Variable frequency compressor start control method

Abstract

The present application relates to the technical field of variable frequency compressor control, in order to improve the starting performance of the variable frequency compressor, a variable frequency compressor starting control method is provided, comprising: 1, whether there is a starting instruction, if yes, then enter 2; 2, the driver starts the compressor clockwise with the first starting current, and the starting time is T1; 3, calculate the mechanical angle ω of the motor rotor rotating in T1; 4, judge whether ω is greater than the first angle threshold, if yes, then enter 5, if not, then enter 6; 5, the driver starts the compressor clockwise with the second starting current; 6, the driver starts the compressor counterclockwise with the third starting current, and the starting time is variable T2; 7, calculate the mechanical angle ξ of the motor rotor rotating in T2, judge whether ξ is greater than the second angle threshold, if yes, then enter step 8, if not, then reacquire T2 and repeat step 7; 8, the driver disconnects the third starting current and enters step 5. The above method can improve the starting performance of the variable frequency compressor.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of variable frequency compressor control, and particularly relates to a variable frequency compressor starting control method. BACKGROUND

[0002] The permanent magnet synchronous motor has the characteristics of simple structure, small size, no mechanical commutator and convenient maintenance of an alternating current motor, and has the advantages of large torque density and reliable operation, and thus is widely applied to refrigerator compressors. However, in the actual refrigerator matching process, the variable frequency compressor starting performance directly affects the refrigerator energy consumption matching test and noise matching test due to the relatively harsh working environment and use conditions of the permanent magnet synchronous motor. How to improve the starting performance of the variable frequency compressor has become one of the problems to be solved. SUMMARY

[0003] In order to improve the starting performance of the variable frequency compressor, the application provides a variable frequency compressor starting control method.

[0004] The application adopts the technical scheme that:

[0005] The variable frequency compressor starting control method comprises the following steps:

[0006] Step 1, determining whether the compressor control system sends a starting instruction to the variable frequency compressor, if yes, entering step 2, if no, continuing to execute step 1;

[0007] Step 2, the variable frequency compressor driver starts the compressor clockwise with a preset first starting current I1, and the starting time is a preset first starting time T1, when the starting time counter reaches the set first starting time T1, the input of the first starting current I1 is disconnected;

[0008] Step 3, acquiring the phase difference of the three-phase phase current of the variable frequency compressor in the first starting time T1 respectively, and calculating the first mechanical angle omega of the rotation of the rotor of the permanent magnet synchronous motor of the variable frequency compressor in the first starting time T1 according to the phase difference;

[0009] Step 4, determining whether the first mechanical angle omega is greater than a preset first angle threshold value omega th1 , if yes, entering step 5, if no, entering step 6;

[0010] Step 5, the variable frequency compressor driver starts the compressor clockwise with a preset second starting current I2, and normally operates according to the signal instruction sent by the compressor control system, and the process is ended; the second starting current I2 is greater than or equal to the first starting current I1;

[0011] Step 6, the variable frequency compressor driver starts the compressor counterclockwise with a preset third starting current I3, the starting time is a variable second starting time T2, and I1≤I3≤I2;

[0012] Step 7, record the phase difference of U, V, W three-phase current of the variable frequency compressor in real time within the second starting time T2, calculate the second mechanical angle ξ of the permanent magnet synchronous motor rotor of the variable frequency compressor rotating within the second starting time T2 according to the phase difference, and judge whether the second mechanical angle ξ is greater than a preset second angle threshold ω th2 If yes, go to step 8, if not, reacquire the second starting time T2, and repeat step 7;

[0013] Step 8, the variable frequency compressor driver disconnects the input of the third starting current I3, and enters step 5.

[0014] Further, in the step 3, the phase difference of U, V, W three-phase current within the first starting time T1 is φu, φv, and φw respectively, then ω=(φ U +φ V +φ W ) / (3×P), wherein P is the pole pair number of the permanent magnet synchronous motor.

[0015] Further, in the step 7, the phase difference of U, V, W three-phase current within the second starting time T2 is Then , wherein P is the pole pair number of the permanent magnet synchronous motor.

[0016] Further, the second angle threshold ω th2 is greater than or equal to ω th1 +ω.

[0017] Further, the first starting current I1 is 0.5-0.7A, the first starting time T1 is 2-3S, the first angle threshold ω th1 is π / 6-π / 4, the second starting current I2 is 0.8-1.0A, the second angle threshold ω th2 is (π / 6+ω)-(π / 3+ω), and the third starting current I3 is 0.6-0.8A.

[0018] The present application has the beneficial effects compared with the prior art: firstly, using constant current constant time driving control method, through the observer records the variable frequency compressor using constant forward starting current in constant starting time, the phase difference of three-phase current of permanent magnet synchronous motor, and then calculates the mechanical angle of the permanent magnet synchronous motor rotor rotating in constant forward starting time, realizes the purpose of monitoring the position of the permanent magnet synchronous motor rotor, then based on the feedback of the position information of the permanent magnet synchronous motor, through the threshold comparison control method, the rotation direction and rotation angle logic of the permanent magnet synchronous motor rotor are adaptively adjusted, the purpose of adjusting the starting state to the best according to the load condition when the variable frequency compressor starts is realized, so as to accurately control the load torque of the variable frequency compressor in the low starting torque range when starting, finally through the soft start control method, the permanent magnet synchronous motor starts smoothly with constant forward starting current set value, reduces the impact torque to the load machine, and then improves the starting performance of the variable frequency compressor, which has the advantages of simple realization, high reliability, strong self-adaptation, high efficiency and energy saving, and can be widely applied to the improvement of the starting performance of variable frequency compressors of any structure. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The variable frequency compressor starting control method flow chart. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below combined with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0021] As shown in Figure 1 The variable frequency compressor starting control method comprises:

[0022] Step 1, judge whether the compressor control system sends a starting instruction to the variable frequency compressor, if yes, go to step 2, if no, continue to execute step 1;

[0023] Step 2, under the rated load condition, the variable frequency compressor driver starts the compressor clockwise with a preset first starting current I1, and the starting time is a preset first starting time T1, when the starting time counter reaches the set first starting time T1, the input of the first starting current I1 is disconnected, in this embodiment, the first starting current I1 is 0.5-0.7A, and the first starting time T1 is 2-3S;

[0024] Step 3, obtain the phase difference of U, V, W three-phase phase current of the variable frequency compressor within the first starting time T1 through the observer respectively, and calculate the first mechanical angle ω of the permanent magnet synchronous motor rotor of the variable frequency compressor within the first starting time T1 according to the phase difference, the phase difference of U, V, W three-phase phase current is φu, φv, φw respectively, then ω = (φu + φv + φw) / (3 × P), wherein P is the pole pair number of the permanent magnet synchronous motor; U +φ V +φ W ) / (3 × P), wherein P is the pole pair number of the permanent magnet synchronous motor;

[0025] Step 4, judge whether the first mechanical angle ω is greater than the preset first angle threshold ω th1 , the first angle threshold ω th1 is π / 6~π / 4, if yes, at this time the load torque of the variable frequency compressor during starting is in the low starting torque range, then enter step 5, if not, the load torque of the variable frequency compressor during starting is in the high starting torque range, then enter step 6;

[0026] Step 5, the variable frequency compressor driver starts the compressor clockwise with a preset second starting current I2, and normally operates according to the signal instruction sent by the compressor control system, and the process is ended; the second starting current I2 is greater than or equal to the first starting current I1;

[0027] Step 6, the variable frequency compressor driver starts the compressor counterclockwise with a preset third starting current I3, I3 is 0.6~0.8A, the starting time is variable second starting time T2, and I1≤I3≤I2;

[0028] Step 7, record the phase difference of U, V, W three-phase phase current of the variable frequency compressor within the second starting time T2 in real time, and calculate the second mechanical angle ξ of the permanent magnet synchronous motor rotor of the variable frequency compressor within the second starting time T2 according to the phase difference, the phase difference of U, V, W three-phase phase current is then wherein P is the pole pair number of the permanent magnet synchronous motor, judge whether the second mechanical angle ξ is greater than the preset second angle threshold ω th2 , the second angle threshold ω th2 is greater than or equal to ω th1 +ω, ω th2 is (π / 6+ω)~(π / 3+ω), if yes, the load torque of the variable frequency compressor at the second starting time T2 is in the low starting torque range, then enter step 8, if not, reacquire the second starting time T2, and repeat step 7; T2 is acquired according to the elapse of time;

[0029] Step 8, the variable frequency compressor driver disconnects the input of the third starting current I3, and enters step 5, so that the load torque of the variable frequency compressor during starting is in the low starting torque range, the starting vibration and noise are reduced, and the starting performance of the variable frequency compressor is improved.

[0030] It should be noted that the preset values can be set according to actual needs, and the specific values are not limited in the application. The method has the advantages of simple implementation, high reliability, strong self-adaptation, high efficiency and energy saving, and can be widely applied to the improvement of the starting performance of variable frequency compressors of any structure.

Claims

1. A variable frequency compressor start control method, characterized by, Comprise: Step 1, judge whether the compressor control system sends start instruction to variable frequency compressor, if yes, enter step 2, if no, continue to execute step 1; Step 2, variable frequency compressor driver clockwise starts compressor with preset first starting current I1, and the starting time is preset first starting time T1, when the starting time counter reaches the set first starting time T1, the input of the first starting current I1 is disconnected; Step 3, the phase difference of U, V, W three-phase current of variable frequency compressor in the first starting time T1 is obtained respectively, and the first mechanical angle ω of the permanent magnet synchronous motor rotor of variable frequency compressor rotating in the first starting time T1 is calculated according to the phase difference; Step 4, judging whether the first mechanical angle ω is greater than a preset first angle threshold ω th1 , if yes, entering step 5, if no, entering step 6; Step 5, variable frequency compressor driver clockwise starts compressor with preset second starting current I2, and normally operates according to the signal instruction sent by the compressor control system, and the process is ended;The second starting current I2 is greater than or equal to the first starting current I1; Step 6, variable frequency compressor driver counterclockwise starts compressor with preset third starting current I3, and the starting time is variable second starting time T2, and I1≤I3≤I2; Step 7, record the phase difference of U, V, W three-phase phase current of the variable frequency compressor in the second starting time T2, calculate the second mechanical angle ξ of the permanent magnet synchronous motor rotor of the variable frequency compressor rotating in the second starting time T2 according to the phase difference, and judge whether the second mechanical angle ξ is greater than the preset second angle threshold ω th2 If yes, go to step 8, if not, reacquire the second starting time T2, and repeat step 7; Step 8, variable frequency compressor driver disconnects the input of the third starting current I3, and enters step 5.

2. The variable frequency compressor start control method of claim 1, wherein, The phase difference of the three-phase phase currents U, V, W in the first starting time T1 in step 3 is φu, φv, and φw, respectively, ω=(φ U +φ V +φ W ) / (3×P), wherein P is the number of pole pairs of the permanent magnet synchronous motor.

3. The variable frequency compressor start control method of claim 1, wherein, The phase difference of the three-phase phase currents U, V, W in the second starting time T2 in step 7 is respectively Then Wherein, P is the pole pair number of the permanent magnet synchronous motor.

4. The variable frequency compressor start control method of claim 1, wherein, the second angle threshold ω th2 greater than or equal to ω th1 + ω.

5. The variable frequency compressor start control method according to any one of claims 1-4, wherein, The first starting current I1 is 0.5-0.7A, the first starting time T1 is 2-3S, the first angle threshold ω th1 is π / 6-π / 4, the second starting current I2 is 0.8-1.0A, and the second angle threshold ω th2 is (π / 6+ω)-(π / 3+ω), and the third starting current I3 is 0.6-0.8A.

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