System and method for detecting position and rotating speed of rotor of switched reluctance motor

Abstract

The invention discloses a system and method for detecting the rotor position and rotating speed of a switched reluctance motor, and belongs to the technical field of switched reluctance motor position detection and rotating speed control. Which comprises a position coding fluted disc (2) and a sensor mechanism (3) which rotate synchronously, and is characterized in that the position coding fluted disc (2) comprises an absolute position coding fluted disc (5) and an increment position coding fluted disc (6) which are coaxially arranged, and the absolute position coding fluted disc (5) or the increment position coding fluted disc (6) is coaxially fixed with a motor shaft (4); the sensor mechanism (3) includes an absolute position sensor (24) and an incremental position sensor (27). According to the detection system and the detection method for the rotor position and the rotating speed of the switched reluctance motor, by arranging the incremental position coding fluted disc, high-resolution incremental position coding is increased, the dynamic response performance of the switched reluctance motor is good when the switched reluctance motor runs at a low speed, and the rotating speed of the motor can still be kept stable when the load torque fluctuates in a large range.

Description

Technical Field

[0001] The invention discloses a detection system and a detection method for the rotor position and speed of a switched reluctance motor, belonging to the technical field of position detection and speed control of switched reluctance motors. Background Art

[0002] The switched reluctance motor is a variable reluctance motor with double salient poles on the stator and rotor. The stator and rotor are both made of laminated silicon steel sheets. The stator poles are wound with concentrated windings, and the rotor has neither windings nor permanent magnets. The motor can be designed into a variety of different phase structures, and the number of poles of the stator and rotor can also be matched in a variety of different ways. This motor has the advantages of simple structure, reliable performance, strong impact resistance, small starting current, large starting torque, wide speed regulation range and high efficiency.

[0003] In order to control the operation of the switched reluctance motor, the controller needs to know the position information of the rotor, which can be collected by the position detection sensor, and the position signal is converted into an electrical pulse signal and sent to the controller. The rotor position detection performance is the key to the reliable operation of the switched reluctance motor and is also a hot research topic.

[0004] The most commonly used rotor position detection method for switched reluctance motors is the method of encoder gear plus position sensor. The encoder gear adopts a tooth structure, and the position sensor adopts a slot type Hall sensor or a slot type photoelectric sensor. The tooth of the gear rotates in the slot of the sensor to generate a position code. The angle period of the code is the angle of the encoder gear rotating through one tooth and one slot, which is also the angle of the motor rotor rotating through one tooth and one slot. The position code characterizes the relative position of the motor rotor and the stator, including at least the maximum inductance position and the minimum inductance position of the switched reluctance motor. The switched reluctance controller controls the switching and commutation of the motor current according to the position code, and calculates the actual speed of the motor according to the position signal. The controller controls the motor winding current according to the deviation between the set speed and the actual speed, thereby controlling the torque of the motor. The problem with this detection method is that when the motor is running at a low speed, the time for the position code to change is long, resulting in a longer time for the speed calculation update. If there is a sudden change in load, the motor speed will fluctuate greatly, and the dynamic response performance of the motor will deteriorate. This affects the performance of the use of rapier looms, electric screw presses, pumping units, etc., which require low-speed operation, frequent start and stop, and frequent forward and reverse operation.

[0005] The switched reluctance motor also uses an integrated encoder installed on the non-shaft end of the motor through a mechanical connection to detect the motor rotor position. One rotation of the motor can generate many pulses, which can solve the dynamic response problem of the motor when running at low speed. However, when the motor is used in situations with large impact loads, frequent starts and stops, or frequent forward and reverse rotation, the encoder is easily damaged by impact.

[0006] The switched reluctance motor can also use a split rotary transformer for rotor position detection, overcoming the mechanical connection problem of the integrated encoder. Due to its high angular resolution, the rotary transformer can solve the dynamic response problem at low speeds. However, when used in situations where there are frequent starts and stops, frequent forward and reverse rotations, and large impact loads, the motor shaft will move, and the bearings will wear quickly and the clearance will increase, resulting in large fluctuations in the clearance between the stator and rotor of the rotary transformer, thereby affecting the acquisition accuracy of the rotary transformer. Since the signal generated by the rotary transformer is a sine-cosine voltage signal, which is generated by the magnetic field induction between its stator and rotor, the signal is easily affected by the motor magnetic field or external magnetic field, and its reliability will also be affected. Summary of the invention

[0007] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art and to provide a detection system and method for the rotor position and speed of a switched reluctance motor, which increases high-resolution incremental position coding by setting an incremental position coding gear disk, has good dynamic response performance when the switched reluctance motor runs at low speed, and can keep the motor speed stable when the load torque fluctuates over a large range.

[0008] The technical solution adopted by the present invention to solve its technical problems is: the detection system of the rotor position and speed of the switched reluctance motor includes a position coding toothed disc rotating synchronously with the motor shaft, and a sensor mechanism rotating relative to the position coding toothed disc, the position coding toothed disc and the sensor mechanism are coaxially arranged, and is characterized in that: the position coding toothed disc includes an absolute position coding toothed disc and an incremental position coding toothed disc coaxially arranged, the absolute position coding toothed disc or the incremental position coding toothed disc is coaxially fixed with the motor shaft, and the sensor mechanism includes an absolute position sensor that mutually senses with the absolute position coding toothed disc and generates a pulse signal, and an incremental position sensor that mutually senses with the incremental position coding toothed disc and generates a pulse signal.

[0009] Preferably, the absolute position encoding gear disc is spaced apart and mounted on the outside of the incremental position encoding gear disc, and absolute gear disc teeth are vertically arranged at the edge of the absolute position encoding gear disc, and the absolute gear disc teeth pass through the absolute position sensor, and incremental gear disc teeth are vertically arranged at the edge of the incremental position encoding gear disc, and the incremental gear disc teeth pass through the incremental position sensor.

[0010] Preferably, a plurality of absolute gear fixing holes are provided on the disk surface of the absolute position encoding gear, and incremental gear fastening holes corresponding to the absolute gear fixing holes are provided on the disk surface of the incremental position encoding gear, and a positioning mechanism is also provided between the absolute position encoding gear and the incremental position encoding gear.

[0011] Preferably, the sensor mechanism comprises a cover body, which is fixed to the surface of the motor end cover of the switched reluctance motor, through which the motor shaft passes, and the cover body covers the position encoding gear disc.

[0012] Preferably, a detection circuit board is fixed on the inner wall of the cover body, a position signal processing circuit is arranged on the surface of the detection circuit board, and the absolute position sensor and the incremental position sensor are connected to the position signal processing circuit.

[0013] Preferably, the detection circuit board is fan-shaped, and multiple absolute position sensors and incremental position sensors are respectively provided, with the center of the detection circuit board as the vertex, and multiple absolute position sensors are arranged at equal angles, and multiple incremental position sensors are arranged at equal angles.

[0014] Preferably, on the surface of the detection circuit board, with the center of the detection circuit board as the vertex, the angle between any two adjacent absolute position sensors is 15°, the angle between any two adjacent incremental position sensors is 18°, and the incremental position sensor is arranged between two adjacent absolute position sensors.

[0015] Preferably, a lead terminal is provided on the side of the cover body, and the guide is connected to the detection circuit board through the lead terminal.

[0016] A detection method implemented by the detection system for the rotor position and speed of a switched reluctance motor according to any one of claims 1 to 8, characterized in that it comprises the following steps: Step 1, define a 32-bit circular queue array. The number of pulses generated by one rotation of the incremental encoder gear is P, then the array length is: P+2, define a 16-bit head pointer variable and a 16-bit tail pointer variable; Step 2, the incremental position encoder gear wheel rotates, the incremental position sensor signal jumps, the microprocessor connected to the incremental position sensor captures the jump and generates an interrupt, and the interrupt program records the timer time and code of the interrupt; Step 3, the interrupt program determines whether the circular queue is full. If so, the head pointer is incremented by one, the tail pointer is incremented by one, and the current position interrupt time is stored in the circular queue; Step 4, the microprocessor determines the number of pulses of the current calculated speed according to the previous speed value. Assume that the previous speed value is S, the proportional coefficient is R, and the number of pulses of the current calculated speed is C, then C=S / R. If C is greater than the number of pulses P generated by one rotation of the incremental position encoder toothed disc, then C=P. If C is less than 1, then C=1. Step 5, determine whether the length of the data stored in the circular queue is greater than or equal to C+1: if not, wait for a sufficient number of position pulse times to be stored in the circular queue; if yes, take out the data T1 pointed to by the tail pointer from the circular queue, and then take out the data T2 at the Cth position before the tail pointer, and calculate the time difference between the two as T; Step 6, assume that the time of the M timing units of the timer is 1μs, and calculate the motor speed n according to the total number of pulses P when the gear rotates one circle, the number of pulses C required to calculate the speed, and the interval time T of C pulses: n = 60000000*M*C / T / P (r / min).

[0017] Compared with the prior art, the present invention has the following beneficial effects: In the detection system and method for the rotor position and speed of the switched reluctance motor, high-resolution incremental position encoding is added by setting an incremental position encoding gear. The switched reluctance motor has good dynamic response performance when running at low speed, and the motor speed can still remain stable when the load torque fluctuates over a large range.

[0018] In the detection system and method for the rotor position and speed of the switched reluctance motor, the encoder gear and the position sensor are installed separately, and the rotor position signal is detected contactlessly, which can meet the requirements of motor applications with frequent impacts, frequent starts and stops, and frequent forward and reverse rotations.

[0019] In the detection system and method for the rotor position and speed of the switched reluctance motor, an algorithm is adopted to dynamically change the number of pulses required for calculating the speed according to the actual speed. A set of PID parameters can be used to achieve the same dynamic response performance within the full speed range of the motor, eliminating the problem of unstable operation caused by changing the PID parameters according to different speeds.

[0020] In the detection system and method for the rotor position and speed of the switched reluctance motor, the position circuit board is installed in the sensor cover, and the cable is connected through a cable fastening head, which has good sealing performance and is convenient for installation, adjustment and maintenance.

[0021] The detection system and method for the rotor position and speed of the switched reluctance motor can have good dynamic response performance and impact resistance at low speed. The detection system can be applied to switched reluctance motor driving occasions that require low-speed operation, impact loads, frequent starts and stops, or frequent forward and reverse reversals. It has the advantages of simple structure, reliable operation, low cost, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the exploded diagram of the detection system for the rotor position and speed of the switched reluctance motor.

[0023] Figure 2 This is a schematic diagram of the position encoding gear structure of the switched reluctance motor rotor position and speed detection system.

[0024] Figure 3 This is a schematic diagram of the incremental position encoding gear structure of the switched reluctance motor rotor position and speed detection system.

[0025] Figure 4 This is a schematic diagram of the absolute position encoding gear structure of the switched reluctance motor rotor position and speed detection system.

[0026] Figure 5 Schematic diagram of the sensor mechanism of the detection system for the rotor position and speed of the switched reluctance motor.

[0027] Figure 6 This is a schematic diagram of the cover structure of the detection system for the rotor position and speed of the switched reluctance motor.

[0028] Figure 7 This is a schematic diagram of the structure of the detection circuit board of the detection system for the rotor position and speed of the switched reluctance motor.

[0029] Figure 8 This is a schematic diagram of the motor end cover structure of the switched reluctance motor rotor position and speed detection system.

[0030] Fig. 9 This is the schematic diagram of the position detection circuit of the detection system for the rotor position and speed of the switched reluctance motor.

[0031] Fig.10 This is the schematic diagram of the isolation circuit and microprocessor pulse signal input of the detection system for the rotor position and speed of the switched reluctance motor.

[0032] Fig.11 The figure is a flow chart of a method for detecting the rotor position and speed of a switched reluctance motor.

[0033] Wherein: 1, motor end cover 2, position coding gear disc 3, sensor mechanism 4, motor shaft 5, absolute position coding gear disc 6, incremental position coding gear disc 7, incremental gear ring 8, incremental gear disc surface 9, incremental gear disc fastening hole 10, incremental gear disc positioning hole 11, incremental gear disc stop 12, absolute gear disc teeth 13, absolute gear disc surface 14, absolute gear disc fixing hole 15, absolute gear disc positioning column 16, absolute gear disc stop 17, detection circuit board 18, lead terminal 19, cover body shaft hole 20, cover body 21, circuit board fixing hole 22, cover body mounting hole 23, cover body fixing hole 24, absolute position sensor 25, plate body 26, plate body fixing hole 27, incremental position sensor 28, end cover mounting stop 29, end cover fixing hole. DETAILED DESCRIPTION

[0034] Figures 1 to 11 The best embodiment of the present invention is shown below in conjunction with the attached Figures 1 to 11 The present invention is further described.

[0035] like Figure 1As shown, a detection system for the rotor position and speed of a switched reluctance motor (hereinafter referred to as the detection system) includes a position encoding toothed disc 2 coaxially fixed with the motor shaft 4 of the switched reluctance motor, and a sensor mechanism 3. The sensor mechanism 3 is coaxially fixed with the motor end cover 1 of the switched reluctance motor, and the position encoding toothed disc 2 is covered therein. In this detection system, the motor end cover 1 is the end cover of the non-axial extension end of the switched reluctance motor. After the motor shaft 4 passes through the center of the motor end cover 1, the switched reluctance motor drives the motor shaft 4 to rotate coaxially at the motor end cover 1 when rotating. Since the position encoding toothed disc 2 is coaxially fixed with the motor shaft 4, and the sensor mechanism 3 is coaxially fixed with the motor end cover 1, when the motor shaft 4 rotates, the position encoding toothed disc 2 and the sensor mechanism 3 rotate relative to each other.

[0036] like Figure 2 As shown, the position coding toothed disc 2 includes a coaxially fixed absolute position coding toothed disc 5 and an incremental position coding toothed disc 6, wherein the incremental position coding toothed disc 6 is located as a whole on the inner side of the absolute position coding toothed disc 5, wherein the absolute position coding toothed disc 5 is coaxially fixed to the motor shaft 4 by means of a shrink sleeve, so that even if the switched reluctance motor is frequently started and stopped, it will not loosen. The outer ring of the absolute position coding toothed disc 5 is spaced from the outer ring of the incremental position coding toothed disc 6, and the difference between the outer diameter of the absolute position coding toothed disc 5 and the outer diameter of the incremental position coding toothed disc 6 is preferably 10 mm.

[0037] Combination Figure 3 The incremental position coding toothed disc 6 includes a circular incremental toothed disc surface 8, a circular incremental gear ring 7 is arranged at the edge of the incremental toothed disc surface 8, the incremental gear ring 7 is perpendicular to the incremental toothed disc surface 8, and a plurality of incremental position teeth are arranged at intervals in the incremental gear ring 7. The incremental toothed disc stop 11 of the incremental position coding toothed disc 6 is located at the center hole of the incremental toothed disc surface 8, and three incremental toothed disc fastening holes 9 are evenly arranged on the outside of the incremental toothed disc stop 11. The incremental toothed disc fastening holes 9 are arc-shaped holes that penetrate the incremental toothed disc surface 8, and the three incremental toothed disc fastening holes 9 are located on the same circumference. An incremental toothed disc positioning hole 10 is opened on the side of any incremental toothed disc fastening hole 9.

[0038] Combination Figure 4The absolute position coding toothed disc 5 includes a circular absolute toothed disc surface 13, and a plurality of absolute toothed disc teeth 12 are evenly arranged at the edge of the incremental toothed disc surface 8. An absolute toothed disc stop 16 is provided at the center hole of the incremental toothed disc surface 8. The center hole of the absolute toothed disc stop 16 is equal in diameter to the center hole of the incremental toothed disc surface 8, and the thickness of the absolute toothed disc stop 16 is about 10 mm greater than the thickness of the incremental toothed disc surface 8, so as to ensure that the absolute position coding toothed disc 5 has a sufficiently large clamping force when fixed to the motor shaft 4. The diameter of the absolute toothed disc surface 13 of the absolute position coding toothed disc 5 is determined by the motor frame number. The larger the frame number, the larger the diameter of the motor shaft 4, and the larger the diameter of the toothed disc. For motors with frame numbers of 180 to 315, a disc diameter of 150 mm is generally selected. For the commonly used stator and rotor 12 / 8 pole switched reluctance motor, the rotor is a structure of 8 teeth and 8 slots. In this detection system, the absolute position coding toothed disc 5 is also designed as a structure of 8 teeth and 8 slots.

[0039] Three absolute gear fixing holes 14 are evenly arranged on the outside of the absolute gear stop 16, and the three absolute gear fixing holes 14 correspond to the three incremental gear fastening holes 9 on the incremental position encoding gear 6. And an absolute gear positioning column 15 is arranged on the side of any absolute gear fixing hole 14. The absolute gear positioning column 15 on the surface of the absolute gear disc surface 13 corresponds to the incremental gear disc positioning hole 10 on the surface of the incremental gear disc surface 8.

[0040] When the absolute position coding toothed disc 5 and the incremental position coding toothed disc 6 are combined, the absolute toothed disc positioning column 15 passes through the incremental toothed disc positioning hole 10. At this time, the three absolute toothed disc fixing holes 14 are correspondingly located at the lower side of the three incremental toothed disc fastening holes 9. Since the incremental toothed disc fastening holes 9 are arc-shaped holes, they are easy to align with the absolute toothed disc fixing holes 14 and are easy to assemble. The absolute position coding toothed disc 5 and the incremental position coding toothed disc 6 are arranged radially at intervals through the absolute toothed disc stop 16. Finally, the absolute position coding toothed disc 5 and the incremental position coding toothed disc 6 are coaxially fixed by bolts that pass through the incremental toothed disc fastening holes 9 and are screwed into the absolute toothed disc fixing holes 14.

[0041] After the absolute position encoding gear disc 5 and the incremental position encoding gear disc 6 are coaxially fixed, the incremental position gear disc teeth of the outer ring of the incremental position encoding gear disc 6 are located on the outside of the absolute gear disc teeth 12 of the outer ring of the absolute position encoding gear disc 5, and the number of the incremental position gear disc teeth is 10 to 20 times the number of the absolute gear disc teeth 12. Since the tooth width of the incremental position gear disc is small, the edge of the incremental position gear disc teeth cannot be punched out to ensure that the edges of the gear disc teeth are connected as a whole and will not be deformed due to bumps.

[0042] like Figure 5As shown, the sensor mechanism 3 includes a cover 20, a detection circuit board 17 is fixed on the cavity wall of the inner cavity of the cover 20, and a lead terminal 18 is provided on one side of the cavity wall of the inner cavity of the cover 20. The wire is connected to the detection circuit on the detection circuit board 17 through the lead terminal 18, and the signal output by the detection circuit is led out. A cover shaft hole 19 is opened in the middle of the cover 20, and the motor shaft 4 passes through the cover shaft hole 19, and a labyrinth seal is provided at the cover shaft hole 19 to prevent dust from entering the cover 20.

[0043] like Figure 6 As shown, a circuit board fixing hole 21 is provided on the surface of the inner cavity of the cover body 20, and the detection circuit board 17 is fixed in the cover body 20 through the circuit board fixing hole 21. An annular edge is provided on the outer ring of the cover body 20, and a plurality of cover body mounting holes 22 are evenly provided in the edge. The cover body mounting holes 22 are arc-shaped through holes. A cover body fixing hole 23 is also provided between any two cover body mounting holes 22, and there are three cover body fixing holes 23. A knocking groove is provided on the outer side of each cover body fixing hole 23, and the knocking groove is provided along the radial direction of the edge.

[0044] like Figure 7 As shown, the detection circuit board 17 includes a fan-shaped plate body 25, and three absolute position sensors 24 are evenly arranged on the surface of the plate body 25. With the center of the circle on the surface of the detection circuit board 17 as the vertex, the angle between any two adjacent absolute position sensors 24 of the three absolute position sensors 24 is 15°. The absolute position sensor 24 adopts a slot-type photoelectric sensor or a slot-type Hall sensor known in the art. After the sensor mechanism 3 is fixed on the surface of the motor end cover 1, the absolute gear teeth 12 of the outer ring of the absolute position encoding gear 5 in the position encoding gear 2 pass through the three absolute position sensors 24.

[0045] The teeth 12 of the absolute gear disc rotate in the three absolute position sensors 24 slots, generating three position signals with a phase difference of 120°, which can synthesize 6 pulse codes. The forward code of the motor is "101->100->110->010->011->001", and the reverse code is "001->011->010->110->100->101". The code is Gray code, with only one bit jump at any time, which is convenient for the microprocessor to filter out interference pulses. The absolute position encoding gear disc 5 generates 48 pulses when the rotor rotates one circle. The absolute position code characterizes the relative position of the rotor and stator of the switched reluctance motor, which is used to control the winding current switch and commutation, control the opening angle and the closing angle, and can be used to calculate the speed of the motor when the speed is relatively high.

[0046] Two incremental position sensors 27 are also arranged between any two adjacent absolute position sensors 24, and the diameter of the circumference of the two incremental position sensors 27 is smaller than the diameter of the circumference of the three absolute position sensors 24. With the center of the plate 25 as the vertex, the angle between the two incremental position sensors 27 is 18°. After the sensor mechanism 3 is fixed on the surface of the motor end cover 1, the incremental gear teeth of the outer ring of the incremental position encoding gear 6 in the position encoding gear 2 pass through the two incremental position sensors 27.

[0047] In this detection system, the incremental position encoding toothed disc 6 uses 80 teeth and 80 slots, and the incremental position sensor 27 uses a slot-type photoelectric sensor or a slot-type Hall sensor known in the art, and the teeth of the incremental toothed disc pass through the incremental position sensor 27. The teeth of the incremental toothed disc rotate in the two incremental position sensors 27, and can synthesize two sequences of pulse codes for forward rotation and reverse rotation. The forward rotation code is "00->10->11->01", and the reverse rotation code is "01->11->10->00". The incremental position code is also Gray code, with only one bit jumping at any time, which is convenient for the microprocessor to filter out interference pulses. The incremental position code can be used to calculate the speed of the motor when it is running at medium and low speeds, and can also participate in the control of the opening angle and the closing angle. In the case of frequent start and stop and forward and reverse rotation, the incremental position code can improve the accuracy of the opening angle and the closing angle. The incremental position encoder toothed disc 6 generates 320 position pulses per rotation. When the motor speed reaches a low speed of 10r / min, the interval between two pulses is 18.75ms. The microprocessor can calculate and refresh the speed every 18.75ms. With the appropriate PID parameters, it can meet the dynamic response performance requirements of load mutations. If only absolute encoding acquisition is used, the microprocessor can refresh the speed every 125ms when the motor runs at 10r / min, and the dynamic response performance is poor.

[0048] Board fixing holes 26 are respectively provided on both sides of the surface of the detection circuit board 17. The arrangement of the board fixing holes 26 on both sides corresponds to the arrangement of the circuit board fixing holes 21. The fixing bolts pass through each board fixing hole 26 and are screwed into the corresponding circuit board fixing hole 21 to fix the board 25 in the cover body 20.

[0049] like Figure 8 As shown, an end cover mounting stop 28 is provided at the center of the motor end cover 1, and three end cover fixing holes 29 are evenly arranged on the outer circle of the end cover mounting stop 28. The three end cover fixing holes 29 correspond one to one with the three cover body fixing holes 23 at the edge of the cover body 20. The fixing bolts pass through each cover body fixing hole 23 and are screwed into the corresponding end cover fixing holes 29 to fix the cover body 20 on the surface of the motor end cover 1, thereby realizing the fixation of the sensor mechanism 3 and the motor end cover 1.

[0050] Since the absolute position coding toothed disc 5 does not perform angular positioning in the circumferential direction when it is shrink-fitted onto the shaft, it is necessary to rotate the cover body 20 to obtain the corresponding relationship between the position coding and the position of the motor rotor and stator. Therefore, the cover body mounting hole 22 at the edge of the cover body 20 adopts an arc hole, and the angle of the cover body mounting hole 22 is the angle of one tooth and one slot of the absolute position coding toothed disc 5, ensuring that it can be turned to the required positioning code. The positioning method of the position coding is specifically operated as follows: the controller is used to energize the A-phase winding of the motor, so that the stator salient pole of the A-phase winding is aligned with the rotor salient pole, and the cover body 20 is rotated to a certain position. When the position coding jumps between two codes, such as the jump between 001 and 101, the position is the maximum inductance position of the A-phase, and the positioning is completed. Then, the bolts used to fix the cover body 20 are tightened. The knocking groove set at the edge of the cover body 20 is used to knock the cover body 20 to rotate it during positioning.

[0051] As can be seen from the above, there are five absolute position sensors 24 and incremental position sensors 27, and five corresponding position signal processing circuits with the same circuit structure are provided. The detection circuit board 17 is powered by a 12V power supply, and the power supply is provided by the power isolation module S1 of the controller main control board. Since the voltage and current of the switched reluctance motor winding are controlled by the controller IGBT, and the time for the IGBT to switch a large current is about 1μs, there will be ringing wave interference, and the position signal processing circuit also needs to be provided with an isolation circuit to achieve an anti-interference effect. The position signal processing circuit and the isolation circuit are both arranged on the surface of the board 25.

[0052] like Fig. 9 As shown, the position signal processing circuit includes a position sensor H1 (absolute position sensor 24 or incremental position sensor 27), the ground end of the position sensor H1 is grounded, and its signal output end is simultaneously connected to a resistor R1 and one end of a capacitor C2, the other end of the resistor R1 is connected to the positive electrode of a 12V DC power supply, and the other end of the capacitor C2 is grounded. The output end of the position sensor H1 is simultaneously connected to the input end of a Darlington tube T1, the ground end of the Darlington tube T1 is grounded, the output end of the Darlington tube T1 is connected to the anode of a diode D1 and the cathode of a diode D2, the cathode of the diode D1 is connected to the positive electrode of a 12V DC power supply, and the anode of the diode D2 is grounded. The output end of the Darlington tube T1 is also connected to one end of a resistor R2, the other end of the resistor R2 is connected to one end of a capacitor C3 and the controller mainboard U2, and the other end of the capacitor C3 is grounded.

[0053] The position sensor H1 senses the absolute gear teeth 12 or the incremental gear teeth to generate a pulse signal. The pulse signal is filtered by the low-pass filter circuit composed of resistor R1 and capacitor C2, and then passes through Darlington tube T1 to improve the current driving ability, and then passes through the level clamping diodes D1~D2 to filter out possible high-voltage interference, and then passes through the output current limiting resistor R2 and filter capacitor C3 to the controller main control board. The Darlington tube can be selected as ULN2004, which has 7-way drive to meet the requirements of 5-way sensor signals.

[0054] The detection circuit board 17 sends the position coding signal to the controller main board U2 through a cable. The signal needs to be isolated before being sent to the microprocessor U3 to reduce the impact of motor side interference on the control circuit. The isolation circuit includes a high-speed optical coupler device U1, such as Fig.10 As shown, the signal output by Darlington tube T1 is connected to one end of resistor R3 through the corresponding port of controller mainboard U2, and the other end of resistor R3 is simultaneously connected to one end of capacitor C6, one end of resistor R4, the anode of diode D3 and the negative input electrode of optocoupler U1. The positive electrode of 12V DC power supply is simultaneously connected to the other end of capacitor C6, the other end of resistor R4, the cathode of diode D3 and the positive input electrode of optocoupler U1.

[0055] The positive electrode of the 3.3V DC power supply is connected to one end of the capacitor C7 and the power input end of the optocoupler U1. The output end of the optocoupler U1 is connected in series with the resistor R5 to the capacitor C8 and the input end of the inverter U4. The other end of the capacitor C8 is grounded. The output end of the inverter U4 is connected to the microprocessor U3.

[0056] The position pulse signal is sent to the high-speed optocoupler input port through the current limiting resistor R3, filter capacitor C6, protection resistor R4, and reverse voltage clamping diode D3. The optocoupler output signal is low-pass filtered by R5 and C8, and then shaped by inverter U4, and then sent to the high-speed capture input port CIN0~CIN4 of the microprocessor U3. The high-speed optocoupler can be TLP2168, and the microprocessor U3 can be ARM core chip, such as LPC43xx series, which has multiple high-speed capture input ports and PWM output, suitable for motor control.

[0057] When the position signal pulse jumps, the high-speed capture input port of the microprocessor U3 will trigger an interrupt. The interrupt program can record the absolute position code and incremental position code at this time, as well as the time of the jump. The interrupt program of the absolute position code controls the on and off of the winding current and can also be used for speed calculation. The interrupt control program of the incremental position code is mainly used for pulse time storage and speed calculation, and can also be used for high-precision opening angle and closing angle control.

[0058] Microprocessor U3 uses a circular queue to store incremental position pulse time. When the queue is full, the newly collected pulse time automatically covers the earliest pulse time. The circular queue saves the latest position pulse sequence time in order. The speed calculation program takes data from the circular queue to calculate the motor speed. Microprocessor U3 determines the number of position pulses for calculating the motor speed based on the previous motor speed value. The number of pulses is proportional to the speed. The maximum value is the number of pulses generated by one rotation of the rotor plus 1, and the minimum value is 2 pulses.

[0059] like Fig.11 As shown, the detection method implemented by the above detection system includes the following steps: Step 1, program initialization, establish a circular queue: Define a 32-bit circular queue array. The number of pulses generated by one rotation of the incremental encoder gear is P, so the array length is: P+2. Define a 16-bit head pointer variable and a 16-bit tail pointer variable.

[0060] Step 2, interrupt the program to record the position pulse jump time: The incremental position encoder toothed disc 6 rotates, the incremental position sensor 27 signal jumps, the high-speed capture input pin CTIN_3 or CTIN_4 of the microprocessor U3 jumps, an interrupt is generated, and the interrupt program records the timer time and code of the interrupt.

[0061] Step 3, store the position pulse interruption time into the circular queue: The interrupt program determines whether the circular queue is full. If so, the head pointer is incremented by 1. The tail pointer is incremented by 1, and the current position interrupt time is stored in the circular queue.

[0062] Step 4, determine the number of position pulses required to calculate the speed: The speed calculation program determines the number of pulses of the current speed calculation based on the previous speed value. Assume that the previous speed value is S, the proportional coefficient is R, and the number of pulses of the current speed calculation is C, then C=S / R. If C is greater than the number of pulses P generated by one rotation of the incremental position encoder toothed disc 6, then C=P. If C is less than 1, then C=1.

[0063] Step 5, take out the corresponding position pulse time from the circular queue and calculate the time difference: Determine whether the length of the data stored in the circular queue is greater than or equal to C+1: If not, wait for a sufficient number of position pulse times to be stored in the circular queue; if so, take out the data T1 pointed to by the tail pointer from the circular queue, and then take out the data T2 at the Cth position before the tail pointer, and calculate the time difference between the two as T.

[0064] Step 6, calculate the motor speed: Assume that the time of M timing units of the timer is 1μs. According to the total number of pulses P when the gear rotates one circle, the number of pulses C required to calculate the speed, and the interval time T of C pulses, the speed n of the motor is calculated as: n = 60000000*M*C / T / P (r / min).

[0065] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A system for detecting the rotor position and speed of a switched reluctance motor, comprising a position encoding toothed disc (2) rotating synchronously with a motor shaft (4), and a sensor mechanism (3) rotating relative to the position encoding toothed disc (2), wherein the position encoding toothed disc (2) and the sensor mechanism (3) are coaxially arranged, and characterized in that: The position encoding toothed disc (2) comprises an absolute position encoding toothed disc (5) and an incremental position encoding toothed disc (6) which are coaxially arranged, the absolute position encoding toothed disc (5) or the incremental position encoding toothed disc (6) being coaxially fixed to the motor shaft (4), and the sensor mechanism (3) comprises an absolute position sensor (24) which senses the absolute position encoding toothed disc (5) and generates a pulse signal, and an incremental position sensor (27) which senses the incremental position encoding toothed disc (6) and generates a pulse signal.

2. The detection system for the rotor position and speed of a switched reluctance motor according to claim 1, characterized in that: The absolute position encoding toothed disc (5) is spaced apart and mounted outside the incremental position encoding toothed disc (6); absolute toothed disc teeth (12) are vertically arranged at the edge of the absolute position encoding toothed disc (5); the absolute toothed disc teeth (12) pass through the absolute position sensor (24); incremental toothed disc teeth are vertically arranged at the edge of the incremental position encoding toothed disc (6); the incremental toothed disc teeth pass through the incremental position sensor (27).

3. The detection system for the rotor position and speed of a switched reluctance motor according to claim 2, characterized in that: A plurality of absolute gear fixing holes (14) are provided on the disk surface of the absolute position coding gear disk (5), and incremental gear fastening holes (9) corresponding one-to-one to the absolute gear fixing holes (14) are provided on the disk surface of the incremental position coding gear disk (6). A positioning mechanism is also provided between the absolute position coding gear disk (5) and the incremental position coding gear disk (6).

4. The detection system for the rotor position and speed of a switched reluctance motor according to claim 1, characterized in that: The sensor mechanism (3) comprises a cover body (20), the cover body (20) being fixed on the surface of a motor end cover (1) of the switched reluctance motor, the motor shaft (4) passing through the cover body (20), and the cover body (20) housing the position encoding toothed disc (2) therein.

5. The detection system for the rotor position and speed of a switched reluctance motor according to claim 4, characterized in that: A detection circuit board (17) is fixed on the inner wall of the cover body (20), a position signal processing circuit is arranged on the surface of the detection circuit board (17), and the absolute position sensor (24) and the incremental position sensor (27) are connected to the position signal processing circuit.

6. The detection system for the rotor position and speed of a switched reluctance motor according to claim 5, characterized in that: The detection circuit board (17) is fan-shaped, and a plurality of absolute position sensors (24) and incremental position sensors (27) are respectively provided, with the center of the detection circuit board (17) as the vertex, the plurality of absolute position sensors (24) are arranged at equal angles, and the plurality of incremental position sensors (27) are arranged at equal angles.

7. The detection system for the rotor position and speed of a switched reluctance motor according to claim 5 or 6, characterized in that: On the surface of the detection circuit board (17), with the center of the detection circuit board (17) as the vertex, the angle between any two adjacent absolute position sensors (24) is 15°, the angle between any two adjacent incremental position sensors (27) is 18°, and the incremental position sensor (27) is arranged between two adjacent absolute position sensors (24).

8. The detection system for the rotor position and speed of a switched reluctance motor according to claim 4, characterized in that: A lead terminal (18) is provided on the side of the cover body (20), and the guide is connected to the detection circuit board (17) through the lead terminal (18).

9. A detection method implemented by the detection system for the rotor position and speed of a switched reluctance motor according to any one of claims 1 to 8, characterized in that: The steps include: Step 1, define a 32-bit circular queue array. The number of pulses generated by one rotation of the incremental encoder gear is P, then the array length is: P+2, define a 16-bit head pointer variable and a 16-bit tail pointer variable; Step 2, the incremental position encoding toothed disc (6) rotates, the incremental position sensor (27) signal jumps, the microprocessor connected to the incremental position sensor (27) captures the jump and generates an interrupt, and the interrupt program records the timer time and code of the interrupt occurrence; Step 3, the interrupt program determines whether the circular queue is full. If so, the head pointer is incremented by one, the tail pointer is incremented by one, and the current position interrupt time is stored in the circular queue; Step 4, the microprocessor determines the number of pulses of the current calculated speed according to the previous speed value. Assume that the previous speed value is S, the proportional coefficient is R, and the number of pulses of the current calculated speed is C, then C=S / R. If C is greater than the number of pulses P generated by one rotation of the incremental position encoder toothed disc (6), then C=P. If C is less than 1, then C=1. Step 5, determine whether the length of the data stored in the circular queue is greater than or equal to C+1: if not, wait for a sufficient number of position pulse times to be stored in the circular queue; if yes, take out the data T1 pointed to by the tail pointer from the circular queue, and then take out the data T2 at the Cth position before the tail pointer, and calculate the time difference between the two as T; Step 6, assume that the time of the M timing units of the timer is 1μs, and calculate the motor speed n according to the total number of pulses P when the gear rotates one circle, the number of pulses C required to calculate the speed, and the interval time T of C pulses: n = 60000000*M*C / T / P (r / min).

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