Fan control method of air blower

Abstract

The invention discloses a fan control method of an air blower, which comprises the following steps: when the air blower starts to work, the control process comprises the following steps of: controlling the rotating speed of a motor through a switch conduction duty ratio of an inverter circuit by using an open-loop PWM (Pulse Width Modulation) control mode until the air blower reaches a steady state; the control process when the blasted equipment is in the steady state comprises the steps that a closed loop control mode is used, the rotating speed of a motor is adjusted in real time according to the pressure value in the blasted equipment, and the air blower is kept in the steady state; the control process when the blasted equipment is extruded and the pressure value is subjected to step-type sudden change comprises the following steps of: adjusting the rotating speed of the motor according to the step-type sudden change quantity by using a flexible control mode until the blasted equipment recovers to a steady state. High-precision and large-range rotating speed control and precise position control can be achieved, and the problems that an existing air blower is delayed in response, poor in air blowing effect and the like are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of fan control, and in particular to a fan control method for a blower. Background Art

[0002] In recent years, permanent magnet synchronous motors have gradually become the mainstream choice in the field of motor applications due to their advantages of high efficiency, low loss, and good power indicators. From small-power electric toothbrushes and shavers to medium-power blowers and air conditioners, to high-power CNC machine tools, electric vehicles, and even subway trains and spacecraft, permanent magnet synchronous motors can be found.

[0003] Blowers are general equipment in the industrial field, widely used in sewage treatment industry, chemical industry, pharmaceutical industry, power industry, food industry, etc., with huge market demand. Centrifugal blowers use permanent magnet synchronous motors to drive impellers equipped with many blades to convert mechanical energy into gas kinetic energy, and then convert gas kinetic energy into pressure energy, thereby meeting the needs of the blown equipment. Most permanent magnet synchronous motors use vector control systems, which can achieve high-precision, wide-range speed control and precise position control. In different application scenarios of blown equipment, the status of the blown equipment will change in real time. This change is not fully considered in the control process of permanent magnet synchronous motors, which will cause problems such as delayed blower response and poor blowing effect. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a blower control method for a blower to solve the technical problems in the prior art of delayed blower response and poor blowing effect.

[0005] The present invention provides a fan control method for a blower, comprising:

[0006] The control process when the blower starts working, the control process when the blown equipment is in a steady state, and the control process when the blown equipment is squeezed and the pressure value undergoes a step-like mutation;

[0007] Among them, the control process when the blower starts working includes:

[0008] Use open-loop PWM control to control the motor speed through the switch duty cycle of the inverter circuit until the blower reaches a steady state;

[0009] The control process when the blown equipment is in steady state includes:

[0010] Use closed-loop control to adjust the motor speed in real time according to the pressure value in the blown equipment to keep the blower in a steady state;

[0011] When the blown equipment is squeezed and the pressure value undergoes a step-like mutation, the control process includes:

[0012] Use flexible control method to adjust the motor speed according to the step-type mutation amount until the blown equipment returns to a steady state.

[0013] Furthermore, the closed-loop control method comprises the following steps:

[0014] Step 11: Convert the phase current into three-phase current values ​​according to the phase current reconstruction;

[0015] Step 12: Convert the three-phase current values ​​into dq axis currents;

[0016] Step 13: Obtain the rotor angular velocity and the rotor electrical angle as the actual feedback speed;

[0017] Step 14: Obtain the expected current value according to the target speed and the actual feedback speed;

[0018] Step 15: Obtain the dq axis adjustment voltage value according to the dq axis current and the current expected value;

[0019] Step 16: Perform coordinate inverse transformation and space vector pulse width modulation on the regulated voltage values ​​of the dq axes to obtain the PWM duty cycle and control the output of the three-phase inverter.

[0020] Furthermore, in step 14, the target speed is calculated as follows:

[0021]

[0022] In the formula, ω ref is the target speed; ω r is the rated speed of the motor; P is the internal pressure value of the blown equipment, P a is the standard atmospheric pressure value; λ is a fixed coefficient; ΔP=(λ-1)P a .

[0023] Furthermore, the step mutation is specifically:

[0024] If the pressure data in the blown device obtained within two consecutive judgment cycles changes beyond the pressure mutation threshold, it is considered that a step mutation occurs in the pressure value.

[0025] Furthermore, the flexible control method is:

[0026] The target speed of the motor in the closed-loop control method is obtained through the pressure step mutation and the pressure value in the blown equipment, and the PWM duty cycle is obtained according to the target speed and the actual feedback speed to control the output of the three-phase inverter until the blown equipment returns to a steady state.

[0027] Furthermore, the calculation formula for obtaining the motor target speed through the pressure step mutation amount and the pressure value in the blown device is:

[0028]

[0029] In the formula, ω ref is the target speed; ω r is the rated speed of the motor; P is the internal pressure value of the blown equipment, P a is the standard atmospheric pressure value; λ is a fixed coefficient; ΔP=(λ-1)P a ;P step is the pressure step mutation amount.

[0030] Beneficial effects of the present invention:

[0031] The present invention can achieve high-precision, wide-range speed control and precise position control, effectively alleviating the problems of delayed response and poor blowing effect of existing blowers. The present invention adjusts the motor speed according to the real-time state of the blown equipment to form a systematic closed-loop intelligent control. Different control strategies are adopted when the blown equipment is started, in steady state, and when squeezed, to ensure that the blown equipment can achieve better control effect in different states. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0033] Figure 1 It is a schematic diagram of a flow chart of a specific embodiment of the present invention;

[0034] Figure 2 Schematic diagram of the closed-loop control controller in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0036] The present invention is further illustrated below in conjunction with specific embodiments. Those skilled in the art should understand that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention, and modifications to various equivalent forms of the present invention fall within the scope defined by the appended claims of this application.

[0037] like Figure 1 As shown, the present invention provides a fan control method for a blower, comprising:

[0038] The control process when the blower starts working, the control process when the blown equipment is in a steady state, and the control process when the blown equipment is squeezed and the pressure value undergoes a step-like mutation;

[0039] Among them, the control process when the blower starts working includes:

[0040] Use open-loop PWM control to control the motor speed through the switch duty cycle of the inverter circuit until the blower reaches a steady state;

[0041] The control process when the blown equipment is in steady state includes:

[0042] Use closed-loop control to adjust the motor speed in real time according to the pressure value in the blown equipment to keep the blower in a steady state;

[0043] The specific steps are as follows:

[0044] Step S11: using an ADC converter to obtain the voltage value of the shunt resistor, and converting it into a three-phase current value through phase current reconstruction;

[0045] Step S12: performing Clark and Park transformation on the phase current values ​​to obtain dq axis currents;

[0046] Step S13: using the Hall position sensor to calculate the actual motor speed and rotor position angle as the actual feedback speed;

[0047] Step S14: Compare the target speed with the actual feedback speed, send the result to the speed PI controller for speed control, and output the expected current value i qref ;

[0048] Step S15: The obtained i d 、i q The difference between each and its expected value is sent to the current PI controller to output the regulated voltage value v required by the dq axis d 、v q ;

[0049] Step S16: performing coordinate inverse transformation and space vector pulse width modulation on the regulated voltage values ​​of the dq axes, and finally obtaining a PWM duty cycle to control the output of the three-phase inverter;

[0050] Repeat the above process to gradually reduce the speed difference between the target speed and the actual feedback speed to complete the motor speed regulation.

[0051] like Figure 2 As shown, the closed-loop control method of the permanent magnet synchronous motor is id =0 vector control controller architecture.

[0052] For the measurement of target speed: the air pressure sensor built into the blower device measures the pressure value, and the motor target speed is calculated from the pressure value. The calculation formula is:

[0053]

[0054] Where, ΔP = (λ-1)P a ;ω ref is the motor target speed; ω r is the rated speed of the motor; P is the internal pressure value of the blown equipment; P a is the standard atmospheric pressure value, which is approximately 1.01325×10 5 pa; λ is a fixed coefficient.

[0055] When the blown equipment is squeezed and the pressure value undergoes a step-like mutation, the control process includes:

[0056] Use flexible control method to adjust the motor speed according to the step-type mutation amount until the blown equipment returns to a steady state.

[0057] The specific step mutation is:

[0058] If the pressure data in the blown equipment obtained within two consecutive judgment cycles exceeds the pressure mutation threshold, it is considered that the pressure value has a step mutation.

[0059] For example, a judgment cycle lasts for ten system scanning cycles, each scanning cycle is 250us, and the real-time pressure value is recorded once in each system scanning cycle. The ten recorded pressure values ​​are averaged every ten scanning cycles. When the difference between the average pressure values ​​of two consecutive judgment cycles exceeds the pressure mutation threshold, it is considered that a step mutation occurs in the pressure value inside the blower equipment, thereby changing the control method of the motor.

[0060] In the step mutation judgment process, the pressure mutation threshold is not a fixed value, but is set to different values ​​according to different blown equipment, and is determined by factors such as the material, environment, and tolerance of the blown equipment.

[0061] The flexible control method is actually to change the method of obtaining the motor target speed on the basis of the closed-loop control method. The motor target speed in the closed-loop control method is obtained by using the pressure step mutation and the pressure value in the blown equipment. The PWM duty cycle is obtained according to the target speed and the actual feedback speed, and the three-phase inverter output is controlled until the blown equipment returns to a steady state.

[0062] The calculation formula for obtaining the motor target speed through the pressure step mutation and the pressure value in the blown equipment is:

[0063]

[0064] In the formula, ω ref is the target speed; ω r is the rated speed of the motor; P is the internal pressure value of the blown equipment, P a is the standard atmospheric pressure value; λ is a fixed coefficient; ΔP=(λ-1)P a ;P step is the pressure step mutation amount.

[0065] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A fan control method for a blower, characterized in that: include: The control process when the blower starts working, the control process when the blown equipment is in a steady state, and the control process when the blown equipment is squeezed and the pressure value undergoes a step-like mutation; Among them, the control process when the blower starts working includes: Use open-loop PWM control to control the motor speed through the switch duty cycle of the inverter circuit until the blower reaches a steady state; The control process when the blown equipment is in steady state includes: Use closed-loop control to adjust the motor speed in real time according to the pressure value in the blown equipment to keep the blower in a steady state; When the blown equipment is squeezed and the pressure value undergoes a step-like mutation, the control process includes: Use flexible control method to adjust the motor speed according to the step-type mutation amount until the blown equipment returns to a steady state.

2. The fan control method of the blower according to claim 1, characterized in that: The closed-loop control method comprises the following steps: Step 11: Convert the phase current into three-phase current values ​​according to the phase current reconstruction; Step 12: Convert the three-phase current values ​​into dq axis currents; Step 13: Obtain the rotor angular velocity and the rotor electrical angle as the actual feedback speed; Step 14: Obtain the expected current value according to the target speed and the actual feedback speed; Step 15: Obtain the dq axis adjustment voltage value according to the dq axis current and the current expected value; Step 16: Perform coordinate inverse transformation and space vector pulse width modulation on the regulated voltage values ​​of the dq axes to obtain the PWM duty cycle and control the output of the three-phase inverter.

3. The fan control method of the blower according to claim 1, characterized in that: In step 14, the target speed is calculated as follows: In the formula, ω ref is the target speed; ω r is the rated speed of the motor; P is the internal pressure value of the blown equipment, P a is the standard atmospheric pressure value; λ is a fixed coefficient; ΔP=(λ-1)P a .

4. The fan control method of the blower according to claim 1, characterized in that: The step mutation is specifically: If the pressure data in the blown device obtained within two consecutive judgment cycles changes beyond the pressure mutation threshold, it is considered that a step mutation occurs in the pressure value.

5. The fan control method of the blower according to claim 1, characterized in that: The flexible control method is: The target speed of the motor in the closed-loop control method is obtained through the pressure step mutation and the pressure value in the blown equipment, and the PWM duty cycle is obtained according to the target speed and the actual feedback speed to control the output of the three-phase inverter until the blown equipment returns to a steady state.

6. The fan control method of the blower according to claim 1, characterized in that: The calculation formula for obtaining the motor target speed through the pressure step mutation and the pressure value in the blown equipment is: In the formula, ω ref is the target speed; ω r is the rated speed of the motor; P is the internal pressure value of the blown equipment, P a is the standard atmospheric pressure value; λ is a fixed coefficient; ΔP=(λ-1)P a ;P step is the pressure step mutation amount.

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