Electrical angle detection device

Abstract

The utility model discloses an electrical angle detection device, which is used for detecting the current electrical angle of a rotor of a servo motor and comprises a control unit, an input unit, a detection unit and a recording unit. The input unit is connected with the control unit, and the control unit controls the input unit to input the target electrical angle and the q-axis current into the servo motor. The detection unit is connected with the control unit, and the control unit controls the detection unit to detect the moving direction of the rotor of the servo motor. And the recording unit is connected with the control unit, and the control unit controls the recording unit to record the moving direction of the rotor of the servo motor. When the moving direction of the rotor of the servo motor is not moving, the control unit controls the input unit to stop electrical angle detection. The control unit controls the input unit to change the target electrical angle when the mover of the servo motor moves in the positive direction or the negative direction.

Description

Technical Field

[0001] The utility model relates to an electrical angle detection device, in particular to a detection device for detecting the electrical angle of a motor mover of a motor in a servo driver. Background Art

[0002] The servo motor, as it's commonly known in the industry, is a general term for devices such as servo motors or linear motors controlled by a servo drive. These devices operate according to the servo drive's instructions. A servo drive typically includes an instruction unit that issues instructions, a control unit that controls the servo motor's movements based on the instructions issued by the instruction unit, and a detection unit that detects and provides feedback on the servo motor's displacement. To detect servo motor displacement, the motor drive typically includes a position detection unit (such as an encoder).

[0003] When controlling a servo motor, the indicator unit requires information about the servo motor's current electrical angle. However, in some servo drives with different servo motors, such as linear motors with incremental encoders, this information is lost after the linear motor loses power. Therefore, after power is restored, the electrical angle phase must be initialized to obtain the current electrical angle information before feedback control can begin.

[0004] Traditionally, Hall effect sensors are installed on the servo motor's actuator to read and convert the current electrical angle. However, Hall effect sensors are expensive, so using other components or methods to detect the servo motor's electrical angle after power is restored has become a pressing issue. Utility Model Content

[0005] In view of the above problems, the purpose of the present invention is to provide an electrical angle detection device that does not require a Hall sensor, so as to reduce costs.

[0006] In addition, during the electrical angle detection process, the mover of the servo motor will move back and forth, and this movement will generate noise. The utility model provides a device that can reduce the movement of the mover of the servo motor while maintaining the accuracy of electrical angle detection, so as to reduce the noise generated by the movement of the mover of the servo motor.

[0007] In order to achieve the above-mentioned purpose, the utility model provides an electrical angle detection device, including a control unit, an input unit, a detection unit and a recording unit, wherein the control unit is connected to the input unit, the detection unit and the recording unit. The control unit controls the input unit to input a target electrical angle and a q-axis current into the servo motor. The control unit controls the detection unit to detect the moving direction of the mover of the servo motor. The control unit controls the recording unit to record the moving direction of the mover of the servo motor after an input time, wherein the moving direction is +, - or 0, representing that the mover of the servo motor moves in a positive direction, moves in a negative direction and does not move, respectively. When the moving direction of the mover of the servo motor is 0, the control unit controls the input unit to stop electrical angle detection, and when the moving direction of the mover of the servo motor is + or -, the control unit controls the input unit to change the target electrical angle.

[0008] In order to further illustrate the features and technical contents of the present invention, preferred embodiments are listed and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a flow chart of the electrical angle detection method of the present invention.

[0010] Figure 2 This is another flow chart of the electrical angle detection method of the present invention.

[0011] Figure 3 FIG. 1 is a schematic diagram of a servo motor mover moving on a magnetic pole in one embodiment.

[0012] Figures 4 to 7 This is a diagram showing changes in the q-axis current of the servo motor input in an example of the electrical angle detection method of the present invention.

[0013] Figure 8 This is a circuit block diagram of the electrical angle detection device of the present invention.

[0014] The reference numerals in the figures are: 100: method; 110, 120, 130, 132, 134, 140, 142: steps; 10: control unit; 12: input unit; 14: detection unit; 16: recording unit; 2: servo motor. Implementation Method

[0015] The embodiments of the present invention are further explained below with reference to the accompanying drawings. Whenever possible, identical reference numerals in the drawings and the specification represent identical or similar components. In the drawings, shapes and thicknesses may be exaggerated for simplicity and convenience. It should be understood that components not specifically shown in the drawings or described in the specification are generally known to those skilled in the art. Those skilled in the art may make various changes and modifications based on the disclosure of the present invention.

[0016] See also Figure 1 、 2 , which shows a flow chart of the electrical angle detection method 100 of the present invention. The electrical angle detection method 100 of the present invention uses an electrical angle detection device to detect the current electrical angle of the mover of the servo motor. The electrical angle detection device can be a servo driver. The electrical angle detection method 100 includes the following steps: the control unit of the electrical angle detection device controls the input unit of the electrical angle detection device to input a target electrical angle and a q-axis current into the servo motor (step 110). After an input time, the control unit controls the detection unit of the electrical angle detection device to detect the moving direction of the mover of the servo motor, and the control unit controls the recording unit to record the moving direction of the mover of the servo motor, wherein the moving direction is +, -, or 0, respectively, represent that the servo motor's mover moves in a positive direction (+), moves in a negative direction (-), and does not move (0) (step 120). The control unit determines whether to continue electrical angle detection based on the moving direction of the servo motor's mover in the recording unit (step 130): when the moving direction of the servo motor's mover is + or -, the control unit controls the input unit to change the target electrical angle and repeats step 120 (step 134). When the moving direction of the servo motor's mover is 0, the control unit controls the input unit to stop electrical angle detection and records the target electrical angle (step 132).

[0017] Furthermore, the electrical angle detection method 100 of the present invention may further include a confirmation step (step 140) after step 132: the control unit controls the input unit to input the target electrical angle and an increased q-axis current into the servo motor, the control unit controls the detection unit to detect the movement direction of the servo motor's mover, and the control unit controls the recording unit to periodically record the movement direction of the servo motor's mover. When the movement direction of the servo motor's mover is + or -, step 120 is repeated. When the movement direction of the servo motor's mover is 0, automatic magnetic pole detection is completed (step 142). When the movement direction of the servo motor's mover is 0, step 140 may be repeated until the q-axis current input to the servo motor reaches a predetermined time period.

[0018] In step 134, when the servo motor's mover is moving in a positive or negative direction, the control unit controls the input unit to change the target electrical angle so that the target electrical angle converges toward the current electrical angle of the servo motor's mover. In one embodiment, the target electrical angle may be approximated to the current electrical angle of the servo motor's mover using an iterative method. For example, the target electrical angle may be changed as follows: when the servo motor's mover is moving in a positive direction, the control unit controls the input unit to decrease the target electrical angle; and when the servo motor's mover is moving in a negative direction, the control unit controls the input unit to increase the target electrical angle.

[0019] In a preferred embodiment, the target electrical angle can be converged to the current electrical angle of the servo motor's mover by a binary method: the control unit sets an electrical angle lower limit θ min , an electrical angle upper limit θ max and a target electrical angle θ r , where the target electrical angle θ r =truncate(θ min +(θ max -θ min ) / 2), i.e., a truncation function of the intermediate value of the upper and lower limits of the electrical angle. The upper and lower limits of the electrical angle are related to the number of poles of the servo motor. In step 134, when the moving direction of the servo motor is + or -, the target electrical angle is changed in the following manner: when the moving direction of the servo motor is +, θ min =θ r ,θ max =θ max ,θ r =truncate(θ min +(θ max -θ min ) / 2), when the moving direction of the servo motor is -, θ min =θ min ,θ max =θ r ,θ r =truncate(θ min +(θ max -θ min ) / 2). When the bisection method is used to converge the target electrical angle, the target electrical angle may use other rounding functions and is not limited to the truncation function.

[0020] In order to shorten the moving distance of the servo motor during electrical angle detection while ensuring the accuracy of electrical angle detection, the present invention provides the following four different implementations of q-axis current input:

[0021] Implementation Method 1

[0022] During the electrical angle detection process, the control unit controls the input unit to continuously input a maximum q-axis current iq max To the servo motor, the maximum q-axis current iq max is the maximum value of an output current of the input unit. The control unit determines whether the target electrical angle has converged to the current electrical angle of the mover of the servo motor every time an input time t1 is inputted. If not, the control unit controls the input unit to change the target electrical angle and continues electrical angle detection until the mover of the servo motor stops moving.

[0023] Implementation Method 2

[0024] During the electrical angle detection process, the control unit controls the input unit to continuously input the maximum q-axis current iq max To the servo motor, the control unit determines whether the target electrical angle has converged to the current electrical angle of the servo motor's mover at each input time t1. If not, the control unit controls the input unit to change the target electrical angle and interrupt the input of the q-axis current. The control unit controls the input unit to resume the input of the q-axis current iq after an interruption time t2. max , where t2≧t1, continue electrical angle detection until the mover of the servo motor stops moving.

[0025] In the above embodiment, the control unit controls the input unit to adjust the ratio of the interruption time t2 to the input time t1 to, for example, 1:1, 1:2, 1:5, 1:10, 1:15, or 1:20, and is not limited to the ratios listed above.

[0026] Implementation 3

[0027] During the electrical angle detection process, the control unit controls the input unit to continuously input a q-axis current iq, which is a constant and less than the maximum value iq of an output current of the input unit. max The control unit determines whether the target electrical angle has converged to the current electrical angle of the servo motor's actuator at each input time interval t1. If not, the control unit controls the input unit to change the target electrical angle and interrupt the input of the q-axis current. The control unit controls the input unit to interrupt for a time interval t2 and then resumes the input of the q-axis current iq. max , where t2≧t1, continue electrical angle detection until the mover of the servo motor stops moving.

[0028] In the above embodiment, the q-axis current iq may be iq max The ratio of the interruption time t2 to the input time t1 can be, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and is not limited to the proportions listed above; the ratio of the interruption time t2 to the input time t1 can be, for example, 1:1, 1:2, 1:5, 1:10, 1:15, 1:20, and is not limited to the proportions listed above.

[0029] Implementation 4

[0030] During the electrical angle detection process, the control unit controls the input unit to continuously input a gradually increasing q-axis current iq, for example, iq=iq0+iq(t1), where the initial value of iq0 is 0, t1 is the input time, iq(t1) is a function that gradually increases with the input time t1, and iq≦iq max , when iq has reached the maximum q-axis current iq maxThen stop increasing iq; the control unit judges whether the target electrical angle has converged to the current electrical angle of the servo motor's mover at each input interval t1. If not, the control unit controls the input unit to change the target electrical angle, make iq0=iq, and intermittently input the q-axis current. The control unit controls the input unit to interrupt for an interruption time t2 and then resume the input of the q-axis current iq, where t2≧t1, and continues the electrical angle detection until the mover of the servo motor stops moving.

[0031] In the above embodiment, iq(t1) may be a function that increases linearly with the input time t1 iq(t1)=c×t1×iq max The coefficient c can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, and is not limited to the proportions listed above; the ratio of the interruption time t2 to the input time t1 can be, for example, 1:1, 1:2, 1:5, 1:10, 1:15, 1:20, and is not limited to the proportions listed above.

[0032] In addition, the electrical angle detection method 100 of the present invention may further include a confirmation step after the control unit stops the electrical angle detection (step 132) when the moving direction of the servo motor is zero: the control unit controls the recording unit to record the target electrical angle θ r The current electrical angle x of the mover of the servo motor is recorded, the control unit input unit inputs the current electrical angle x and the q-axis current iq into the servo motor, the control unit controls the detection unit to periodically detect the moving direction of the mover of the servo motor, and the control unit controls the recording unit to periodically record the moving direction of the mover of the servo motor until the input time of the q-axis current iq input to the servo motor reaches a predetermined time length.

[0033] The following example uses the above four different q-axis current inputs to detect the current electrical angle of a linear motor, where the target electrical angle is converged by a binary method, and the initial electrical angle lower limit θ min =-180°, electrical angle upper limit θ max =180°, target electrical angle θ r =truncate(θ min +(θ max -θ min ) / 2)=0°.

[0034] Reference Figure 3 , which is a schematic diagram of the linear motor. The moving direction of the linear motor's mover moving toward the right is defined as +, and the moving direction moving toward the left is defined as -. Assuming that the current electrical angle x of the linear motor's mover is between -180° and 0°, that is, in the area A shown in the figure, the control unit controls the input unit to input the target electrical angle θ r= 0° will make the linear motor move in the + direction. Assuming that the current electrical angle x of the linear motor is between 0° and 180°, that is, in the area B shown in the figure, the control unit controls the input unit to input the target electrical angle θ r =0° will move the linear motor's actuator in the - direction.

[0035] Example 1

[0036] Figure 4 This graph shows the changes in the q-axis current of the linear motor in Example 1. In this example, the q-axis current iq is a constant iq max The control unit controls the recording unit to record the moving direction of the mover of the linear motor once every time period, and the control unit determines whether to continue the electrical angle detection. Figure 4 The hollow circles in the figure represent the time points at which the target electrical angle is changed, and the hollow triangles represent the time points at which the mover of the linear motor stops moving. The changes in the target electrical angle of Example 1 are shown in Table 1.

[0037] Table 1

[0038]

[0039] Example 2

[0040] Figure 5 This graph shows the changes in the q-axis current of the linear motor in Example 2. In this example, the q-axis current iq is a constant iq max The control unit controls the input unit to interrupt the input of the q-axis current for 10 time periods each time the target electrical angle is changed, and then resumes the input of the q-axis current iq max After a time period, the control unit determines whether to continue electrical angle detection based on whether the target electrical angle has converged to the current electrical angle of the linear motor's mover. Figure 5 The hollow circles in the figure represent the time points at which the target electrical angle is changed, and the hollow triangles represent the time points at which the mover of the linear motor stops moving. The changes in the target electrical angle of Example 2 are shown in Table 2.

[0041] Table 2

[0042]

[0043]

[0044] Example 3

[0045] Figure 6 The graph shows the change of the q-axis current input to the linear motor in Example 3. In this example, the q-axis current iq is iq maxThe control unit controls the input unit to discontinue inputting the q-axis current for 10 time periods each time the target electrical angle is changed, and then resumes inputting the q-axis current iq. After one time period, the control unit determines whether to continue electrical angle detection based on whether the target electrical angle has converged to the current electrical angle of the linear motor's mover. Figure 6 The hollow circles in the figure represent the time points at which the target electrical angle is changed, and the hollow triangles represent the time points at which the mover of the linear motor stops moving. The changes in the target electrical angle of Example 3 are shown in Table 3.

[0046] Table 3

[0047]

[0048]

[0049] Example 4

[0050] Figure 7 The graph shows the change of the q-axis current input to the linear motor in Example 4. In this example, the q-axis current is iq=iq0+c×t1×iq max , where the initial value of iq0 is 0, c = 5%, and the control unit controls the input unit to interrupt the input of the q-axis current for 10 time periods each time after changing the target electrical angle and updating iq0 = iq, and then resumes the input of the q-axis current iq. After one time period, the control unit determines whether to continue electrical angle detection based on whether the target electrical angle has converged to the current electrical angle of the linear motor's mover. Figure 7 The hollow circle in the figure indicates the time point when the target electrical angle is changed, and the hollow triangle indicates the time point when the linear motor's mover stops moving. max When the increase of the q-axis current iq is stopped, the target electrical angle of Example 4 changes as shown in Table 4.

[0051] Table 4

[0052]

[0053]

[0054] In the above examples, the electrical angle detected by Example 1 has the highest accuracy, but the linear motor's mover movement is also the largest. The method of Example 4 can achieve high accuracy while reducing the linear motor's mover movement.

[0055] See also Figure 8The utility model provides an electrical angle detection device, including a control unit 10, an input unit 12, a detection unit 14 and a recording unit 16, wherein the control unit 10 is connected to the input unit 12, the detection unit 14 and the recording unit 16. The control unit 10 controls the input unit 12 to input a target electrical angle and a q-axis current into the servo motor 2. After an input time, the control unit 10 controls the detection unit 14 to detect the moving direction of the mover of the servo motor 2, and the control unit 40 controls the recording unit 16 to record the moving direction of the mover of the servo motor 2, wherein the moving direction is +, - or 0, respectively representing that the mover of the servo motor 2 moves in a positive direction (+), moves in a negative direction (-) and does not move (0). When the moving direction of the mover of the servo motor 2 is 0, the control unit 10 controls the input unit 12 to stop electrical angle detection, and when the moving direction of the mover of the servo motor 2 is + or -, the control unit 10 controls the input unit 12 to change the target electrical angle.

[0056] In some embodiments of the present invention, the control unit 10 may be a microcontroller, the input unit 12 may be a Pi controller, the detection unit 14 may be a magnetic pole detector, and the recording unit 16 may be a memory, a hard disk, a flash memory, etc.

[0057] Although the above example is used to detect linear motors, the electrical angle detection device of the present invention is not limited to the types of servo motors that can be applied. Servo drives and linear motors are both within the application scope of the electrical angle detection device of the present invention.

[0058] The above description is merely an example of a preferred embodiment of the present invention and is not intended to limit the scope of implementation. Any simple replacement or equivalent change based on the scope of the patent application and the content of the patent specification of the present invention shall fall within the scope of the patent application of the present invention.

Claims

1. An electrical angle detection device, characterized in that: include: a control unit; an input unit connected to the control unit, the control unit controlling the input unit to input a target electrical angle and a q-axis current into a servo motor; a detection unit connected to the control unit, the control unit controlling the detection unit to detect the moving direction of the mover of the servo motor; and a recording unit connected to the control unit, the control unit controlling the recording unit to record the movement direction of the mover of the servo motor, wherein the movement direction is +, -, or 0, respectively representing that the mover of the servo motor moves in a positive direction, moves in a negative direction, and does not move; In which, when the moving direction of the mover of the servo motor is 0, the control unit controls the input unit to stop electrical angle detection, and when the moving direction of the mover of the servo motor is + or -, the control unit controls the input unit to change the target electrical angle.

2. The electrical angle detection device according to claim 1, wherein: The moving direction of the mover of the servo motor is in a positive moving direction, and the control unit controls the input unit to reduce the angle of the target electrical angle.

3. The electrical angle detection device according to claim 1, wherein: When the moving direction of the mover of the servo motor is in a negative direction, the control unit controls the input unit to increase the target electrical angle.

4. The electrical angle detection device according to claim 1, wherein: The target electrical angle can be converged toward the current electrical angle of the servo motor's mover by a dichotomous method. The control unit sets an electrical angle lower limit θ. min , an electrical angle upper limit θ max and the target electrical angle θ r , where the target electrical angle θ r =truncate(θ min +(θ max -θ min ) / 2).

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