A control system and control method for avoiding saturation of an instantaneous filter

Abstract

The application discloses a control system and a control method for avoiding saturation of an instantaneous filter, and the control system comprises a filter circuit, a rectifier circuit, an inverter circuit, an input voltage detection circuit and a control circuit, wherein the control circuit is used for controlling the inverter circuit to output a pulse width modulation signal when the input voltage of the filter circuit is within a preset zero point range. The control system for avoiding saturation of the instantaneous filter can detect the value of the input grid voltage, and only when the grid voltage is within the preset zero point range, the inverter circuit is controlled to output the pulse width modulation signal. Since the value of the grid voltage in the preset zero point range is small, the input grid voltage is low, the diode voltage drop is high, the voltage variation amplitude of the enabled instantaneous Y capacitor is small, and the saturation of the filter and the surge of the ground current can be effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of robot control technology, and more specifically, to a control system that avoids instantaneous filter saturation during enable. Furthermore, this invention also relates to a control method applied to the aforementioned control system. Background Technology

[0002] With the continuous improvement of automation and intelligence in the manufacturing industry, industrial robots have developed rapidly. In the field of processing and manufacturing, the application of industrial robots is becoming more and more mature, and their performance plays a crucial role.

[0003] Multi-axis robots use long, heavy-duty cables between the robot body and the control cabinet. To improve electromagnetic compatibility (EMC), a shielding layer is usually added to the cable. However, this results in a large coupling capacitance between the motor's power line and the shielding layer. This large coupling capacitance places higher demands on the system filter, especially at the moment the system is enabled, when the common-mode current spike is often higher than in steady state. At this time, the filter is prone to saturation. Once the filter is saturated, the ground current will surge, causing the leakage current protection device connected to the robot control system to trip.

[0004] To address the aforementioned issues, existing technologies typically improve the filter's anti-saturation capability by increasing the number of common-mode inductor rings; or by selecting specific models of leakage current circuit breakers (RCCBs) capable of withstanding large ground current spikes. However, increasing the number of common-mode inductor rings increases both the filter's size and cost; furthermore, since existing RCCBs in the field are already standardized, large-scale replacements are difficult.

[0005] In summary, how to avoid instantaneous filter saturation during enable is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a control system that avoids filter saturation at the moment of enable. The system includes an input voltage detection circuit for detecting the voltage value at the input terminal of the filter circuit. When the voltage at the input terminal of the filter circuit is within a preset zero-point range, the control circuit controls the inverter circuit to output a pulse width modulation (PWM) signal to minimize the voltage change amplitude across the Y capacitor in the filter circuit, thereby avoiding ground current spikes caused at the moment of enable and thus preventing filter saturation at the moment of enable.

[0007] Another objective of this invention is to provide a control method for the control system described above that avoids instantaneous filter saturation during enable.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A control system for avoiding instantaneous filter saturation during enable includes a filter circuit, a rectifier circuit, and an inverter circuit connected in sequence, characterized in that it further includes an input voltage detection circuit and a control circuit.

[0010] The output terminal of the inverter circuit is connected to the motor; the input terminal of the input voltage detection circuit is connected to the input terminal of the filter circuit to detect the voltage value at the input terminal of the filter circuit; the output terminal of the input voltage detection circuit is connected to the input terminal of the control circuit, and the output terminal of the control circuit is connected to the inverter circuit.

[0011] The control circuit is used to control the inverter circuit to output a pulse width modulation signal when the input voltage of the filter circuit is within a preset zero range.

[0012] Preferably, the input voltage detection circuit includes an AC optocoupler;

[0013] When the voltage value at the input terminal of the filter circuit is within the preset zero-point range, the AC optocoupler outputs a high level; when the voltage value at the input terminal of the filter circuit is outside the preset zero-point range, the AC optocoupler outputs a low level.

[0014] Preferably, the control circuit includes a control chip. When the control chip receives the high level, it controls the inverter circuit to send a pulse width modulation signal to control the motor to run. When the control chip receives the low level, it controls the motor to maintain its original operating state.

[0015] Preferably, the input voltage detection circuit includes a voltage divider detection circuit, the input terminal of which is connected to the input terminal of the filter circuit, and the output terminal of which is connected to the control circuit.

[0016] Preferably, the voltage divider detection circuit includes a first branch connected to the live wire of the input terminal of the filter circuit and a second branch connected to the neutral wire of the input terminal of the filter circuit, both the first branch and the second branch being connected to the ground wire.

[0017] Preferably, the control circuit includes a voltage acquisition unit and a control unit connected to the voltage acquisition unit;

[0018] The voltage acquisition unit is connected to the voltage divider detection circuit to acquire the voltage at the input terminal of the filter circuit and transmit the acquired voltage value to the control unit.

[0019] The control unit is used to compare the received voltage value with a preset voltage. When the received voltage value is within the preset voltage range, the control unit controls the inverter circuit to send a pulse width modulation signal to control the motor to run. When the received voltage value is outside the preset voltage range, the control unit controls the motor to maintain its original operating state.

[0020] A control method, applied to the control system described in any one of the above claims for avoiding instantaneous filter saturation during enable, comprising:

[0021] The input voltage detection circuit obtains the voltage value at the input terminal of the filter circuit;

[0022] The input voltage detection circuit outputs voltage value information to the control circuit;

[0023] When the input voltage of the filter circuit is within a preset zero range, the control circuit controls the inverter circuit to output a pulse width modulation signal.

[0024] Preferably, the input voltage detection circuit includes an AC optocoupler;

[0025] The input voltage detection circuit outputs voltage value information to the control circuit, including:

[0026] When the voltage value obtained by the input voltage detection circuit is within the preset zero point range, it outputs a high level; when the voltage value obtained by the input voltage detection circuit is outside the preset zero point range, it outputs a low level.

[0027] Preferably, when the input voltage of the filter circuit is within a preset zero range, the control circuit controls the inverter circuit to output a pulse width modulation signal, including:

[0028] When the control circuit receives the high level, it controls the inverter circuit to send a pulse width modulation signal to control the motor to run; when the control chip receives the low level, it controls the motor to maintain its original operating state.

[0029] Preferably, the input voltage detection circuit includes a voltage divider detection circuit.

[0030] The voltage value information refers to the voltage value at the input terminal of the filter circuit.

[0031] In the process of using the control system provided by this invention to avoid instantaneous filter saturation, the grid voltage is input through the input terminal of the filter circuit. Since the input terminal of the input voltage detection circuit is connected to the input terminal of the filter circuit, the grid voltage is also input to the input voltage detection circuit. The input voltage detection circuit detects the grid voltage in real time and transmits the detection result to the control circuit. The control circuit receives the voltage information transmitted by the input voltage detection circuit and controls the inverter circuit to output a pulse width modulation signal when the grid voltage is within the preset zero point range, thereby controlling the motor to operate. When the voltage is outside the preset zero point range, the control circuit controls the inverter circuit not to output a pulse width modulation signal, so that the motor maintains its original rotation state.

[0032] Throughout the entire power grid frequency cycle, the diode voltage drop in the rectifier circuit varies with the input voltage. The higher the power grid input voltage, the smaller the diode voltage drop, resulting in a larger voltage change amplitude across the Y capacitor at the moment of enable, making the filter more prone to saturation. Conversely, the lower the instantaneous power grid voltage, the higher the diode voltage drop, resulting in a smaller voltage change amplitude across the Y capacitor at the moment of enable, making the filter less prone to saturation. The Y capacitor is the capacitor connected to ground in the filter circuit.

[0033] The magnitude of the instantaneous current spike that enables the capacitor is related to the amplitude of the voltage change across the Y capacitor; the larger the amplitude of the voltage change across the Y capacitor, the larger the instantaneous current spike that enables the capacitor, and the smaller the amplitude of the voltage change across the Y capacitor, the smaller the instantaneous current spike that enables the capacitor.

[0034] Compared to existing technologies, the control system in this invention that avoids filter saturation during the enable moment can detect the value of the input grid voltage. Only when the grid voltage is within a preset zero-point range will the inverter circuit output a pulse width modulation signal. Since the grid voltage value within the preset zero-point range is small, the grid input voltage is low, the diode voltage drop is high, and the voltage change amplitude across the Y capacitor during the enable moment is small, which can effectively avoid filter saturation and ground current surge.

[0035] Furthermore, the present invention also provides a control method for the control system described above that avoids instantaneous filter saturation during the enable phase. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] Figure 1This is a schematic diagram of the structure of filter circuits, rectifier circuits, and inverter circuits in the prior art;

[0038] Figure 2 A schematic diagram of a specific embodiment of the control system for avoiding instantaneous saturation of the enable filter provided by the present invention;

[0039] Figure 3 This is a schematic diagram of a specific embodiment of the input voltage detection circuit;

[0040] Figure 4 This is a schematic diagram of a specific embodiment of the input voltage detection circuit (Version 2).

[0041] Figure 5 This is a schematic diagram of the power grid voltage.

[0042] Figure 6 This is a schematic diagram of the output voltage of an AC coupler;

[0043] Figure 7 This is a flowchart illustrating the control method provided by the present invention.

[0044] Figure 1-7 middle:

[0045] 1 is the filter circuit, 2 is the rectifier circuit, 3 is the inverter circuit, 4 is the input voltage detection circuit, 41 is the AC coupler, 42 is the voltage divider detection circuit, 5 is the control circuit, 51 is the control chip, CM is the common mode inductor, CX is the X capacitor, CY1 and CY2 are the Y capacitors, D1, D2, D3, and D4 are the rectifier circuit diodes, COUT is the bus capacitor, Q1, Q2, Q3, Q4, Q5, and Q6 are the IGBTs (Insulated Gate Bipolar Transistors) of the inverter bridge, and CU, CV, and CW are the coupling capacitors between the motor UVW phase lines and ground. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] The core of this invention is to provide a control system that avoids filter saturation during the enable instant. When the input voltage of the filter circuit is within a preset zero range, the control circuit controls the inverter circuit to output a pulse width modulation signal (PWM signal) to minimize the voltage change amplitude across the Y capacitor in the filter circuit, thereby avoiding ground current spikes caused by the enable instant and thus preventing filter saturation during the enable instant.

[0048] Another core aspect of this invention is to provide a control method for the aforementioned control system that avoids instantaneous filter saturation during enable.

[0049] Please refer to Figures 1 to 7 , Figure 1 This is a schematic diagram of the structure of filter circuits, rectifier circuits, and inverter circuits in the prior art; Figure 2 A schematic diagram of a specific embodiment of the control system for avoiding instantaneous saturation of the enable filter provided by the present invention; Figure 3 This is a schematic diagram of a specific embodiment of the input voltage detection circuit; Figure 4 This is a schematic diagram of a specific embodiment of the input voltage detection circuit (Version 2). Figure 5 This is a schematic diagram of the power grid voltage. Figure 6 This is a schematic diagram of the output voltage of an AC coupler; Figure 7 This is a flowchart illustrating the control method provided by the present invention.

[0050] Because industrial robots have long cables connecting the control system to the robot body, there is a significant coupling capacitance between the motor's UVW phase wires and the cable shielding layer. Figure 1 In the common-mode circuit, the common-mode inductor CM carries a larger common-mode voltage due to its larger capacitance and smaller capacitive reactance, which can easily lead to saturation. Furthermore, the common-mode current is unstable during the enable phase, and overshoot often occurs during the transient transition to steady state, meaning the peak current during the transition is greater than the steady-state current. This further exacerbates the saturation of the common-mode inductor. This can result in anything from failing electromagnetic compatibility (EMC) tests to tripping the system's residual current device (RCD), rendering the system inoperable.

[0051] like Figure 1 As shown, CX is the X capacitor, COUT is the bus capacitor, Q1, Q2, Q3, Q4, Q5, and Q6 are all IGBTs (Insulated Gate Bipolar Transistors) of the inverter bridge, and D1, D2, D3, and D4 are diodes of the rectifier circuit. When the L-phase voltage is higher than the N-phase voltage, the upper transistor Q1 of the U-phase is turned on. Then, the common-mode current path when the inverter circuit 3 is working is as follows: from the insulated gate bipolar transistor Q1 through the coupling capacitor Cu, the ground PE, to the filter circuit 1, the rectifier bridge diode D1, and the insulated gate bipolar transistor Q1.

[0052] This specific embodiment discloses a control system to avoid instantaneous filter saturation during enable, including: filter circuit 1, rectifier circuit 2, inverter circuit 3, input voltage detection circuit 4, and control circuit 5, wherein filter circuit 1, rectifier circuit 2, and inverter circuit 3 are connected in sequence.

[0053] The output terminal of inverter circuit 3 is connected to the motor; the input terminal of input voltage detection circuit 4 is connected to the input terminal of filter circuit 1 to detect the voltage value at the input terminal of filter circuit 1; the output terminal of input voltage detection circuit 4 is connected to the input terminal of control circuit 5, and the output terminal of control circuit 5 is connected to inverter circuit 3; control circuit 5 is used to control inverter circuit 3 to output pulse width modulation signal when the input voltage of filter circuit 1 is within a preset zero point range.

[0054] In the process of using the control system for avoiding instantaneous filter saturation provided in this specific embodiment, the grid voltage is input through the input terminal of the filter circuit 1. Since the input terminal of the input voltage detection circuit 4 is connected to the input terminal of the filter circuit 1, the grid voltage is also input to the input voltage detection circuit 4. The input voltage detection circuit 4 detects the grid voltage in real time and transmits the detection result to the control circuit 5. The control circuit 5 receives the voltage information transmitted by the input voltage detection circuit 4 and controls the inverter circuit 3 to output a pulse width modulation signal when the grid voltage is within the preset zero point range, thereby controlling the motor to operate. When the voltage is outside the preset zero point range, the control circuit 5 controls the inverter circuit 3 not to output a pulse width modulation signal, so that the motor maintains its original rotation state.

[0055] Throughout the entire power grid frequency cycle, the diode voltage drop in rectifier circuit 2 varies with the input voltage. The higher the power grid input voltage, the smaller the diode voltage drop, resulting in a larger voltage change amplitude across the Y capacitor at the moment of enable, making the filter more prone to saturation. Conversely, the lower the instantaneous power grid voltage, the higher the diode voltage drop, resulting in a smaller voltage change amplitude across the Y capacitor at the moment of enable, making the filter less prone to saturation. The Y capacitor is the capacitor connected to ground in filter circuit 1.

[0056] The magnitude of the instantaneous current spike that enables the capacitor is related to the amplitude of the voltage change across the Y capacitor; the larger the amplitude of the voltage change across the Y capacitor, the larger the instantaneous current spike that enables the capacitor, and the smaller the amplitude of the voltage change across the Y capacitor, the smaller the instantaneous current spike that enables the capacitor.

[0057] Compared to existing technologies, the control system in this specific embodiment that avoids filter saturation during the enable instant can detect the value of the input grid voltage. Only when the grid voltage is within a preset zero-point range will the inverter circuit 3 output a pulse width modulation signal. Since the grid voltage value within the preset zero-point range is small, the grid input voltage is low, the diode voltage drop is high, and the voltage change amplitude across the Y capacitor during the enable instant is small, which can effectively avoid filter saturation and ground current surge.

[0058] Based on the above embodiments, the input voltage detection circuit 4 can include an AC optocoupler; when the voltage value at the input terminal of the filter circuit 1 is within a preset zero-point range, the AC optocoupler outputs a high level; when the voltage value at the input terminal of the filter circuit 1 is outside the preset zero-point range, the AC optocoupler outputs a low level.

[0059] like Figure 3 As shown, the input terminal of the AC optocoupler is connected to the neutral and live wires of the input terminal of the filter circuit 1, and the output terminal of the AC optocoupler is connected to the control circuit 5. The control circuit 5 can be set as the control chip 51. When the control chip 51 receives a high level, it controls the inverter circuit 3 to send a pulse width modulation signal to control the motor to run. When the control chip 51 receives a low level, it controls the motor to maintain its original running state.

[0060] Alternatively, the AC optocoupler can output a low level when the voltage value at the input terminal of filter circuit 1 is within the preset zero-point range; and output a high level when the voltage value at the input terminal of filter circuit 1 is outside the preset zero-point range. When the control chip 51 receives a low level, it controls the inverter circuit 3 to send a pulse width modulation signal to control the motor to run; when the control chip 51 receives a high level, it controls the inverter circuit 3 not to send a pulse width modulation signal to control the motor to maintain its original operating state.

[0061] Based on the above embodiments, the input voltage detection circuit 4 includes a voltage divider detection circuit 42, the input terminal of which is connected to the input terminal of the filter circuit 1, and the output terminal of which is connected to the control circuit 5.

[0062] like Figure 4 As shown, the voltage divider detection circuit 42 includes a first branch connected to the live wire of the input terminal of the filter circuit 1 and a second branch connected to the neutral wire of the input terminal of the filter circuit 1. Both the first branch and the second branch are connected to the ground wire. The first branch is provided with two resistors in series, and the second branch is provided with two resistors in series. The resistance values ​​of these four resistors are the same. The control circuit 5 is connected between the two resistors in the first branch and between the two resistors in the second branch.

[0063] The control circuit 5 may include a voltage acquisition unit and a control unit connected to the voltage acquisition unit;

[0064] The voltage acquisition unit is connected to the voltage divider detection circuit 42 to acquire the voltage at the input terminal of the filter circuit 1 and transmit the acquired voltage value to the control unit.

[0065] The control unit compares the received voltage value with the preset voltage. When the received voltage value is within the preset voltage range, it controls the inverter circuit 3 to send a pulse width modulation signal to control the motor to run. When the received voltage value is outside the preset voltage range, it controls the motor to maintain its original operating state.

[0066] It should be noted that the preset zero-point range mentioned in this application is the range near the zero value of the grid input voltage, based on the premise that it does not exceed the maximum current during stable operation. The instantaneous value of the grid input voltage at the moment of enabling must not exceed 1 / 2 of the peak value of the grid input voltage. To achieve a smoother effect, the preset zero-point range is generally limited to within 20% of the peak value of the grid voltage. For example, if the grid voltage input value is [-5, 5], the preset zero-point range can be [-1, 1], or other values, depending on the actual situation. Figure 5 The diagram shown illustrates the mains voltage. Since it is alternating current (AC), the voltage value fluctuates over time. Figure 6 The figure shows the voltage at the output terminal of AC coupler 41. When the mains voltage is within the preset zero point range, it can effectively avoid filter saturation and ground current surge; the specific value should be determined according to the actual situation, which will not be elaborated here.

[0067] In addition to the control system described above for avoiding instantaneous filter saturation during enable, this invention also provides a control method applied to the control system for avoiding instantaneous filter saturation during enable disclosed in the above embodiments. The control method includes:

[0068] Step S1: The input voltage detection circuit 4 obtains the voltage value at the input terminal of the filter circuit 1;

[0069] Step S2: The input voltage detection circuit 4 outputs voltage value information to the control circuit 5;

[0070] Step S3: Determine whether the input voltage of filter circuit 1 is within the preset zero point range. If yes, control inverter circuit 3 to output pulse width modulation signal; if no, control inverter circuit 3 not to output pulse width modulation signal.

[0071] When the input voltage detection circuit 4 includes an AC optocoupler, step S2 includes:

[0072] In step S21, when the voltage value obtained by the input voltage detection circuit 4 is within the preset zero point range, a high level is output; when the voltage value obtained by the input voltage detection circuit 4 is outside the preset zero point range, a low level is output.

[0073] Step S3 includes:

[0074] In step S31, when the control circuit 5 receives a high level, it controls the inverter circuit 3 to send a pulse width modulation signal to control the motor to run; when the control chip 51 receives a low level, it controls the motor to maintain its original running state.

[0075] When the input voltage detection circuit 4 includes the voltage divider detection circuit 42,

[0076] The voltage value information is the voltage value at the input terminal of filter circuit 1.

[0077] After receiving the voltage value output by the voltage divider detection circuit 42, the voltage acquisition unit of the control circuit 5 transmits the voltage value to the control unit. The control unit compares the received voltage value with the preset voltage. When the received voltage value is within the preset voltage range, the inverter circuit 3 is controlled to send a pulse width modulation signal to control the motor to run. When the received voltage value is outside the preset voltage range, the motor is controlled to maintain its original operating state.

[0078] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Any combination of all embodiments provided by this invention is within the scope of protection of this invention and will not be elaborated upon here.

[0079] The control system and method for avoiding instantaneous filter saturation during enable, provided by this invention, have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A control system for avoiding saturation of an instantaneous filter, comprising a filter circuit (1), a rectifier circuit (2) and an inverter circuit (3) connected in series, characterized in that, The input voltage detection circuit (4) and the control circuit (5) are further included; The output end of the inverter circuit (3) is connected with the motor; the input end of the input voltage detection circuit (4) is connected with the input end of the filter circuit (1) to detect the voltage value of the input end of the filter circuit (1); the output end of the input voltage detection circuit (4) is connected with the input end of the control circuit (5), and the output end of the control circuit (5) is connected with the inverter circuit (3); The control circuit (5) is used for controlling the inverter circuit (3) to output a pulse width modulation signal when the voltage of the input end of the filter circuit (1) is within a preset zero point range.

2. The control system to avoid enabling the instantaneous filter saturation of claim 1, wherein, The input voltage detection circuit (4) comprises an alternating current optical coupler; When the voltage value of the input end of the filter circuit (1) is within the preset zero point range, the alternating current optical coupler outputs a high level; when the voltage value of the input end of the filter circuit (1) is outside the preset zero point range, the alternating current optical coupler outputs a low level.

3. The control system to avoid enabling the instantaneous filter saturation of claim 2, wherein, The control circuit (5) comprises a control chip (51), the control chip (51) controls the inverter circuit (3) to output a pulse width modulation signal and controls the motor to operate when the high level is received; the control chip (51) controls the motor to maintain the original operating state when the low level is received; The input voltage detection circuit (4) comprises a voltage division detection circuit (42), the input end of the voltage division detection circuit (42) is connected with the input end of the filter circuit (1), and the output end of the voltage division detection circuit (42) is connected with the control circuit (5).

4. The control system to avoid enabling the instantaneous filter saturation of claim 3, wherein, The voltage division detection circuit (42) comprises a first branch connected with a live wire of the input end of the filter circuit (1) and a second branch connected with a zero line of the input end of the filter circuit (1), and the first branch and the second branch are both connected with a ground wire.

5. The control system to avoid enabling the instantaneous filter saturation of claim 3, wherein, The control circuit (5) comprises a voltage acquisition unit and a control unit connected with the voltage acquisition unit; The voltage acquisition unit is connected with the voltage division detection circuit (42) to acquire the voltage of the input end of the filter circuit (1) and transmit the acquired voltage value to the control unit; The control unit is used for comparing the received voltage value with a preset voltage, when the received voltage value is within the preset voltage range, the inverter circuit (3) is controlled to output a pulse width modulation signal to control the motor to operate, and when the received voltage value is outside the preset voltage range, the motor is controlled to maintain the original operating state.

6. A control method characterized by, The control system for avoiding enabling the instantaneous filter to be saturated is applied to any one of claims 1-5, comprising: The input voltage detection circuit (4) acquires the voltage value of the input end of the filter circuit (1); The input voltage detection circuit (4) outputs the voltage value information to the control circuit (5); The control circuit (5) controls the inverter circuit (3) to output a pulse width modulation signal when the voltage of the input end of the filter circuit (1) is within a preset zero point range.

7. The control method according to claim 6, characterized by The input voltage detection circuit (4) comprises an AC optical coupler; The input voltage detection circuit (4) outputs voltage value information to the control circuit (5), comprising: When the voltage value obtained by the input voltage detection circuit (4) is within a preset zero point range, a high level is output; when the voltage value obtained by the input voltage detection circuit (4) is outside the preset zero point range, a low level is output.

8. The control method according to claim 7, characterized by, The control circuit (5) controls the inverter circuit (3) to output a pulse width modulation signal when the input voltage of the filter circuit (1) is within a preset zero point range, comprising: When the control circuit (5) receives the high level, the inverter circuit (3) is controlled to send a pulse width modulation signal to control the motor to operate; when the control chip (51) receives the low level, the motor is controlled to maintain the original operating state.

9. The control method according to claim 6, characterized by, The input voltage detection circuit (4) comprises a voltage division detection circuit (42), The voltage value information is the voltage value of the input end of the filter circuit (1).

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