Constant air temperature control method for silicon controlled rectifier heating wire

Abstract

The invention discloses a constant air temperature control method for a silicon controlled rectifier heating wire, and relates to the field of electric hair dryers, the constant air temperature control method for the silicon controlled rectifier heating wire comprises the following steps: step 1, selecting a wave resolution and a wave period, and making a two-dimensional table, the horizontal coordinate of which is a duty ratio and the vertical coordinate of which is a silicon controlled rectifier switching value; step 2, calibrating a duty ratio D0 which needs to reach a set temperature under a fixed voltage U0 in a room temperature environment; the method has the advantages that PID adjustment is carried out based on the real-time temperature and the set temperature, an output result Dpid is obtained, a conversion coefficient K is obtained based on the collected voltage Uin and the fixed voltage U0, the duty ratio D0 which needs to reach the set temperature under the fixed voltage U0 and is calibrated in the room temperature environment is obtained, and finally the final output duty ratio Dout is obtained through real-time calculation; and the air temperature output can be quickly and stably controlled to adapt to different environment temperatures while the voltage change of the power grid can be adapted.

Description

Technical Field

[0001] The invention relates to the field of hair dryers, in particular to a constant wind temperature control method for a thyristor heating wire. Background Art

[0002] Currently, most of the hair dryers with heating wires available on the market still use open-loop control, that is, the heating wire output is controlled directly to give a fixed duty cycle. Although this method is simple to control, it is difficult to cause changes in wind temperature due to changes in ambient temperature, which will bring a bad experience to users.

[0003] At the same time, this method also has certain technical risks and is difficult to cope with fluctuations in grid voltage. When the grid voltage changes significantly, the heating wire power changes accordingly. Especially when the grid voltage is high, the wind temperature controlled by the heating wire increases accordingly. In severe cases, it may cause damage to the equipment or even harm to personnel.

[0004] In summary, the existing hair dryer with a heating wire provides a fixed duty cycle to control the operation of the heating wire, which leads to poor user experience and the possibility of equipment damage and personal injury, and needs to be improved. Summary of the invention

[0005] The object of the present invention is to provide a constant air temperature control method for a thyristor heating wire to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A constant air temperature control method for a thyristor heating wire comprises the following steps:

[0008] Step 1, select the wave resolution and wave period, and make a two-dimensional table, whose horizontal axis is the duty cycle and the vertical axis is the thyristor switch value;

[0009] Step 2: calibrate the duty cycle D0 required to reach the set temperature under the fixed voltage U0 at room temperature (near the set temperature is also acceptable);

[0010] Step 3: Collect the AC input voltage in real time and convert the collected voltage U in Perform linear conversion with fixed voltage U0 to obtain conversion coefficient k;

[0011] Step 4: multiply the conversion coefficient K and the duty cycle D0 to offset the fluctuation of the grid voltage;

[0012] Step 5: PID adjustment is performed on the collected real-time temperature and the set temperature. At the same time, the PID calculation result is also converted according to the grid voltage fluctuation to obtain the final output duty cycle D out , to drive the thyristor.

[0013] As a further solution of the present invention: in step 1, 25 half waves are selected as a wave period, and the minimum resolution of the duty cycle is 4%, and a 26X25 two-dimensional table is produced, wherein the horizontal axis is the duty cycle, and the vertical axis is the thyristor switch value, 0 represents off, and 1 represents on.

[0014] As a further solution of the present invention: in step 2, 220V AC power is selected as the fixed voltage U0, and the duty cycle D0 required to reach the set temperature under the fixed voltage U0 is calibrated under room temperature.

[0015] As a further solution of the present invention: In step 3, the AC input voltage is collected in real time to obtain the collected voltage U in Since the heating wire is a pure resistive load (conventional heating wire), the voltage U in Perform linear conversion with fixed voltage U0 to obtain the conversion coefficient

[0016] As a further solution of the present invention: In step 4, the conversion coefficient K is multiplied by the duty cycle D0 to offset the fluctuation of the grid voltage, and D base =K*D0.

[0017] As a further solution of the present invention: In step 5, the collected real-time temperature and the set temperature are PID-adjusted to obtain the output result D pid The adjustment cycle is the same frequency as the wave cycle, which is 250ms (the wave cycle is 250ms corresponding to AC220V, 50HZ alternating current). At the same time, the PID operation output result D pid Multiply it by the conversion factor K and then add it to D base The final output duty cycle D is obtained by superposition. out =D base +K*D pid , to drive the thyristor.

[0018] As a further solution of the present invention: in step 5, the output result D pid Limit to closed interval

[0019] Compared with the prior art, the present invention has the following beneficial effects: the present invention performs PID adjustment based on the real-time temperature and the set temperature to obtain the output result D pid , based on the collected voltage U in The conversion coefficient K is obtained from the fixed voltage U0, and the duty cycle D0 required to reach the set temperature under the fixed voltage U0 is calibrated under room temperature to finally calculate the final output duty cycle D in real time. out , that is, it can adapt to changes in grid voltage and can also quickly and stably control the wind temperature output to adapt to different ambient temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a flow chart of a method for controlling the constant air temperature of a thyristor heating wire.

[0021] Figure 2 Schematic diagram of the wave number of a single control cycle.

[0022] Figure 3 Schematic diagram of the waveform with a 50% duty cycle.

[0023] Figure 4 Schematic diagram of the waveform with a 30% duty cycle. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] See also Figure 1 A constant air temperature control method for a thyristor heating wire comprises the following steps:

[0026] Step 1, select the wave resolution and wave period, and make a two-dimensional table, whose horizontal axis is the duty cycle and the vertical axis is the thyristor switch value;

[0027] Step 2: calibrate the duty cycle D0 required to reach the set temperature under the fixed voltage U0 at room temperature (near the set temperature is also acceptable);

[0028] Step 3: Collect the AC input voltage in real time and convert the collected voltage U in Perform linear conversion with fixed voltage U0 to obtain conversion coefficient K;

[0029] Step 4: multiply the conversion coefficient K and the duty cycle D0 to offset the fluctuation of the grid voltage;

[0030] Step 5: PID adjustment is performed on the collected real-time temperature and the set temperature. At the same time, the PID calculation result is also converted according to the grid voltage fluctuation to obtain the final output duty cycle D out , to drive the thyristor.

[0031] In this example: See Figure 1 In step 1, 25 half waves are selected as a wave cycle, and the minimum resolution of the duty cycle is 4%. A 26X25 two-dimensional table is produced, with the horizontal axis being the duty cycle and the vertical axis being the thyristor switch value, 0 representing off and 1 representing on.

[0032] See also Figure 2 Taking AC220V, 50Hz mains as an example, the wave period is 250ms, and 25 half waves as shown in the figure are one wave period.

[0033] Under different duty cycles, the number of on and off waves should be evenly distributed as much as possible, such as Figure 3 , 4 The waveforms are shown below with a duty cycle of 50% and 30% respectively.

[0034] In this example: See Figure 1 In step 2, select 220V AC power as the fixed voltage U0, and calibrate the duty cycle D0 required to reach the set temperature under the fixed voltage U0 at room temperature.

[0035] The common mains voltage is 220V, so 220V mains voltage is selected as the fixed voltage U0.

[0036] In this example: See Figure 1 In step 3, the AC input voltage is collected in real time to obtain the collected voltage U in Since the heating wire is a pure resistive load (conventional heating wire), the voltage U in Perform linear conversion with fixed voltage U0 to obtain the conversion coefficient

[0037] In the previous step, 220V voltage is selected as the base value. In actual situations, the voltage may not be stable at the base value of 220V. Therefore, it is necessary to divide the actual collected voltage by the base value of 220V to obtain the conversion coefficient.

[0038] In this example: See Figure 1 In step 4, the conversion coefficient K is multiplied by the duty cycle D0 to offset the fluctuation of the grid voltage. base =K*D0. Voltage fluctuation refers to a period of time when the actual voltage amplitude changes "dramatically" and deviates from the rated voltage. The deviation is dynamic, that is, the rise and fall of the voltage. Therefore, in this step, the fixed duty cycle set in the previous step is also linearly converted with the same conversion coefficient by linear conversion of the collected voltage and the fixed voltage. This method is used to offset the voltage fluctuation.

[0039] In this example: See Figure 1 In step 5, the collected real-time temperature and the set temperature are PID-adjusted to obtain the output result D pid The adjustment cycle is the same frequency as the wave cycle, which is 250ms (the wave cycle is 250ms corresponding to AC220V, 50HZ alternating current). At the same time, the PID operation output result D pid Multiply it by the conversion factor K and then add it to Dbase The final output duty cycle D is obtained by superposition. out =D base +K*D pid , to drive the thyristor. Because an incremental PID control algorithm is used, under this algorithm, there is no need to accumulate errors. The incremental output is only related to the most recent sampling times, and a better control effect can be obtained through weighted processing. Therefore, when the voltage fluctuates, the incremental output can be quickly based on the results of ambient temperature sampling, and then combined with Dbase operation, a stable duty cycle can be quickly output to drive the thyristor.

[0040] PID regulation is a basic regulation method of control systems in classical control theory. It is a linear regulation law with proportional (P), integral (I) and differential (D) effects. It is a common technology and will not be described in detail here.

[0041] In this example: See Figure 1 , in step 5, output result D pid Limit to closed interval

[0042] Limiting is used to limit the output result D pid , acting on the system to ensure the stability and control effect of the system. Because Dpid needs to be superimposed with Dbase, the duty cycle of the final output cannot be less than 0% and exceed 100%, so the limit range of Dpid is [Dbase+K*Dpid=0,Dbase+K*Dpid=1], which is simplified to

[0043] The present invention performs PID adjustment based on the real-time temperature and the set temperature to obtain the output result D pid , based on the collected voltage U in The conversion coefficient K is obtained from the fixed voltage U0, and the duty cycle D0 required to reach the set temperature under the fixed voltage U0 is calibrated under room temperature to finally calculate the final output duty cycle D in real time. out , that is, it can adapt to changes in grid voltage and can also quickly and stably control the wind temperature output to adapt to different ambient temperatures.

[0044] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered as exemplary and non-restrictive in all respects.

[0045] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A constant air temperature control method for a thyristor heating wire, characterized in that: The constant air temperature control method of the thyristor heating wire comprises the following steps: Step 1, select the wave resolution and wave period, and make a two-dimensional table, whose horizontal axis is the duty cycle and the vertical axis is the thyristor switch value; Step 2, calibrate the duty cycle D0 required to reach the set temperature under a fixed voltage U0 at room temperature; Step 3: Collect the AC input voltage in real time and convert the collected voltage U in Perform linear conversion with fixed voltage U0 to obtain conversion coefficient K; Step 4: multiply the conversion coefficient K and the duty cycle D0 to offset the fluctuation of the grid voltage; Step 5: PID adjustment is performed on the collected real-time temperature and the set temperature. At the same time, the PID calculation result is also converted according to the grid voltage fluctuation to obtain the final output duty cycle D out , to drive the thyristor.

2. The constant air temperature control method of the thyristor heating wire according to claim 1, characterized in that: In step 1, 25 half waves are selected as a wave cycle, and the minimum resolution of the duty cycle is 4%. A 26X25 two-dimensional table is produced, with the horizontal axis being the duty cycle and the vertical axis being the thyristor switch value, 0 representing off and 1 representing on.

3. The constant air temperature control method of the thyristor heating wire according to claim 1, characterized in that: In step 2, 220V mains power is selected as the fixed voltage U0, and the duty cycle D0 required to reach the set temperature under the fixed voltage U0 is calibrated under room temperature.

4. The constant air temperature control method of the thyristor heating wire according to claim 1 or 3, characterized in that: In step 3, the AC input voltage is collected in real time to obtain the collected voltage U in Since the heating wire is a pure resistive load, the voltage U in Perform linear conversion with fixed voltage U0 to obtain the conversion coefficient 5. The constant air temperature control method of the thyristor heating wire according to claim 1, characterized in that: In step 4, the conversion factor K is multiplied by the duty cycle D0 to offset the fluctuation of the grid voltage. base =K*D0.

6. The constant air temperature control method of the thyristor heating wire according to claim 1, characterized in that: In step 5, the collected real-time temperature and the set temperature are PID-adjusted to obtain the output result D pid The adjustment cycle is the same as the wave cycle, which is 250ms. At the same time, the PID operation output result D pid Multiply it by the conversion factor K and then add it to D base The final output duty cycle D is obtained by superposition. out =D base +K*D pid , to drive the thyristor.

7. The constant air temperature control method of the thyristor heating wire according to claim 6, characterized in that: In step 5, output result D pid Limit to closed interval

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