A real-time angle estimation method for BLDC motor

Abstract

This invention discloses a real-time angle estimation method for a BLDC motor, belonging to the field of motor control. In offline mode, the method identifies the installation deviation of the Hall position encoder to obtain the corrected position information, which is then stored in the driver's memory chip. Subsequently, during normal operation, the corrected angle is used as a basis and compared with the estimated angle to obtain a speed compensation amount for estimating the angle. This speed compensation amount is then superimposed with the average speed and integrated to obtain the real-time motor angle. This allows for rapid correction of the Hall position sensor installation deviation, and the real-time rotor position of the motor is estimated using the corrected position as a reference.

Description

Technical Field

[0001] This invention belongs to the field of motor control, and in particular relates to a real-time angle estimation method for BLDC motors. Background Technology

[0002] In recent years, with the rapid development of new energy vehicles, various types of vehicles on the market have gradually become new energy vehicles, from bicycles to buses. New energy vehicles use unconventional vehicle fuels as their power source, and their power is directly or indirectly derived from electricity, with the motor as the main power output mechanism. In the field of electric motorcycles, considering factors such as cost, brushless DC motors (BLDCMs) are widely used. BLDCMs are equipped with Hall position sensors, but these sensors have low resolution and only provide six position pulses per electrical cycle. Therefore, square waves are often used for driving. However, square wave control has obvious commutation torque pulsation, which affects the driving comfort of the vehicle. In addition, the back EMF of brushless DC motors is mostly sine wave. Therefore, vector control (FOC) has become the first choice for high-performance electric motorcycle controllers. Vector control technology uses the real-time rotor position information of the motor as a reference to control the current amplitude and phase. However, the resolution of Hall position encoders is too low and cannot meet the requirements. Therefore, we propose a real-time angle estimation method for BLDC motors. Summary of the Invention

[0003] This invention provides a real-time angle estimation method for BLDC motors to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a real-time angle estimation method for a BLDC motor, comprising the following steps;

[0005] S1. Identify the installation deviation of the Hall position encoder offline and obtain the corrected position information;

[0006] S1-1. Disconnect the motor load to ensure the motor can rotate freely;

[0007] S1-2, The driver control mode is set to if control, and the motor is driven to run at 20% of the motor's rated speed;

[0008] S1-3. Calculate the encoder angle using the rising edge of the U phase of the Hall encoder as the reference zero point.

[0009]

[0010] In the formula: θ(k) and θ(k-1) are the angles calculated in the k-th and k-1th steps, respectively, vn is the rated speed of the motor, and Ts is the sampling period;

[0011] S1-4. When the edge of the Hall signal is captured, record the encoder angle value calculated in S1-3, and record it continuously for 10 electrical cycles.

[0012] S1-5. Accumulate and average the data from the same edge in step 4 to obtain the actual edge angle θi (i = 1~6), which corresponds to the rising edge of the U phase, falling edge of the W phase, rising edge of the V phase, falling edge of the U phase, rising edge of the W phase, and falling edge of the V phase Hall signal, respectively.

[0013] S1-6. Store the 6 angle values ​​obtained in S1-5 into the driver memory chip. This completes stage one. In the subsequent motor operation, these 6 angles will be used as the actual angles of the Hall signal edge.

[0014] S2. Based on S1, estimate the real-time angle of the motor;

[0015] S2-1. The six edge signals of the Hall encoder divide one electrical cycle of the motor into six sectors.

[0016] S2-2. After the driver is powered on for the first time, it reads the Hall encoder signal to determine the sector where the motor rotor is located. It assumes that the motor rotor is located at the center of the sector, and calculates the initial angle θ0 of the motor based on the angle of the left and right edges of the sector, and drives the motor to run with this angle.

[0017] S2-3. When the encoder signal edge is captured, calculate the average rotational speed between two adjacent edges.

[0018]

[0019] In the formula: Δθ and ΔT are the angular difference between two adjacent edges and the time consumed, respectively;

[0020] S2-4. Record the estimated angle corresponding to the signal edge. The velocity compensation amount vcomp is calculated by comparing it with the actual edge angle and using the adjustable parameter kp.

[0021]

[0022] In the formula: the adjustable parameter kp can be adjusted according to the actual situation;

[0023] S2-5. Estimate the real-time angle of the motor rotor based on the average speed and compensation calculated in steps S2-3 and S2-4.

[0024]

[0025] In the formula: The angles are estimated for the kth and k-1th frames, respectively.

[0026] S2-6. Repeat steps S2-3 to S2-5 during motor operation.

[0027] Furthermore, the Hall effect sensor in S2 can be installed at either 120° or 60°.

[0028] The beneficial effects of this invention are:

[0029] This method first identifies the installation deviation of the Hall position encoder in offline mode to obtain the corrected position information, which is then stored in the driver's memory chip. Subsequently, during normal operation, the corrected angle is used as a basis and compared with the estimated angle to obtain the speed compensation amount used for the estimated angle. This speed compensation amount is then superimposed with the average speed and integrated to obtain the real-time motor angle. This allows for rapid correction of the Hall position sensor installation deviation, and the corrected position is used as a reference to estimate the real-time rotor position of the motor. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the framework structure of the present invention. Detailed Implementation

[0031] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given in conjunction with the accompanying drawings.

[0032] Example:

[0033] like Figure 1 As shown, a real-time angle estimation method for a BLDC motor includes the following steps;

[0034] S1. Identify the installation deviation of the Hall position encoder offline and obtain the corrected position information;

[0035] S1-1. Disconnect the motor load to ensure the motor can rotate freely;

[0036] S1-2, The driver control mode is set to if control, and the motor is driven to run at 20% of the motor's rated speed;

[0037] S1-3. Calculate the encoder angle using the rising edge of the U phase of the Hall encoder as the reference zero point.

[0038]

[0039] In the formula: θ(k) and θ(k-1) are the angles calculated in the k-th and k-1th steps, respectively, vn is the rated speed of the motor, and Ts is the sampling period;

[0040] S1-4. When the edge of the Hall signal is captured, record the encoder angle value calculated in S1-3, and record it continuously for 10 electrical cycles.

[0041] S1-5. Accumulate and average the data from the same edge in step 4 to obtain the actual edge angle θi (i = 1~6), which corresponds to the rising edge of the U phase, falling edge of the W phase, rising edge of the V phase, falling edge of the U phase, rising edge of the W phase, and falling edge of the V phase Hall signal, respectively.

[0042] S1-6. Store the 6 angle values ​​obtained in S1-5 into the driver memory chip. This completes stage one. In the subsequent motor operation, these 6 angles will be used as the actual angles of the Hall signal edge.

[0043] S2. Based on S1, estimate the real-time angle of the motor;

[0044] S2-1. The six edge signals of the Hall encoder divide one electrical cycle of the motor into six sectors.

[0045] S2-2. After the driver is powered on for the first time, it reads the Hall encoder signal to determine the sector where the motor rotor is located. It assumes that the motor rotor is located at the center of the sector, and calculates the initial angle θ0 of the motor based on the angle of the left and right edges of the sector, and drives the motor to run with this angle.

[0046] S2-3. When the encoder signal edge is captured, calculate the average rotational speed between two adjacent edges.

[0047]

[0048] In the formula: Δθ and ΔT are the angular difference between two adjacent edges and the time consumed, respectively;

[0049] S2-4. Record the estimated angle corresponding to the signal edge. The velocity compensation amount vcomp is calculated by comparing it with the actual edge angle and using the adjustable parameter kp.

[0050]

[0051] In the formula: the adjustable parameter kp can be adjusted according to the actual situation;

[0052] S2-5. Estimate the real-time angle of the motor rotor based on the average speed and compensation calculated in steps S2-3 and S2-4, such as... Figure 1 As shown

[0053]

[0054] In the formula: The angles are estimated for the kth and k-1th frames, respectively.

[0055] S2-6. Repeat steps S2-3 to S2-5 during motor operation.

[0056] In other embodiments, the Hall position in S2 can be installed at either 120° or 60°.

[0057] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0058] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A real-time angle estimation method for a BLDC motor, characterized in that: Includes the following steps; S1. Identify the installation deviation of the Hall position encoder offline and obtain the corrected position information; S1-1. Disconnect the motor load to ensure the motor can rotate freely; S1-2, The driver control mode is set to if control, and the motor is driven to run at 20% of the motor's rated speed; S1-3. Calculate the encoder angle using the rising edge of the U phase of the Hall encoder as the reference zero point. In the formula: θ(k) and θ(k-1) are the angles calculated in the k-th and k-1th steps, respectively, vn is the rated speed of the motor, and Ts is the sampling period; S1-4. When the edge of the Hall signal is captured, record the encoder angle value calculated in S1-3, and record it continuously for 10 electrical cycles. S1-5. Accumulate and average the data from the same edge in step 4 to obtain the actual edge angle θi (i = 1~6), which corresponds to the rising edge of the U phase, falling edge of the W phase, rising edge of the V phase, falling edge of the U phase, rising edge of the W phase, and falling edge of the V phase Hall signal, respectively. S1-6. Store the 6 angle values ​​obtained in S1-5 into the driver memory chip. This completes stage one. In the subsequent motor operation, these 6 angles will be used as the actual angles of the Hall signal edge. S2. Based on S1, estimate the real-time angle of the motor; S2-1. The six edge signals of the Hall encoder divide one electrical cycle of the motor into six sectors. S2-2. After the driver is powered on for the first time, it reads the Hall encoder signal to determine the sector where the motor rotor is located. It assumes that the motor rotor is located at the center of the sector, and calculates the initial angle θ0 of the motor based on the angle of the left and right edges of the sector, and drives the motor to run with this angle. S2-3. When the encoder signal edge is captured, calculate the average rotational speed between two adjacent edges. In the formula: Δθ and ΔT are the angular difference between two adjacent edges and the time consumed, respectively; S2-4. Record the estimated angle corresponding to the signal edge. The velocity compensation amount vcomp is calculated by comparing it with the actual edge angle and using the adjustable parameter kp. In the formula: the adjustable parameter kp can be adjusted according to the actual situation; S2-5. Estimate the real-time angle of the motor rotor based on the average speed and compensation calculated in steps S2-3 and S2-4. In the formula: The angles are estimated for the kth and k-1th frames, respectively. S2-6. Repeat steps S2-3 to S2-5 during motor operation.

2. The real-time angle estimation method for a BLDC motor according to claim 1, characterized in that: The Hall effect sensor in S2 can be installed at either 120° or 60°.

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