A sensorless sine wave control stall detection method

Abstract

A sensorless sine wave control stall detection method collects three-way back EMF signals; performs Clark and Park transformations to obtain q-axis back EMF values; uses the back EMF signals after Clark transformation as the input of a back EMF observer to obtain an observed estimated speed value; calculates the back EMF proportional coefficient between the speed and the back EMF value of the motor under normal operation according to the q-axis back EMF, and constructs a back EMF value table at different speeds; and makes a difference between the speed value estimated by the back EMF observer and the value obtained by looking up the back EMF value table according to the q-axis back EMF, and if it exceeds the set threshold, it is determined that a stall event has occurred. This method can be implemented on existing brushless DC motors and has good adaptability; the steps are simple and easy to implement. In the case of a speed mutation caused by a torque mutation, the power over-limit caused by a power mutation can be better limited, and the safety of equipment use is effectively guaranteed under the condition of high-speed operation of the motor, and the effectiveness and reliability of stall detection are achieved.

Description

Technical Field

[0001] The invention relates to the field of brushless DC motor control, and in particular to a sensorless sine wave control stall detection method. Background Art

[0002] As the degree of automobile automation continues to improve, the application of motors in automobiles is becoming more and more extensive. Whether it is a traditional fuel vehicle or a new energy vehicle, the motor plays an increasingly important role as an actuator. In the large family of automotive motors, there is a type of motor called a fluid control motor. Many of these motors currently use brushless DC motors or are in the process of switching to brushless DC motors. Brushless DC motors have the characteristics of high efficiency and high reliability. In addition, fluid motors almost never work in the low-speed zone, so sensorless brushless DC motor control is particularly suitable for these automotive applications.

[0003] With the popularity of sensorless sine wave vector control algorithms, high-performance motor applications can operate within the entire frequency range, output rated torque at zero speed, and accelerate and decelerate quickly. At the same time, it also promotes the reduction of motor size, cost and energy consumption, and therefore begins to attract attention from the industry. Commonly used sine wave vector control algorithms include i d =0 control mode and maximum torque current control mode. d =0 control mode, when the motor still outputs torque at zero speed, it will be stalled. There are many reasons for motor stalling, including mechanical or artificial, such as: the rotor and stator are stuck in contact, the driven equipment is stuck, the equipment load is too large and the motor cannot be driven, etc., which will cause stalling. Since there is no access to sensor signals, once encountering external resistance or huge load mutations, the system may enter a stalled state. In this stalled state, the motor just shakes in place and consumes current, and the system will be in an abnormal state. Maintaining this state for a long time is undoubtedly harmful.

[0004] Therefore, a method for detecting stall of a brushless DC motor under sensorless sinusoidal wave control is needed. Summary of the invention

[0005] The present invention provides a sensorless sine wave control stall detection method to solve the problem in the prior art that it is inconvenient to perform stall abnormality detection when a brushless DC motor is in a sensorless sine wave control condition.

[0006] A sensorless sine wave controlled stall detection method, characterized in that it comprises the following steps:

[0007] Step 1: Collect three-phase back electromotive force signals;

[0008] Step 2: Perform Clark and Park transformation on the back-electromotive force signal obtained in step 1 to obtain the q-axis back-electromotive force value;

[0009] Step 3: using the back-EMF signal obtained in step 2 after Clark transformation as the input of the back-EMF observer to obtain an observed estimated speed value;

[0010] Step 4: According to the q-axis back-EMF obtained in step 2, the back-EMF proportional coefficient between the motor speed and the back-EMF value under normal operation is calculated, and a back-EMF value table under different speeds is constructed;

[0011] Step 5: Subtract the q-axis back EMF obtained in step 2 from the speed value estimated by the back EMF observer according to the back EMF value table in step 4. If the difference exceeds the set threshold, it is determined that a stall event has occurred.

[0012] Furthermore, in step 1, collecting three counter-electromotive force signals is replaced by collecting two counter-electromotive force signals.

[0013] Furthermore, in step 2, the Clarke transformation matrix is:

[0014]

[0015] Among them, i A 、i B 、i C is the three-phase stator phase current, which is calculated from the three-phase back electromotive force signal; i α 、i β are the α-axis and β-axis components of the stator current;

[0016] Among them, the Clark transformation of the three-phase back electromotive force signal is:

[0017]

[0018] Among them, u A 、u B 、u C is the three-phase back electromotive force, and the three-phase stator phase current is calculated from the three-phase back electromotive force signal; u α 、u β are the α-axis and β-axis components of the three-phase back electromotive force;

[0019] The Park transformation matrix is:

[0020]

[0021] The angle between the d-axis and the α-axis is defined as θ, that is, the position angle of the rotor relative to the A-phase winding. The q-axis leads the d-axis by 90°, and the i q and id are the q-axis and d-axis components of the stator current.

[0022]

[0023] Among them, u q and u d are the q-axis and d-axis components of the three-way back electromotive force.

[0024] Furthermore, in step three, the back-EMF observer is composed of a Lumberg observer and a phase-locked loop, and the back-EMF signal is Clark transformed and the α-axis and β-axis components of the three-phase stator phase current are used as input signals of the Lumberg observer.

[0025] Furthermore, in step 4, the speed and back electromotive force U of the motor under normal operation are calculated. q The back-EMF proportional coefficient between the values ​​is calculated based on the speed regulation and control method of the sinusoidal wave vector control. When the back-EMF observer works normally, the back-EMF U q The value is proportional to the actual motor speed. According to the rated motor speed ω, the back electromotive force U is calculated in every ω / 100 interval. q The value is calibrated to determine the back electromotive force proportional coefficient k e , construct a back EMF value table at different speeds, and pre-calculate the back EMF U at different speeds according to the back EMF positive proportional coefficient q value and store it.

[0026] Furthermore, in step five, the threshold range for determining a stall event is a percentage of the allowable deviation range, and the threshold range design is given according to the actual power range, which includes inherent deviation compensation for the back-electromotive force proportionality coefficient.

[0027] Beneficial effects of the present invention:

[0028] 1. The sensorless control stall detection method in the technical solution of the present invention can be implemented on the existing brushless DC motor drive hardware structure and has good adaptability.

[0029] 2. The sensorless sine wave control stall detection method in the technical solution of the present invention has a simple step structure and is easy to implement. In the case of a speed mutation caused by a torque mutation, the power overrun caused by a power mutation can be better limited, and the safety of the equipment is effectively guaranteed under the condition of high-speed operation of the motor, and the effectiveness and reliability of stall detection are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Flow chart of the sensorless sine wave control stall detection method in an embodiment of the present invention.

[0031] Figure 21 is a system structure block diagram of a sensorless sinusoidal wave control stall detection method in an embodiment of the present invention.

[0032] Figure 3 1 is an input and output structure diagram of the Lumberg observer and the phase-locked loop in an embodiment of the present invention.

[0033] Figure 4 The figure is a flow chart of stall detection fault detection in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0035] The present invention provides a sensorless sine wave control stall detection method, such as Figure 1 As shown, the optional system structure includes: a three-phase stator winding of a brushless DC motor, an inverter module, a back-EMF acquisition module, and a control module, wherein: the inverter module is connected to the three-phase stator winding of the brushless DC motor, and is used to drive the motor and feedback phase line voltage and current information; the back-EMF acquisition module is connected to the inverter module, and is used to collect three-phase back-EMF; the Lumberg observer is connected to the back-EMF acquisition module, and is used to obtain the estimated value of the three-phase back-EMF after Park; the phase-locked loop module is connected to the Lumberg observer, and is used to decouple the position information of the motor rotor; the control module is connected to the phase-locked loop module, and is used to realize sinusoidal wave control.

[0036] The present invention provides a sensorless sine wave control stall detection method, such as Figure 2 As shown, including:

[0037] Step S10: collecting three-phase back electromotive force signals;

[0038] According to the symmetrical three-phase brushless DC motor, the sum of all back-electromotive force voltage signals is zero, and the acquisition of three back-electromotive force signals can be replaced by the acquisition of two back-electromotive force electrical signals. The digital signals converted by the two ADCs are connected to the control module.

[0039] Step S20: Perform Clark and Park transformation on the back-electromotive force signal obtained in step S10 to obtain the q-axis back-electromotive force value.

[0040] The Clarke transformation matrix in step S20 is:

[0041]

[0042] Among them, i A 、i B 、i C is the three-phase stator phase current, which is calculated from the three-phase back electromotive force signal. α 、iβ are the α-axis and β-axis components of the stator current.

[0043] Optionally, the Park transformation matrix in step S20 is:

[0044]

[0045] The angle between the d-axis and the α-axis is defined as θ, that is, the position angle of the rotor relative to the A-phase winding. The q-axis leads the d-axis by 90°, and the i q and i d are the q-axis and d-axis components of the stator current.

[0046] Step S30: using the back-electromotive force signal obtained in step S20 after Clark transformation as the input of the back-electromotive force observer to obtain an observed estimated rotation speed value.

[0047] like Figure 3 As shown, the back-EMF observer in step S30 is composed of a Romberg observer and a phase-locked loop, wherein the input signal of the Romberg observer is the three-phase back-EMF signal after Clarke transformation and the α-axis and β-axis components of the three-phase stator phase current, the input of the phase-locked loop is the back-EMF signal before decoupling, and the output result is the estimated speed and rotor position information.

[0048] Step S40: According to the q-axis back-EMF value obtained in step S20, the back-EMF proportional coefficient between the motor speed and the back-EMF value under normal operation is calculated, and a back-EMF value table at different speeds is constructed.

[0049] like Figure 4 As shown, in step S40, the speed and back electromotive force U of the motor under normal operation are calculated. q The back-EMF proportional coefficient between the values ​​is calculated based on the speed regulation and control method of the sinusoidal wave vector control. When the back-EMF observer works normally, the back-EMF U q The value is directly proportional to the actual speed of the motor. The back EMF U can be calculated in every ω / 100 interval according to the rated speed ω of the motor. q The value is calibrated to determine the back electromotive force proportional coefficient k e In step S40, a back-electromotive force value table at different speeds is constructed, and the back-electromotive force U at different speeds is pre-calculated according to the back-electromotive force proportional coefficient. q The value is stored in the storage area of ​​the control module.

[0050] Step S50: Subtract the q-axis back EMF obtained in step S20 from the speed value estimated by the back EMF observer according to the back EMF value table in step S40. If the difference exceeds the set threshold, it can be determined that a stall event has occurred.

[0051] like Figure 4As shown, the threshold range for determining a stall event in step S50 is a percentage of the allowable deviation range, and the threshold range design is given according to the actual power range, which includes inherent deviation compensation for the back-electromotive force proportional coefficient.

[0052] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed by the present invention should be included in the protection scope recorded in the claims.

Claims

1. A sensorless sine wave control stall detection method, characterized in that: The steps include: Step 1: Collect three-phase back electromotive force signals; Step 2: Perform Clark and Park transformation on the back-electromotive force signal obtained in step 1 to obtain the q-axis back-electromotive force value; Step 3: using the back-EMF signal obtained in step 2 after Clark transformation as the input of the back-EMF observer to obtain an observed estimated speed value; In step 3, the back-EMF observer is composed of a Lumberg observer and a phase-locked loop, and the back-EMF signal is Clark transformed and the α-axis and β-axis components of the three-phase stator phase current are used as input signals of the Lumberg observer; Among them, the Clark transformation of the three-phase back electromotive force signal is: Among them, u A 、u B 、u C is the three-phase back electromotive force, and the three-phase stator phase current is calculated from the three-phase back electromotive force signal; u α 、u β are the α-axis and β-axis components of the three-phase back electromotive force; Step 4: According to the q-axis back EMF obtained in step 2, the back EMF proportional coefficient between the motor speed and the back EMF value under normal operation is calculated, and a back EMF value table under different speeds is constructed; In step 4, calculate the motor speed and back EMF U under normal operation q The back-EMF proportional coefficient between the values ​​is calculated based on the speed regulation and control method of the sinusoidal wave vector control. When the back-EMF observer works normally, the back-EMF U q The value is proportional to the actual motor speed. According to the rated motor speed ω, the back electromotive force U is calculated in every ω / 100 interval. q The value is calibrated to determine the back electromotive force proportional coefficient k e , construct a back EMF value table at different speeds, and pre-calculate the back EMF U at different speeds according to the back EMF positive proportional coefficient q value and store it; Step 5: Subtract the q-axis back EMF obtained in step 2 from the speed value estimated by the back EMF observer according to the back EMF value table in step 4. If the difference exceeds the set threshold, it is determined that a stall event has occurred.

2. The sensorless sine wave control stall detection method according to claim 1, characterized in that: In step 1, three-phase back electromotive force signals are collected by collecting three-phase sampling resistor voltage or three-phase MOS voltage to achieve three-phase back electromotive force signal collection.

3. The sensorless sine wave control stall detection method according to claim 2, characterized in that: In step 2, the Clarke transformation matrix is: Among them, i A 、i B 、i C is the three-phase stator phase current, which is calculated from the three-phase back electromotive force signal; i α 、i β are the α-axis and β-axis components of the stator current; The Park transformation matrix is: The angle between the d-axis and the α-axis is defined as θ, that is, the position angle of the rotor relative to the A-phase winding. The q-axis leads the d-axis by 90°, and the i q and i d are the q-axis and d-axis components of the stator current.

4. The sensorless sine wave control stall detection method according to claim 3, characterized in that: In step five, the threshold range for determining a stall event is a percentage of the allowable deviation range, and the threshold range design is given according to the actual power range, which includes inherent deviation compensation for the back-electromotive force proportionality coefficient.

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