Motor rotating speed control method

Abstract

The embodiment of the invention provides a method for controlling the rotating speed of a motor, and the method comprises the steps: obtaining an initial current value and an actual current value of a motor in an idle state and an operation state through a current sampling point in a preset period, so as to obtain a maximum change value and a minimum change value in actual current change values in the preset period; obtaining an effective current change value and a maximum effective current change value of the motor in the preset period based on a difference value between the actual current change value and the minimum change value and a difference value between the maximum change value and the minimum change value; and based on the actual output power of the actual maximum available power of the motor under the actual power output proportion and the power factor, obtaining the rotating speed information of the motor corresponding to the actual output power. The state of the rotating speed adjusting unit is automatically adjusted through the main control chip, and it is ensured that the motor always operates at the optimal working point.

Description

Technical Field

[0001] The present disclosure relates to the technical field of motor control, and in particular to a method for controlling a motor speed. Background Art

[0002] In modern industrial automation, household appliances, transportation and other fields, motors are important power sources, and the accuracy of their speed control directly affects the overall performance and efficiency of the system. Traditional motor speed control methods mainly include the following: Control the motor speed by setting a fixed power supply voltage. This method is simple but inflexible and cannot adapt to complex load changes. Use PWM signals to adjust the input voltage or current of the motor to change the speed. Although PWM control has a high response speed and good dynamic characteristics, it is easy to generate noise at low speeds and has limited adaptability to load changes. Combined with sensors to detect the actual speed of the motor and compare it with the preset target, the drive signal is adjusted through the PID algorithm to achieve the desired speed. However, this solution relies on high-precision sensors, which increases system cost and complexity. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of the present disclosure is to provide a method for controlling the speed of a motor to solve the problems in the related art.

[0004] A first aspect of the present disclosure provides a method for controlling the speed of a motor, wherein the speed of the motor is controlled by a motor control circuit, and the motor control circuit comprises:

[0005] A power interface, comprising: a positive terminal and a negative terminal; the positive terminal of the power interface is coupled to the first terminal of the motor via a speed regulating unit, and the negative terminal of the power interface is coupled to the second terminal of the motor via a switch element;

[0006] A main control chip, comprising a chip adjustment end, a chip control end, a chip feedback end and a current detection end; the chip adjustment end is coupled to a regulation circuit, for receiving the speed information of the motor output by the regulation circuit; the chip control end is coupled to the control end of the speed adjustment unit via a first resistor, for controlling the on / off of the speed adjustment unit according to the speed information; the chip feedback end is coupled to the other end of the speed adjustment unit via a feedback circuit, for detecting the on state of the speed adjustment unit; the current detection end is coupled to the speed adjustment unit via a current detection circuit, and the current detection circuit is coupled to a current sampling point located between the positive terminal and the first end of the motor;

[0007] Wherein, the main control chip applies the control method, including:

[0008] Within a preset period, the initial current value and the actual current value of the motor when it is idle and when it is running are respectively obtained through the current sampling point;

[0009] Obtaining an actual current change value of the motor within the preset period based on the initial current value and the actual current value, so as to obtain a maximum change value and a minimum change value of the actual current change value within the preset period;

[0010] Based on the difference between the actual current change value and the minimum change value, and the difference between the maximum change value and the minimum change value, respectively, an effective current change value and a maximum effective current change value of the motor in a preset cycle are obtained;

[0011] Based on the actual maximum available power of the motor, the actual output power under the actual power output ratio and power factor, and the speed information of the motor corresponding to the actual output power is obtained; wherein the actual power output ratio is the ratio of the effective current change value to the maximum effective current change value.

[0012] In an embodiment of the first aspect, obtaining the initial current value and the actual current value of the motor when it is idle and when it is running through the current sampling point within a preset period includes:

[0013] In the preset period, when the motor is idle, the current value of the motor is collected through the current sampling end to obtain a first maximum current value and a first minimum current value in the preset period, and the initial current value is obtained according to the difference between the first maximum current value and the first minimum current value;

[0014] Within the preset cycle, when the motor is in operation, the current value of the motor is collected through the current sampling end to obtain a second maximum current value and a second minimum current value within the preset cycle, and the actual current value is obtained according to the difference between the second maximum current value and the second minimum current value.

[0015] In an embodiment of the first aspect, an amplification circuit is further provided between the current detection terminal and the current sampling point, and the initial current value and the actual current value of the motor when idle and when running are respectively obtained through the current sampling point within a preset period, including:

[0016] Within the preset period, the current value of the motor in the idle state and the running state is respectively obtained through the current sampling circuit, and output to the amplification circuit through the current sampling point;

[0017] amplifying the collected current value via the amplifying circuit and outputting it to the current detection end;

[0018] In the preset period, the initial current value and the actual current value are obtained according to the difference between the maximum current value and the minimum current value collected and amplified in the idle state and the running state, respectively.

[0019] In an embodiment of the first aspect, the actual output power is a product of the power factor, the actual power output ratio, and the actual maximum available power.

[0020] In an embodiment of the first aspect, obtaining the speed information of the motor corresponding to the actual output power includes:

[0021] Based on the actual output power, a ratio of the actual output power to the maximum power of the motor is obtained, and the speed information of the motor within the preset period is obtained according to the ratio.

[0022] In an embodiment of the first aspect, the current detection circuit includes: a second resistor and a third resistor;

[0023] One end of the second resistor is coupled to the current detection end, the other end of the second resistor is coupled to the positive terminal via the third resistor, and the third resistor is coupled to the first end of the motor via the speed adjustment unit.

[0024] In an embodiment of the first aspect, the regulating circuit includes:

[0025] An adjustable resistor, one end of the adjustable resistor is coupled to a reference power supply, the other end of the adjustable resistor is grounded, the adjustable end of the adjustable resistor is coupled to the chip adjustment end, and the chip adjustment end generates the speed information according to the resistance value of the adjustable resistor.

[0026] In an embodiment of the first aspect, the main control chip further includes a chip power supply terminal, and the chip power supply terminal is coupled to a power supply circuit; the feedback circuit includes:

[0027] A fourth resistor, one end of the fourth resistor is coupled to the output end of the power supply circuit, the other end of the fourth resistor is coupled to the first end of the motor via a fifth resistor, and the voltage dividing point between the fourth resistor and the fifth resistor leads to the chip feedback end.

[0028] In an embodiment of the first aspect, the main control chip further includes a chip power supply terminal, and the chip power supply terminal is coupled to a power supply circuit; the power supply circuit includes at least one of the following elements:

[0029] A voltage zener diode, wherein the anode of the voltage zener diode is coupled to the cathode terminal, and the cathode of the voltage zener diode is coupled to the anode terminal;

[0030] An energy storage capacitor is connected in parallel with the voltage stabilizing diode, the positive electrode of the energy storage capacitor is coupled to the chip power supply terminal, and the negative electrode of the energy storage capacitor is grounded;

[0031] A first diode, wherein an anode of the first diode is coupled to a cathode of the energy storage capacitor, and a cathode of the first diode is coupled to the cathode terminal via a sixth resistor.

[0032] In an embodiment of the first aspect, the speed adjustment unit includes a bidirectional thyristor.

[0033] The beneficial effects of the present invention are as follows: by setting a current sampling point between the power supply interface and the motor, the initial current value and the actual current value in the idle state and the running state of the motor are obtained in real time. Through the application of the main control chip, the state of the speed regulation unit is automatically adjusted to ensure that the motor always runs at the optimal working point, thereby improving the stability and efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A structural block diagram of a motor control circuit in an embodiment of the present disclosure is shown.

[0035] Figure 2 A circuit connection diagram of a motor control circuit in an embodiment of the present disclosure is shown.

[0036] Figure 3 A flow chart showing a method for controlling the speed of a motor in an embodiment of the present disclosure.

[0037] Figure 4 A schematic diagram showing a flow chart of obtaining an initial current value and an actual current value in a method for controlling a motor speed in one embodiment of the present disclosure.

[0038] Figure 5 A schematic diagram showing a flow chart of obtaining an initial current value and an actual current value in a method for controlling a motor speed in another embodiment of the present disclosure. DETAILED DESCRIPTION

[0039] The following is an explanation of the embodiments of the present disclosure by specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the information disclosed by the present disclosure. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in the present disclosure can also be modified or changed in various ways according to different viewpoints and application modules without departing from the spirit of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0040] The following is a detailed description of the embodiments of the present disclosure with reference to the accompanying drawings so that those skilled in the art can easily implement the present disclosure. The present disclosure can be embodied in many different forms and is not limited to the embodiments described herein.

[0041] In the representations of the present disclosure, the reference terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" and the like mean that the specific features, structures, materials or characteristics represented in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. Moreover, the specific features, structures, materials or characteristics represented may be combined in any one or a group of embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples represented in the present disclosure and the features of different embodiments or examples, unless they are mutually contradictory.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the representation of the present disclosure, "a group" means two or more, unless otherwise clearly and specifically defined.

[0043] In order to clearly describe the present disclosure, components not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

[0044] Throughout the specification, when a device is said to be "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" by placing other elements therebetween. In addition, when a device is said to "include" a certain component, unless otherwise stated, it does not exclude other components, but means that other components may be included.

[0045] Although the terms first, second, etc. are used to represent various elements in this article in some examples, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first interface and the second interface, etc. are represented. Moreover, as used in this article, the singular forms "one", "one" and "the" are intended to also include plural forms, unless there is an opposite indication in the context. It should be further understood that the terms "comprising" and "including" indicate the existence of features, steps, operations, elements, modules, projects, kinds, and / or groups, but do not exclude the existence, occurrence or addition of one or a group of other features, steps, operations, elements, modules, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Only when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way, will there be an exception to this definition.

[0046] The technical terms used herein are only used to refer to specific embodiments and are not intended to limit the present disclosure. The singular form used herein also includes the plural form unless the sentence clearly indicates the contrary meaning. The meaning of "including" used in the specification is to specify specific characteristics, regions, integers, steps, operations, elements and / or components, and does not exclude the existence or addition of other characteristics, regions, integers, steps, operations, elements and / or components.

[0047] Although not defined differently, all terms, including technical and scientific terms used herein, have the same meaning as those generally understood by those skilled in the art to which the present disclosure belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with relevant technical literature and the message of the present disclosure, and shall not be overly interpreted as ideal or very formal meanings unless defined.

[0048] The existing control system has a slow response speed to load changes and cannot adjust the working state of the motor in time to cope with sudden load changes. This results in the motor's efficiency and performance being affected in practical applications, especially in scenarios where frequent start and stop are required or load fluctuations are large.

[0049] The first aspect of the present disclosure provides a method for controlling the speed of a motor, wherein the motor controls the speed through a motor control circuit, and a main control chip obtains an initial current value and an actual current value of the motor when it is idle and when it is running through a current sampling point in each preset cycle. This method ensures accurate monitoring of the working state of the motor.

[0050] exist Figure 1In an embodiment, the motor 100 comprises:

[0051] The power interface 200 includes a positive terminal 201 and a negative terminal 202; the positive terminal 201 of the power interface 200 is coupled to the first terminal of the motor 100 via a speed adjustment unit 300, and the negative terminal 202 of the power interface 200 is coupled to the second terminal of the motor 100 via a switch element 400;

[0052] The main control chip 500 includes a chip adjustment terminal 501, a chip control terminal 502, a chip feedback terminal 503 and a current detection terminal 504; the chip adjustment terminal 501 is coupled to a regulation circuit 600, for receiving the speed information of the motor 100 output by the regulation circuit 600; the chip control terminal 502 is coupled to the control terminal of the speed adjustment unit 300 via a first resistor R1, for controlling the on / off of the speed adjustment unit 300 according to the speed information; the chip feedback terminal 503 is coupled to the other end of the speed adjustment unit 300 via a feedback circuit 700, for detecting the conduction state of the speed adjustment unit 300; the current detection terminal 504 is coupled to the speed adjustment unit 300 via a current detection circuit 800, and the current detection circuit 800 is coupled to a current sampling point located between the positive terminal 201 and the first end of the motor 100.

[0053] Specifically, the regulating circuit 600 outputs the speed information that the motor 100 needs to reach according to actual needs, ensuring that the system can flexibly adjust the speed of the motor 100 according to different application scenarios. The regulating circuit 600 outputs the speed information that the motor 100 needs to reach according to actual needs, ensuring that the system can flexibly adjust the speed of the motor 100 according to different application scenarios. At the same time, the main control chip 500 detects the conduction state of the speed regulating unit 300 in real time through the chip feedback terminal 503 to ensure the stable operation of the system.

[0054] Optionally, the current detection circuit 800 includes: a second resistor R2 and a third resistor R3;

[0055] One end of the second resistor R2 is coupled to the current detection end 504 , and the other end of the second resistor R2 is coupled to the positive terminal 201 via the third resistor R3 . The third resistor R3 is coupled to the first end of the motor 100 via the speed adjustment unit 300 .

[0056] Specifically, in some embodiments, when the motor 100 is running, the current flows through the path formed by the second resistor R2 and the third resistor R3. Since the voltage drop across the resistor is proportional to the current, the main control chip 500 can calculate the current of the motor 100 by measuring the voltage difference across the second resistor R2. The main control chip 500 monitors the current of the motor 100 in real time through the current detection terminal 504 to ensure that the motor 100 can operate stably under different load conditions. If an abnormal situation is detected (such as too large or too small current), the main control chip 500 will immediately take measures, such as adjusting the conduction angle of the speed adjustment unit 300 or triggering an alarm to protect the motor 100 and the system from damage. A first capacitor C1 is also provided, which is connected in parallel with the third resistor R3 for filtering.

[0057] When the load driven by the motor 100 increases, in order to overcome the greater resistance to do work, the motor 100 needs to consume more electrical energy, which will cause the current flowing through the motor 100 winding to increase. On the contrary, if the load decreases, the required current will also decrease accordingly. When the load of the motor 100 suddenly increases, due to the lack of an effective power regulation mechanism, the motor speed will drop significantly and may even enter a stalled state. At this time, the current of the motor 100 winding rises sharply, generating a large amount of heat, which may cause damage to the motor 100 and shorten its service life in severe cases. In order to solve the above problems, Figure 3 In an embodiment, a method for controlling the motor speed is provided, and the main control chip 500 applies the control method including:

[0058] Step S1: within a preset period, obtaining the initial current value and the actual current value of the motor 100 when it is idle and when it is running through the current sampling point.

[0059] Specifically, in some embodiments, the initial current value of the motor 100 when it is idle is recorded to provide a comparison benchmark for the current change during subsequent actual operation, so as to eliminate errors. The actual current value reflects the mechanical load borne by the motor 100. When the load increases, the motor 100 needs to consume more electrical energy to overcome the resistance, resulting in an increase in current; conversely, the current decreases when the load decreases. By continuously monitoring the actual current value, the working status of the motor 100 and the changing trend of its load can be understood in a timely manner.

[0060] Optionally, in some embodiments, Figure 4 In the embodiment, obtaining the initial current value and the actual current value of the motor 100 when it is idle and when it is running through the current sampling point within the preset period includes:

[0061] Step S111: Within the preset period, when the motor 100 is idle, the current value of the motor 100 is collected through the current sampling end to obtain a first maximum current value and a first minimum current value within the preset period, and the initial current value is obtained according to the difference between the first maximum current value and the first minimum current value.

[0062] Step S112: Within the preset cycle, when the motor 100 is in operation, the current value of the motor 100 is collected through the current sampling end to obtain a second maximum current value and a second minimum current value within the preset cycle, and the actual current value is obtained according to the difference between the second maximum current value and the second minimum current value.

[0063] Specifically, within a preset cycle, when the motor 100 is in an idle state (i.e., unloaded or lightly loaded), the current value of the motor 100 is continuously collected through the current sampling end. Also within the preset cycle, but at this time the motor 100 is in a running state (i.e., a working state), the current value of the motor 100 is continuously collected through the current sampling end. In the present application, current sampling is achieved through a resistor (commonly referred to as a shunt or sampling resistor). Although this sampling method is simple and low-cost, it is also easily affected by various factors, resulting in errors in the measurement results. Therefore, when calculating the initial current value and the actual current value, the difference between the maximum current value and the minimum current value is used. Within a cycle, the possible fluctuation errors are offset by the maximum and minimum values ​​of the current value, so that the difference is closer to the actual current change. Because the actual current value may not reach 0, a relatively accurate and effective initial current value of the motor in the idle state and the actual current value of the motor in the running state can be obtained by subtracting the actual minimum value from the maximum value.

[0064] Optionally, in another embodiment, considering that the current value directly sampled from the current sampling end is too small and it is difficult to accurately obtain its change, an amplification circuit may be further provided between the current detection end 504 and the current sampling point. Figure 5 In the embodiment, obtaining the initial current value and the actual current value of the motor 100 when it is idle and when it is running through the current sampling point within the preset period includes:

[0065] Step S121: within the preset period, the current value of the motor 100 in the idle state and the running state is obtained through the current sampling circuit, and output to the amplification circuit through the current sampling point.

[0066] Step S122 : amplifying the collected current value via the amplifier circuit and outputting the amplified current value to the current detection terminal 504 .

[0067] Step S123: within the preset period, obtaining the initial current value and the actual current value according to the difference between the maximum current value and the minimum current value collected and amplified in the idle state and the running state, respectively.

[0068] Specifically, Figure 2 As shown in the embodiment, the motor control circuit collects current by resistor sampling, but the original current signal collected by the resistor sampling is usually weak, especially in a low load or idle state. The amplifier circuit can amplify the weak current signal to a level that is easier to handle. In this application, although there is no specific connection diagram of the amplifier circuit, the amplifier circuit also belongs to the protection scope of this application.

[0069] Step S2: obtaining the actual current change value of the motor 100 within the preset period based on the initial current value and the actual current value, so as to obtain the maximum change value and the minimum change value of the actual current change value within the preset period.

[0070] Specifically, in some embodiments, in order to determine the change in the load of the motor 100, it is necessary to calculate the actual current change value from the idle state to the running state. The actual current change value is obtained by calculating the difference between the actual current value and the initial current value, and the initial current value is used as a reference. The change in power is reflected by subtracting the current value in the idle state from the current value in the running state.

[0071] Wherein, in step S3: based on the difference between the actual current change value and the minimum change value, and the difference between the maximum change value and the minimum change value, the effective current change value and the maximum effective current change value of the motor 100 in the preset cycle are obtained.

[0072] Specifically, the difference between the actual current change value and the minimum change value is the effective current change value. By making the difference, the lowest current change effect in the cycle can be removed and the error can be reduced to obtain a more stable reference value. The difference between the maximum change value and the minimum change value is the maximum effective current change value. The maximum effective current change value reflects the maximum current change between the maximum power and minimum power states of the motor 100 in the cycle.

[0073] Step S4: Based on the actual maximum available power of the motor 100, the actual output power under the actual power output ratio and power factor is obtained, and the speed information of the motor 100 corresponding to the actual output power is obtained; wherein the actual power output ratio is the ratio of the effective current change value to the maximum effective current change value.

[0074] Specifically, in some embodiments, the actual maximum available power is the maximum power (e.g., rated power) marked on the motor 100 or the difference between the maximum output power and the minimum power determined during design. The ratio of the effective current change value to the maximum effective current change value reflects the ratio of the power output to the maximum available power under the current working state, and reflects the working state of the motor 100 under different load conditions. The power factor represents the ratio of the actual consumed effective power to the apparent power. By calculating the proportional relationship between the effective current change value and the maximum effective current change value, it is possible to know the actual output power of the current motor 100, wherein the actual output power is the product of the power factor, the actual power output ratio, and the actual maximum available power.

[0075] Optionally, obtaining the speed information of the motor 100 corresponding to the actual output power includes:

[0076] Based on the actual output power, a ratio of the actual output power to the maximum power of the motor 100 is obtained, and the speed information of the motor 100 within the preset period is obtained according to the ratio.

[0077] Specifically, in some embodiments, the speed information includes the conduction time of the motor 100. According to the ratio between the actual output power and the maximum power, it can be known whether the motor 100 has increased the load to determine whether the power output needs to be adjusted. By continuously monitoring and adjusting the actual output power, it can be ensured that the motor 100 stably runs at the required speed to meet the application requirements. At the same time, it prevents the motor 100 from entering a stalled state or overheating, thereby extending the life of the motor 100.

[0078] Optionally, in Figure 2 In an embodiment, the regulating circuit 600 includes:

[0079] An adjustable resistor RV1, one end of the adjustable resistor RV1 is coupled to a reference power supply, the other end of the adjustable resistor RV1 is grounded, the adjustable end of the adjustable resistor RV1 is coupled to the chip adjustment end 501, and the chip adjustment end 501 generates the speed information according to the resistance value of the adjustable resistor RV1.

[0080] Specifically, in some embodiments, the main control chip 500 calculates the current resistance value by reading the voltage difference across the adjustable resistor RV1. According to a preset mapping relationship, the main control chip 500 converts the resistance value into corresponding speed information. The user can manually or automatically adjust the resistance value of the adjustable resistor RV1 to change the speed setting of the motor 100. For example, in manual mode, the user can directly rotate the knob of the adjustable resistor RV1; in automatic mode, the main control chip 500 can automatically adjust the resistance value according to a preset program. Figure 3In the embodiment, a third capacitor C3 is further provided, one end of the third capacitor C3 is coupled to the chip regulating end 501 , the other end of the third capacitor C3 is grounded, and the third capacitor C3 is used for filtering.

[0081] Optionally, in Figure 2 In the embodiment, the main control chip 500 further includes a chip power supply terminal 506, and the chip power supply terminal 506 is coupled to a power supply circuit; the feedback circuit 700 includes:

[0082] A fourth resistor R4, one end of which is coupled to the output end of the power supply circuit, and the other end of which is coupled to the first end of the motor 100 via a fifth resistor R5, and a voltage dividing point between the fourth resistor R4 and the fifth resistor R5 leads to the chip feedback end 503. Optionally, Figure 2 In the embodiment, the speed adjustment unit 300 includes a bidirectional thyristor.

[0083] Specifically, in some embodiments, a bidirectional thyristor is a bidirectionally triggered semiconductor device that can be turned on or off within two half cycles of alternating current. By changing the conduction time (i.e., conduction angle) of the bidirectional thyristor, the effective value of the input voltage of the motor 100 can be adjusted, thereby controlling the speed of the motor 100. The fourth resistor R4 and the fifth resistor R5 constitute a voltage divider circuit for detecting the conduction state of the bidirectional thyristor. When the bidirectional thyristor is turned on, current flows through the fourth resistor R4 and the fifth resistor R5, forming a voltage divider point between them. The main control chip 500 reads the voltage value of the voltage divider point through the chip feedback terminal 503 to determine the actual conduction state of the bidirectional thyristor. The main control chip 500 detects the conduction state of the bidirectional thyristor in real time through the chip feedback terminal 503 to ensure the stable operation of the system. If an abnormal situation is detected (such as the conduction angle deviates from the set value), the main control chip 500 will immediately adjust the control signal to restore the normal conduction state.

[0084] Optionally, in Figure 2 In an embodiment, the power supply circuit 800 includes at least one of the following elements:

[0085] A voltage-stabilizing diode DW1, wherein the anode of the voltage-stabilizing diode DW1 is coupled to the cathode terminal 202, and the cathode of the voltage-stabilizing diode DW1 is coupled to the anode terminal 201;

[0086] An energy storage capacitor CV1 is connected in parallel with the voltage stabilizing diode DW1, the positive electrode of the energy storage capacitor CV1 is coupled to the chip power supply terminal 506, and the negative electrode of the energy storage capacitor CV1 is grounded;

[0087] A first diode D1 , wherein an anode of the first diode D1 is coupled to a cathode of the energy storage capacitor CV1 , and a cathode of the first diode D1 is coupled to the cathode terminal 202 via a sixth resistor R6 .

[0088] Specifically, in some embodiments, the function of the voltage stabilizing diode DW1 is to maintain the power supply voltage within a stable range to prevent voltage fluctuations from affecting the normal operation of the main control chip 500 and other circuit elements. The function of the first diode D1 is to prevent reverse current from flowing into the power supply interface 200 and protect the circuit from damage. The sixth resistor R6 is used to limit the current to ensure the safe operation of the first diode D1. The energy storage capacitor CV1 is charged when the power supply voltage is stable, and is discharged when the power supply voltage drops instantaneously or the power is off for a short time, ensuring that the main control chip 500 obtains a continuous power supply. A second capacitor C2 is also provided, which is connected in parallel with the voltage stabilizing diode DW1 for filtering.

[0089] Optionally, in Figure 2 In the embodiment, the main control chip 500 further includes a protection terminal 505, and the protection terminal 505 is coupled to the switch element 400 via a protection circuit; the protection circuit includes:

[0090] A seventh resistor R7, one end of the seventh resistor R7 is grounded, the other end of the seventh resistor R7 is coupled to the negative terminal 202 via an eighth resistor R8, the protection end 505 is led out between the seventh resistor R7 and the eighth resistor R8, the protection end 505 receives a level signal, and the main control chip 500 determines the on-off state of the switch element 400 based on the level signal being a high level or a high-low level change, so as to set the disconnected switch element 400 to be turned on.

[0091] Specifically, in some embodiments, the seventh resistor R7 and the eighth resistor R8 constitute a voltage divider circuit for detecting the on-off state of the switch element 400. When the switch element 400 is turned on, the protection terminal 505 of the main control chip 500 is led out through the voltage divider point between the seventh resistor R7 and the eighth resistor R8. When the plug is connected to the socket, the main control chip 500 detects the level signal through the protection terminal 505. If a square wave signal is detected, it means that the switch is in the on state. At this time, the main control chip 500 sends a start signal to the speed adjustment unit 300 through the chip control terminal 502 to ensure that the motor 100 will not start immediately to prevent accidental damage. Then, the main control chip 500 waits for the user to manually reconnect the switch to start the motor 100. If a low level or a high level that does not reach the preset voltage value is detected, it means that the switch is in the off state, and the motor 100 is not allowed to be started at this time. Only when the main control chip 500 detects a high level signal that reaches a preset voltage value or more, will the motor 100 be started when the switch element 400 is closed again. This ensures that in any case, the motor 100 will not start until the switch element 400 is confirmed to be properly closed, thereby improving safety. The main function of the protection unit is to prevent the switch from being in the closed state when the plug is plugged in, thereby preventing the motor 100 from operating immediately and injuring people. By detecting the level signal, the main control chip 500 can intelligently determine the state of the switch element 400 to ensure that the motor 100 will not start immediately when the plug is inserted.

[0092] Optionally, in Figure 2 In an embodiment, the protection circuit further includes:

[0093] The fourth capacitor C4 is connected in parallel with the seventh resistor R7 and is used to filter out high-frequency noise.

[0094] The above embodiments are merely illustrative of the principles and effects of the present disclosure, and are not intended to limit the present disclosure. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present disclosure shall still be covered by the protection scope of the present disclosure.

Claims

1. A method for controlling the speed of a motor, characterized in that: The motor is controlled to rotate speed by a motor control circuit, and the motor control circuit comprises: A power interface, comprising: a positive terminal and a negative terminal; the positive terminal of the power interface is coupled to the first terminal of the motor via a speed regulating unit, and the negative terminal of the power interface is coupled to the second terminal of the motor via a switch element; A main control chip, comprising a chip adjustment end, a chip control end, a chip feedback end and a current detection end; the chip adjustment end is coupled to a regulation circuit, for receiving the speed information of the motor output by the regulation circuit; the chip control end is coupled to the control end of the speed adjustment unit via a first resistor, for controlling the on / off of the speed adjustment unit according to the speed information; the chip feedback end is coupled to the other end of the speed adjustment unit via a feedback circuit, for detecting the on state of the speed adjustment unit; the current detection end is coupled to the speed adjustment unit via a current detection circuit, and the current detection circuit is coupled to a current sampling point located between the positive terminal and the first end of the motor; Wherein, the main control chip applies the control method, including: Within a preset period, the initial current value and the actual current value of the motor when it is idle and when it is running are respectively obtained through the current sampling point; Obtaining an actual current change value of the motor within the preset period based on the initial current value and the actual current value, so as to obtain a maximum change value and a minimum change value of the actual current change value within the preset period; Based on the difference between the actual current change value and the minimum change value, and the difference between the maximum change value and the minimum change value, respectively, an effective current change value and a maximum effective current change value of the motor in a preset cycle are obtained; Based on the actual maximum available power of the motor, the actual output power under the actual power output ratio and power factor, and the speed information of the motor corresponding to the actual output power is obtained; wherein the actual power output ratio is the ratio of the effective current change value to the maximum effective current change value.

2. The control method according to claim 1, characterized in that: The obtaining of the initial current value and the actual current value of the motor when the motor is idle and when the motor is running through the current sampling point within the preset period includes: In the preset period, when the motor is idle, the current value of the motor is collected through the current sampling end to obtain a first maximum current value and a first minimum current value in the preset period, and the initial current value is obtained according to the difference between the first maximum current value and the first minimum current value; Within the preset cycle, when the motor is in operation, the current value of the motor is collected through the current sampling end to obtain a second maximum current value and a second minimum current value within the preset cycle, and the actual current value is obtained according to the difference between the second maximum current value and the second minimum current value.

3. The control method according to claim 1, characterized in that: An amplifying circuit is also provided between the current detection terminal and the current sampling point. Then, within a preset period, the initial current value and the actual current value of the motor when idle and when running are obtained through the current sampling point respectively, including: Within the preset period, the current value of the motor in the idle state and the running state is respectively obtained through the current sampling circuit, and output to the amplification circuit through the current sampling point; amplifying the collected current value via the amplifying circuit and outputting it to the current detection end; In the preset period, the initial current value and the actual current value are obtained according to the difference between the maximum current value and the minimum current value collected and amplified in the idle state and the running state, respectively.

4. The control method according to claim 1, characterized in that: The actual output power is the product of the power factor, the actual power output ratio, and the actual maximum available power.

5. The control method according to claim 1, characterized in that: The obtaining of the motor speed information corresponding to the actual output power includes: Based on the actual output power, a ratio of the actual output power to the maximum power of the motor is obtained, and the speed information of the motor within the preset period is obtained according to the ratio.

6. The control method according to claim 1, characterized in that: The current detection circuit comprises: a second resistor and a third resistor; One end of the second resistor is coupled to the current detection end, the other end of the second resistor is coupled to the positive terminal via the third resistor, and the third resistor is coupled to the first end of the motor via the speed adjustment unit.

7. The control method according to claim 1, characterized in that: The regulating circuit comprises: An adjustable resistor, one end of which is coupled to a reference power supply, the other end of which is grounded, the adjustable end of which is coupled to the chip adjustment end, and the chip adjustment end generates the rotation speed information according to the resistance value of the adjustable resistor.

8. The control method according to claim 1, characterized in that: The main control chip further includes a chip power supply terminal, and the chip power supply terminal is coupled to a power supply circuit; The feedback circuit comprises: A fourth resistor, one end of the fourth resistor is coupled to the output end of the power supply circuit, the other end of the fourth resistor is coupled to the first end of the motor via a fifth resistor, and the voltage dividing point between the fourth resistor and the fifth resistor leads to the chip feedback end.

9. The control method according to claim 1, characterized in that: The main control chip further includes a chip power supply terminal, and the chip power supply terminal is coupled to a power supply circuit; the power supply circuit includes at least one of the following components: A voltage zener diode, wherein the anode of the voltage zener diode is coupled to the cathode terminal, and the cathode of the voltage zener diode is coupled to the anode terminal; An energy storage capacitor is connected in parallel with the voltage stabilizing diode, the positive electrode of the energy storage capacitor is coupled to the chip power supply terminal, and the negative electrode of the energy storage capacitor is grounded; A first diode, wherein an anode of the first diode is coupled to a cathode of the energy storage capacitor, and a cathode of the first diode is coupled to the cathode terminal via a sixth resistor.

10. The control method according to claim 1, characterized in that: The speed regulating unit includes a bidirectional thyristor.

Images