WO2013044440A1 - Servo motor and servo control system - Google Patents

Abstract

A servo motor and a servo control system. The servo motor comprises a stator (1), a rotor, a linear Hall element (2), and a switch Hall element (3). The linear Hall element (2) and the switch Hall element (3) are provided therebetween with an angle of 90 degrees. The servo motor also comprises a counter-electromotive force detection coil (4). The servo control system comprises a servo controller and the servo motor, while data outputted by the linear Hall element (2), by the switch Hall element (3), and by the counter-electromotive force detection coil (4) enter the servo controller. The servo motor and the servo control system employ only one type of linear Hall sensor (2) and one switch Hall sensor (3) to detect the position of the motor, also, the arrangement of the Hall elements is unrelated to the scheme of motor winding wiring, to the technology of the motor, and to the number of grooves of the motor, and is not sensitive to both installation precision and armature reaction, thus allowing for greatly reduced costs.

Description

 Servo motor and servo control system Technical field

 The present invention relates to a servo motor, and more particularly to a servo motor and a servo control system.

Background technique

Conventional permanent magnet motors and concentrated winding permanent magnet motors may use independent position sensors, such as resolvers or photoelectric encoders, which are not only costly but also difficult to install. In electric bicycles and electric motorcycles, in order to reduce the cost, three switch Halls or 3-4 linear Halls are usually directly mounted on the stator of the motor to form a simple position sensor to realize motor commutation or position detection. In this method, the Hall mounting position is required to be very precise, because when the motor pole pair P is large, the precision of the mechanical installation needs to be increased by P times, and the position of the installation and the winding mode of the motor winding, the number of poles of the motor, and the motor The number of slots has a relationship, especially the armature reaction of the motor has a ±3-5° influence on the position detection. Therefore, the position detection of the simple position sensor is within ±3-10°, which hinders the motor and the controller for a long time. Production and development.

Conventional permanent magnet motors and servo permanent magnet motors may use separate position sensors, such as resolvers or photoelectric encoders, but are costly and difficult to install. In electric bicycles and electric motorcycles, in order to reduce the cost, three switch Hall sensors or 3-4 linear Hall sensors are usually directly mounted on the motor stator to form a simple position sensor to realize motor commutation or position detection. In this method, the mounting position of the Hall sensor is required to be very precise, because when the pole P of the motor is large, the precision of the mechanical installation needs to be increased by P times, and the position of the installation and the winding mode of the motor winding, the number of poles of the motor, There is a relationship between the number of slots of the motor, especially the influence of the armature reaction of the motor on the position detection is ±3-5°. Therefore, the deviation of the position detection of the simple position sensor is about ±3-10°, which hinders the motor and Controller production.

Sine wave drive is the development direction of the motor. It requires complete position information to realize sine wave vector control, but the production cost of sine wave drive is high. In order to reduce costs, the current controller also adopts an estimation based 180° sine wave driving method. It uses the U, V, W switch Hall motor magnetic pole position square wave information, uses the position estimation method to construct the estimated sine wave position information, and then realizes a simple 180 ° sine wave drive. The simple 180° sine wave drive has poor performance during shifting and reliability is not high.

In the Chinese patent No. CN200972824Y, an independent position sensor, namely a Hall resolver, is used, which uses four linear Hall elements to subtract the output voltages of two linear Hall elements arranged at 180°. Trying to compensate for the eccentricity of the stator and rotor assembly, but because it can not compensate the radial and tangential magnetic field components at the same time, it can not play a good compensation effect, and there are also problems such as magnetic pole uniformity. The cost of electric bicycles and electric motorcycles is too high, and independent structure sensors cannot be installed and used.

The Hall resolver in ZL200820207106.9 adds a ring-shaped soft magnetic core to constrain the three-dimensional magnetic field into a two-dimensional magnetic field, which greatly improves the deviation caused by the assembly, but still requires at least two 90° orthogonal Linear Hall elements, or three linear Hall elements with 120° distribution, the accuracy of the distribution and the consistency of the linear Hall elements directly lead to the amplitude error and phase error of the Hall resolver, resulting in position detection deviations, and multiple Linear Hall elements are costly and independent structures cannot be installed and used.

The positional deviation of the existing independent Hall resolver can only reach 0.5°~1°, and the cost performance is not high enough. In addition, the existing Hall encoder cannot directly detect the speed of rotation, and must increase Ω = dθ / dt or the corresponding processing link.

Summary of the invention

The technical problem to be solved by the present invention is to provide a servo motor and a servo control system for the above-mentioned drawbacks of the prior art.

The technical solution adopted by the present invention to solve the technical problem is to construct a servo motor including a stator, a rotor, and a linear Hall element and a switch disposed on the end surface of the stator for detecting the position of the magnetic field of the rotor. The linear Hall element and the switch Hall element are both located on an inner circumferential surface of the stator die, the electrical angle between the linear Hall element and the switching Hall element is 90°, and The magnetic sensitive surfaces of the linear Hall element and the switching Hall element are both opposite to the magnetic pole surface of the rotor;

a counter electromotive force detecting coil for detecting a rotational speed of the rotor is further disposed on the stator pole corresponding to the switch Hall element;

The linear Hall element, the switching Hall element, and the back electromotive force detecting coil are respectively connected to the private controller; when the stator and the rotor are relatively rotated, the linear Hall element, the switching Hall element, and the counter electromotive force The detection coil output data is entered into the servo controller.

The servo motor of the present invention, wherein the slot of the first winding slot of the stator punch is provided with a linear Hall slot matching the size of the linear Hall element; the stator punch is first The stator poles are provided with switch Hall slots matching the size of the switching Hall elements;

The center of the stator slot linear Hall slot is electrically separated from the center of the switch Hall slot by an electrical angle of 90°;

The linear Hall element is located in the linear Hall slot, the switching Hall element is located in the switching Hall slot, and the back electromotive force detecting coil is wound around the first stator pole of the stator chip .

In the servo motor of the present invention, the potential coefficient Ke of the counter electromotive force detecting coil satisfies the following formula:

Ke = V / nmax, and Ke ≤ VCC, where nmax is the maximum speed of the motor, VCC is the power supply voltage of the servo controller control circuit, and V is the potential.

The servo motor of the present invention, wherein the uniqueness of the position and the rotational speed of the servo motor in the range of 360° electrical angle is determined by the following parameters:

Defining the number of pole pairs P=N of the servo motor, the ideal output of the linear Hall element is Vh=V0+VsinNθ, and the ideal output of the switching Hall element is Vk=±Sig∣sinN (θ + 90°) ∣, the ideal output of the counter electromotive force detecting coil is Ve=ΩKsinNθ, and the sign function of the counter electromotive force detecting coil is ±Sig∣Ve∣, where N is a natural number greater than or equal to 1, Ω The speed of the servo motor.

Another technical solution adopted by the present invention to solve the technical problem is to construct a servo control system including a servo controller and a servo motor as described above, the servo controller including a corner conversion circuit, a speed conversion circuit and an Id, An Iq vector control module, wherein the Id, Iq vector control module controls the torque and speed of the servo motor by the quadrature axis current Iq, and expands the speed range of the motor by the direct axis current Id;

The corner conversion circuit is coupled to the linear Hall element, the switching Hall element, and the back electromotive force detecting coil of the servo motor, and includes a sine wave analog output voltage for converting the output of the linear Hall element into a digital A a /D conversion module, the digital quantity obtained by the A/D conversion module is used to distinguish the sine wave by a sign function provided by the switch Hall element, and the sinusoidal wave is multi-valued by a period of 90°, and the back electromotive force detecting coil is used The symbol function ±Sig∣Ve∣ determines the direction of the corner and the speed, and finally obtains a unique digital position signal by the control core operation of the servo controller; the speed conversion circuit includes the back electromotive force detecting coil The ideal output is converted into an analog or digital speed output signal signal filter or A/D conversion module.

The servo control system of the present invention, wherein the control core of the servo controller is a digital signal DSP or a single-chip MCU.

The servo control system of the present invention, wherein the control core of the servo controller is a field programmable gate array FPGA or an application specific integrated circuit ASIC.

In the servo control system of the present invention, the servo motor is an inner rotor motor having a magnetic pole pair P=3 and a slot number S=9.

In the servo control system of the present invention, the servo motor is an outer rotor hub motor having a magnetic pole pair number P=23 and a slot number S=51.

The servo motor and the servo control system embodying the present invention have the following beneficial effects: the present invention uses only one linear Hall sensor and one switch Hall sensor to detect the position of the motor, and simultaneously detects the speed of the motor by using a back electromotive force detecting coil; The arrangement of the Hall element is independent of the winding mode of the motor winding, the number of poles of the motor, and the number of slots of the motor. It is not sensitive to the mounting accuracy and armature reaction, and the cost is very low, and the phase error and amplitude are not generated in principle. difference. The servo control system uses the accurate position and velocity information obtained to control the torque and speed of the motor through the cross-axis current Iq; the speed range of the motor is expanded by the direct-axis current Id control.

DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

1 is a schematic structural view of P=3, S=9 in a preferred embodiment of the servo motor of the present invention;

2 is a schematic structural view of P=23, S=51 in a preferred embodiment of the servo motor of the present invention;

3 is a diagram showing output waveforms of a linear Hall element, a switching Hall element, and a counter electromotive force detecting coil in a preferred embodiment of the servo motor of the present invention;

4 is a circuit block diagram of a servo controller in a preferred embodiment of the servo control system of the present invention;

Figure 5 is a digital output diagram of the corner output of Figure 4 in a preferred embodiment of the servo control system of the present invention;

Figure 6 is a diagram showing digital and analog speed output in a preferred embodiment of the servo control system of the present invention;

7 is a circuit diagram of a preferred embodiment of the servo control system of the present invention when the control core of the servo controller employs an FPGA and an ASIC;

Figure 8 is a perspective view of a preferred embodiment of the servo control system of the present invention;

Figure 9 is a schematic diagram of a preferred embodiment of the servo control system of the present invention.

detailed description

As shown in FIGS. 1 and 2, in a preferred embodiment of the present invention, the servo motor includes a stator 1, a rotor, and a linear Hall element 2 and a switch disposed on an end surface of the stator 1 for detecting a magnetic field position of the rotor. Hall element 3. The linear Hall element 2 and the switching Hall element 3 are provided on the end faces of the stator 1 for the convenience of the leads. As can be seen from the figure, both the linear Hall element 2 and the switching Hall element 3 are located on the inner circumferential surface of the stator punch, and the electrical angle between the linear Hall element 2 and the switching Hall element 3 is 90°. Angle = number of pole pairs × mechanical angle, and the magnetic sensing surfaces of the linear Hall element 2 and the switching Hall element 3 are opposite to the magnetic pole surface of the rotor so that the stator 1 and the rotor move relative to each other, the linear Hall element 2 and the switch Hall The position of the magnetic field of the sensitive permanent magnet of component 3;

A counter electromotive force detecting coil 4 for detecting the rotational speed of the rotor is further provided on the stator pole corresponding to the above-described switching Hall element 3, and the pins of the linear Hall element 2, the switching Hall element 3, and the counter electromotive force detecting coil 4 are both printed and printed. The circuit board is soldered or directly taken out by wires; further, the servo motor further includes a servo controller connected to the linear Hall element 2, the switching Hall element 3, and the counter electromotive force detecting coil 4. When the stator 1 and the rotor rotate relative to each other, the data output from the linear Hall element 2, the switching Hall element 3, and the back electromotive force detecting coil 4 enters the servo controller, and the servo controller controls the torque and speed of the motor.

1 is a schematic structural view when the servo motor is an inner rotor motor with a pole pair number P=3 and a slot number S=9. When the motor rotates at an angular speed ω=PΩ, θ=ωt, the rotation angle is a function of time. The position signal of the linear Hall element 2 is Vh=V0+Vsin3θ, where the sine wave quantity: Vsin3θ=Vsin3ωt, and the motor U's opposite electromotive force eA(t)= E1(t)+ e4(t)+ e7(t), where e1(t), e4(t), and e7(t) are the back electromotive forces of the U-phase windings on the three stator poles of j1, j4, and j7, respectively. , U opposite electromotive force eA(t)= e1(t)+ e4(t)+ e7(t)=3 e1(t)=3Vmsin3ωt, U opposite electromotive force eA(t) and The phase of e1(t) is the same. Since the position of the linear Hall element is in the slot of the stator pole where e1(t) is located, the position signal Vh of the linear Hall element is in phase with the opposite electromotive force of U, which provides the controller with Convenient.

2 is a schematic structural view when the servo motor is an outer rotor motor with a pole pair number P=23 and a number of slots=51. When the motor rotates at an angular speed ω=PΩ, θ=ωt, the rotation angle is a function of time, linear The position signal of the Hall element is Vh=V0+VsinPθ, where the sine wave quantity: VsinPθ=VsinPωt, and the U of the motor is opposite to the electromotive force:

eA(t)=e1(t)-e2(t)+e3(t)-e4(t)+e12(t)-e13(t)+e14(t)+e22(t)-e23(t)+ E24(t)+e32(t)-e33(t)+e34(t)+ E42(t)- E43(t)+e44(t)-e45(t)=VmsinP(θ+φ), the opposite electromotive force of U is made up of series of counter electromotive forces on 17 poles. Since the phase of each pole is different, after U is connected in series, U is reversed. Electromotive force eA(t) and The phase of e1(t) is different, and there is a fixed phase difference φ. The phase difference φ can be measured or calculated by the above equation. The electrical angle phase difference φ=190.5883°=-10.5883° of this embodiment. The phase difference can be biased by software or hardware. After the bias, the U-electromotive force is in phase with the position signal Vh of the linear Hall element to facilitate the controller.

Further, in order to ensure the mechanical mounting accuracy, the slot of the first winding slot of the stator punch is matched with the linear Hall slot of the size of the linear Hall element 2, and the first stator pole of the stator punch is provided with a switch Hall slot having a matching size of the switch Hall element, and when the servo motor is an inner rotor motor, the switch Hall slot is located on the inner circumferential surface of the stator punch, and when the servo motor is an outer rotor hub motor, The switch Hall slot is located on the outer circumferential surface of the stator punch and the linear Hall element 2 is located in the linear Hall slot of the aforementioned stator punch, and the switch Hall element is located in the switch Hall slot, and the back electromotive force detecting coil 4 is wound. On the first stator pole of the stator chip, the pins can be directly indexed by lines. It will be appreciated that the center of the linear Hall slot should be at an electrical angle of 90[deg.] from the center of the Hall slot.

Further, the potential coefficient Ke of the counter electromotive force detecting coil 4 described above satisfies the following formula:

Ke = V / nmax, and Ke ≤ VCC, where nmax is the maximum speed of the motor, VCC is the power supply voltage of the servo controller control circuit, and V is the potential. In a preferred embodiment of the invention, V = 5V, nmax = 1500 rpm, VCC = 5V.

Further, the magnetic pole pair P=N of the servo motor is defined, the ideal output of the linear Hall element 2 is Vh=V0+VsinNθ, and the ideal output of the switching Hall element 3 is Vk=±Sig∣sinN (θ+90°) ∣, the ideal output of the counter electromotive force detecting coil 4 is Ve=ΩKsinNθ, and the sign function of the counter electromotive force detecting coil 4 is ±Sig∣Ve∣, where N is a natural number greater than or equal to 1, Ω is the The speed of the servo motor. If n=3, the output waveforms of the linear Hall element 2, the switching Hall element 3, and the counter electromotive force detecting coil 4 are as shown in FIG.

As shown in FIG. 4, in another embodiment of the present invention, a servo control system includes a servo controller and the above servo motor, and the servo controller includes a corner conversion circuit, a speed conversion circuit, and an Id, Iq vector. The control module, the Id, Iq vector control module is capable of controlling the torque and speed of the servo motor through the quadrature axis current Iq, and expanding the speed range of the motor through the direct axis current Id. Wherein, the corner conversion circuit includes an A/D conversion module for converting the sine wave analog output voltage output from the linear Hall element 2 into a digital quantity, and the digital quantity obtained by the A/D conversion module is provided by the switch Hall element 3. The symbol function is used to distinguish the sinusoidal multi-valued period by 90°, and the sign function ±Sig∣Ve∣ of the back electromotive force detecting coil 4 is used to determine the direction of the corner and the velocity, and finally the uniqueness is obtained by the control core operation of the servo controller. The digital position signal; the speed conversion circuit includes a signal filter or an A/D conversion module for converting the ideal output of the back potential detecting coil 4 into an analog or digital speed output signal.

The working principle of the servo controller is: the A/D conversion module converts the sine wave analog output voltage outputted by the linear Hall element 2 into a digital quantity, and then distinguishes the sine wave by 90° by switching the symbol function provided by the Hall element 3. It is a multi-valued period; the counter-electromotive force detecting coil 4 is converted into a symbol function ±Sig∣Ve∣ by a comparator to determine the direction of the corner and the speed, and then the position determining module is operated to obtain a unique digital position signal. The speed conversion circuit utilizes the ideal output Ve=ΩKsinPθ of the counter electromotive force detecting coil 4 on the stator pole, and converts it into a digital quantity through a signal filter or an A/D conversion module, that is, an analog output or a digital speed output signal Ω. As shown in FIG. 5 and FIG. 6, when a 16-bit A/D conversion module is employed, the speed conversion circuit converts the ideal output of the counter electromotive force detecting coil 4 into a digital quantity by a signal filter or an A/D conversion module, that is, an analog A quantity or digital speed output signal Ω.

Preferably, the control core of the above servo controller may be a digital signal DSP or a single-chip MCU, or a field programmable gate array FPGA or an application specific integrated circuit ASIC.

7 is a schematic diagram showing the circuit structure when the corner conversion circuit is an FPGA and an ASIC. In a specific embodiment of the present invention, a 10-bit A/D conversion circuit, a 12-bit EPROM, and a linear Hall element 2 are used. The output Vh=V0+Vsinθ is filtered and sent to the analog input terminal of the 10-bit A/D conversion circuit. The converted 10-bit digital signals D0-D9 are sequentially connected to the A0-A9 address input terminals of the 12-bit EPROM, as shown in the figure. 9; ideal output of the switching Hall element 3 Vk = ± Sig ∣ sinN (θ+90°)∣ is connected to the A10 address end of the 12-bit EPROM. The ideal output of the back electromotive force detecting coil 4 is Ve=ΩKsinθ, and the sign function is ±Sig∣Ve∣, which is connected to the A11 address end of the 12-bit EPROM. The precision position generating device generates a linearly varying position of 10-bit resolution, and the output Vh of the linear Hall element 2 is converted into a corresponding 10-bit digital signal D (D0 to D9), and the 10-bit digital signal D (D0~) D9), assigned to the A0~A9 address space of the 12-bit EPROM; together with the level of the A10 address terminal to determine the phase of Vh, as shown in Figure 3, since the output of the A/D conversion circuit is connected to the EPROM output, this will The Vh transform is a sawtooth digital output signal that varies linearly with position. The level of the A11 address is used to determine the direction of displacement and velocity. As shown in FIG. 8 and FIG. 9, the angle conversion circuit implemented by the method, U is opposite to the electromotive force eA(t) and The phase of e1(t) may have a fixed phase difference φ. It can be changed from the zero address space by changing the value in the 12-bit EPROM address space. The phase difference φ is subtracted from the value, and the offset is made. The opposite electromotive force is in phase with the position signal Vh of the linear Hall element.

The above embodiments are merely illustrative of the technical concept and the features of the present invention. The purpose of the present invention is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention without limiting the scope of the present invention. Equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the appended claims.

Claims (9)

A servo motor, comprising: a stator (1), a rotor, and a linear Hall element (2) and a switch disposed on an end surface of the stator (1) for detecting a position of the magnetic field of the rotor Element (3); the linear Hall element (2) and the switching Hall element (3) are both located on the circumferential surface of the stator chip, the linear Hall element (2) and the switching Hall element ( 3) The electrical angle between the two is 90°, and the magnetic sensitive surfaces of the linear Hall element (2) and the switching Hall element (3) are both opposite to the magnetic pole surface of the rotor; a counter electromotive force detecting coil (4) for detecting a rotation speed of the rotor is further disposed on the stator pole corresponding to the switching Hall element (3); The linear Hall element (2), the switching Hall element (3), and the counter electromotive force detecting coil (4) are respectively connected to the servo controller. The servo motor according to claim 1, wherein a notch of the first winding groove of the stator punch is provided with a linear Hall matching the size of the linear Hall element (2). a slot of the first stator pole of the stator chip is provided with a switch Hall slot matching the size of the switch Hall element (3); a center of the stator die linear Hall slot and the switch The center of the Hall slot is at an electrical angle of 90° from the space; The linear Hall element (2) is located in the linear Hall slot, the switching Hall element (3) is located in the switching Hall slot, and the counter electromotive force detecting coil (4) is wound around the stator The first stator pole of the punch. The servo motor according to claim 1, characterized in that the potential coefficient Ke of the counter electromotive force detecting coil (4) satisfies the following formula: Ke = V / nmax, and Ke ≤ VCC, where nmax is the maximum speed of the motor, VCC is the power supply voltage of the servo controller control circuit, and V is the potential. 4. The servo motor according to claim 1, wherein the uniqueness of the position and the rotational speed of the servo motor within a range of 360[deg.] electrical angle is determined by the following parameters: Defining the number of pole pairs P=N of the servo motor, the ideal output of the linear Hall element (2) is Vh=V0+VsinNθ, and the ideal output of the switching Hall element (3) is Vk=±Sig∣sinN (θ+90°), the ideal output of the counter electromotive force detecting coil (4) is Ve=ΩKsinNθ, and the sign function of the counter electromotive force detecting coil (4) is ±Sig∣Ve∣, where N is greater than or A natural number equal to 1, Ω is the speed of the servo motor. A servo control system, comprising: a servo controller, and the servo motor according to any one of claims 1 to 4, wherein the servo controller comprises a corner conversion circuit, a speed conversion circuit, and an Id, An Iq vector control module, wherein the Id, Iq vector control module controls the torque and speed of the servo motor by the quadrature axis current Iq, and expands the speed range of the motor by the direct axis current Id; The corner conversion circuit is coupled to the linear Hall element (2) of the servo motor, the switching Hall element (3), and the counter electromotive force detecting coil (4), and includes the output of the linear Hall element (2) The sine wave analog output voltage is converted into a digital A/D conversion module, and the digital quantity obtained by the A/D conversion module is distinguished by a symbol function provided by the switching Hall element (3) to distinguish the sine wave by 90°. For the multi-value of the period, the direction of the rotation angle and the speed is determined by the sign function ±Sig∣Ve∣ of the back electromotive force detecting coil (4), and finally the digital quantity with uniqueness is obtained by the control core operation of the servo controller. Position signal The speed conversion circuit includes a signal filter or an A/D conversion module for converting an ideal output of the counter electromotive force detecting coil (4) into an analog or digital speed output signal. The control system according to claim 5, wherein the control core of the servo controller is a digital signal DSP or a single-chip MCU. 7. The control system of claim 6 wherein the control core of the servo controller comprises a field programmable gate array FPGA or an application specific integrated circuit ASIC. The servo control system according to any one of claims 5-7, wherein the servo motor is an inner rotor motor having a magnetic pole pair P=3 and a slot number S=9. The servo control system according to any one of claims 5-7, wherein the servo motor is an outer rotor hub motor having a magnetic pole pair number P=23 and a slot number S=51.

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