High-torque upwind starting control method

Abstract

The invention provides a high-torque headwind starting control method, which relates to the technical field of air conditioners and comprises the steps of rotating state detection, rotating speed detection, high-speed headwind speed reduction, low-speed headwind speed reduction and forward starting. In the execution process, the motor runs according to the following steps: the terminal voltages Vu, Vv and Vw of the three-phase line of the motor; phase voltages Ua, Ub and Uc are obtained through calculation; calculating rotating speed and position information; and judging the state of the fan so as to distinguish five states, namely headwind high-speed, headwind low-speed, static, downwind low-speed and downwind high-speed, and then running according to a corresponding strategy. The method has the beneficial effects that the reversing success rate and the starting success rate of the method are far higher than those of a traditional headwind starting scheme, and compared with the traditional scheme, headwind starting can be achieved under headwind with the higher rotating speed and the larger torque; the difficulty of a traditional scheme is solved, and the upwind starting success rate is remarkably increased.

Description

Technical Field

[0001] The invention relates to the technical field of air conditioning, and in particular to a high-torque headwind starting control method. Background Art

[0002] Due to the influence of outdoor wind, the outdoor fan of the air conditioner may be in forward rotation, reverse rotation, or stationary state when starting. Especially in typhoon weather, the air conditioner faces a very serious problem of starting against the wind. In order to make the fan rotate forward at the desired speed after starting, it is necessary to start it with the wind and against the wind, among which starting against the wind is particularly difficult.

[0003] Headwind starting includes steps such as rotation status detection, braking deceleration, reversing, and forward starting acceleration.

[0004] Traditionally, the rotation state detection generally adopts the current detection scheme, the braking adopts the zero vector method to decelerate, and the forward start acceleration generally adopts the standard three-stage start of "positioning-open loop-closed loop".

[0005] The prior art adopts the following methods:

[0006] (1) The solution for detecting the rotation state by current is generally to collect two-phase current and calculate the third-phase current, and then use Clark transformation to calculate I α ,I β .

[0007] Assume Is satisfies:

[0008] Compare Is with the threshold value IsThreshold set by yourself. If it is less than the threshold, it is considered to be stationary, otherwise there is wind.

[0009] (2) For speed measurement, only the current loop is run, the reference values ​​idref and iqref of id and iq are set to 0, and the observer is run to calculate the angle θ for Park transformation and inverse Park transformation. This can minimize the impact on the current state of the motor and enable the observer to operate normally, thereby obtaining the speed and position.

[0010] (3) The braking deceleration adopts the zero vector method, which turns on the three lower bridges of the three-phase inverter to generate a zero vector, causing the motor to decelerate until it reaches almost zero speed.

[0011] (4) Forward starting adopts standard three-stage starting: positioning, open-loop drag acceleration, and closed-loop control, thereby achieving forward rotation of the motor.

[0012] The above processes are executed in sequence to realize the counterwind start of the fan.

[0013] However, the prior art has the following disadvantages:

[0014] (1) The speed measurement uses current detection. When the external wind speed is high, the upper and lower bridges of the three-phase inverter are turned on to form a loop, which will cause the bus voltage to rise too high, posing a safety hazard.

[0015] (2) Forward starting uses a three-stage starter, which may not be able to be fixed in the specified position during positioning, causing the fan to still reverse under the action of external wind force, resulting in a start failure.

[0016] Therefore, it is necessary to disclose a high torque headwind starting control method to overcome the existing defects. Summary of the invention

[0017] The present invention overcomes the shortcomings of the prior art and provides a high-torque headwind starting control method. The commutation success rate and starting success rate are much higher than those of traditional headwind starting solutions, which solves the difficulties of traditional solutions and significantly improves the headwind starting success rate.

[0018] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0019] A high torque headwind starting control method, the operating steps include:

[0020] S1, collecting the terminal voltages Vu, Vv, and Vw of the three-phase circuit of the motor;

[0021] S2, calculated phase voltages Ua, Ub, Uc;

[0022] S3, calculate the speed and position information;

[0023] S4. Determine the fan status:

[0024] (1) In the low-speed headwind state, open-loop deceleration, open-loop acceleration, and closed-loop control are performed in sequence;

[0025] (2) In the high-speed headwind state, the zero vector method is used for deceleration, and the current is used to measure whether the speed is lower than the set state switching speed value SpdHighToLow; if so, the back electromotive force detection is used to calculate the speed and position, and then switch to the headwind low-speed processing program; if not, the zero vector method is used for deceleration again until the speed measured by the current is lower than the set state switching speed value SpdHighToLow;

[0026] (3) In the low-speed tailwind state, open-loop acceleration is performed first, and then closed-loop operation is switched after reaching the set speed;

[0027] (4) When in a stationary state, a three-stage start-up is performed: positioning, open-loop acceleration, and closed-loop control;

[0028] (5) When in high-speed downwind state, it directly enters closed-loop operation.

[0029] Furthermore, the headwind low-speed processing procedure refers to executing open-loop deceleration, open-loop acceleration, and closed-loop control in sequence.

[0030] Furthermore, a resistor R1, R2, R3 with equal and larger resistance and a sampling resistor R4, R5, R6 with equal and smaller resistance are added between the end of the three-phase line of the motor and the ground, and R1 and R4 are connected in series, R2 and R5 are connected in series, and R3 and R6 are connected in series to produce a voltage divider effect, so that the voltage values ​​of the measured values ​​Vu, Vv, and Vw are within the measurement range of the chip ADC module.

[0031] Because when the motor rotates, a back electromotive force is generated on the coil of each phase, and its magnitude changes with time as a sine wave, while the terminal voltage between the terminal and the ground changes with time as a saddle wave. By measuring Vu, Vv, and Vw, the waveform of the terminal voltage can be obtained, and the phase voltage Ua, Ub, and Uc of each phase can be calculated from the terminal voltage.

[0032] Furthermore, for the three-phase voltage values ​​Ua, Ub, and Uc, Clarke transform is performed on them to obtain Uα and Uβ, and then Uα and Uβ are used by using methods such as "inverse tangent to calculate the angle, and then differentiate to calculate the speed" or "phase-locked loop to calculate the speed angle" to calculate the motor speed and position information.

[0033] Furthermore, when the three-phase voltage amplitude is less than the set value VoltThreshold, the motor is considered to be stationary, otherwise it is considered that the motor is rotating; if the motor is in a rotating state, the speed Spd is positive when it is with the wind, and negative when it is against the wind.

[0034] Furthermore, the absolute value of the rotation speed Spd is considered to be high speed when it is greater than a set threshold value SpdThreshold, and is considered to be low speed when it is less than the threshold value.

[0035] Furthermore, when in a high-speed headwind state, the zero vector method is used to decelerate. The three lower bridges of the three-phase inverter are turned on to generate a zero vector, which slows down the motor. While decelerating, the three-phase current is sampled and the speed is calculated.

[0036] Furthermore, when a headwind low speed or deceleration to a headwind low speed is detected, only the current loop is used for foc control; the d-axis reference value Idref of the current loop is 0, the q-axis reference value Iqref is an appropriate value, and the angle is given by the program.

[0037] Furthermore, at the beginning of the headwind and low-speed stage, the angle and speed calculated using the back electromotive force in the previous state are obtained as the initial values ​​of the set angle and the set speed, where the speed is a negative value; then the set speed is increased linearly with time, and the increment of the set angle = set speed * operation time interval; when the set speed increases to the switching speed SpdOpenToClose from open loop to closed loop, the system is switched to the closed-loop forward state.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) Because the state and speed detection are realized by back-electromotive force detection, only the voltage on the terminal voltage sampling resistor needs to be detected, so there is no need to turn on the three-phase inverter, which will not cause the bus voltage to rise.

[0040] (2) Using the back-EMF detection method, the back-EMF value is directly measured and then the speed and angle are calculated. There is no need to run the observer algorithm to estimate the back-EMF. Therefore, the calculation results of the speed and angle are highly accurate.

[0041] (3) At low speed, open-loop dragging is used throughout the entire process from reverse to forward rotation. It is only necessary to obtain the initial values ​​of speed and angle at the start of the open loop, and the subsequent angle values ​​of the entire open loop can be obtained recursively. Even when approaching zero speed, a relatively accurate angle value can be calculated, thereby successfully decelerating from reverse to zero speed and then starting forward. There is no risk of positioning failure in the traditional three-stage start, so the success rate of headwind start is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are used to provide a further understanding of the present invention and are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0043] Figure 1 It is the overall flow chart of the present invention;

[0044] Figure 2 It is the resistance wiring diagram of the three-phase circuit of the motor;

[0045] Figure 3 It is a flow chart that distinguishes five states: high speed against the wind, low speed against the wind, stationary, low speed with the wind, and high speed with the wind;

[0046] Figure 4 This is the bus voltage and current waveform diagram of high-speed adverse wind starting;

[0047] Figure 5 This is the initial waveform diagram of the high-speed headwind stage. DETAILED DESCRIPTION

[0048] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0049] like Figure 1 As shown, the present invention provides a high torque headwind start control method. The overall implementation concept of this scheme is: rotation state detection, speed detection, high speed headwind deceleration, low speed headwind deceleration, and forward start. Therefore, the following steps are followed during the execution process. The flow chart is as follows Figure 1 As shown:

[0050] S1, collecting the terminal voltages Vu, Vv, and Vw of the three-phase circuit of the motor;

[0051] S2, calculated phase voltages Ua, Ub, Uc;

[0052] S3, calculate the speed and position information;

[0053] S4. Determine the fan status:

[0054] (1) In the low-speed headwind state, open-loop deceleration, open-loop acceleration, and closed-loop control are performed in sequence;

[0055] (2) In the high-speed headwind state, the zero vector method is used for deceleration, and the current is used to measure whether the speed is lower than the set state switching speed value SpdHighToLow; if so, the back electromotive force detection is used to calculate the speed and position, and then switch to the headwind low-speed processing program; if not, the zero vector method is used for deceleration again until the speed measured by the current is lower than the set state switching speed value SpdHighToLow;

[0056] (3) In the low-speed tailwind state, open-loop acceleration is performed first, and then closed-loop operation is switched after reaching the set speed;

[0057] (4) When in a stationary state, a three-stage start-up is performed: positioning, open-loop acceleration, and closed-loop control;

[0058] (5) When in high-speed downwind state, it directly enters closed-loop operation.

[0059] like Figure 2 As shown, in the above steps, a resistor R1, R2, R3 with equal and larger resistance and a sampling resistor R4, R5, R6 with equal and smaller resistance are added between the end of the three-phase line of the motor and the ground, and R1 and R4 are connected in series, R2 and R5 are connected in series, and R3 and R6 are connected in series to produce a voltage divider effect, so that the voltage values ​​of the measured values ​​Vu, Vv, and Vw are within the measurement range of the chip ADC module.

[0060] Because when the motor rotates, a back electromotive force is generated on the coil of each phase, and its magnitude changes with time as a sine wave, while the terminal voltage between the terminal and the ground changes with time as a saddle wave. By measuring Vu, Vv, and Vw, the waveform of the terminal voltage can be obtained, and the phase voltage Ua, Ub, and Uc of each phase can be calculated from the terminal voltage.

[0061] For the three-phase voltage values ​​Ua, Ub, and Uc, Clarke transform is performed on them to obtain Uα and Uβ. Then, the motor speed and position information can be obtained by using methods such as "inverse tangent to calculate the angle, and then differentiate to calculate the speed" or "phase-locked loop to calculate the speed angle" for Uα and Uβ.

[0062] like Figure 3 as well as Figure 4 As shown in the figure, when the three-phase voltage amplitude is less than the set value VoltThreshold, the motor is considered to be stationary, otherwise it is considered to be rotating. If the motor is in a rotating state, the speed Spd is positive if it is with the wind, and negative if it is against the wind. The absolute value of the speed Spd is greater than the set threshold SpdThreshold and is considered to be high speed, and below the threshold is considered to be low speed.

[0063] The above-mentioned headwind low-speed processing procedure refers to executing open-loop deceleration, open-loop acceleration, and closed-loop control in sequence.

[0064] The above method can be used to distinguish five states: high speed against the wind, low speed against the wind, stationary, low speed with the wind, and high speed with the wind.

[0065] When the speed is high against the wind, the zero vector method is used to decelerate, and the three lower bridges of the three-phase inverter are turned on to generate a zero vector, so that the motor decelerates. While decelerating, the three-phase current is sampled to calculate the speed. When the speed is lower than the set state switching speed value SpdHighToLow, the back electromotive force detection is used again to calculate the speed and position, and then switch to the low-speed processing program against the wind.

[0066] (4) When a low speed against the wind is detected or the speed is reduced to a low speed against the wind, only the current loop is used for FOC control. The d-axis reference value Idref of the current loop is 0, the q-axis reference value Iqref is an appropriate value, and the angle is given by the program.

[0067] At the beginning of the headwind low-speed stage, the angle and speed calculated using the back electromotive force in the previous state are obtained as the initial values ​​of the set angle and set speed, where the speed is a negative value. Then the set speed is increased linearly with time, and the increment of the set angle = set speed * operation time interval. When the set speed increases to the switching speed SpdOpenToClose of the open-loop to closed-loop, the system is switched to the closed-loop forward state.

[0068] When the status detection result is static, the normal "positioning - open loop - closed loop" three-stage start is performed.

[0069] When the status detection result is a low-speed tailwind, it will first run in open loop, and then switch to closed loop after reaching the set speed.

[0070] When the status detection result is high-speed tailwind, it directly enters closed-loop operation.

[0071] Experimental results:

[0072] The yellow line is the bus voltage waveform, and the green line is the current waveform of one phase.

[0073] The motor has 5 pole pairs and a rated speed of 2400r / min.

[0074] like Figure 5 As shown, the electrical frequency at the start is 149.25 Hz, so the starting speed under high-speed headwind = 149.25*60 / 5 = 1791 r / min.

[0075] like Figure 4 As shown in the figure, under the action of zero vector, the motor gradually decelerates to the specified speed w1, and then switches to open-loop braking. After decelerating to zero speed, the motor turns to the forward direction and accelerates under open-loop starting. When the speed reaches the specified speed w2, the motor switches to closed-loop operation. The reverse wind start-up runs successfully, and there is no bus voltage rise.

[0076] According to experiments, the commutation success rate and start success rate of this solution are much higher than the traditional headwind start solution of "first decelerating to near zero speed, then positioning - open loop - closed loop", and compared with the traditional solution, headwind start can be achieved under headwind with higher speed and greater torque. The difficulties of the traditional solution have been solved, and the success rate of headwind start has been significantly improved.

[0077] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high torque headwind starting control method, characterized in that: The operation steps include: S1, collecting the terminal voltages Vu, Vv, and Vw of the three-phase circuit of the motor; S2, calculated phase voltages Ua, Ub, Uc; S3, calculate the speed and position information; S4. Determine the fan status: (1) In the low-speed headwind state, open-loop deceleration, open-loop acceleration, and closed-loop control are performed in sequence; (2) In the high-speed headwind state, the zero vector method is used for deceleration, and the current is used to measure whether the speed is lower than the set state switching speed value SpdHighToLow; if so, the back electromotive force detection is used to calculate the speed and position, and then switch to the headwind low-speed processing program; if not, the zero vector method is used for deceleration again until the speed measured by the current is lower than the set state switching speed value SpdHighToLow; (3) In the low-speed tailwind state, open-loop acceleration is performed first, and then closed-loop operation is switched after reaching the set speed; (4) When in a stationary state, a three-stage start-up is performed: positioning, open-loop acceleration, and closed-loop control; (5) When in high-speed downwind state, it directly enters closed-loop operation.

2. The high torque headwind starting control method according to claim 1, characterized in that: The headwind low-speed processing procedure refers to executing open-loop deceleration, open-loop acceleration, and closed-loop control in sequence.

3. The high torque headwind starting control method according to claim 1, characterized in that: A resistor R1, R2, R3 with equal and larger resistance and a sampling resistor R4, R5, R6 with equal and smaller resistance are added between the end of the three-phase line of the motor and the ground, and R1 and R4, R2 and R5, and R3 and R6 are connected in series to produce a voltage divider effect, so that the voltage values ​​of the measured values ​​Vu, Vv, and Vw are within the measurement range of the chip ADC module.

4. The high torque headwind starting control method according to claim 3 is characterized in that: By measuring Vu, Vv, and Vw, the waveform of the terminal voltage can be obtained, and the phase voltage Ua, Ub, and Uc of each phase can be calculated from the terminal voltage.

5. The high torque headwind starting control method according to claim 4, characterized in that: Clark transform is performed on the three-phase voltage values ​​Ua, Ub, and Uc to obtain Uα and Uβ. Then, the motor speed and position information can be obtained by using methods such as "inverse tangent to obtain the angle, and then differentiate to obtain the speed" or "phase-locked loop to obtain the speed angle" for Uα and Uβ.

6. The high torque headwind starting control method according to claim 5, characterized in that: When the three-phase voltage amplitude is less than the set value VoltThreshold, the motor is considered to be stationary, otherwise it is considered to be rotating; if the motor is in a rotating state, the speed Spd is positive when it is with the wind, and negative when it is against the wind.

7. The high torque headwind starting control method according to claim 6, characterized in that: The absolute value of the rotation speed Spd is greater than the set threshold SpdThreshold, which is considered as high speed, and is lower than the threshold, which is considered as low speed.

8. The high torque headwind starting control method according to claim 1, characterized in that: When in a high-speed headwind state, the zero vector method is used to decelerate. The three lower bridges of the three-phase inverter are turned on to generate a zero vector, which slows down the motor. While decelerating, the three-phase current is sampled to calculate the speed.

9. The high torque headwind starting control method according to claim 1, characterized in that: When a headwind low speed is detected or the speed is decelerated to a headwind low speed, only the current loop is used for FOC control; the d-axis reference value Idref of the current loop is 0, the q-axis reference value Iqref is an appropriate value, and the angle is given by the program.

10. The high torque headwind starting control method according to claim 1, characterized in that: At the beginning of the headwind and low-speed stage, the angle and speed calculated using the back electromotive force in the previous state are obtained as the initial values ​​of the set angle and the set speed, where the speed is a negative value; then the set speed is increased linearly with time, and the increment of the set angle = set speed * operation time interval; when the set speed increases to the switching speed SpdOpenToClose from open loop to closed loop, the system is switched to the closed-loop forward state.

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