Motor driving method and system

Abstract

The invention discloses a motor driving method and system. The invention relates to a method. Pulse width modulation signals (a first pulse width modulation signal and a second pulse width modulation signal) are output through a single-chip microcomputer based on the direction of alternating current and position signals (a first position signal, a second position signal, a third position signal and a fourth position signal) of a rotor in the single-phase synchronous motor. Compared with a mode of starting and driving a plurality of IGBT power devices, the mode of starting and driving the single-phase synchronous motor only through the bidirectional silicon controlled rectifier has the advantages that the cost is reduced, and the reliability is improved. And moreover, the required computing power is reduced, the requirement on the single chip microcomputer is also reduced, and the cost is further reduced.

Description

Technical Field

[0001] The present invention relates to the field of motor drive technology, and in particular to a motor drive method and system. Background Art

[0002] In some home appliances, in order to solve the problems of short life of brushed motors and the generation of sparks and noise during use, single-phase synchronous motors have begun to be widely used in some home appliances due to their advantages such as high efficiency, low noise, long life and low cost.

[0003] At present, when a single-phase synchronous motor is driven, the AC power that drives the single-phase synchronous motor needs to be rectified and filtered by a rectifier bridge, and the external signal is collected by a single-chip microcomputer. Then, a sine wave is simulated through complex mathematical operations, and a pulse width modulation (PWM) signal is output to a high-voltage IGBT (insulated gate bipolar transistor) power device to control the single-phase synchronous motor. Among them, multiple IGBT power devices need to be set, resulting in high costs, and the computing power required for controlling multiple IGBT power devices is relatively high, which also increases the requirements for the single-chip microcomputer, making the cost further higher.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a motor driving method and system to solve the problem in the prior art that when driving a single-phase synchronous motor, multiple IGBT power devices need to be set, resulting in high cost, and the computing power required for controlling multiple IGBT power devices is high, and the requirements for the single-chip microcomputer are relatively increased, which further increases the cost.

[0006] The technical solution adopted by the present invention to solve the technical problem is: to provide a motor driving method, the motor driving method drives a single-phase synchronous motor connected to an alternating current based on a bidirectional thyristor and a zero-crossing detection module, the single-phase synchronous motor is provided with a position detection sensor for detecting the rotor position in the single-phase synchronous motor, the zero-crossing detection module is connected to the alternating current connected to the single-phase synchronous motor, and the motor driving method comprises:

[0007] Step A: obtaining a first position signal of a rotor in the single-phase synchronous motor, wherein the first position signal is a position signal of the rotor detected by the position detection sensor before the single-phase synchronous motor is started;

[0008] Step B: outputting a first pulse width modulation signal to the bidirectional thyristor based on the positive half cycle of the alternating current;

[0009] Step C: acquiring a second position signal of the rotor, where the second position signal is a position signal of the rotor detected by the position detection sensor after the first pulse width modulation signal is output to the bidirectional thyristor;

[0010] Wherein, when the first difference between the first position signal and the second position signal is not within a first range, the single-phase synchronous motor is started successfully, and the first range is a preset range;

[0011] When the first difference between the first position signal and the second position signal is within the first range, executing step D and step E;

[0012] Step D: outputting a second pulse width modulation signal to the bidirectional thyristor based on the negative half cycle of the alternating current;

[0013] Step E: obtaining a third position signal of the rotor, wherein the third position signal is a position signal of the rotor detected by the position detection sensor after the second pulse width modulation signal is output to the bidirectional thyristor;

[0014] Wherein, when the second difference between the third position signal and the first position signal is not within the first range, the single-phase synchronous motor is started successfully;

[0015] When the second difference between the first position signal and the third position signal is within the first range, the process starts from step B until the single-phase synchronous motor is successfully started;

[0016] After the single-phase synchronous motor is started, executing step F;

[0017] The step F: acquiring a fourth position signal of the rotor at intervals of a first time, wherein the fourth position signal is a position signal of the rotor at intervals of the first time after the single-phase synchronous motor is successfully started, detected by the position detection sensor;

[0018] When the fourth position signal is in an increasing state and the alternating current is in a positive half cycle, a third pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating. When the fourth position signal is in a decreasing state and the alternating current is in a negative half cycle, a fourth pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating.

[0019] According to a further configuration of the present invention, after the single-phase synchronous motor is started, the motor driving method further comprises:

[0020] Acquire a time value of a zero-crossing signal of the fourth position signal during an increasing or decreasing process;

[0021] After each time value of the zero-crossing signal of the fourth position signal is obtained, determining a second difference between the obtained time value of the zero-crossing signal and the last obtained time value of the zero-crossing signal of the fourth position signal;

[0022] The operating frequency of the single-phase synchronous motor is determined based on the second difference. When the operating frequency is not within the second range, the single-phase synchronous motor operates abnormally.

[0023] According to a further configuration of the present invention, the second range is greater than half of the frequency of the alternating current and less than twice the frequency of the alternating current.

[0024] A further configuration of the present invention comprises, before step A:

[0025] Determine that the single-phase synchronous motor is connected to alternating current. When the single-phase synchronous motor is connected to alternating current, execute from step A after a second time.

[0026] According to a further configuration of the present invention, the second time period ranges from 2 to 5 cycles of the alternating current.

[0027] According to a further configuration of the present invention, the alternating current is 110V and 60HZ, or the alternating current is 220V and 50HZ.

[0028] According to a further configuration of the present invention, the first time ranges from 200 to 300 μs.

[0029] The present invention also provides a system using the motor driving method as described above, the system is used to drive a single-phase synchronous motor connected to an alternating current, the single-phase synchronous motor is provided with a position detection sensor for detecting the rotor position in the single-phase synchronous motor, and the system comprises:

[0030] A bidirectional thyristor, wherein the bidirectional thyristor is arranged in series on a connection path where the single-phase synchronous motor is connected to the alternating current;

[0031] A zero-crossing detection module connected to the alternating current connected to the single-phase synchronous motor;

[0032] A single-chip microcomputer is connected to the position detection sensor, the zero-crossing detection module and the output bidirectional thyristor, and the single-chip microcomputer is used to perform step A, wherein step A is to obtain a first position signal of a rotor in the single-phase synchronous motor, wherein the first position signal is a position signal of the rotor detected by the position detection sensor before the single-phase synchronous motor is started;

[0033] Also used to perform step B, wherein the step B is to output a first pulse width modulation signal to the bidirectional thyristor based on the positive half cycle of the alternating current;

[0034] Also used to perform step C, wherein step C is to obtain a second position signal of the rotor, wherein the second position signal is a position signal of the rotor detected by the position detection sensor after the first pulse width modulation signal is output to the bidirectional thyristor;

[0035] Wherein, when the first difference between the first position signal and the second position signal is not within a first range, the single-phase synchronous motor is started successfully, and the first range is a preset range;

[0036] When the first difference between the first position signal and the second position signal is within the first range, the method is further used to execute step D and step E;

[0037] The step D is to output a second pulse width modulation signal to the bidirectional thyristor based on the negative half cycle of the alternating current;

[0038] The step E is to obtain a third position signal of the rotor, wherein the third position signal is a position signal of the rotor detected by the position detection sensor after the second pulse width modulation signal is output to the bidirectional thyristor;

[0039] Wherein, when the second difference between the third position signal and the first position signal is not within the first range, the single-phase synchronous motor is started successfully;

[0040] When the second difference between the first position signal and the third position signal is within the first range, the single chip microcomputer is further used to execute from step B until the single-phase synchronous motor is successfully started;

[0041] After the single-phase synchronous motor is started, the single-chip microcomputer is further used to execute step F, wherein step F is to obtain a fourth position signal of the rotor at every first time interval, and the fourth position signal is a position signal of the rotor at every first time interval after the single-phase synchronous motor is successfully started, detected by the position detection sensor;

[0042] When the fourth position signal is in an increasing state and the alternating current is in a positive half cycle, a third pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating. When the fourth position signal is in a decreasing state and the alternating current is in a negative half cycle, a fourth pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating.

[0043] According to a further configuration of the present invention, after the single-phase synchronous motor is started, the single-chip microcomputer is further used to obtain a time value of a zero-crossing signal of the fourth position signal during an increasing or decreasing process;

[0044] Also used for establishing a second difference between the time values ​​of two adjacent zero-crossing signals based on the zero-crossing signal of the fourth position signal in the process of increasing or decreasing;

[0045] It is also used to determine the operating frequency of the single-phase synchronous motor based on the second difference. When the operating frequency is not within the second range, the single-phase synchronous motor operates abnormally.

[0046] According to a further configuration of the present invention, the motor drive system further comprises:

[0047] When the single-phase synchronous motor is connected to alternating current, the single chip microcomputer starts to execute from step A after a second time.

[0048] The beneficial effects of the present invention are:

[0049] When starting and driving a single-phase synchronous motor, a single-chip microcomputer outputs a pulse width modulation signal (a first pulse width modulation signal, a second pulse width modulation signal, a third pulse width modulation signal and a fourth pulse width modulation signal) based on the direction of the alternating current and the position signal (a first position signal, a second position signal, a third position signal and a fourth position signal) of the rotor in the single-phase synchronous motor to control the state of the bidirectional thyristor to start and continue to drive the single-phase synchronous motor. Compared with the starting and driving method of multiple IGBT power devices, the method of starting and driving the single-phase synchronous motor only by bidirectional thyristors reduces costs, reduces the required computing power, and reduces the requirements for the single-chip microcomputer, thereby further reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary personnel in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0051] Figure 1 It is a flow chart of the motor driving method of the present invention.

[0052] Figure 2 It is a partial curve in a rotor position signal diagram collected by a position detection sensor in one embodiment of the present invention.

[0053] Figure 3is a graph of alternating current in one embodiment of the present invention.

[0054] Figure 4 It is a principle block diagram of the motor drive system of the present invention.

[0055] Figure 5 It is a specific circuit structure diagram of a zero-crossing detection module in one embodiment of the present invention.

[0056] The symbols in the attached drawings are: 100, single-chip microcomputer; 200, zero-crossing detection module; 300, position detection sensor; 400, single-phase synchronous motor; Q1, bidirectional thyristor. DETAILED DESCRIPTION

[0057] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0058] like Figure 4 , Figure 1 As shown, the present invention provides a motor drive system, which is used to drive a single-phase synchronous motor 400 connected to alternating current. The single-phase synchronous motor 400 is provided with a position detection sensor 300 for detecting the rotor position in the single-phase synchronous motor 400, wherein the alternating current can be 110V / 60HZ alternating current or 220V / 50HZ alternating current.

[0059] The motor drive system may include a bidirectional thyristor Q1, a zero-crossing detection module 200, and a single-chip microcomputer 100, wherein the single-chip microcomputer 100 is connected to the bidirectional thyristor Q1 and the zero-crossing detection module 200. When the single-phase synchronous motor 400 is connected to the alternating current, the live wire in the alternating current is connected to the power supply terminal corresponding to the live wire in the single-phase synchronous motor 400, and the neutral wire is connected to the power supply terminal corresponding to the neutral wire in the single-phase synchronous motor 400 through the bidirectional thyristor Q1. When the bidirectional thyristor Q1 is turned on, the neutral wire is connected to the power supply terminal corresponding to the neutral wire in the single-phase synchronous motor 400. The zero-crossing detection module 200 is connected to the alternating current, and the zero-crossing detection module 200 is used to detect the direction of the alternating current (whether the alternating current is output in a positive half-cycle or a negative half-cycle during operation).

[0060] The single chip computer 100 is used to execute step 101 , step 102 and step 103 .

[0061] Step 101 is to obtain a first position signal of a rotor in the single-phase synchronous motor 400 . The first position signal is a position signal of the rotor detected by the position detection sensor 300 before the single-phase synchronous motor 400 is started.

[0062] Step 102 is to output a first pulse width modulation signal to the bidirectional thyristor Q1 based on the positive half cycle of the alternating current after the first position signal is acquired.

[0063] Step 103 is to obtain a second position signal of the rotor, where the second position signal is a position signal of the rotor detected by the position detection sensor 300 after the first pulse width modulation signal is output to the bidirectional thyristor Q1.

[0064] Among them, when the first difference between the first position signal and the second position signal is not within the first range, the single-phase synchronous motor 400 is started successfully, and the first range is a preset range, which is preset and stored in the microcontroller 100; when the first difference between the first position signal and the second position signal is within the first range, the microcontroller 100 is also used to execute steps 104 and 105.

[0065] Step 104 is to output a second pulse width modulation signal to the bidirectional thyristor Q1 based on the negative half cycle of the alternating current.

[0066] Step 105 is to obtain a third position signal of the rotor, where the third position signal is a position signal of the rotor detected by the position detection sensor 300 after the second pulse width modulation signal is output to the bidirectional thyristor Q1.

[0067] Among them, when the second difference between the third position signal and the first position signal is not within the first range, the single-phase synchronous motor 400 starts successfully; when the second difference between the first position signal and the third position signal is within the first range, the microcontroller 100 is also used to execute from step 102 until the single-phase synchronous motor 400 starts successfully.

[0068] Wherein, after the single-phase synchronous motor 400 is started, the single chip microcomputer 100 is further used to execute step 106 .

[0069] Step 106 is to obtain a fourth position signal of the rotor at every first time interval, and the fourth position signal is a position signal of the rotor at every first time interval during the operation of the single-phase synchronous motor 400 after successful startup detected by the position detection sensor 300; when the fourth position signal is in an increasing state and the alternating current is in a positive half cycle, a third pulse width modulation signal is generated to the bidirectional thyristor Q1 to drive the single-phase synchronous motor 400 to continue rotating, and when the fourth position signal is in a decreasing state and the alternating current is in a negative half cycle, a fourth pulse width modulation signal is generated to the bidirectional thyristor Q1 to drive the single-phase synchronous motor 400 to continue rotating.

[0070] Specifically, when driving the single-phase synchronous motor 400 , the single-phase synchronous motor 400 needs to be started first, and the single-phase synchronous motor 400 can be further driven only after the single-phase synchronous motor 400 is started.

[0071] Among them, when the single-phase synchronous motor 400 is started, the direction of the alternating current connected to the single-phase synchronous motor 400 is determined by the zero-crossing detection module 200, and the position signal (first position signal) of the rotor of the single-phase synchronous motor 400 before starting is further detected by the position detection module and transmitted to the single-chip microcomputer 100. After obtaining the first position signal, the single-chip microcomputer 100 outputs a first pulse signal to the bidirectional thyristor Q1 based on the positive half cycle of the alternating current. At this time, the bidirectional thyristor Q1 is in the on state, and the alternating current is to the single-phase synchronous motor 400. After the first pulse signal is output to the bidirectional thyristor Q1, the position detection module is used to detect the single-phase synchronous motor 400 again. After the first pulse signal of the single-phase synchronous motor 400 is output to the thyristor, the rotor position signal (second position signal) is obtained. After the second position signal is obtained, the single-chip microcomputer 100 further calculates and determines the first difference between the first position signal and the second position signal according to the first position signal and the second position signal. When the first difference is within the first range (indicating that the rotor position of the single-phase synchronous motor 400 has not changed), it means that the single-phase synchronous motor 400 has not started successfully. When the first difference is not within the first range (indicating that the rotor position of the single-phase synchronous motor 400 has changed), it means that the single-phase synchronous motor 400 has started successfully.

[0072] The first range is preset in advance in the single-chip microcomputer 100. The purpose of setting the first range is that the position detection module outputs an electrical signal after detecting the position signal of the rotor, and the electrical signal will be transmitted to the single-chip microcomputer 100, and analog-to-digital conversion will be performed inside the single-chip microcomputer 100. Therefore, it is necessary to set a first range to avoid misjudgment due to the error of the analog-to-digital converter inside the single-chip microcomputer 100 during the analog-to-digital conversion process, that is, it is necessary to set a first range to determine whether the position of the rotor of the single-phase synchronous motor 400 has changed, and the range is not affected by the error of the analog-to-digital converter. When the first range is set, the specific setting range is related to the conversion accuracy of the analog-to-digital converter in the single-chip microcomputer 100, that is, if the position of the rotor of the single-phase synchronous motor 400 can be accurately obtained after the position of the rotor of the single-phase synchronous motor 400 changes, for example, when the accuracy of the analog-to-digital converter in the single-chip microcomputer 100 is 12, the first range is set between 10-20 digital quantities.

[0073] Among them, when the single-phase synchronous motor 400 is started, the first difference between the first position signal and the second position signal may be less than the minimum value in the first range, or the first difference between the first position signal and the second position signal may be greater than the maximum value in the first range. At this time, it means that the single-phase synchronous motor 400 is started successfully.

[0074] After the first pulse signal is output in the positive half cycle of the alternating current to start the single-phase synchronous motor 400, if the single-phase synchronous motor 400 fails to start successfully, it is necessary to output a second pulse signal to the bidirectional thyristor Q1 based on the negative half cycle of the alternating current. At this time, the bidirectional thyristor Q1 is in the on state, and the alternating current is to the single-phase synchronous motor 400. After the second pulse signal is output to the bidirectional thyristor Q1, the position signal (third position signal) of the rotor of the single-phase synchronous motor 400 after the second pulse signal is output to the thyristor is also detected by the position detection module. After the third position signal is obtained, the single-chip microcomputer 100 further calculates and determines the second difference between the first position signal and the third position signal based on the first position signal and the third position signal. When the second difference is within the first range, it means that the single-phase synchronous motor 400 has not started successfully. When the second difference is not within the first range, it means that the single-phase synchronous motor 400 has started successfully.

[0075] When outputting the second pulse signal to the bidirectional thyristor Q1 , the second pulse signal to the bidirectional thyristor Q1 may be output after a certain delay after determining that the single-phase synchronous motor 400 has not started successfully, for example, the delay may be 2ms, 3ms, etc.

[0076] After outputting the second pulse signal to the bidirectional thyristor Q1 , if the single-phase synchronous motor 400 has not started successfully, it is necessary to re-execute from step 102 until the single-phase synchronous motor 400 starts successfully.

[0077] When the single-phase synchronous motor 400 is further driven after the single-phase synchronous motor 400 is successfully started, the single-chip microcomputer 100 obtains the position signal (fourth position signal) of the rotor in the single-phase synchronous motor 400 once at a first time interval, and compares the latter fourth position signal with the previous fourth position signal in the obtained fourth position signal, and determines whether the fourth position signal is in an increasing state or a decreasing state by comparing the fourth position signals twice (the latter fourth position signal and the previous fourth position signal).

[0078] When the fourth position signal is in an increasing state and the alternating current is in a positive half cycle, the single-chip microcomputer 100 outputs a third pulse width modulation signal to the bidirectional thyristor Q1 to drive the single-phase synchronous motor 400 to continue rotating; when the fourth position signal is in a decreasing state and the alternating current is in a negative half cycle, the single-chip microcomputer 100 outputs a fourth pulse width modulation signal to the bidirectional thyristor Q1 to drive the single-phase synchronous motor 400 to continue rotating, wherein when the positive half cycle waveform of the alternating current overlaps with the N-pole position waveform of the permanent magnet in the single-phase synchronous motor 400 and the negative half cycle waveform of the alternating current overlaps with the S-pole position waveform of the permanent magnet in the single-phase synchronous motor 400, the single-phase synchronous motor 400 has the highest efficiency and the lowest noise.

[0079] In this embodiment, when the single-phase synchronous motor 400 is started and driven, the single-chip microcomputer 100 outputs a pulse width modulation signal (a first pulse width modulation signal, a second pulse width modulation signal, a third pulse width modulation signal, and a fourth pulse width modulation signal) based on the direction of the alternating current and the position signal (a first position signal, a second position signal, a third position signal, and a fourth position signal) of the rotor in the single-phase synchronous motor 400 to control the state of the bidirectional thyristor Q1 to start and continue to drive the single-phase synchronous motor 400. Compared with the starting and driving method of multiple IGBT power devices, the method of starting and driving the single-phase synchronous motor 400 only through the bidirectional thyristor Q1 reduces costs, reduces the required computing power, and reduces the requirements for the single-chip microcomputer 100, thereby further reducing costs.

[0080] In addition, when the bidirectional thyristor Q1 controls the switch, it controls the bidirectional thyristor Q1 to be turned on in the positive half cycle or negative half cycle of the alternating current. Compared with the IGBT power device, the switching frequency is reduced, the switching loss is reduced, and because the internal resistance of the bidirectional thyristor Q1 is low, the loss and heat are reduced during the start-up and continued driving of the single-phase synchronous motor 400.

[0081] Furthermore, if Figure 1 As shown, during the driving process of the single-phase synchronous motor 400 , the single chip microcomputer 100 is also used to execute step 107 , step 108 , and step 109 .

[0082] Step 107 is to obtain the time value of the zero-crossing signal of the fourth position signal during the increasing or decreasing process.

[0083] Step 108 is to determine a third difference between the acquired time value of the zero-crossing signal and the last acquired time value of the zero-crossing signal after acquiring the time value of the zero-crossing signal each time.

[0084] Step 109 is to determine the operating frequency of the single-phase synchronous motor 400 based on the third difference. When the operating frequency is not within the second range, the single-phase synchronous motor 400 operates abnormally.

[0085] Specifically, during the operation of the single-phase synchronous motor 400, the curve formed by the position signal within one cycle is a sinusoidal wave curve, wherein, when the single-phase synchronous motor 400 operates normally, the operating frequency of the single-phase synchronous motor 400 is within a range, and the operating frequency of the single-phase synchronous motor 400 can be calculated by the third difference between the time values ​​corresponding to the two zero-crossing signals in the curve formed by the fourth position signal detected by the position detection sensor 300. Specifically, during the calculation, the third difference between the time values ​​corresponding to the two adjacent zero-crossing signals is half a cycle, and the operating frequency of the single-phase synchronous motor 400 can be determined based on the relationship between the cycle and the frequency.

[0086] It can be seen that according to this characteristic, the time value of the zero-crossing signal of the fourth position signal during the increasing or decreasing process can be obtained through the single-chip microcomputer 100, and after each time the time value of the zero-crossing signal is obtained, the third difference between the time value of the zero-crossing signal obtained and the time value of the zero-crossing signal obtained last time is determined, and the operating frequency of the single-phase synchronous motor 400 is determined by the third difference, and then according to the operating frequency of the single-phase synchronous motor 400 determined by the single-phase synchronous motor 400, it is determined whether the single-phase synchronous motor 400 is operating normally (the single-phase synchronous motor 400 is blocked or shaking).

[0087] In some embodiments, the second range is greater than half of the frequency of the AC power and less than twice the frequency of the AC power.

[0088] In this embodiment, when the AC power is 110V / 60HZ, the second range is greater than 30HZ and less than 120HZ; when the AC power is 220 / 50HZ, the second range is greater than 25HZ and less than 100HZ; wherein, the second range can be stored in the single chip computer 100 in advance according to the frequency of the AC power.

[0089] In some embodiments, before the single chip computer 100 executes step 101 , it is also used to execute step 110 .

[0090] Step 110 is to determine whether the single-phase synchronous motor 400 is connected to AC power. When the single-phase synchronous motor 400 is connected to AC power, the process starts from step 101 after a second time.

[0091] Specifically, according to the characteristics of the bidirectional thyristor Q1, when the bidirectional thyristor Q1 is in the case of direct current, the bidirectional thyristor Q1 cannot be automatically shut down. Therefore, before the single-chip microcomputer 100 executes step 101, it is first determined that the single-phase synchronous motor 400 is connected to alternating current. After the single-chip microcomputer 100 determines that the single-phase synchronous motor 400 is connected to alternating current, after the second time, the single-chip microcomputer 100 starts to execute from the above step 101. The purpose of setting the second time is to make the alternating current connected to the single-phase synchronous motor 400 in a stable working state, wherein the second time can be stored in the single-chip microcomputer 100 in advance.

[0092] In some embodiments, the second time ranges from 2 to 5 cycles of the alternating current.

[0093] In this embodiment, the second time may be 3 cycles of the connected alternating current power, or the second time may be 2, 3.5, 4, etc. cycles of the connected alternating current power.

[0094] In some embodiments, the single chip computer 100 may be, but is not limited to, a chip of model number PY32F002AL15STU.

[0095] In some embodiments, the zero-crossing detection module 200 can be any circuit structure in the prior art that can achieve the above functions, and no further limitation is made here. Figure 5 , which is a specific circuit structure diagram of a zero-crossing detection module 200 in the prior art that can be applied to the motor drive system.

[0096] In some embodiments, the position detection module may be a linear Hall sensor, which detects the position of the rotor in the single-phase synchronous motor 400 and outputs a position signal. The model of the linear Hall sensor may be AH602SU.

[0097] In some embodiments, the bidirectional thyristor Q1 may be, but is not limited to, model RS405K-800B.

[0098] In some embodiments, Figure 1 , Figure 2 and Figure 3 As shown, the present invention also provides a motor driving method, which can be applied to the above-mentioned motor driving system. The motor driving method drives a single-phase synchronous motor connected to an alternating current based on a bidirectional thyristor and a zero-crossing detection module. A position detection sensor for detecting a rotor position in the single-phase synchronous motor is provided in the single-phase synchronous motor. The zero-crossing detection module is connected to the alternating current, and the zero-crossing detection module is used to detect the direction of the alternating current. The motor driving method includes:

[0099] Step 101: obtaining a first position signal of a rotor in a single-phase synchronous motor, where the first position signal is a position signal of the rotor detected by a position detection sensor before the single-phase synchronous motor is started;

[0100] Step 102: outputting a first pulse width modulation signal to a bidirectional thyristor based on a positive half cycle of the alternating current;

[0101] Step 103: Acquire a second position signal of the rotor, where the second position signal is a position signal of the rotor detected by the position detection sensor after the first pulse width modulation signal is output to the bidirectional thyristor;

[0102] Wherein, when the first difference between the first position signal and the second position signal is not within the first range, the single-phase synchronous motor is started successfully, and the first range is a preset range;

[0103] When the first difference between the first position signal and the second position signal is within the first range, executing step 104 and step 105;

[0104] Step 104: outputting a second pulse width modulation signal to the bidirectional thyristor based on the negative half cycle of the alternating current;

[0105] Step 105: obtaining a third position signal of the rotor, where the third position signal is a position signal of the rotor detected by the position detection sensor after the second pulse width modulation signal is output to the bidirectional thyristor;

[0106] Wherein, when the second difference between the third position signal and the first position signal is not within the first range, the single-phase synchronous motor is started successfully;

[0107] When the second difference between the first position signal and the third position signal is within the first range, the process starts from step 102 until the single-phase synchronous motor is successfully started;

[0108] After the single-phase synchronous motor is started, execute step 106;

[0109] Step 106: acquiring a fourth position signal of the rotor at every first time interval, wherein the fourth position signal is a position signal of the rotor at every first time interval after the single-phase synchronous motor is successfully started and detected by the position detection sensor;

[0110] When the fourth position signal is in an increasing state and the alternating current is in a positive half cycle, a third pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating. When the fourth position signal is in a decreasing state and the alternating current is in a negative half cycle, a fourth pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating.

[0111] Specifically, when driving a single-phase synchronous motor, the single-phase synchronous motor needs to be started first, and the single-phase synchronous motor can be further driven only after the single-phase synchronous motor is started.

[0112] Among them, when the single-phase synchronous motor is started, the direction of the alternating current connected to the single-phase synchronous motor is determined by the zero-crossing detection module, and the position detection module is further used to detect the position signal (first position signal) of the rotor of the single-phase synchronous motor before starting and transmit it to the single-chip microcomputer. After obtaining the first position signal, the single-chip microcomputer outputs a first pulse signal to the bidirectional thyristor based on the positive half cycle of the alternating current. At this time, the bidirectional thyristor is in a conducting state, and the alternating current is to the single-phase synchronous motor. After the first pulse signal is output to the bidirectional thyristor, the position detection module is used again to detect the position signal (second position signal) of the rotor of the single-phase synchronous motor after the first pulse signal is output to the thyristor. After the second position signal is obtained, the single-chip microcomputer further calculates and determines the first difference between the first position signal and the second position signal according to the first position signal and the second position signal. When the first difference is within the first range (indicating that the rotor position of the single-phase synchronous motor has not changed), it means that the single-phase synchronous motor has not started successfully. When the first difference is not within the first range (indicating that the rotor position of the single-phase synchronous motor has changed), it means that the single-phase synchronous motor has started successfully.

[0113] The first range is preset in the single-chip microcomputer in advance. The purpose of setting the first range is that the position detection module outputs an electrical signal after detecting the position signal of the rotor. After the electrical signal is transmitted to the single-chip microcomputer, analog-to-digital conversion is performed inside the single-chip microcomputer. Therefore, a first range needs to be set to avoid misjudgment due to the error of the analog-to-digital converter inside the single-chip microcomputer during the analog-to-digital conversion process, that is, a first range needs to be set to determine whether the position of the rotor of the single-phase synchronous motor has changed, and the range is not affected by the error of the analog-to-digital converter. When the first range is set, the specific setting range is related to the conversion accuracy of the analog-to-digital converter in the single-chip microcomputer, that is, if the position of the rotor of the single-phase synchronous motor can be accurately obtained after the position of the rotor of the single-phase synchronous motor changes, for example, when the analog-to-digital converter in the single-chip microcomputer has a 12-bit accuracy, the first range is set between 10-20 digital quantities.

[0114] Among them, when the single-phase synchronous motor is started, the first difference between the first position signal and the second position signal may be less than the minimum value in the first range, or the first difference between the first position signal and the second position signal may be greater than the maximum value in the first range, which indicates that the single-phase synchronous motor is started successfully.

[0115] After the first pulse signal is output in the positive half cycle of the alternating current to start the single-phase synchronous motor, if the single-phase synchronous motor fails to start successfully, it is necessary to output a second pulse signal to the bidirectional thyristor based on the negative half cycle of the alternating current. At this time, the bidirectional thyristor is in the on state, and the alternating current is to the single-phase synchronous motor. After the second pulse signal is output to the bidirectional thyristor, the position detection module is also used to detect the position signal (third position signal) of the rotor of the single-phase synchronous motor after the second pulse signal is output to the thyristor. After the third position signal is obtained, the single-chip microcomputer further calculates and determines the second difference between the first position signal and the third position signal based on the first position signal and the third position signal. When the second difference is within the first range, it indicates that the single-phase synchronous motor has not started successfully. When the second difference is not within the first range, it indicates that the single-phase synchronous motor has started successfully.

[0116] After the second pulse signal is output to the bidirectional thyristor, if the single-phase synchronous motor has not started successfully, it is necessary to re-execute from step 102 until the single-phase synchronous motor starts successfully.

[0117] When the single-phase synchronous motor is further driven after being successfully started, the single-chip microcomputer obtains a position signal (fourth position signal) of the rotor in the single-phase synchronous motor once at a first time interval, and compares a latter fourth position signal with a former fourth position signal in the obtained fourth position signal, and determines whether the fourth position signal is in an increasing state or a decreasing state by comparing the fourth position signals twice (the latter fourth position signal with the former fourth position signal).

[0118] When the fourth position signal is in an increasing state and the alternating current is in a positive half cycle, the single-chip microcomputer outputs a third pulse width modulation signal to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating; when the fourth position signal is in a decreasing state and the alternating current is in a negative half cycle, the single-chip microcomputer outputs a fourth pulse width modulation signal to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating.

[0119] In this embodiment, when the single-phase synchronous motor is started and driven, the single-chip microcomputer outputs pulse width modulation signals (first pulse width modulation signal, second pulse width modulation signal, third pulse width modulation signal and fourth pulse width modulation signal) based on the direction of the alternating current and the position signal of the rotor in the single-phase synchronous motor (first position signal, second position signal, third position signal and fourth position signal) to control the state of the bidirectional thyristor to start and continue to drive the single-phase synchronous motor. Compared with the starting and driving method of multiple IGBT power devices, the method of starting and driving the single-phase synchronous motor only by bidirectional thyristors reduces costs, reduces the required computing power, and reduces the requirements for the single-chip microcomputer, thereby further reducing costs.

[0120] After the single-phase synchronous motor is started, the motor driving method further includes:

[0121] Step 107: Obtaining a time value of a zero-crossing signal of the fourth position signal during an increasing or decreasing process;

[0122] Step 108: after each acquisition of the time value of the zero-crossing signal of the fourth position signal, determining a third difference between the time value of the acquired zero-crossing signal and the time value of the zero-crossing signal of the fourth position signal acquired last time;

[0123] Step 109: Determine the operating frequency of the single-phase synchronous motor based on the third difference. When the operating frequency is not within the second range, the single-phase synchronous motor operates abnormally. Specific details are as described in an embodiment of a motor drive system based on bidirectional thyristors, which will not be repeated here.

[0124] In some embodiments, the second range is greater than half of the frequency of the alternating current and less than twice the frequency of the alternating current. Specific details are as described in an embodiment of a motor drive system based on a bidirectional thyristor, which will not be repeated here.

[0125] In some embodiments, the step 101 includes the following steps:

[0126] Step 100: Determine whether the single-phase synchronous motor is connected to AC power. When the single-phase synchronous motor is connected to AC power, after a second time, the process starts from step 101. The details are as described in an embodiment of a motor drive system based on bidirectional thyristors, which will not be described in detail here.

[0127] In some embodiments, the second time ranges from 2 to 5 cycles of the alternating current. Specific details are as described in an embodiment of a motor drive system based on a bidirectional thyristor, which will not be repeated here.

[0128] In some embodiments, the first time ranges from 200 to 300 μs. The details are as described in an embodiment of a motor drive system based on a bidirectional thyristor, which will not be described in detail here.

[0129] Here, it should be noted that the description of the above motor driving method embodiment is similar to the description of the above motor driving system embodiment, and has similar beneficial effects as the above motor driving system. For technical details not disclosed in the motor driving method embodiment, please refer to the description of the motor driving system embodiment of the present invention for understanding.

[0130] In summary, the present invention provides a motor driving method and system, which have the following beneficial effects:

[0131] When starting and driving a single-phase synchronous motor, a single-chip microcomputer outputs a pulse width modulation signal (a first pulse width modulation signal, a second pulse width modulation signal, a third pulse width modulation signal and a fourth pulse width modulation signal) based on the direction of the alternating current and the position signal (a first position signal, a second position signal, a third position signal and a fourth position signal) of the rotor in the single-phase synchronous motor to control the state of the bidirectional thyristor to start and continue to drive the single-phase synchronous motor. Compared with the starting and driving method of multiple IGBT power devices, the method of starting and driving the single-phase synchronous motor only by bidirectional thyristors reduces costs, reduces the required computing power, and reduces the requirements for the single-chip microcomputer, thereby further reducing costs.

[0132] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A motor driving method, wherein the motor driving method drives a single-phase synchronous motor connected to an alternating current based on a bidirectional thyristor and a zero-crossing detection module, wherein a position detection sensor for detecting a rotor position in the single-phase synchronous motor is provided in the single-phase synchronous motor, and the zero-crossing detection module is connected to the alternating current connected to the single-phase synchronous motor, characterized in that: The motor driving method comprises: Step A: obtaining a first position signal of a rotor in the single-phase synchronous motor, wherein the first position signal is a position signal of the rotor detected by the position detection sensor before the single-phase synchronous motor is started; Step B: outputting a first pulse width modulation signal to the bidirectional thyristor based on the positive half cycle of the alternating current; Step C: acquiring a second position signal of the rotor, where the second position signal is a position signal of the rotor detected by the position detection sensor after the first pulse width modulation signal is output to the bidirectional thyristor; Wherein, when the first difference between the first position signal and the second position signal is not within a first range, the single-phase synchronous motor is started successfully, and the first range is a preset range; When the first difference between the first position signal and the second position signal is within the first range, executing step D and step E; Step D: outputting a second pulse width modulation signal to the bidirectional thyristor based on the negative half cycle of the alternating current; Step E: obtaining a third position signal of the rotor, wherein the third position signal is a position signal of the rotor detected by the position detection sensor after the second pulse width modulation signal is output to the bidirectional thyristor; Wherein, when the second difference between the third position signal and the first position signal is not within the first range, the single-phase synchronous motor is started successfully; When the second difference between the first position signal and the third position signal is within the first range, the process starts from step B until the single-phase synchronous motor is successfully started; After the single-phase synchronous motor is started, executing step F; The step F: acquiring a fourth position signal of the rotor at intervals of a first time, wherein the fourth position signal is a position signal of the rotor at intervals of the first time after the single-phase synchronous motor is successfully started, detected by the position detection sensor; When the fourth position signal is in an increasing state and the alternating current is in a positive half cycle, a third pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating. When the fourth position signal is in a decreasing state and the alternating current is in a negative half cycle, a fourth pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating.

2. The motor driving method according to claim 1, characterized in that: After the single-phase synchronous motor is started, the motor driving method further includes: Acquire a time value of a zero-crossing signal of the fourth position signal during an increasing or decreasing process; After each time value of the zero-crossing signal of the fourth position signal is obtained, determining a third difference between the obtained time value of the zero-crossing signal and the last obtained time value of the zero-crossing signal of the fourth position signal; The operating frequency of the single-phase synchronous motor is determined based on the third difference. When the operating frequency is not within the second range, the single-phase synchronous motor operates abnormally.

3. The motor driving method according to claim 2, characterized in that: The second range is greater than half of the frequency of the alternating current and less than twice the frequency of the alternating current.

4. The motor driving method according to claim 1, characterized in that: Prior to step A, the method comprises: Determine that the single-phase synchronous motor is connected to alternating current. When the single-phase synchronous motor is connected to alternating current, execute from step A after a second time.

5. The motor driving method according to claim 4, characterized in that: The second time ranges from 2 to 5 cycles of the alternating current.

6. The motor driving method according to claim 5, characterized in that: The alternating current is 110V and 60HZ, or the alternating current is 220V and 50HZ.

7. The motor driving method according to claim 1, characterized in that: The first time range is 200-300μs.

8. A system using the motor driving method according to any one of claims 1 to 7, wherein the system is used to drive a single-phase synchronous motor connected to an alternating current, wherein the single-phase synchronous motor is provided with a position detection sensor for detecting the rotor position of the single-phase synchronous motor, wherein: The system comprises: A bidirectional thyristor, wherein the bidirectional thyristor is arranged in series on a connection path where the single-phase synchronous motor is connected to the alternating current; A zero-crossing detection module connected to the alternating current connected to the single-phase synchronous motor; A single-chip microcomputer is connected to the position detection sensor, the zero-crossing detection module and the bidirectional thyristor, and the single-chip microcomputer is used to perform step A, wherein step A is to obtain a first position signal of a rotor in the single-phase synchronous motor, wherein the first position signal is a position signal of the rotor detected by the position detection sensor before the single-phase synchronous motor is started; Also used to perform step B, wherein the step B is to output a first pulse width modulation signal to the bidirectional thyristor based on the positive half cycle of the alternating current; Also used to perform step C, wherein step C is to obtain a second position signal of the rotor, wherein the second position signal is a position signal of the rotor detected by the position detection sensor after the first pulse width modulation signal is output to the bidirectional thyristor; Wherein, when the first difference between the first position signal and the second position signal is not within a first range, the single-phase synchronous motor is started successfully, and the first range is a preset range; When the first difference between the first position signal and the second position signal is within the first range, the method is further used to execute step D and step E; The step D is to output a second pulse width modulation signal to the bidirectional thyristor based on the negative half cycle of the alternating current; The step E is to obtain a third position signal of the rotor, wherein the third position signal is a position signal of the rotor detected by the position detection sensor after the second pulse width modulation signal is output to the bidirectional thyristor; Wherein, when the second difference between the third position signal and the first position signal is not within the first range, the single-phase synchronous motor is started successfully; When the second difference between the first position signal and the third position signal is within the first range, the single chip microcomputer is further used to execute from step B until the single-phase synchronous motor is successfully started; After the single-phase synchronous motor is started, the single-chip microcomputer is further used to execute step F, wherein step F is to obtain a fourth position signal of the rotor at every first time interval, and the fourth position signal is a position signal of the rotor at every first time interval after the single-phase synchronous motor is successfully started, detected by the position detection sensor; When the fourth position signal is in an increasing state and the alternating current is in a positive half cycle, a third pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating. When the fourth position signal is in a decreasing state and the alternating current is in a negative half cycle, a fourth pulse width modulation signal is generated to the bidirectional thyristor to drive the single-phase synchronous motor to continue rotating.

9. The motor drive system according to claim 8, characterized in that: After the single-phase synchronous motor is started, the single-chip microcomputer is further used to obtain a time value of a zero-crossing signal of the fourth position signal during an increasing or decreasing process; Also used for establishing a third difference between the time values ​​of two adjacent zero-crossing signals based on the zero-crossing signal of the fourth position signal in the process of increasing or decreasing; It is also used to determine the operating frequency of the single-phase synchronous motor based on the third difference. When the operating frequency is not within the second range, the single-phase synchronous motor operates abnormally.

10. The motor drive system according to claim 8, characterized in that: The motor drive system further comprises: When the single-phase synchronous motor is connected to alternating current, the single chip microcomputer starts to execute from step A after a second time.

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