Preferably, the signal injection terminals of the three pre-detection circuits are connected to the IO1, IO2, and IO3 terminals of the controller, and the signal sampling terminals of the three pre-detection circuits are connected to the ADC1, ADC2, and ADC3 terminals of the controller. The coil windings corresponding to the U, V, and W terminals on the three-phase motor are RZ1, RZ2, and RZ3, respectively.
[0009] The steps for cyclic setting and data acquisition include:
[0010] Step 1: Output a high-frequency pulse signal at IO1, set IO2 and IO3 to output low level, and use ADC1 and ADC2 to detect the amplitude of the received signal.
[0011] If no signal is received at either ADC2 or ADC3, then coil RZ1 is open-circuited; if the signal amplitude received at ADC2 is significantly increased, then coils RZ1 and RZ2 are short-circuited; if the signal amplitude received at ADC3 is significantly increased, then coils RZ1 and RZ3 are short-circuited.
[0012] Step 2: Output a high-frequency pulse signal at IO2, set IO3 and IO1 to output low level, and use ADC2 and ADC3 to detect the amplitude of the received signal.
[0013] If no signal is received at either ADC3 or ADC1, then coil RZ2 is open-circuited; if the signal amplitude received at ADC3 is significantly increased, then coils RZ2 and RZ3 are short-circuited; if the signal amplitude received at ADC1 is significantly increased, then coils RZ2 and RZ1 are short-circuited.
[0014] Step 3: Output a high-frequency pulse signal at IO3, set IO1 and IO2 to low level, and use ADC3 and ADC1 to detect the amplitude of the received signal.
[0015] If no signal is received at either ADC1 or ADC2, then coil RZ3 is open-circuited; if the signal amplitude received at ADC1 is significantly increased, then coil RZ3 and coil RZ1 are short-circuited; if the signal amplitude received at ADC2 is significantly increased, then coil RZ3 and coil RZ2 are short-circuited.
[0016] Preferably, the detection results collected by the controller each time are stored in the storage unit. The controller's storage unit will always record a certain number of recent data for comparison. The newly detected data is compared with the old data to determine whether the trend of change is consistent and whether the variable is within the normal range.
[0017] Preferably, the controller calculates the average value of all the detection results in the storage unit.
[0018] Preferred options also include:
[0019] Step A: The controller puts the three-phase motor into an independent state through the motor control circuit, and controls the relay module to connect the pre-detection circuit to the three-phase motor;
[0020] Step B: A high-frequency pulse signal is output from IO1, and the integrated voltage is detected by ADC2 and ADC3 to obtain a set of detection data; a high-frequency pulse signal is output from IO2, and the integrated voltage is detected by ADC1 and ADC3 to obtain a set of detection data; a high-frequency pulse signal is output from IO3, and the integrated voltage is detected by ADC1 and ADC2 to obtain a set of detection data.
[0021] Step C: Filter or average the detection data to obtain the final detection data;
[0022] Step D: Determine whether the motor has a short circuit or open circuit based on the test results data, and compare the test results with historical data. If the change is not significant, set a flag and drive the motor normally. If there is a short circuit or open circuit or a large difference, set an alarm.
[0023] Step E: After the test is completed, the control relay module disconnects the pre-test circuit from the three-phase motor, and the controller resumes operation of the three-phase motor through the motor control circuit.
[0024] Preferably, the pre-detection circuit includes an input resistor, an integrating resistor, and an integrating capacitor. One end of the input resistor serves as a signal injection terminal, and the other end of the input resistor is connected to one end of the integrating resistor and used to connect to a three-phase motor. The other end of the integrating resistor is connected to the integrating capacitor and serves as a signal sampling terminal, and the other end of the integrating capacitor is grounded.
[0025] Preferably, the pre-detection circuit includes an input circuit, an integrating resistor, an integrating capacitor, and a clamping circuit. The input circuit includes a transistor N2, a resistor R1, and a capacitor C4. The base of transistor N2 is connected to the controller as a signal injection terminal, the emitter of transistor N2 is grounded, the collector of transistor N2 is connected to a voltage source through resistor R1, and the collector of transistor N2 is connected to one phase terminal of a three-phase motor through capacitor C4.
[0026] One end of the integrating capacitor is used as a signal sampling terminal to connect to the clamping circuit and one end of the integrating resistor. The other end of the integrating resistor is used to connect to one phase terminal of the three-phase motor, and the other end of the integrating capacitor is grounded.
[0027] Preferably, the clamping circuit includes diode D1 and diode D2, the cathode of diode D1 is connected to the voltage source VCC, the cathode of diode D1 is connected to the cathode of diode D2 and serves as the clamping voltage terminal, and the anode of diode D2 is grounded.
[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0029] 1. This invention, through a simpler hardware structure, combined with the signal output and sampling of the controller, performs data processing and can effectively distinguish the state of a three-phase motor and whether it is suitable for operation, avoiding operation with faults. It can perform safety checks before the three-phase motor starts and drives normally, judging whether the coil is in normal condition, thus avoiding greater safety accidents. Due to the adoption of a simpler circuit structure, it avoids the problems of circuit complexity and the cost and reliability reduction caused by complex circuits.
[0030] 2. In this invention, the pre-detection circuit realizes the cross-multiplexing of signal output and sampling input, simplifies the circuit structure, and realizes the judgment of short circuit and open circuit of coil in three-phase motor;
[0031] 3. The present invention improves the reliability and accuracy of judgment by retaining and averaging the data;
[0032] 4. This invention also provides a solution for fault prediction of motors with high impedance, which can solve the fault prediction problem of three-phase motors with high impedance.
[0033] Other additional advantages and benefits of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0034] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.
[0035] In the attached diagram:
[0036] Figure 1 This is a schematic diagram of the overall circuit principle of Embodiment 1 of this application;
[0037] Figure 2 This is a schematic diagram of the signal acquisition circuit at the ADC2 terminal in an embodiment of this application;
[0038] Figure 3 This is a schematic diagram of the signal acquisition circuit at the ADC3 terminal in an embodiment of this application;
[0039] Figure 4 This is a schematic diagram of the pre-detection circuit in Example 2;
[0040] Figure 5 This is a circuit diagram illustrating the detection of one phase of a circuit in Example 2.
[0041] Explanation of reference numerals for major components:
[0042] 100. Controller; 200. Relay module; 300. Three-phase motor; 400. Motor control circuit; 500. Pre-detection circuit; 501. Signal injection terminal; 502. Signal sampling terminal. Detailed Implementation
[0043] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. The following specific examples illustrate the embodiments of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.
[0044] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The illustrations only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be changed at will, and the layout of the components may also be more complex.
[0045] It should be noted that in the description of this application, the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention. Furthermore, it should be noted that in the description of this application, unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in the invention based on the specific circumstances.
[0046] Example 1:
[0047] This invention discloses a pre-protected motor control method, including a controller 100, a relay module 200, a three-phase motor 300, and a motor control circuit 400. The controller 100 is connected to the three-phase terminals of the three-phase motor 300 (U, V, and W terminals) through the motor control circuit 400. The controller 100 can be a microcontroller, a single-chip microcomputer, or a control chip; in this embodiment, a single-chip microcomputer is used. The appropriate model of the microcontroller can be selected according to the motor control requirements, such as ES7P169C or ES8P5066. The motor control circuit 400 is not the focus of this solution and is not considered a core protection point of this patent. It is related to practical applications in the prior art, so it is simply represented as the motor control circuit 400. It is used for motor control and can be a frequency converter, etc. The relay module 200 has relay devices; three single-pole single-throw relays or one triple-pole single-throw relay can be selected. The selection of relays needs to consider the operating voltage of the motor and ensure that it does not exceed the contact withstand voltage of the relays.
[0048] exist Figure 1 As can be seen, three pre-detection circuits 500 are connected between the controller 100 and the three-phase terminals of the three-phase motor 300. Each pre-detection circuit 500 includes a signal injection terminal 501 and a signal sampling terminal 502. The signal injection terminal 501 is provided with a high-frequency pulse signal or a low signal by the controller 100, and the signal sampling terminal 502 provides a feedback signal to the controller 100. The relay module 200 controls the connection and disconnection between the three-phase terminals and the pre-detection circuits 500. When the signal injection terminal 501 of one pre-detection circuit 500 is set to a high-frequency pulse signal input, and the signal injection terminals 501 of the other two pre-detection circuits are set to a low level, the feedback signals from the signal sampling terminals 502 of the other two pre-detection circuits are provided to the controller 100 as a judgment basis. The controller 100 cyclically sets the signal injection terminals 501 of the three pre-detection circuits 500 and cyclically acquires signals from the signal sampling terminals 502.
[0049] In this embodiment, the specific circuit is described as follows. The signal injection terminals 501 of the three pre-detection circuits 500 are connected to the IO1, IO2, and IO3 terminals of the controller 100. The signal sampling terminals 502 of the three pre-detection circuits 500 are connected to the ADC1, ADC2, and ADC3 terminals of the controller 100. The coil windings corresponding to the U, V, and W terminals on the three-phase motor 300 are RZ1, RZ2, and RZ3, respectively.
[0050] Specifically, the pre-detection circuit 500 includes an input resistor, an integrating resistor, and an integrating capacitor. One end of the input resistor serves as a signal injection terminal 501, and the other end of the input resistor is connected to one end of the integrating resistor and used to connect to the three-phase motor 300. The other end of the integrating resistor is connected to the integrating capacitor and serves as a signal sampling terminal 502. The other end of the integrating capacitor is grounded.
[0051] Resistors R1, R3, and R5 serve as input resistors, resistors R2, R4, and R6 serve as integrating resistors, and capacitors C1, C2, and C3 serve as integrating capacitors. R2 and C1, R4 and C2, and R6 and C3 form an integrating circuit that integrates the received signal. The integrated voltage signal is then sent to the microcontroller's ADC (analog-to-digital converter) module for detection.
[0052] The specific process is as follows:
[0053] The following explanation uses the output signal of IO1 and the received signals of ADC2 and ADC3 as examples. The same applies to the output signal of IO2 and the received signals of ADC1 and ADC3, and the output signal of IO3 and the received signals of ADC1 and ADC2.
[0054] Before the motor starts, the motor control circuit 400 is disconnected, the relay switch on the detection relay module 200 is closed, and the IO1 terminal outputs a high-frequency pulse signal (generally a signal above 100KHz is selected; we selected 200KHz). The IO2 and IO3 terminals are set to output low level. The ADC1 and ADC2 terminals detect the amplitude of the received signal.
[0055] The impedance formula for a motor coil can be simply expressed as:
[0056] Z = 2 × π × f × L;
[0057] In the formula, Z is the impedance, f is the signal frequency, and L is the coil inductance.
[0058] Because of the high signal frequency, the impedance of the motor coil is also relatively large. The signal returned from the three-phase motor 300 and sent to the ADC2 terminal can be simplified as follows: Figure 2 As shown.
[0059] The amplitude of the signal received by ADC2 is the value of the output signal amplitude of IO1 after being divided by (R1+RZ1+RZ2) / R3. RZ1 is the impedance of motor coil 1, and RZ2 is the impedance of motor coil 2. Under normal circumstances, the motor impedance is a fixed value, so the signal received by ADC2 is also basically unchanged.
[0060] The ADC3 end is also simplified as follows: Figure 3 As shown. The signal amplitude received by ADC3 is the value of the output signal amplitude of IO1 after being divided by (R1+RZ1+RZ3) / R5. RZ3 is the impedance of motor coil 3. Under normal circumstances, the motor impedance is a fixed value, so the signal received by ADC3 is also basically unchanged.
[0061] Based on the above analytical principles:
[0062] The steps for cyclic setting and data acquisition include:
[0063] Step 1: Output a high-frequency pulse signal at IO1, set IO2 and IO3 to output low level, and use ADC1 and ADC2 to detect the amplitude of the received signal.
[0064] If no signal is received at either ADC2 or ADC3, then coil RZ1 is open-circuited; if the signal amplitude received at ADC2 is significantly increased, then coils RZ1 and RZ2 are short-circuited; if the signal amplitude received at ADC3 is significantly increased, then coils RZ1 and RZ3 are short-circuited.
[0065] Step 2: Output a high-frequency pulse signal at IO2, set IO3 and IO1 to output low level, and use ADC2 and ADC3 to detect the amplitude of the received signal.
[0066] If no signal is received at either ADC3 or ADC1, then coil RZ2 is open-circuited; if the signal amplitude received at ADC3 is significantly increased, then coils RZ2 and RZ3 are short-circuited; if the signal amplitude received at ADC1 is significantly increased, then coils RZ2 and RZ1 are short-circuited.
[0067] Step 3: Output a high-frequency pulse signal at IO3, set IO1 and IO2 to low level, and use ADC3 and ADC1 to detect the amplitude of the received signal.
[0068] If no signal is received at either ADC1 or ADC2, then coil RZ3 is open-circuited; if the signal amplitude received at ADC1 is significantly increased, then coil RZ3 and coil RZ1 are short-circuited; if the signal amplitude received at ADC2 is significantly increased, then coil RZ3 and coil RZ2 are short-circuited.
[0069] Because motor parameters may shift slightly over time, but not significantly, it is generally necessary to average the results of multiple tests to obtain a valid result. Preferably, the controller 100 stores the test results collected each time in a storage unit. The controller 100's storage unit will always record a certain number of recent data entries for comparison. Newly detected data is compared with old data to determine whether the trend of change is consistent and whether the variable is within the normal range.
[0070] The control method for controller 100 is as follows:
[0071] Step A: The controller 100 puts the three-phase motor 300 into an independent state through the motor control circuit 400, and controls the relay module 200 to connect the pre-detection circuit 500 to the three-phase motor 300.
[0072] Step B: A high-frequency pulse signal is output from IO1, and the integrated voltage is detected by ADC2 and ADC3 to obtain a set of detection data; a high-frequency pulse signal is output from IO2, and the integrated voltage is detected by ADC1 and ADC3 to obtain a set of detection data; a high-frequency pulse signal is output from IO3, and the integrated voltage is detected by ADC1 and ADC2 to obtain a set of detection data.
[0073] Step C: Filter or average the detection data to obtain the final detection data;
[0074] Step D: Determine whether the motor has a short circuit or open circuit based on the test results data, and compare the test results with historical data. If the change is not significant, set a flag and drive the motor normally. If there is a short circuit or open circuit or a large difference, set an alarm.
[0075] Step E: After the test is completed, the control relay module 200 disconnects the pre-test circuit 500 from the three-phase motor 300, and the controller 100 resumes operation of the three-phase motor 300 through the motor control circuit 400.
[0076] This invention, through a simpler hardware structure, combined with the signal output and sampling of the controller 100, performs data processing and can effectively distinguish the state of the three-phase motor 300, whether it is suitable for operation, and avoid operation with faults. It can perform safety detection before the three-phase motor 300 starts and drives normally, and determine whether the coil is in normal condition, thus avoiding greater safety accidents. Due to the adoption of a simpler circuit structure, it avoids the problems of circuit complexity and the cost and reliability reduction caused by complex circuits.
[0077] Example 2:
[0078] Based on Example 1, further optimizations and modifications can be made to accommodate pre-protection for high-impedance motors. Specific differences are as follows:
[0079] refer to Figure 4 As shown, the pre-detection circuit 500 includes an input circuit, an integrating resistor, an integrating capacitor, and a clamping circuit. The input circuit includes a transistor N2, a resistor R1, and a capacitor C4. The base of transistor N2 is connected to the controller 100 as a signal injection terminal 501. The emitter of transistor N2 is grounded. The collector of transistor N2 is connected to a voltage source through resistor R1. The collector of transistor N2 is connected to one phase terminal of the three-phase motor 300 through capacitor C4. Figure 4 This example illustrates a pre-detection circuit 500. In practice, there are three such pre-detection circuits 500 with the same structure. Figure 4 The diagram illustrates the connection method of the IO1 terminal, ADC1 terminal, and U-phase terminal. The connection methods of the other two phases and other microcontroller terminals are similar.
[0080] To simplify the explanation of the principle, Figure 5 The diagram illustrates the working principle of one phase; the working principles of the other two phases can be deduced by analogy.
[0081] exist Figure 4 Specifically, one end of the integrating capacitor serves as the signal sampling terminal 502, connected to the clamping circuit and one end of the integrating resistor. The other end of the integrating resistor is used to connect to one phase terminal of the three-phase motor 300, and the other end of the integrating capacitor is grounded. The clamping circuit includes diodes D1 and D2. The cathode of diode D1 is connected to the voltage source VCC, and the cathode of diode D1 is connected to the cathode of diode D2 as the clamping voltage terminal. The anode of diode D2 is grounded.
[0082] For motors with high impedance, this Example 2 scheme is adopted. Because of the high motor impedance, the signal transmitted through the three-phase motor 300 is significantly attenuated, and the higher the impedance, the greater the attenuation. In this case, the motor impedance is divided by the impedance of capacitor C1 or C2 to obtain the detection signal.
[0083] The output pulse from IO3 is driven by transistor N2 to obtain a higher voltage pulse signal (usually VDD is 12V and VCC is 5V). After the DC component is removed by capacitor C6, the signal sent to the motor coil becomes an AC signal.
[0084] The signal returned from the motor is integrated through R2 and C1 and sent to ADC1. After being integrated through R4 and C2, it is sent to ADC2. Diodes D2 and D3 clamp the signal sent to ADC1, and diodes D4 and D5 clamp the signal sent to ADC2 to ensure that the signal is within the allowable range.
[0085] The method for determining the state of the three-phase motor 300 is the same as the scheme in the aforementioned embodiment 1.
[0086] In Examples 1 and 2, the pre-detection circuit 500 achieves cross-multiplexing of signal output and sampling input, simplifying the circuit structure and enabling the determination of short circuits and open circuits in the coils of the three-phase motor 300. The present invention improves the reliability and accuracy of the judgment by retaining and averaging the data.
[0087] This embodiment also provides a solution for fault prediction of motors with high impedance, which can solve the fault prediction of this type of three-phase motor with high impedance of 300.
[0088] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A pre-protected motor control method, comprising a controller (100), a relay module (200), a three-phase motor (300), and a motor control circuit (400), wherein the controller (100) is connected to the three-phase terminals of the three-phase motor (300): U terminal, V terminal, and W terminal, through the motor control circuit (400), characterized in that, Three pre-detection circuits (500) are connected between the controller (100) and the three-phase terminals of the three-phase motor (300). Each pre-detection circuit (500) includes a signal injection terminal (501) and a signal sampling terminal (502). The signal injection terminal (501) is provided with a high-frequency pulse signal or a low signal by the controller (100), and the signal sampling terminal (502) provides a feedback signal to the controller (100). The relay module (200) controls the connection and disconnection between the three-phase terminals and the pre-detection circuits (500). When the signal injection terminal (501) of one of the pre-detection circuits (500) is set to high-frequency pulse signal input, and the signal injection terminals (501) of the other two pre-detection circuits (500) are set to low level, the feedback signals of the signal sampling terminals (502) of the other two pre-detection circuits (500) are provided to the controller (100) as a judgment basis. The controller (100) cycles through the signal injection terminals (501) of the three pre-detection circuits (500) and cycles through the signal sampling terminals (502).
2. The pre-protection motor control method according to claim 1, characterized in that, The signal injection terminals (501) of the three pre-detection circuits (500) are connected to the IO1, IO2 and IO3 terminals of the controller (100), and the signal sampling terminals (502) of the three pre-detection circuits (500) are connected to the ADC1, ADC2 and ADC3 terminals of the controller (100). The coil windings corresponding to the U, V and W terminals on the three-phase motor (300) are RZ1, RZ2 and RZ3 respectively. The steps for cyclic setting and data acquisition include: Step 1: Output a high-frequency pulse signal at IO1, set IO2 and IO3 to output low level, and use ADC1 and ADC2 to detect the amplitude of the received signal. If no signal is received at either ADC2 or ADC3, then coil RZ1 is open-circuited; if the signal amplitude received at ADC2 is significantly increased, then coils RZ1 and RZ2 are short-circuited; if the signal amplitude received at ADC3 is significantly increased, then coils RZ1 and RZ3 are short-circuited. Step 2: Output a high-frequency pulse signal at IO2, set IO3 and IO1 to output low level, and use ADC2 and ADC3 to detect the amplitude of the received signal. If no signal is received at either ADC3 or ADC1, then coil RZ2 is open-circuited; if the signal amplitude received at ADC3 is significantly increased, then coils RZ2 and RZ3 are short-circuited; if the signal amplitude received at ADC1 is significantly increased, then coils RZ2 and RZ1 are short-circuited. Step 3: Output a high-frequency pulse signal at IO3, set IO1 and IO2 to low level, and use ADC3 and ADC1 to detect the amplitude of the received signal. If no signal is received at either ADC1 or ADC2, then coil RZ3 is open-circuited; if the signal amplitude received at ADC1 is significantly increased, then coil RZ3 and coil RZ1 are short-circuited; if the signal amplitude received at ADC2 is significantly increased, then coil RZ3 and coil RZ2 are short-circuited.
3. The pre-protection motor control method according to claim 1, characterized in that, The detection results collected by the controller (100) each time are stored in the storage unit. The storage unit of the controller (100) will always record a certain number of recent data for comparison. The newly detected data is compared with the old data to determine whether the trend of change is consistent and whether the variable is within the normal range.
4. The pre-protection motor control method according to claim 3, characterized in that, The controller (100) calculates the average value of the detection results in the storage unit.
5. The pre-protection motor control method according to claim 1, characterized in that, Also includes: Step A: The controller (100) puts the three-phase motor (300) into an independent state through the motor control circuit (400), and controls the relay module (200) to connect the pre-detection circuit (500) to the three-phase motor (300); Step B: A high-frequency pulse signal is output from IO1, and the integrated voltage is detected by ADC2 and ADC3 to obtain a set of detection data; a high-frequency pulse signal is output from IO2, and the integrated voltage is detected by ADC1 and ADC3 to obtain a set of detection data; a high-frequency pulse signal is output from IO3, and the integrated voltage is detected by ADC1 and ADC2 to obtain a set of detection data. Step C: Filter or average the detection data to obtain the final detection data; Step D: Determine whether the motor has a short circuit or open circuit based on the test results data, and compare the test results with historical data. If the change is not significant, set a flag and drive the motor normally. If there is a short circuit or open circuit or a large difference, set an alarm. Step E: After the test is completed, the control relay module (200) disconnects the pre-test circuit (500) from the three-phase motor (300), and the controller (100) resumes operation of the three-phase motor (300) through the motor control circuit (400).
6. The pre-protection motor control method according to claim 1, characterized in that, The pre-detection circuit (500) includes an input resistor, an integrating resistor, and an integrating capacitor. One end of the input resistor serves as a signal injection terminal (501), and the other end of the input resistor is connected to one end of the integrating resistor and used to connect to a three-phase motor (300). The other end of the integrating resistor is connected to the integrating capacitor and serves as a signal sampling terminal (502). The other end of the integrating capacitor is grounded.
7. The pre-protection motor control method according to claim 1, characterized in that, The pre-detection circuit (500) includes an input circuit, an integrating resistor, an integrating capacitor, and a clamping circuit. The input circuit includes a transistor N2, a resistor R1, and a capacitor C4. The base of transistor N2 is connected to a controller (100) as a signal injection terminal (501). The emitter of transistor N2 is grounded. The collector of transistor N2 is connected to a voltage source through an electronic resistor R1. The collector of transistor N2 is connected to one phase terminal of a three-phase motor (300) through a capacitor C4. One end of the integrating capacitor is used as a signal sampling terminal (502) connected to the clamping circuit and one end of the integrating resistor. The other end of the integrating resistor is used to connect to one phase terminal of the three-phase motor (300), and the other end of the integrating capacitor is grounded.
8. The pre-protection motor control method according to claim 7, characterized in that, The clamping circuit includes diodes D1 and D2. The cathode of diode D1 is connected to the voltage source VCC, and the cathode of diode D1 is connected to the cathode of diode D2 as the clamping voltage terminal. The anode of diode D2 is grounded.