Control circuit with self-adaptive PWM (Pulse Width Modulation) driving and control method

Abstract

The invention discloses a control circuit with self-adaptive PWM (Pulse Width Modulation) driving and a control method. The control circuit comprises a load connected with an AC (Alternating Current) power supply; the MCU controller is connected with an external PWM driving circuit so as to be suitable for receiving a first PWM signal and a second PWM signal of which the high frequency and the low frequency can be dynamically switched; the input end of the silicon controlled switch circuit is connected with the first pin of the MCU controller, and the output end of the silicon controlled switch circuit is connected with a load; the input end of the relay switch circuit is connected with the second pin of the MCU controller, the output end of the relay switch circuit is connected with the load and the output end of the silicon controlled rectifier switch circuit, and the MCU controller adjusts the current PWM value according to the first PWM signal and the second PWM signal. And then actions of the silicon-controlled switching circuit and the relay switching circuit are controlled according to the on-off of the load so as to realize soft start or soft close. The problem that oil stains inside and outside the range hood are difficult to collect can be effectively solved, so that the use experience of a user is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of household appliances, and in particular to a control circuit and a control method with adaptive PWM drive. Background Art

[0002] In the market, high-voltage (220VAC) load drivers generally use single relay control circuits to achieve load switching. The simple high and low level (0 / 1) driving algorithm leads to a single control process, and the instantaneous current of the switch is too large, which generates sparks and shortens the service life of the relay. Due to the limitations of technological advancement, innovation and improvement of this part of the application are often ignored, which directly leads to objective phenomena such as low product reliability, high development process costs, and reduced brand quality. Summary of the invention

[0003] The present invention aims to solve at least one of the problems existing in the existing related technologies to a certain extent. To this end, the present invention proposes a control circuit with adaptive PWM drive, which has a reasonable design and realizes adaptive PWM drive adjustment control signal through dynamic cruise circuit state, thereby realizing multi-dimensional soft start or shutdown.

[0004] In addition, the present invention also proposes a control method with adaptive PWM drive, which is simple and feasible. By adopting a combined alternating staggered control algorithm, sparks in the load switching process can be eliminated, thereby extending the service life of the product.

[0005] The first objective is achieved through the following technical solutions:

[0006] A control circuit with adaptive PWM drive, comprising:

[0007] Loads connected to the AC power supply;

[0008] An MCU controller, the MCU controller is connected to an external PWM driving circuit and is suitable for receiving a first PWM signal and a second PWM signal with high and low frequencies that can be dynamically switched;

[0009] A thyristor switch circuit, wherein an input end of the thyristor switch circuit is connected to the first pin of the MCU controller, and an output end of the thyristor switch circuit is connected to the load;

[0010] A relay switch circuit, wherein the input end of the relay switch circuit is connected to the second pin of the MCU controller, and the output end thereof is respectively connected to the load and the output end of the thyristor switch circuit, the MCU controller adjusts the current PWM value according to the first PWM signal and the second PWM signal, and then controls the actions of the thyristor switch circuit and the relay switch circuit according to the switch of the load to achieve soft start or soft shutdown.

[0011] In some embodiments, the thyristor switching circuit includes a first resistor, a thyristor, and a second resistor, wherein the first pin of the MCU controller is respectively connected to one end of the first resistor, the first pin of the thyristor, and the load, the other end of the first resistor is connected to the live wire of the AC power supply through the second resistor, the second pin of the thyristor is connected to a common node between the first resistor and the second resistor, and the third pin of the thyristor is connected to the live wire of the AC power supply.

[0012] In some embodiments, the relay switch circuit includes a diode and a relay, wherein the second pin of the MCU controller is respectively connected to the anode of the diode and one end of the coil of the relay, the cathode of the diode and the other end of the coil of the relay are respectively connected to an external power supply, one end of the switch of the relay is connected to the live wire of the AC power supply, and the other end of the switch of the relay is respectively connected to the load, the thyristor switch circuit, and the first pin of the MCU controller.

[0013] The above second purpose is achieved through the following technical solutions:

[0014] A control method with adaptive PWM drive, further comprising a control circuit as described in any one of the above embodiments, wherein the PWM adaptive control method comprises the following steps:

[0015] The duty cycle values ​​of the first PWM signal and the second PWM signal are set according to the initial duty cycle values, the frequency values ​​of the two are set according to the initial frequency values, and the voltage values ​​of the first PWM signal and the second PWM signal are collected;

[0016] Within a preset acquisition period, averaging is performed on a plurality of first high-level signal values ​​acquired when the first PWM signal is at a high level and a plurality of first low-level signal values ​​acquired when the first PWM signal is at a low level, respectively, to obtain an average value of the plurality of first high-level signal values ​​and an average value of the plurality of first low-level signal values; and averaging is performed on a plurality of second high-level signal values ​​acquired when the second PWM signal is at a high level and a plurality of second low-level signal values ​​acquired when the second PWM signal is at a low level, respectively, to obtain an average value of the plurality of second high-level signal values ​​and an average value of the plurality of second low-level signal values;

[0017] Determine whether an average of the first high-level signal values ​​and an average of the second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the first low-level signal values ​​and an average of the second low-level signal values ​​are respectively greater than a preset second voltage value, and determine whether to adjust the duty cycle values ​​of the first PWM signal and the second PWM signal according to the determination result;

[0018] Until the PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value;

[0019] According to the switching action of the load, soft start or soft shutdown is achieved by controlling the switching of the relay and / or the thyristor.

[0020] In some embodiments, the step of controlling the switching of the relay and / or the thyristor to achieve soft start or soft shutdown according to the switching action of the load includes:

[0021] When the load is turned on, the duty cycle of the first PWM signal is set to 0 to close the relay, and the duty cycle of the second PWM signal is set to 1 to turn on the thyristor, so that the load can achieve high voltage and high current soft start protection;

[0022] After the conduction time of the thyristor reaches a preset conduction time, the duty cycle of the first PWM signal is set to 1 to turn on the relay, and then the first PWM signal is controlled to maintain the current duty cycle value to work;

[0023] After the on-time of the relay reaches the preset on-time, the duty cycle of the second PWM signal is set to 0 to turn off the thyristor, thereby achieving soft start.

[0024] In some embodiments, the step of controlling the switching of the relay and / or the thyristor to achieve soft start or soft shutdown according to the switching action of the load further includes:

[0025] When the load is turned off, the first PWM signal duty cycle is set to 1 to turn on the relay, and the second PWM signal duty cycle is set to 1 to turn on the thyristor;

[0026] After the conduction time of the thyristor reaches a preset conduction time, the duty cycle of the first PWM signal is set to 0 to turn off the relay, so that the load can achieve high voltage and high current soft-off protection;

[0027] Once again, until the conduction time of the thyristor reaches the preset conduction time, the duty cycle of the second PWM signal is set to 0 to turn off the thyristor, thereby achieving soft closing.

[0028] In some embodiments, the step of determining whether an average of the first high-level signal values ​​and an average of the second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the first low-level signal values ​​and an average of the second low-level signal values ​​are respectively greater than a preset second voltage value, and determining whether to adjust the duty cycle values ​​of the first PWM signal and the second PWM signal according to the determination result comprises:

[0029] Determine whether an average of the first high-level signal values ​​and an average of the second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the first low-level signal values ​​and an average of the second low-level signal values ​​are respectively greater than a preset second voltage value;

[0030] If yes, it is determined that the PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value;

[0031] If not, it is determined that the PWM drive circuit cannot complete normal charging and discharging operations according to the current duty cycle value.

[0032] In some implementations, if not, the steps after determining that the PWM drive circuit cannot complete normal charging and discharging operations according to the current duty cycle value include:

[0033] The duty cycle values ​​of the first PWM signal and the second PWM signal are increased according to a preset duty cycle adjustment value.

[0034] In some implementations, the step of increasing the duty cycle values ​​of the first PWM signal and the second PWM signal according to the preset duty cycle adjustment value includes:

[0035] In the next preset acquisition cycle, the multiple first high-level signal values, the multiple first low-level signal values, the multiple second high-level signal values, and the multiple second low-level signal values ​​collected again are averaged to obtain the mean value of the multiple first high-level signal values, the mean value of the multiple first low-level signal values, the mean value of the multiple second high-level signal values, and the mean value of the multiple second low-level signal values;

[0036] determining again whether an average of the first high-level signal values ​​and an average of the second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the first low-level signal values ​​and an average of the second low-level signal values ​​are respectively greater than a preset second voltage value, and determining whether to adjust the duty cycle values ​​of the first PWM signal and the second PWM signal according to the determination result;

[0037] Until the PWM driving circuit can complete normal charging and discharging work according to the current duty cycle value.

[0038] In some implementations, the initial duty cycle value is 50%, and / or the initial frequency value is 16Khz.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] 1. The present invention has an adaptive PWM driven control circuit, which is reasonably designed and realizes adaptive PWM drive adjustment control signal through dynamic cruise circuit state, thereby achieving multi-dimensional soft start or shutdown.

[0041] 2. The present invention has an adaptive PWM drive control method, which is simple and feasible. By adopting a combined alternating staggered control algorithm, sparks during load switching can be eliminated, thereby extending the service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 is a circuit schematic diagram of a control circuit in an embodiment of the present invention;

[0044] Figure 2 It is a flow chart of the control method in the embodiment of the present invention. DETAILED DESCRIPTION

[0045] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in combination with the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, but not all of the embodiments. The components of the embodiment of the present invention can be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the technical solution claimed for protection of the present invention.

[0047] Embodiment 1:

[0048] like Figure 1 As shown, this embodiment provides a control circuit with adaptive PWM drive, including:

[0049] A load 4 connected to an AC power source;

[0050] An MCU controller 1, the MCU controller 1 is connected to an external PWM driving circuit to receive a first PWM signal and a second PWM signal with high and low frequencies that can be dynamically switched;

[0051] A thyristor switch circuit 2, wherein an input end of the thyristor switch circuit 2 is connected to a first pin of the MCU controller 1, and an output end of the thyristor switch circuit 2 is connected to a load 4;

[0052] Relay switch circuit 3, the input end of the relay switch circuit 3 is connected to the second pin of the MCU controller 1, and the output end thereof is respectively connected to the load 4 and the output end of the thyristor switch circuit 2. The MCU controller 1 adjusts the current PWM value according to the first PWM signal and the second PWM signal, and then controls the actions of the thyristor switch circuit 2 and the relay switch circuit 3 according to the switch of the load 4 to achieve soft start or soft shutdown.

[0053] In this embodiment, the MCU controller 1 is connected to the external PWM drive circuit to be suitable for receiving the first PWM signal and the second PWM signal that can be dynamically switched between high and low frequencies. The first pin of the MCU controller 1 is connected to the load 4 through the thyristor switch circuit 2, and the second pin of the MCU controller 1 is connected to the load 4 through the relay switch circuit 3. Since the power supply end of the load 4 is connected to the neutral line of the AC power supply, and at the same time, the power supply end of the thyristor switch circuit 2 and the power supply end of the relay switch circuit 3 are respectively connected to the live line of the AC power supply, the MCU controller 1 determines whether the external PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value according to the first PWM signal and the second PWM signal, thereby realizing the dynamic cruise circuit state PWM adjustment control signal until P After the WM driving circuit can complete the normal charging and discharging work according to the current duty cycle value, when the load 4 is turned on, the thyristor switch circuit 2 is first turned on, and then the relay switch circuit 3 is turned on to shunt the current. After the two have worked for a certain period of time, the thyristor switch circuit 2 is disconnected to keep the relay switch circuit 3 running, thereby realizing soft starting, or when the load 4 is turned off, since the relay switch circuit 3 is in normal operating state, the thyristor switch circuit 2 is first turned on, and then the relay switch circuit 3 is turned off. After the thyristor switch circuit 2 is disconnected for a certain period of time, the thyristor switch circuit 2 is finally turned off, thereby realizing soft closing. The design is reasonable, and the adaptive PWM drive adjustment control signal is realized through the dynamic cruise circuit state, thereby realizing multi-dimensional soft starting or closing.

[0054] Furthermore, the thyristor switch circuit 2 includes a first resistor R3, a thyristor Q2 and a second resistor R2, wherein the first pin of the MCU controller 1 is respectively connected to one end of the first resistor R3, the first pin of the thyristor Q2, and the load 4, the other end of the first resistor R3 is connected to the live wire of the AC power supply through the second resistor R2, the second pin of the thyristor Q2 is connected to the common node between the first resistor R3 and the second resistor R2, and the third pin of the thyristor Q2 is connected to the live wire of the AC power supply.

[0055] Specifically, the relay switch circuit 3 includes a diode D1 and a relay REL1, wherein the second pin of the MCU controller 1 is respectively connected to the anode of the diode D1 and one end of the coil of the relay REL1, the cathode of the diode D1 and the other end of the coil of the relay REL1 are respectively connected to an external power supply, one end of the switch of the relay REL1 is connected to the live wire of the AC power supply, and the other end of the switch of the relay REL1 is respectively connected to the load 4, the thyristor switch circuit 2, and the first pin of the MCU controller 1.

[0056] In this embodiment, since the relay REL1 is arranged corresponding to the on-off switch K1, the relay REL1 controls the on-off switch K1 through magnetic induction, that is, the relay REL1 generates magnetic force when it is energized, and the on-off switch K1 can be controlled to be on or off through the magnetic force.

[0057] In this embodiment, until the PWM drive circuit can complete the normal charging and discharging work according to the current duty cycle value, then, when the load 4 is turned on, since the current is relatively large at the beginning, in order to avoid the spark phenomenon caused by the instantaneous excessive current, the thyristor Q2 is first turned on, thereby realizing the soft start protection of the load 4 with high voltage and high current. After the thyristor Q2 has worked for a certain period of time, the relay REL1 is then turned on to shunt the current. After the relay REL1 and the thyristor Q2 have both worked for a certain period of time, the jitter phenomenon caused by the relay REL1 when the on-off switch K1 is attracted is avoided. Then the thyristor Q2 is disconnected so that the current is completely conducted by the relay REL1. In this way, the current can be transferred from the thyristor Q2 to the relay REL1 for conduction. Since the resistance is relatively small at this time, and the thyristor Q2 is an electronic switch to avoid Sparks are generated, but the resistance of the thyristor Q2 is large. Therefore, by maintaining the on state of relay REL1 so that the current is completely conducted by relay REL1, the power consumption of the circuit is smaller and more reliable, thereby realizing soft starting, that is, realizing multi-dimensional soft starting of relay REL1; or when closing load 4, since relay REL1 is in normal operating state, relay REL1 cannot be quickly cut off at this time to avoid instantaneous arcing during closing and causing sparking. Therefore, first turn on the thyristor Q2, and then turn off the relay REL1. When the thyristor Q2 is disconnected for a certain period of time, the current can be completely transferred from relay REL1 to the thyristor Q2 for conduction, and finally the thyristor Q2 is turned off to achieve the purpose of completely closing the load 4, thereby realizing soft closing, that is, realizing multi-dimensional soft closing of relay REL1.

[0058] Embodiment 2:

[0059] like Figure 2 As shown, the present embodiment provides a control method with adaptive PWM drive, which is applied to any adaptive PWM drive control circuit as described in the first embodiment, and determines whether the external PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value according to the first PWM signal and the second PWM signal, thereby realizing the dynamic cruise circuit state PWM adjustment control signal, until the PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value, and then through the switch of the load, the switch of the relay and / or the thyristor is controlled to realize soft start or soft shutdown. The method is simple and feasible. By adopting a combined alternating staggered control algorithm, the spark in the load switching process can be eliminated, thereby extending the service life of the product.

[0060] The PWM adaptive control method in this embodiment includes the following steps:

[0061] Step S101, setting the duty cycle values ​​of the first PWM signal and the second PWM signal according to the initial duty cycle values, setting the frequency values ​​of the two according to the initial frequency values, and collecting the voltage values ​​of the first PWM signal and the second PWM signal.

[0062] In this embodiment, the initial duty cycle value is 50%, and / or the initial frequency value is 16Khz.

[0063] Step S102: within a preset acquisition period, averaging the multiple first high-level signal values ​​collected when the first PWM signal is at a high level and the multiple first low-level signal values ​​collected when the first PWM signal is at a low level to obtain the mean of the multiple first high-level signal values ​​and the mean of the multiple first low-level signal values; and averaging the multiple second high-level signal values ​​collected when the second PWM signal is at a high level and the multiple second low-level signal values ​​collected when the second PWM signal is at a low level to obtain the mean of the multiple second high-level signal values ​​and the mean of the multiple second low-level signal values.

[0064] Step S103, determining whether an average of the plurality of first high-level signal values ​​and an average of the plurality of second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the plurality of first low-level signal values ​​and an average of the plurality of second low-level signal values ​​are respectively greater than a preset second voltage value, and determining whether to adjust the duty cycle values ​​of the first PWM signal and the second PWM signal according to the determination results.

[0065] In this embodiment, the step of determining whether the average of the plurality of first high-level signal values ​​and the average of the plurality of second high-level signal values ​​are respectively greater than a preset first voltage value, and whether the average of the plurality of first low-level signal values ​​and the average of the plurality of second low-level signal values ​​are respectively greater than a preset second voltage value, and determining whether to adjust the duty cycle values ​​of the first PWM signal and the second PWM signal according to the determination result includes:

[0066] Determine whether an average of the plurality of first high-level signal values ​​and an average of the plurality of second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the plurality of first low-level signal values ​​and an average of the plurality of second low-level signal values ​​are respectively greater than a preset second voltage value;

[0067] If so, it is determined that the PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value;

[0068] If not, it is determined that the PWM drive circuit cannot complete normal charging and discharging work according to the current duty cycle value.

[0069] In this embodiment, the preset first voltage value is preferably 4V, and the preset second voltage value is preferably 0.7V.

[0070] Preferably, if not, the steps after determining that the PWM drive circuit cannot complete normal charging and discharging work according to the current duty cycle value include:

[0071] The duty cycle values ​​of the first PWM signal and the second PWM signal are increased according to the preset duty cycle adjustment value.

[0072] In addition, the steps after increasing the duty cycle values ​​of the first PWM signal and the second PWM signal according to the preset duty cycle adjustment value include:

[0073] In the next preset acquisition cycle, the multiple first high-level signal values, the multiple first low-level signal values, the multiple second high-level signal values, and the multiple second low-level signal values ​​collected again are averaged to obtain the mean value of the multiple first high-level signal values, the mean value of the multiple first low-level signal values, the mean value of the multiple second high-level signal values, and the mean value of the multiple second low-level signal values;

[0074] again determining whether an average of the plurality of first high-level signal values ​​and an average of the plurality of second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the plurality of first low-level signal values ​​and an average of the plurality of second low-level signal values ​​are respectively greater than a preset second voltage value, and determining whether to adjust the duty cycle values ​​of the first PWM signal and the second PWM signal according to the determination result;

[0075] Until the PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value.

[0076] Step S104, until the PWM driving circuit can complete normal charging and discharging work according to the current duty cycle value.

[0077] Step S105, according to the switching action of the load, soft start or soft shutdown is achieved by controlling the switching of the relay and / or the thyristor.

[0078] In this embodiment, according to the switching action of the load, the steps of controlling the switching of the relay and / or the thyristor to achieve soft start or soft shutdown include:

[0079] When the load is turned on, the duty cycle of the first PWM signal is set to 0 to close the relay, and the duty cycle of the second PWM signal is set to 1 to turn on the thyristor, so that the load can achieve high voltage and high current soft start protection;

[0080] After the conduction time of the thyristor reaches the preset conduction time, the duty cycle of the first PWM signal is set to 1 to turn on the relay, and then the first PWM signal is controlled to maintain the current duty cycle value to work;

[0081] After the on-time of the relay reaches the preset on-time, the duty cycle of the second PWM signal is set to 0 to turn off the thyristor, thereby achieving soft start.

[0082] In addition, according to the switching action of the load, the step of controlling the switching of the relay and / or the thyristor to achieve soft start or soft shutdown also includes:

[0083] When the load is turned off, the duty cycle of the first PWM signal is set to 1 to turn on the relay, and the duty cycle of the second PWM signal is set to 1 to turn on the thyristor;

[0084] After the conduction time of the thyristor reaches the preset conduction time, the duty cycle of the first PWM signal is set to 0 to turn off the relay, so that the load can achieve soft-off protection of high voltage and high current;

[0085] Once again, until the conduction time of the thyristor reaches the preset conduction time, the duty cycle of the second PWM signal is set to 0 to turn off the thyristor, thereby achieving soft closing.

[0086] In this embodiment, when the load is turned on, since the current is relatively large at the beginning, in order to avoid sparking caused by the instantaneous excessive current, the thyristor is turned on first, thereby realizing the soft start protection of the load high voltage and high current. After the thyristor has worked for a certain period of time, the relay is turned on to shunt the current. After the relay and the thyristor have worked for a certain period of time, the jitter phenomenon caused by the relay when the switch is turned on and off is avoided. Then the thyristor is turned off so that the current is completely conducted by the relay. In this way, the current can be transferred from the thyristor to the relay for conduction. Since the resistance is relatively small at this time, and the thyristor is an electronic switch to avoid sparking, but the electrical resistance of the thyristor is relatively small. The resistance is large, therefore, by maintaining the relay in the on state so that the current is completely conducted by the relay, the power consumption of the circuit is smaller and more reliable, thereby realizing soft starting, that is, realizing multi-dimensional soft starting of the relay; or when closing the load, because the relay is in normal operating state, the relay cannot be quickly cut off at this time to avoid instantaneous arcing when closing and causing sparking. Therefore, the thyristor is turned on first, and then the relay is closed. When the thyristor is disconnected for a certain period of time, the current can be completely transferred from the relay to the thyristor for conduction, and finally the thyristor is turned off to achieve the purpose of completely closing the load, thereby realizing soft closing, that is, realizing multi-dimensional soft closing of the relay.

[0087] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A control circuit with adaptive PWM drive, characterized in that: include: A load (4) connected to an AC power source; An MCU controller (1), the MCU controller (1) being connected to an external PWM drive circuit so as to be adapted to receive a first PWM signal and a second PWM signal with high and low frequencies that can be dynamically switched; A thyristor switch circuit (2), wherein an input end of the thyristor switch circuit (2) is connected to a first pin of the MCU controller (1), and an output end of the thyristor switch circuit (2) is connected to the load (4); A relay switch circuit (3), wherein an input end of the relay switch circuit (3) is connected to a second pin of the MCU controller (1), and an output end thereof is respectively connected to the load (4) and the output end of the thyristor switch circuit (2); the MCU controller (1) adjusts a current PWM value according to the first PWM signal and the second PWM signal, and then controls the actions of the thyristor switch circuit (2) and the relay switch circuit (3) according to the switching of the load (4) to achieve soft start or soft shutdown.

2. A control circuit with adaptive PWM drive according to claim 1, characterized in that: The thyristor switch circuit (2) comprises a first resistor, a thyristor and a second resistor, wherein the first pin of the MCU controller (1) is respectively connected to one end of the first resistor, the first pin of the thyristor and the load (4), the other end of the first resistor is connected to the live wire of the AC power supply through the second resistor, the second pin of the thyristor is connected to a common node between the first resistor and the second resistor, and the third pin of the thyristor is connected to the live wire of the AC power supply.

3. A control circuit with adaptive PWM drive according to claim 2, characterized in that: The relay switch circuit (3) comprises a diode and a relay, wherein the second pin of the MCU controller (1) is respectively connected to the anode of the diode and one end of the coil of the relay, the cathode of the diode and the other end of the coil of the relay are respectively connected to an external power supply, one end of the switch of the relay is connected to the live wire of the AC power supply, and the other end of the switch of the relay is respectively connected to the load (4), the thyristor switch circuit (2), and the first pin of the MCU controller (1).

4. A control method with adaptive PWM drive, characterized in that: Also comprising the control circuit as claimed in claim 3, the PWM adaptive control method comprising the following steps: The duty cycle values ​​of the first PWM signal and the second PWM signal are set according to the initial duty cycle values, the frequency values ​​of the two are set according to the initial frequency values, and the voltage values ​​of the first PWM signal and the second PWM signal are collected; Within a preset acquisition period, averaging is performed on a plurality of first high-level signal values ​​acquired when the first PWM signal is at a high level and a plurality of first low-level signal values ​​acquired when the first PWM signal is at a low level, respectively, to obtain an average value of the plurality of first high-level signal values ​​and an average value of the plurality of first low-level signal values; and averaging is performed on a plurality of second high-level signal values ​​acquired when the second PWM signal is at a high level and a plurality of second low-level signal values ​​acquired when the second PWM signal is at a low level, respectively, to obtain an average value of the plurality of second high-level signal values ​​and an average value of the plurality of second low-level signal values; Determine whether an average of the first high-level signal values ​​and an average of the second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the first low-level signal values ​​and an average of the second low-level signal values ​​are respectively greater than a preset second voltage value, and determine whether to adjust the duty cycle values ​​of the first PWM signal and the second PWM signal according to the determination result; Until the PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value; According to the switching action of the load, soft start or soft shutdown is achieved by controlling the switching of the relay and / or the thyristor.

5. A control method with adaptive PWM drive according to claim 4, characterized in that: The step of controlling the switching of the relay and / or the thyristor to achieve soft start or soft shutdown according to the switching action of the load includes: When the load is turned on, the duty cycle of the first PWM signal is set to 0 to close the relay, and the duty cycle of the second PWM signal is set to 1 to turn on the thyristor, so that the load can achieve high voltage and high current soft start protection; After the conduction time of the thyristor reaches a preset conduction time, the duty cycle of the first PWM signal is set to 1 to turn on the relay, and then the first PWM signal is controlled to maintain the current duty cycle value to work; After the on-time of the relay reaches the preset on-time, the duty cycle of the second PWM signal is set to 0 to turn off the thyristor, thereby achieving soft start.

6. A control method with adaptive PWM drive according to claim 5, characterized in that: The step of controlling the switching of the relay and / or the thyristor to achieve soft start or soft shutdown according to the switching action of the load also includes: When the load is turned off, the first PWM signal duty cycle is set to 1 to turn on the relay, and the second PWM signal duty cycle is set to 1 to turn on the thyristor; After the conduction time of the thyristor reaches a preset conduction time, the duty cycle of the first PWM signal is set to 0 to turn off the relay, so that the load can achieve high voltage and high current soft-off protection; Once again, until the conduction time of the thyristor reaches the preset conduction time, the duty cycle of the second PWM signal is set to 0 to turn off the thyristor, thereby achieving soft closing.

7. The control method with adaptive PWM driving according to claim 4, characterized in that: The step of judging whether an average of the first high-level signal values ​​and an average of the second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the first low-level signal values ​​and an average of the second low-level signal values ​​are respectively greater than a preset second voltage value, and determining whether to adjust the duty cycle values ​​of the first PWM signal and the second PWM signal according to the judgment result comprises: Determine whether an average of the first high-level signal values ​​and an average of the second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the first low-level signal values ​​and an average of the second low-level signal values ​​are respectively greater than a preset second voltage value; If yes, it is determined that the PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value; If not, it is determined that the PWM drive circuit cannot complete normal charging and discharging operations according to the current duty cycle value.

8. A control method with adaptive PWM driving according to claim 7, characterized in that: If not, the steps after determining that the PWM drive circuit cannot complete normal charging and discharging work according to the current duty cycle value include: The duty cycle values ​​of the first PWM signal and the second PWM signal are increased according to a preset duty cycle adjustment value.

9. A control method with adaptive PWM driving according to claim 8, characterized in that: The steps after increasing the duty cycle values ​​of the first PWM signal and the second PWM signal according to the preset duty cycle adjustment value include: In the next preset acquisition cycle, the multiple first high-level signal values, the multiple first low-level signal values, the multiple second high-level signal values, and the multiple second low-level signal values ​​collected again are averaged to obtain the mean value of the multiple first high-level signal values, the mean value of the multiple first low-level signal values, the mean value of the multiple second high-level signal values, and the mean value of the multiple second low-level signal values; determining again whether an average of the first high-level signal values ​​and an average of the second high-level signal values ​​are respectively greater than a preset first voltage value, and whether an average of the first low-level signal values ​​and an average of the second low-level signal values ​​are respectively greater than a preset second voltage value, and determining whether to adjust the duty cycle values ​​of the first PWM signal and the second PWM signal according to the determination result; Until the PWM driving circuit can complete normal charging and discharging work according to the current duty cycle value.

10. The control method with adaptive PWM driving according to claim 4, characterized in that: The initial duty cycle value is 50%, and / or the initial frequency value is 16Khz.

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