Control circuit with self-adaptive PWM (Pulse Width Modulation) drive

Abstract

The utility model discloses a control circuit with adaptive PWM drive. The control circuit comprises a load connected with an AC 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 utility model relates to domestic appliance technical field especially relates to a control circuit with adaptive PWM drive. BACKGROUND

[0002] The single relay control circuit is generally adopted to realize the switching of load on the market about high voltage (220VAC) load drive, and the simple high and low level (0 / 1) driving algorithm leads to single control process, too large switching transient current and short service life of relay due to spark, and the like, and the innovation improvement of the part application is often neglected due to the limitation of technical improvement, which directly leads to the objective phenomena such as low product reliability, high development process cost and brand quality decline. SUMMARY

[0003] The utility model aims at at least in a certain extent solve one of the problems existing in prior art related, and for this purpose, the utility model provides a control circuit with adaptive PWM drive, and its design is reasonable, and the adaptive PWM drive adjustment control signal is realized through the dynamic cruise circuit state, so as to realize multidimensional soft start or shutdown.

[0004] The above-mentioned purpose is realized by the following technical schemes:

[0005] A control circuit with adaptive PWM drive comprises:

[0006] Load connected with AC power supply;

[0007] MCU controller, which is connected with external PWM drive circuit to be adapted to receive first PWM signal and second PWM signal of high and low frequency dynamic switching;

[0008] Silicon controlled switch circuit, the input end of the silicon controlled switch circuit is connected with the first pin of the MCU controller, and the output end is connected with the load;

[0009] Relay switch circuit, the input end of the relay switch circuit is connected with the second pin of the MCU controller, and the output end is connected with the load, the output end of the silicon controlled switch circuit respectively, the MCU controller adjusts the current PWM value according to the first PWM signal and the second PWM signal, and then controls the action of the silicon controlled switch circuit and the relay switch circuit according to the switching of the load to realize soft start or soft shutdown.

[0010] In some embodiments, the silicon controlled switch circuit comprises a first resistor, a silicon controlled and a second resistor, wherein the first pin of the MCU controller is connected with one end of the first resistor, the first pin of the silicon controlled, and the load respectively, the other end of the first resistor is connected with the live wire of the AC power source through the second resistor, the second pin of the silicon controlled is connected with the common node between the first resistor and the second resistor, and the third pin of the silicon controlled is connected with the live wire of the AC power source.

[0011] In some embodiments, the relay switch circuit comprises a diode and a relay, wherein the second pin of the MCU controller is connected with the anode of the diode and one end of the coil of the relay respectively, the cathode of the diode and the other end of the coil of the relay are connected with the external power source respectively, one end of the switch of the relay is connected with the live wire of the AC power source, and the other end of the switch of the relay is connected with the load, the silicon controlled switch circuit and the first pin of the MCU controller respectively.

[0012] Compared with the prior art, the utility model at least has following beneficial effects:

[0013] 1、 the utility model has the control circuit of adaptive PWM drive, reasonable in design, realizes adaptive PWM drive regulation control signal through dynamic cruise circuit state, so as to realize multidimensional soft start or close.

[0014] 2、 the utility model has the control method of adaptive PWM drive, and its method is simple and feasible, so as to eliminate the spark in the load switch process by adopting combined alternate staggered control algorithm, thereby prolonging the service life of product. DRAWINGS

[0015] In order to more clearly illustrate the specific embodiments of the utility model or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced as follows, and obviously, the drawings in the following description are some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0016] Figure 1 It is the circuit schematic of the control circuit in the utility model embodiment;

[0017] Figure 2 It is the flow chart of the control method in the utility model embodiment. SPECIFIC EMBODIMENTS

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions in the embodiments of this utility model will be clearly and completely described below in conjunction with the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model can be arranged and designed in various different configurations.

[0019] 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 claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of the claimed invention.

[0020] Example 1:

[0021] like Figure 1 As shown, this embodiment provides a control circuit with adaptive PWM drive, including:

[0022] 4. Load connected to AC power supply;

[0023] MCU controller 1 is connected to an external PWM drive circuit to receive a first PWM signal and a second PWM signal that can be dynamically switched between high and low frequencies.

[0024] The input terminal of the thyristor switch circuit 2 is connected to the first pin of the MCU controller 1, and its output terminal is connected to the load 4.

[0025] The relay switch circuit 3 has its input terminal connected to the second pin of the MCU controller 1, and its output terminal connected to the load 4 and the output terminal of the thyristor switch circuit 2, respectively. The MCU controller 1 adjusts the current PWM value according to the first PWM signal and the second PWM signal, and then controls the action 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 stop.

[0026] In the embodiment, the MCU controller 1 is connected with the external PWM drive circuit to adapt to receive the first PWM signal and the second PWM signal which can be dynamically switched in high and low frequencies, the first pin of the MCU controller 1 is connected with the load 4 through the thyristor switching circuit 2, the second pin of the MCU controller 1 is connected with the load 4 through the relay switching circuit 3, since the power supply end of the load 4 is connected with the zero line of the alternating current power supply, and the power supply end of the thyristor switching circuit 2 and the power supply end of the relay switching circuit 3 are respectively connected with the live line of the alternating current power supply, the MCU controller 1 judges whether the external PWM drive circuit can complete the normal charging and discharging work according to the current duty cycle value, so as to realize the dynamic cruise circuit state PWM adjustment control signal, and after the PWM drive 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 switching circuit 2 is turned on first, and then the relay switching circuit 3 is turned on to shunt the current, after the two work for a certain time, the thyristor switching circuit 2 is turned off to make the relay switching circuit 3 maintain operation, so as to realize soft start, or when the load 4 is turned off, since the relay switching circuit 3 is in normal operation state, the thyristor switching circuit 2 is turned on first, and then the relay switching circuit 3 is turned off, and when the thyristor switching circuit 2 is turned off for a certain time, the thyristor switching circuit 2 is turned off finally, so as to realize soft closing, which is reasonable in design, and realizes multi-dimensional soft start or closing through the dynamic cruise circuit state to realize adaptive PWM drive adjustment control signal.

[0027] Further, the thyristor switching circuit 2 comprises a first resistor R3, a thyristor Q2 and a second resistor R2, wherein the first pin of the MCU controller 1 is connected with one end of the first resistor R3, the first pin of the thyristor Q2 and the load 4 respectively, the other end of the first resistor R3 is connected with the live line of the alternating current 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 with the live line of the alternating current power supply.

[0028] Specifically, the relay switching circuit 3 comprises a diode D1 and a relay REL1, wherein the second pin of the MCU controller 1 is connected with the anode of the diode D1 and one end of the coil of the relay REL1 respectively, the cathode of the diode D1 and the other end of the coil of the relay REL1 are respectively connected with the external power supply, the switch one end of the relay REL1 is connected with the live line of the alternating current power supply, and the switch other end of the relay REL1 is connected with the load 4, the thyristor switching circuit 2 and the first pin of the MCU controller 1 respectively.

[0029] In the embodiment, the relay REL1 is arranged corresponding to the on-off switch K1, so that the relay REL1 controls the on-off switch K1 to be on or off through magnetic induction, i.e. the relay REL1 generates a magnetic force when powered on, and the on-off switch K1 is controlled to be on or off through the magnetic force.

[0030] In the embodiment, until the PWM driving circuit can complete normal charging and discharging work according to the current duty cycle value, when the load 4 is turned on, because the initial current is large, in order to avoid the phenomenon of sparking caused by the instantaneous overlarge current, the thyristor Q2 is first turned on, so as to realize the soft start protection of the high-voltage and high-current load 4. When the thyristor Q2 works for a certain time, the relay REL1 is then turned on to shunt the current. After the relay REL1 and the thyristor Q2 work for a certain time, the phenomenon of jitter of the relay REL1 caused by the attraction of the on-off switch K1 is avoided. Then, the thyristor Q2 is turned off to make the current completely conducted by the relay REL1. In this way, the current is transitioned from the thyristor Q2 to the relay REL1 for conduction. Because the resistance is small at this time, and the thyristor Q2 is an electronic switch to avoid the phenomenon of sparking, but the resistance of the thyristor Q2 is large. Therefore, the relay REL1 is maintained in the on state to make the current completely conducted by the relay REL1, so that the power consumption of the circuit is smaller and more reliable, thereby realizing soft start, i.e. realizing the multi-dimensional soft start of the relay REL1. Or when the load 4 is turned off, because the relay REL1 is in a normal running state, the relay REL1 cannot be quickly turned off to avoid the phenomenon of sparking caused by the instantaneous arc when turned off. Therefore, the thyristor Q2 is first turned on, and then the relay REL1 is turned off. When the thyristor Q2 is turned off for a certain time, the current is completely transitioned from the relay REL1 to the thyristor Q2 for conduction. Finally, the thyristor Q2 is turned off to achieve the purpose of completely turning off the load 4, thereby realizing soft closing, i.e. realizing the multi-dimensional soft closing of the relay REL1.

[0031] Embodiment two:

[0032] As Figure 2As shown, the embodiment provides a control method with adaptive PWM driving, which is applied to the adaptive PWM driving control circuit as described in any embodiment one, judges whether the external PWM driving 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, so as to realize dynamic cruise circuit state PWM adjustment control signal, until the PWM driving circuit can complete normal charging and discharging work according to the current duty cycle value, then through the switch of the load, control the switch of the relay and / or thyristor to realize soft start or soft close, the method is simple and feasible, by adopting the combined alternating staggered control algorithm, so as to eliminate the spark in the process of load switch, thereby prolonging the service life of the product.

[0033] The PWM adaptive control method in the embodiment includes the following steps:

[0034] Step S101, the duty cycle values of the first PWM signal and the second PWM signal are set according to the initial duty cycle value, the frequency values of the two are set according to the initial frequency value, and the voltage values of the first PWM signal and the second PWM signal are collected.

[0035] In the embodiment, the initial duty cycle value is 50%, and / or the initial frequency value is 16Khz.

[0036] Step S102, in a preset collection period, the plurality of first high level signal values collected when the first PWM signal is at high level and the plurality of first low level signal values collected when the first PWM signal is at low level are respectively averaged to obtain the mean value of the plurality of first high level signal values and the mean value of the plurality of first low level signal values; and the plurality of second high level signal values collected when the second PWM signal is at high level and the plurality of second low level signal values collected when the second PWM signal is at low level are respectively averaged to obtain the mean value of the plurality of second high level signal values and the mean value of the plurality of second low level signal values.

[0037] Step S103, judge whether the mean value of the plurality of first high level signal values and the mean value of the plurality of second high level signal values are greater than the preset first voltage value respectively, and whether the mean value of the plurality of first low level signal values and the mean value of the plurality of second low level signal values are greater than the preset second voltage value respectively, according to the judgment result to decide whether to adjust the duty cycle values of the first PWM signal and the second PWM signal.

[0038] In the embodiment, it is judged 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 a step of determining whether to adjust the duty cycle values of the first PWM signal and the second PWM signal according to the judgment result comprises:

[0039] judging 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;

[0040] if yes, it is determined that the PWM driving circuit can complete normal charging and discharging work according to the current duty cycle value;

[0041] if no, it is determined that the PWM driving circuit cannot complete normal charging and discharging work according to the current duty cycle value.

[0042] In the embodiment, the preset first voltage value is preferably 4V, and the preset second voltage value is preferably 0.7V.

[0043] More preferably, if no, the step after it is determined that the PWM driving circuit cannot complete normal charging and discharging work according to the current duty cycle value comprises:

[0044] adjusting the duty cycle values of the first PWM signal and the second PWM signal according to a preset duty cycle adjustment value.

[0045] In addition, the step after the duty cycle values of the first PWM signal and the second PWM signal are adjusted according to the preset duty cycle adjustment value comprises:

[0046] In the next preset collection period, the plurality of first high level signal values, the plurality of first low level signal values, the plurality of second high level signal values and the plurality of second low level signal values collected again are averaged to obtain the average of the plurality of first high level signal values, the average of the plurality of first low level signal values, the average of the plurality of second high level signal values and the average of the plurality of second low level signal values;

[0047] it is again judged 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 a step of determining whether to adjust the duty cycle values of the first PWM signal and the second PWM signal according to the judgment result;

[0048] until the PWM driving circuit can complete normal charging and discharging work according to the current duty cycle value.

[0049] Step S104, until the PWM drive circuit can complete normal charging and discharging work according to the current duty cycle value.

[0050] Step S105, according to the switching action of the load, the switching of the relay and / or thyristor is controlled to realize soft start or soft stop.

[0051] In this embodiment, the step of controlling the switching of the relay and / or thyristor to realize soft start or soft stop according to the switching action of the load includes:

[0052] When the load is turned on, the first PWM signal duty cycle is set to 0 to close the relay, and the second PWM signal duty cycle is set to 1 to turn on the thyristor, so that the load realizes soft start protection of high voltage and high current;

[0053] Until the conduction time of the thyristor reaches the preset conduction time, the first PWM signal duty cycle is set to 1 to turn on the relay, and then the first PWM signal is controlled to keep the current duty cycle value for work;

[0054] Until the conduction time of the relay reaches the preset conduction time, the second PWM signal duty cycle is set to 0 to turn off the thyristor, so as to realize soft start.

[0055] In addition, the step of controlling the switching of the relay and / or thyristor to realize soft start or soft stop according to the switching action of the load also includes:

[0056] 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;

[0057] Until the conduction time of the thyristor reaches the preset conduction time, the first PWM signal duty cycle is set to 0 to turn off the relay, so that the load realizes soft stop protection of high voltage and high current;

[0058] Again, until the conduction time of the thyristor reaches the preset conduction time, the second PWM signal duty cycle is set to 0 to turn off the thyristor, so as to realize soft stop.

[0059] In the embodiment, when the load is turned on, because the initial current is large, in order to avoid the spark phenomenon caused by the too large current instantaneously, the thyristor is first turned on, so as to realize the soft start protection of the high voltage and high current of the load, when the thyristor works for a certain time, then the relay is turned on to shunt the current, after the relay and the thyristor work for a certain time, the hunting phenomenon of the relay when the on-off switch is turned on is avoided, then the thyristor is turned off, so that the current is conducted by the relay completely, so that the current is conducted from the thyristor to the relay, because the resistance is small at this time, and the thyristor is an electronic switch to avoid the spark phenomenon, but the resistance of the thyristor is large, therefore, the relay is kept in the conducting state to make the current conducted by the relay completely, so that the power consumption of the circuit is smaller, and it is more reliable, so as to realize the soft start, that is, the multi-dimensional soft start of the relay; or when the load is turned off, because the relay is in the normal running state, the relay cannot be turned off quickly to avoid the spark phenomenon caused by the instantaneous arc when the load is turned off, therefore, the thyristor is first turned on, then the relay is turned off, when the thyristor is turned off for a certain time, so that the current is conducted from the relay to the thyristor completely, finally the thyristor is turned off to achieve the purpose of turning off the load completely, so as to realize the soft turn-off, that is, the multi-dimensional soft turn-off of the relay.

[0060] The above only describes some embodiments of the present application. For those skilled in the art, without departing from the inventive concept, some modifications and improvements can be made, which are all within the protection scope of the present application.

Claims

1. A control circuit with adaptive PWM drive, characterized in that, include: The load connected to the AC power supply (4); MCU controller (1), the MCU controller (1) is connected to an external PWM drive circuit to be adapted to receive a first PWM signal and a second PWM signal that can be dynamically switched between high and low frequencies; A thyristor switch circuit (2) is provided, the input terminal of which is connected to the first pin of the MCU controller (1), and its output terminal is connected to the load (4). The relay switch circuit (3) has its input terminal connected to the second pin of the MCU controller (1) and its output terminal connected to the load (4) and the output terminal 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 operation 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 stop.

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

Images