WO2023045530A1 - 控制电机低速正转和低速反转的软启动器控制方法 - Google Patents

控制电机低速正转和低速反转的软启动器控制方法 Download PDF

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WO2023045530A1
WO2023045530A1 PCT/CN2022/107725 CN2022107725W WO2023045530A1 WO 2023045530 A1 WO2023045530 A1 WO 2023045530A1 CN 2022107725 W CN2022107725 W CN 2022107725W WO 2023045530 A1 WO2023045530 A1 WO 2023045530A1
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phase
time point
motor
trigger
low
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PCT/CN2022/107725
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English (en)
French (fr)
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陈伟孟
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浙江正泰电器股份有限公司
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Priority to EP22871589.2A priority Critical patent/EP4318935A1/en
Publication of WO2023045530A1 publication Critical patent/WO2023045530A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
    • H02P1/26—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor
    • H02P1/40—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor in either direction of rotation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
    • H02P1/26—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor
    • H02P1/30—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor by progressive increase of frequency of supply to primary circuit of motor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/24—Controlling the direction, e.g. clockwise or counterclockwise
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/047—V/F converter, wherein the voltage is controlled proportionally with the frequency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P80/00—Climate change mitigation technologies for sector-wide applications
    • Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Definitions

  • the invention relates to the technical field of motor control, in particular to a soft starter control method capable of controlling low-speed forward rotation and low-speed reverse rotation of a motor.
  • the soft starter is a novel motor control device that integrates motor soft start, soft stop, light load energy saving and various protection functions. After using the soft starter, the above problems are solved, and the starting current can be set and limited.
  • the speed of the three-phase asynchronous motor is proportional to the speed of the three-phase synchronous rotating magnetic field of the input motor, while the speed of the three-phase synchronous rotating magnetic field of the input motor is only proportional to the frequency of the three-phase current of the input motor; therefore, at the input voltage frequency of the motor Under the same condition, the motor speed can be reduced by reducing the frequency of the three-phase current of the motor, and the phase sequence of the three-phase current of the motor can be changed to change the running direction of the motor.
  • the existing motor soft starter a group of anti-parallel thyristors are connected in series between the input end and the output end of each phase, and there are three phases in total. Since the turn-on and turn-off of the thyristor is based on the turn-on and turn-off of the voltage zero crossing, the frequency of the three-phase current of the motor can only be an integer fraction of the grid frequency.
  • the frequency of the three-phase current of the motor must be reduced, and it is discrete; If there is a soft starter to achieve low-speed forward or reverse rotation of the controlled motor, the phase sequence of the three-phase current input by the motor must be changed at the same time.
  • the input voltage of the motor remains unchanged, if the frequency of the three-phase current of the motor decreases, it is easy to cause the magnetic flux saturation of the motor, so it is necessary to reduce the input voltage of the motor synchronously.
  • the VVVF speed control scheme of the inverter and the soft starter The output voltage amplitude of the motor must also be reduced synchronously, thus avoiding the burning of the controlled motor due to magnetic flux saturation.
  • the purpose of the present invention is to overcome the defects of the prior art, provide a soft starter control method for controlling the low-speed forward rotation and low-speed reverse rotation of the motor, and realize the low-speed forward rotation and low-speed reverse control of the motor through the existing soft starter.
  • the present invention adopts the following technical solutions:
  • a soft starter control method for controlling low-speed forward rotation and low-speed reverse rotation of a motor includes three reverse-parallel thyristors, and the anti-parallel thyristors connected in series between the T-phase of the power grid and the W-phase input end of the motor have a signal terminal V T+ and signal terminal V T- , the anti-parallel thyristor connected in series between the S phase of the grid and the V phase input terminal of the motor has a signal terminal V S+ and a signal terminal V S- , connected in series between the R phase of the grid and the U phase of the motor
  • the anti-parallel thyristor between the input terminals has a signal terminal VR + and a signal terminal VR- ;
  • the forward rotation frequency division coefficient K F of the low-speed forward rotation of the motor satisfies the following formula:
  • n 0 is an integer
  • K F is a positive integer
  • Ne is the rated speed of the motor
  • n1 is an integer
  • K R is a positive integer
  • the soft starter controls the motor to perform low-speed forward rotation with a speed of V F or low-speed reverse with a speed of VR .
  • the soft starter control method makes the input current of each phase of the motor meet the following conditions:
  • the fundamental wave of each phase input current of the motor is a sine wave
  • the phase of the fundamental wave of the V-phase input current of the motor lags the phase of the fundamental wave of the U-phase input current by 1/3 of the fundamental wave period, and the phase of the fundamental wave of the W-phase input current of the motor lags the U-phase input current
  • the phase sequence of the input current of each phase of the motor is a positive phase sequence, and the motor rotates forward at low speed;
  • phase of the fundamental wave of the V-phase input current of the motor lags the phase of the fundamental wave of the U-phase input current by 2/3 of the fundamental cycle and the phase of the fundamental wave of the W-phase input current lags the phase of the fundamental wave of the U-phase input current
  • phase sequence of the input current of each phase of the motor is the reverse phase sequence, and the motor reverses at a low speed.
  • trigger signals can only be sent to two thyristors of different phases at the same time, and the two trigger signals are forward trigger signals and reverse trigger signals respectively.
  • the output torque of the motor is adjusted by controlling the firing angle of the thyristor.
  • the trigger angle and trigger timing of the thyristor and the time point of each input trigger signal to the thyristor are controlled through the following steps:
  • Step 4-1 record the moment when the falling edge signal of the zero-crossing point of the R-phase voltage of the power grid is detected as time point t4-1 , and then detect the falling edge signal of the zero-crossing point of the R-phase voltage of the power grid every T1 base , from The time point t 4-1 after the delay of T pwr /6 is recorded as time point t 4-2 .
  • the trigger signal is sent to the input terminals V T- and V S+ at the same time, and the trigger width is 1.0- 3.3ms;
  • Step 4-2 record the moment after the delay of T pwr /6 from the time point t 4-2 as the time point t 4-3 , at the time point t 4-3 simultaneously send trigger signals to the input terminals VR- and V S+ , the trigger width is 1.0-3.3ms;
  • Step 4-3 record the time after T pwr /6 from time t 4-3 as time t 4-4 , and send trigger signals to input terminals VR- and V T+ at the same time at time t 4-4 , the trigger width is 1.0-3.3ms;
  • Step 4-4 record the moment after the delay T pwr from the time point t 4-4 as the time point t 4-5 , at the time point t 4-5 send trigger signals to the input terminals VR- and V T+ at the same time, trigger
  • the width is 1.0-3.3ms
  • Step 4-5 record the moment after T pwr /6 delay from time point t 4-5 as time point t 4-6 , and send trigger signals to input terminals V S- and V T+ at the same time at time point t 4-6 , the trigger width is 1.0-3.3ms;
  • Step 4-6 the moment after the delay of T pwr /6 from the time point t 4-6 is recorded as the time point t 4-7 , at the time point t 4-7 , trigger signals are simultaneously sent to the input terminals VR+ and V S- , the trigger width is 1.0-3.3ms;
  • Step 4-7 record the moment after the delay T pwr from the time point t 4-7 as the time point t 4-8 , at the time point t 4-8 simultaneously send the trigger signal to the input terminal VR+ , V S- , trigger
  • the width is 1.0-3.3ms
  • Step 4-8 the moment after the delay of T pwr /6 from the time point t 4-8 is recorded as the time point t 4-9 , at the time point t 4-9 , trigger signals are simultaneously sent to the input terminals VR+ and V T- , the trigger width is 1.0-3.3ms;
  • step 4-9 the moment after the delay of T pwr /6 from the time point t 4-9 is recorded as the time point t 4-10 , at the time point t40 the trigger signal is sent to the input terminals V T+ and V S+ at the same time, and the trigger width is 1.0-3.3ms;
  • Step 4-10 detecting the falling edge signal of the zero-crossing point of the R-phase voltage, and repeating steps 4-1 to 4-9 until a shutdown command is received.
  • the trigger angle and trigger timing of the thyristor and the time point of each input trigger signal to the thyristor are controlled through the following steps:
  • Step 5-1 record the moment when the falling edge signal of the zero-crossing point of the R-phase voltage of the power grid is detected as time point t 5-1 , and then detect the falling edge signal of the zero-crossing point of the R-phase voltage of the power grid every T2 base , from The time point t 5-1 after the delay of T pwr /3 is recorded as time point t 5-2 .
  • the trigger signal is sent to the input terminals VR- and V S+ at the same time, and the trigger width is 1.0- 3.3ms;
  • Step 5-2 record the moment after the delay of T pwr /6 from time point t 5-2 as time point t 5-3 , and send trigger signals to input terminals VR- and V T+ at the same time at time point t 5-3 , the trigger width is 1.0-3.3ms;
  • Step 5-3 record the moment after T pwr 2/3 delay from time point t 5-3 as time point t 5-4 , and send triggers to input terminals V S+ and V T- simultaneously at time point t 5-4 signal, the trigger width is 1.0-3.3ms;
  • Step 5-4 record the moment after T pwr /6 delay from time point t 5-4 as time point t 5-5 , and send trigger signals to input terminals VR- and V S+ at the same time at time point t 5-5 , the trigger width is 1.0-3.3ms;
  • Step 5-5 record the moment after the delay of T pwr 2/3 from time point t 5-5 as time point t 5-6 , and send triggers to input terminals VR+ and V T- simultaneously at time point t 5-6 signal, the trigger width is 1.0-3.3ms;
  • Step 5-6 the moment after the delay of T pwr /6 from the time point t 5-6 is recorded as the time point t 5-7 , and the trigger signal is sent to the input terminals V S+ and V T- at the same time at the time point t 5-7 , the trigger width is 1.0-3.3ms;
  • Step 5-7 the moment after the delay of T pwr 2/3 from the time point t 5-7 is recorded as the time point t 5-8 , at the time point t 5-8 , the trigger is simultaneously sent to the input terminals V S- and VR+ signal, the trigger width is 1.0-3.3ms;
  • Step 5-8 the moment after the delay of T pwr /6 from the time point t 5-8 is recorded as the time point t 5-9 , at the time point t 5-9 , trigger signals are simultaneously sent to the input terminals VR+ and V T- , the trigger width is 1.0-3.3ms;
  • Step 5-9 the moment after the delay of T pwr 2/3 from the time point t 5-9 is recorded as the time point t 5-10 , and the trigger is sent to the input terminals V S- and V T+ at the same time at the time point t 5-10 signal, the trigger width is 1.0-3.3ms;
  • Step 5-10 the moment after the delay of T pwr /6 from the time point t 5-10 is recorded as the time point t 5-11 , and at the time point t 5-11 , trigger signals are simultaneously sent to the input terminals V S- and VR+ , the trigger width is 1.0-3.3ms;
  • Step 5-11 the moment after the delay of T pwr 2/3 from the time point t 5-10 is recorded as the time point t 5-12 , at the time point t 5-12 , the trigger is simultaneously sent to the input terminals VR- and V T+ signal, the trigger width is 1.0-3.3ms;
  • Step 5-12 the moment after the delay of T pwr /6 from the time point t 5-11 is recorded as the time point t 5-13 , at the time point t 5-13 , the trigger signal is simultaneously sent to the input terminals V S- and V T+ , the trigger width is 1.0-3.3ms;
  • Step 5-13 detecting the falling edge signal of the zero-crossing point of the R-phase voltage, and repeating steps 5-1 to 5-12 until a shutdown command is received.
  • the soft start control method increases the output torque of the motor by synchronously reducing the trigger angle within the fundamental period of the three-phase input current of the motor.
  • the triggering angle decreases by ⁇ degrees each time, 9 ⁇ 36.
  • the anti-parallel thyristors connected in series between the T-phase of the power grid and the W-phase input end of the motor include a T-phase forward thyristor SCR5 and a T-phase negative thyristor SCR6, and the T-phase forward thyristor SCR5 has a signal terminal V T+ , T
  • the phase negative thyristor SCR6 has a signal terminal V T- ;
  • the anti-parallel thyristor connected in series between the S phase of the power grid and the V phase input terminal of the motor includes the S phase positive thyristor SCR3 and the S phase negative thyristor SCR4, and the S phase positive
  • the thyristor SCR3 has a signal terminal V S+
  • the S-phase negative thyristor SCR4 has a signal terminal V S- ;
  • the forward rotation frequency division coefficient K F of the low-speed forward rotation of the motor is calculated by the following method:
  • the rotational angular velocity of the power frequency magnetic field is ⁇ 1
  • the rotational angular velocity of the magnetic field after forward frequency division is ⁇ 2F
  • the relationship between ⁇ 1 and ⁇ 2F conforms to the following equation:
  • K F is the forward rotation frequency division coefficient and is a positive integer
  • the power grid is a three-phase balanced system, and the phase difference of each phase is 120°.
  • Phase A and phase B are any two phases of the three phases R, S, and T of the power grid.
  • phase angle of phase A is 0°
  • phase B The phase angle of is given by the following equation:
  • n is an integer, and t is time
  • the low-speed forward rotation frequency division power grid system is a three-phase power system input by the soft starter to the motor to make it rotate forward at a low speed, and it is also a three-phase balanced system.
  • the phase difference of each phase is 120°, and the A F phase and the B F phase
  • the phase is any two phases of the three phases of the low-speed forward rotation frequency division grid system (that is, A F phase and B F are any two phases of the U, V, W three-phase input currents that make the motor rotate forward at low speed) , when the phase angle of phase A F is 0°, the phase angle of phase B F is reset to the following equation:
  • the reverse frequency division coefficient K R of the low-speed reverse rotation of the motor is calculated by the following method:
  • the rotational angular velocity of the power frequency magnetic field is ⁇ 1
  • the rotational angular velocity of the magnetic field after reverse frequency division is ⁇ 2R
  • the relationship between ⁇ 1 and ⁇ 2 conforms to the following equation:
  • K R is an inverse frequency division coefficient and is a positive integer
  • the power grid is a three-phase balanced system, and the phase difference of each phase is 120°.
  • Phase A and phase B are any two phases of the three phases R, S, and T of the power grid.
  • phase angle of phase A is 0°
  • phase B The phase angle of is given by the following equation:
  • n is an integer, and t is time
  • the low-speed reverse frequency division power grid system is a three-phase power system that the soft starter inputs to the motor to make it reverse at a low speed, and it is also a three-phase balanced system .
  • the phases are any two of the three phases of the low-speed reverse frequency division grid system (that is, A R phase and B R phase are any two of the U, V, W three-phase input currents that make the motor reverse at a low speed. phase), when the phase angle of the A R phase is 0°, the phase angle of the B R phase is reset to the following equation:
  • the soft starter control method for controlling the low-speed forward rotation and low-speed reverse rotation of the motor in the present invention can determine the low-speed forward rotation of the motor through an improved method without changing the grid input phase sequence, the grid frequency and the main circuit of the transmission motor soft starter.
  • the forward rotation frequency division coefficient K F of the rotation and the reverse frequency division coefficient K R of the low-speed reverse rotation of the motor, and then the three-phase input current of the motor is reduced by controlling the trigger timing of the thyristor and the time point of each input trigger signal to the thyristor Frequency and phase sequence, so as to control the motor to perform low-speed forward rotation with a speed of V F or low-speed reverse with a speed of V R.
  • Fig. 1 is the circuit structural representation of soft starter of the present invention
  • Fig. 2 is the waveform schematic diagram of the fundamental wave of the three-phase input current of motor when 4 frequency division low-speed forward rotations of the present invention
  • Fig. 3 is a schematic waveform diagram of the fundamental wave of the three-phase input current of the motor during low-speed reverse rotation with 5-frequency division in the present invention.
  • the specific implementation of the soft starter control method for controlling the low-speed forward rotation and low-speed reverse rotation of the motor of the present invention will be further described below in conjunction with the embodiments given in the accompanying drawings 1-3.
  • the soft starter control method for controlling the low-speed forward rotation and low-speed reverse rotation of the motor in the present invention is not limited to the description of the following embodiments.
  • the soft starter includes three anti-parallel thyristors, the anti-parallel thyristors connected in series between the T phase of the grid and the W phase input of the motor have signal terminals V T+ and V T- , and are connected in series between the S phase of the grid and the motor
  • the anti-parallel thyristor between the input terminals of the V phase of the V-phase has a signal terminal V S+ and the signal terminal V S-
  • the anti-parallel thyristor connected in series between the R-phase of the power grid and the U-phase input terminal of the motor has a signal terminal V R+ and a signal terminal V R - .
  • the anti-parallel thyristors connected in series between the T-phase of the power grid and the W-phase input terminal of the motor include a T-phase positive thyristor SCR5 and a T-phase negative thyristor SCR6, and the T-phase positive thyristor SCR5 has a signal terminal V T+ , T
  • the phase negative thyristor SCR6 has a signal terminal V T- ;
  • the anti-parallel thyristor connected in series between the S phase of the power grid and the V phase input terminal of the motor includes the S phase positive thyristor SCR3 and the S phase negative thyristor SCR4, and the S phase positive
  • the thyristor SCR3 has a signal terminal V S+
  • the S-phase negative thyristor SCR4 has a signal terminal V S- ;
  • the signal terminal V T+ , signal terminal V T- , signal terminal V S+ , signal terminal V S- , signal terminal VR+ and signal terminal VR- are respectively connected to the T-phase positive thyristor SCR5 and the T-phase negative thyristor.
  • the thyristor SCR6, the S-phase positive thyristor SCR3, the S-phase negative thyristor SCR4, the R-phase positive thyristor SCR1 and the R-phase negative thyristor SCR2 are connected to the G pole.
  • the soft starter control method for controlling the low-speed forward rotation and low-speed reverse rotation of the motor in the present invention is applied to the above-mentioned soft starter;
  • the forward rotation frequency division coefficient K F of the low-speed forward rotation of the motor satisfies the following formula:
  • n 0 is an integer
  • K F is a positive integer
  • Ne is the rated speed of the motor
  • n1 is an integer
  • K R is a positive integer
  • the forward rotation frequency division coefficient K F can be 4, 7, 10, 13, 16, etc.; therefore, the low-speed forward rotation speed of the motor can be wait.
  • the reverse frequency division coefficient K R can be 2, 5, 8, 11, 14, etc.; therefore, the low-speed reverse speed of the motor can be wait.
  • the soft starter control method for controlling the low-speed forward rotation and low-speed reverse rotation of the motor in the present invention can determine the low-speed forward rotation of the motor through an improved method without changing the grid input phase sequence, the grid frequency and the main circuit of the transmission motor soft starter.
  • the forward rotation frequency division coefficient K F of the rotation and the reverse frequency division coefficient K R of the low-speed reverse rotation of the motor, and then the three-phase input current of the motor is reduced by controlling the trigger timing of the thyristor and the time point of each input trigger signal to the thyristor Frequency and phase sequence, so as to control the motor to perform low-speed forward rotation with a speed of V F or low-speed reverse with a speed of V R.
  • the rotational angular velocity of the power frequency magnetic field is ⁇ 1
  • the rotational angular velocity of the magnetic field after forward frequency division is ⁇ 2F
  • the relationship between ⁇ 1 and ⁇ 2F conforms to the following equation:
  • K F is the forward rotation frequency division coefficient and is a positive integer
  • the power grid is a three-phase balanced system, and the phase difference of each phase is 120°.
  • Phase A and phase B are any two phases of the three phases R, S, and T of the power grid.
  • phase angle of phase A is 0°
  • phase B The phase angle of is given by the following equation:
  • n is an integer, and t is time
  • the low-speed forward rotation frequency division power grid system is a three-phase power system input by the soft starter to the motor to make it rotate forward at a low speed, and it is also a three-phase balanced system.
  • the phase difference of each phase is 120°
  • the A F phase and the B F phase The phase is any two phases of the three phases of the low-speed forward rotation frequency division grid system (that is, A F phase and B F are any two phases of the U, V, W three-phase input currents that make the motor rotate forward at low speed)
  • a F phase and B F phase correspond to A phase and B phase respectively
  • the frequency of A phase and B phase three-phase power grid is K F times of the frequency of A F phase and B F phase three-phase power grid system
  • the phase of B F phase When the phase angle of phase A and F is lagged by (2/3) ⁇ , and the phase angle of phase A and F is 0°, the phase angle of phase B and F conforms to the following equation:
  • the rotational angular velocity of the power frequency magnetic field is ⁇ 1
  • the rotational angular velocity of the magnetic field after reverse frequency division is ⁇ 2R
  • the relationship between ⁇ 1 and ⁇ 2 conforms to the following equation:
  • K R is an inverse frequency division coefficient and is a positive integer
  • the power grid is a three-phase balanced system, and the phase difference of each phase is 120°.
  • Phase A and phase B are any two phases of the three phases R, S, and T of the power grid.
  • phase angle of phase A is 0°
  • phase B The phase angle of is given by the following equation:
  • n is an integer, and t is time
  • the low-speed reverse frequency division power grid system is a three-phase power system that the soft starter inputs to the motor to make it reverse at a low speed, and it is also a three-phase balanced system .
  • the phases are any two of the three phases of the low-speed reverse frequency division grid system (that is, A R phase and B R phase are any two of the U, V, W three-phase input currents that make the motor reverse at a low speed.
  • a R phase and B R phase correspond to A phase and B phase respectively
  • the frequency of A phase and B phase three-phase power grid is K R times of the frequency of A R phase and B R phase three-phase power grid system
  • B R The phase of the phase is ahead of the phase of the A R phase by (2/3) ⁇ , and when the phase angle of the AR phase is 0°, the phase angle of the B R phase conforms to the following equation:
  • n 1 is an integer
  • select K R which is a positive integer as the inverted frequency division coefficient.
  • the soft starter control method makes the input current of each phase of the motor meet the following conditions:
  • the fundamental wave of the input current of each phase of the motor is a sine wave. Therefore, the waveforms of the input currents of each phase of the motor are three-phase symmetric, and the phases differ from each other by 1/3 period, and the effective values of the input currents of each phase of the motor are also balanced.
  • phase of the fundamental wave of the V-phase input current of the motor lags the phase of the fundamental wave of the U-phase input current by 1/3 of the fundamental wave period and the phase of the fundamental wave of the W-phase input current of the motor lags the fundamental wave of the U-phase input current
  • the phase sequence of the input current of each phase of the motor is a positive phase sequence, and the motor rotates forward at low speed;
  • the phase of the fundamental wave of the V-phase input current of the motor lags behind the fundamental wave of the U-phase input current
  • the phase sequence of the input current of each phase of the motor is the reverse phase sequence , the motor reverses at low speed.
  • the synthesized rotating magnetic field will perform circular motion, the three-phase current will be balanced, and the vibration will be very small when the motor rotates forward or reverse at low speed.
  • trigger signals can only be sent to two thyristors of different phases at the same time, and the two trigger signals are forward trigger signals and reverse trigger signals respectively, which will be specifically described in the following examples.
  • the soft starter control method of the invention controls the low-speed forward rotation and low-speed reverse rotation of the motor, and adjusts the output torque of the motor by controlling the trigger angle of the thyristor and/or the width of the trigger signal.
  • Step 4-1 record the moment when the falling edge signal of the zero-crossing point of the R-phase voltage of the power grid is detected as time point t4-1 , and then detect the falling edge signal of the zero-crossing point of the R-phase voltage of the power grid every T1 base , from The time point t 4-1 after the delay of T pwr /6 is recorded as time point t 4-2 .
  • the trigger signal is sent to the input terminals V T- and V S+ at the same time, and the trigger width is 1.0- 3.3ms, the T and S phases have current and the R phase has no current (that is, the W and V phases of the motor have input current, and the U phase has no input current);
  • Step 4-2 record the moment after the delay of T pwr /6 from the time point t 4-2 as the time point t 4-3 , at the time point t 4-3 simultaneously send trigger signals to the input terminals VR- and V S+ , the trigger width is 1.0-3.3ms, the R and S phases have current and the T phase has no current (that is, the V and U phases of the motor have input current, and the W phase has no input current);
  • Step 4-3 record the time after T pwr /6 from time t 4-3 as time t 4-4 , and send trigger signals to input terminals VR- and V T+ at the same time at time t 4-4 , the trigger width is 1.0-3.3ms, the R and T phases have current and the S phase has no current (that is, the W and U phases of the motor have input current, and the V phase has no input current);
  • Step 4-4 record the moment after the delay T pwr from the time point t 4-4 as the time point t 4-5 , at the time point t 4-5 send trigger signals to the input terminals VR- and V T+ at the same time, trigger
  • the width is 1.0-3.3ms, the R and T phases have current and the S phase has no current (that is, the U and 2 phases of the motor have input current, and the V phase has no input current);
  • Step 4-5 record the moment after T pwr /6 delay from time point t 4-5 as time point t 4-6 , and send trigger signals to input terminals V S- and V T+ at the same time at time point t 4-6 , the trigger width is 1.0-3.3ms, the S and T phases have current and the R phase has no current (that is, the V and W phases of the motor have input current, and the U phase has no input current);
  • Step 4-6 the moment after the delay of T pwr /6 from the time point t 4-6 is recorded as the time point t 4-7 , at the time point t 4-7 , trigger signals are simultaneously sent to the input terminals VR+ and V S- , the trigger width is 1.0-3.3ms, the S and R phases have current and the T phase has no current (that is, the V and U phases of the motor have input current, and the W phase has no input current);
  • Step 4-7 record the moment after the delay T pwr from the time point t 4-7 as the time point t 4-8 , at the time point t 4-8 simultaneously send the trigger signal to the input terminal VR+ , V S- , trigger
  • the width is 1.0-3.3ms, the S and R phases have current and the T phase has no current (that is, the V and U phases of the motor have input current, and the W phase has no input current);
  • Step 4-8 the moment after the delay of T pwr /6 from the time point t 4-8 is recorded as the time point t 4-9 , at the time point t 4-9 , trigger signals are simultaneously sent to the input terminals VR+ and V T- , the trigger width is 1.0-3.3ms, the R and T phases have current and the S phase has no current (that is, the U and W phases of the motor have input current, and the V phase has no input current);
  • step 4-9 the moment after the delay of T pwr /6 from the time point t 4-9 is recorded as the time point t 4-10 , at the time point t40 the trigger signal is sent to the input terminals V T+ and V S+ at the same time, and the trigger width is 1.0-3.3ms, the S and T phases have current and the R phase has no current (that is, the V and W phases of the motor have input current, and the U phase has no input current);
  • Step 4-10 after the time point t4-10 , the falling edge signal of the zero-crossing point of the R-phase voltage is detected again, and steps 4-1 to 4-9 are repeated until a shutdown command is received.
  • FIG. 2 it is the fundamental wave graph of the three-phase input current of the motor in Example 1.
  • the fundamental wave phases of the R, S, and T phases are sequentially different from each other by T1 base /3, and the input currents of each phase are balanced.
  • the speed of N e performs low-speed forward rotation.
  • Step 5-1 record the moment when the falling edge signal of the zero-crossing point of the R-phase voltage of the power grid is detected as time point t 5-1 , and then detect the falling edge signal of the zero-crossing point of the R-phase voltage of the power grid every T2 base , from The time point t 5-1 after the delay of T pwr /3 is recorded as time point t 5-2 .
  • the trigger signal is sent to the input terminals VR- and V S+ at the same time, and the trigger width is 1.0- 3.3ms, the R and S phases have current, and the T phase has no current (that is, the U and V phases of the motor have current input, and the W phase has no current input);
  • Step 5-2 record the moment after the delay of T pwr /6 from time point t 5-2 as time point t 5-3 , and send trigger signals to input terminals VR- and V T+ at the same time at time point t 5-3 , the trigger width is 1.0-3.3ms, the R and T phases have current, and the S phase has no current (that is, the U and W phases of the motor have current input, and the V phase has no current input);
  • Step 5-3 record the moment after T pwr 2/3 delay from time point t 5-3 as time point t 5-4 , and send triggers to input terminals V S+ and V T- simultaneously at time point t 5-4 signal, the trigger width is 1.0-3.3ms, the S and T phases have current, and the R phase has no current (that is, the V and W phases of the motor have current input, and the U phase has no current input);
  • Step 5-4 record the moment after T pwr /6 delay from time point t 5-4 as time point t 5-5 , and send trigger signals to input terminals VR- and V S+ at the same time at time point t 5-5 , the trigger width is 1.0-3.3ms, the R and S phases have current, and the T phase has no current (that is, the U and V phases of the motor have current input, and the W phase has no current input);
  • Step 5-5 record the moment after the delay of T pwr 2/3 from time point t 5-5 as time point t 5-6 , and send triggers to input terminals VR+ and V T- simultaneously at time point t 5-6 signal, the trigger width is 1.0-3.3ms, the R and T phases have current, and the S phase has no current (that is, the U and W phases of the motor have current input, and the V phase has no current input);
  • Step 5-6 the moment after the delay of T pwr /6 from the time point t 5-6 is recorded as the time point t 5-7 , and the trigger signal is sent to the input terminals V S+ and V T- at the same time at the time point t 5-7 , the trigger width is 1.0-3.3ms, the S and T phases have current, and the R phase has no current (that is, the V and W phases of the motor have current input, and the U phase has no current input);
  • Step 5-7 the moment after the delay of T pwr 2/3 from the time point t 5-7 is recorded as the time point t 5-8 , at the time point t 5-8 , the trigger is simultaneously sent to the input terminals V S- and VR+ signal, the trigger width is 1.0-3.3ms, the S and R phases have current, and the T phase has no current (that is, the V and U phases of the motor have current input, and the W phase has no current input);
  • Step 5-8 the moment after the delay of T pwr /6 from the time point t 5-8 is recorded as the time point t 5-9 , at the time point t 5-9 , trigger signals are simultaneously sent to the input terminals VR+ and V T- , the trigger width is 1.0-3.3ms, the R and T phases have current, and the S phase has no current (that is, the U and W phases of the motor have current input, and the V phase has no current input);
  • Step 5-9 the moment after the delay of T pwr 2/3 from the time point t 5-9 is recorded as the time point t 5-10 , and the trigger is sent to the input terminals V S- and V T+ at the same time at the time point t 5-10 signal, the trigger width is 1.0-3.3ms, the S and T phases have current, and the R phase has no current (that is, the V and W phases of the motor have current input, and the U phase has no current input);
  • Step 5-10 the moment after the delay of T pwr /6 from the time point t 5-10 is recorded as the time point t 5-11 , and at the time point t 5-11 , trigger signals are simultaneously sent to the input terminals V S- and VR+ , the trigger width is 1.0-3.3ms, the S and R phases have current, and the T phase has no current (that is, the V and U phases of the motor have current input, and the W phase has no current input);
  • Step 5-11 record the moment after T pwr 2/3 delay from time point t 5-11 as time point t 5-12 , and send triggers to input terminals VR- and V T+ at the same time at time point t 5-12 signal, the trigger width is 1.0-3.3ms, the T and R phases have current, and the S phase has no current (that is, the W and U phases of the motor have current input, and the V phase has no current input);
  • Step 5-12 record the moment after the delay of T pwr /6 from time point t 5-12 as time point t 5-13 , and send trigger signals to input terminals V S- and V T+ at the same time at time point t 5-13 , the trigger width is 1.0-3.3ms, the S and T phases have current, and the R phase has no current (that is, the V and W phases of the motor have current input, and the U phase has no current input);
  • Step 5-13 after the time point t 5-13 , the falling edge signal of the zero-crossing point of the R-phase voltage is detected again, and steps 5-1 to 5-12 are repeated until a shutdown command is received.
  • FIG 3 it is the fundamental wave graph of the three-phase input current of the motor in Example 2.
  • the fundamental phases of the R, S, and T phases are sequentially different from each other by T1 base 2/3, and the input currents of each phase are balanced.
  • the speed of Ne is reversed at low speed.
  • the control of the motor rotation direction can be realized, that is, the motor can be controlled to rotate forward or reverse;
  • the control of the time point at which the trigger signal is input to the thyristor can be realized, so that the current corresponding to the trigger signal is input to the motor through the thyristor (that is, the steamed bread waveform current in Figures 2 and 3 signal), the fundamental frequency of the current input to the motor is equal to the grid frequency/forward or reverse frequency division factor, that is, the fundamental period of the current input to the motor is equal to the grid cycle ⁇ forward or reverse frequency division coefficient;
  • the current intensity of the thyristor input to the motor can be realized, thereby realizing the adjustment of the output torque of the motor.
  • the soft starter control method of the present invention controls the low-speed forward rotation and low-speed reverse rotation of the motor, by synchronously reducing or increasing the trigger angle within the fundamental wave period of the three-phase input current of the motor to increase or decrease the motor output torque.
  • the trigger angle decreases or increases by ⁇ degrees every time, 9 ⁇ 36, the larger the value of ⁇ , the greater the change value of the output torque of the motor, that is, the larger the value of ⁇ , the greater the The greater the rate of change of the output torque.

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Abstract

本发明涉及电机控制技术领域，具体涉及一种可控制电机低速正转和低速反转的软启动器控制方法，通过改进方法确定电机的低速正转的正转分频系数K F和电机的低速反转的反转分频系数K R，然后通过控制晶闸管的触发时序以及每次向晶闸管输入触发信号的时间点，在不改变电网输入相序、电网频率和传动电机软启动器的主电路的前提下，降低电机的三相输入电流频率和相序，从而控制电机进行转速为V F的低速正转或转速为V R的低速反转。

Description

控制电机低速正转和低速反转的软启动器控制方法 技术领域
本发明涉及电机控制技术领域，具体涉及一种可控制电机低速正转和低速反转的软启动器控制方法。
背景技术
三相异步电机直接起动时，电流通常会达到5～8倍，甚至更大，产生很大冲击电流，对同个系统中的电网产生很大的波动，对整个传动系统、设备产生不良影响。软起动器是一种集电动机软起动、软停车、轻载节能和多种保护功能于一体的新颖电动机控制装置。采用软起动器后，上述问题得到解决，起动电流可以进行设置和限制。
在一些应用场景下，需要控制电机低速正转或低速反转，例如水泵清洗时，需要控制水泵低速正转或低速反转，但是现有软启动器不具备低速正转和低速反转控制功能。已知三相异步电机转速与输入电机的三相同步旋转磁场转速成正比关系，而输入电机的三相同步旋转磁场转速仅与输入电机的三相电流频率成正比；因此，在电机输入电压频率不变的情况下，可通过降低电机的三相电流频率以降低电机转速，改变电机的三相电流的相序以改变电机运行的方向。
现有电机软起动器，在其每相的输入端与输出端之间串接一组反并联晶闸管，共有三相。由于晶闸管的开通与关断是基于电压过零的开通与关断，电机的三相电流频率只能是电网频率的整数份之一。因此在电网频率不变的情况下，现有软起动器若要实现被控电机的低速运行必须降低电机的三相电流频率，而且是离散的；在电网频率相序不变的情况下，现有软起动器若要实现被控电机的低速正转或反转必须同时改变电机输入的三相电流相序。此外，在电机输入电压不变的情况下，若电机的三相电流频率降低时，容易导致电机磁通饱和，故需要同步降低电机输入的电压，参照变频器VVVF调速控制方案，软起动器的输出电压幅值也须同步降低，从而避免了被控电机的因磁通饱和而烧毁。
基于上述情况，亟需一种软启动器，其在不改变电网输入相序、电网频率和现有电机软起动器主电路的条件下，控制电机低速正转和低速反转且运行平稳。
发明内容
本发明的目的在于克服现有技术的缺陷，提供一种控制电机低速正转和低速反转的软启动器控制方法，通过现有软启动器实现了对于电机低速正转和低速反转控制。
为实现上述目的，本发明采用了如下技术方案：
一种控制电机低速正转和低速反转的软启动器控制方法，软启动器包括三相反并联晶闸管，串联在电网的T相和电机的W相输入端之间的反并联晶闸管具有信号端V T+和信号端V T-，串联在电网的S相和电机的V相输入端之间的反并联晶闸管具有信号端V S+和信号端V S-，串联在电网的R相和电机的U相输入端之间的反并联晶闸管具有信号端V R+和信号端V R-；
所述电机的低速正转的正转分频系数K F满足以下公式：
Figure PCTCN2022107725-appb-000001
所述电机低速正转的转速
Figure PCTCN2022107725-appb-000002
其中，n 0为整数，K F为正整数，N e为电机的额定转速；
所述电机的低速反转的反转分频系数K R满足以下公式：
Figure PCTCN2022107725-appb-000003
所述电机低速翻转的转速
Figure PCTCN2022107725-appb-000004
其中，n 1为整数，K R为正整数；
通过控制晶闸管的触发时序及每次向晶闸管输入触发信号的时间点以通过软启动器控制电机进行转速为V F的低速正转或转速为V R的低速反转。
优选的，所述软启动器控制方法使电机的各相输入电流符合以下条件：
(1)所述电机的各相输入电流的基波均为正弦波；
(2)基于正转分频系数K F或反转分频系数K R得到所述电机的各相输入电流的基波周期T base，所述电机的各相输入电流的基波周期T base＝电网周期T pwr*(K F或K R)；
(3)所述电机的各相输入电流的基波相位互差1/3个基波周期T base。
优选的，所述电机的V相输入电流的基波的相位滞后U相输入电流的基波的相位1/3个基波周期且电机的W相输入电流的基波的相位滞后U相输入电流的基波的相位1/3个基波周期时，电机各相输入电流的相序为正相序，电机低速正转；
所述电机的V相输入电流的基波的相位滞后U相输入电流的基波的相位2/3个基波周期且W相输入电流的基波的相位滞后U相输入电流的基波的相位1/3个基波周期时，电机各相输入电流的相序为反相序，电机低速反转。
优选的，同一时刻只能向不同相的两路晶闸管发送触发信号，而且两路触发信号分别为正向触发信号和反向触发信号。
优选的，通过控制晶闸管的触发角度，调整电机的输出扭矩。
优选的，所述正转分频系数K F＝4时，通过以下步骤控制晶闸管的触发角度和触发时序以及每次向晶闸管输入触发信号的时间点：
所述电网的周期为T pwr，则4分频低速正转状态下的电机的三相输入电流的基波的周期为T1 base＝4×T pwr；
步骤4-1，将检测到所述电网R相电压过零点下降沿信号的时刻记为时间点t 4-1，之后每隔1个T1 base检测一次电网R相电压过零点下降沿信号，从时间点t 4-1延时T pwr/6后的时刻记为时间点t 4-2，在时间点t 4-2同时向输入端V T-、V S+发送触发信号，触发宽度为1.0-3.3ms；
步骤4-2，从时间点t 4-2延时T pwr/6后的时刻记为时间点t 4-3，在时间点t 4-3同时向输入端V R-、V S+发送触发信号，触发宽度为1.0-3.3ms；
步骤4-3，从时间点t 4-3延时T pwr/6后的时刻记为时间点t 4-4，在时间点t 4-4同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms；
步骤4-4，从时间点t 4-4延时T pwr后的时刻记为时间点t 4-5，在时间点t 4-5同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms；
步骤4-5，从时间点t 4-5延时T pwr/6后的时刻记为时间点t 4-6，在时间点t 4-6同时向输入端V S-、V T+发送触发信号，触发宽度为1.0-3.3ms；
步骤4-6，从时间点t 4-6延时T pwr/6后的时刻记为时间点t 4-7，在时间点t 4-7同时向输入端V R+、V S-发送触发信号，触发宽度为1.0-3.3ms；
步骤4-7，从时间点t 4-7延时T pwr后的时刻记为时间点t 4-8，在时间点t 4-8同时向输入端V R+、V S-发送触发信号，触发宽度为1.0-3.3ms；
步骤4-8，从时间点t 4-8延时T pwr/6后的时刻记为时间点t 4-9，在时间点t 4-9同时向输入端V R+、V T-发送触发信号，触发宽度为1.0-3.3ms；
步骤4-9，从时间点t 4-9延时T pwr/6后的时刻记为时间点t 4-10，在时间点t40同时向输入端V T+、V S+发送触发信号，触发宽度为1.0-3.3ms；
步骤4-10，检测到所述R相电压过零点下降沿信号，重复步骤4-1至4-9，直至收到停机命令。
优选的，所述反转分频系数K R＝5时，通过以下步骤控制晶闸管的触发角度和触发时序以及每次向晶闸管输入触发信号的时间点：
所述电网的周期为T pwr，则5分频低速反转状态下的电机的三相输入电流的基波的周期为T2 base＝5×T pwr；
步骤5-1，将检测到所述电网R相电压过零点下降沿信号的时刻记为时间点t 5-1，之后每隔1个T2 base检测一次电网R相电压过零点下降沿信号，从时间点t 5-1延时T pwr/3后的时刻记为时间点t 5-2，在时间点t 5-2同时向输入端V R-、V S+发送触发信号，触发宽度为1.0-3.3ms；
步骤5-2，从时间点t 5-2延时T pwr/6后的时刻记为时间点t 5-3，在时间点t 5-3同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms；
步骤5-3，从时间点t 5-3延时T pwr2/3后的时刻记为时间点t 5-4，在时间点t 5-4同时向输入端V S+、V T-发送触发信号，触发宽度为1.0-3.3ms；
步骤5-4，从时间点t 5-4延时T pwr/6后的时刻记为时间点t 5-5，在时间点t 5-5同时向输入端V R-、V S+发送触发信号，触发宽度为1.0-3.3ms；
步骤5-5，从时间点t 5-5延时T pwr2/3后的时刻记为时间点t 5-6，在时间点t 5-6同时向输入端V R+、V T-发送触发信号，触发宽度为1.0-3.3ms；
步骤5-6，从时间点t 5-6延时T pwr/6后的时刻记为时间点t 5-7，在时间点t 5-7同时向输入端V S+、V T-发送触发信号，触发宽度为1.0-3.3ms；
步骤5-7，从时间点t 5-7延时T pwr2/3后的时刻记为时间点t 5-8，在时间点t 5-8同时向输入端V S-、V R+发送触发信号，触发宽度为1.0-3.3ms；
步骤5-8，从时间点t 5-8延时T pwr/6后的时刻记为时间点t 5-9，在时间点t 5-9同时向输入端V R+、V T-发送触发信号，触发宽度为1.0-3.3ms；
步骤5-9，从时间点t 5-9延时T pwr2/3后的时刻记为时间点t 5-10，在时间点t 5-10同时向输入端V S-、V T+发送触发信号，触发宽度为1.0-3.3ms；
步骤5-10，从时间点t 5-10延时T pwr/6后的时刻记为时间点t 5-11，在时间点t 5-11同时向输入端V S-、V R+发送触发信号，触发宽度为1.0-3.3ms；
步骤5-11，从时间点t 5-10延时T pwr2/3后的时刻记为时间点t 5-12，在时间点t 5-12同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms；
步骤5-12，从时间点t 5-11延时T pwr/6后的时刻记为时间点t 5-13，在时间点t 5-13同时向输入端V S-、V T+发送触发信号，触发宽度为1.0-3.3ms；
步骤5-13，检测到所述R相电压过零点下降沿信号，重复步骤5-1至 5-12，直至收到停机命令。
优选的，所述软启动控制方法，通过在电机的三相输入电流的基波周期内，同步减小触发角度以增大电机的输出转矩。
优选的，所述触发角度每次减少δ度，9≤δ≤36。
优选的，串联在电网的T相和电机的W相输入端之间的反并联晶闸管包括T相正向晶闸管SCR5和T相负向晶闸管SCR6，T相正向晶闸管SCR5具有信号端V T+，T相负向晶闸管SCR6具有信号端V T-；串联在电网的S相和电机的V相输入端之间的反并联晶闸管包括S相正向晶闸管SCR3和S相负向晶闸管SCR4，S相正向晶闸管SCR3具有信号端V S+，S相负向晶闸管SCR4具有信号端V S-；串联在电网的R相和电机的U相输入端之间的反并联晶闸管包括R相正向晶闸管SCR1和R相负向晶闸管SCR2，R相正向晶闸管SCR1具有信号端V R+，R相负向晶闸管SCR2具有信号端V R-。
优选的，通过以下方法计算电机的低速正转的正转分频系数K F：
工频磁场旋转角速度为ω 1，正转分频后的磁场旋转角速度为ω 2F，ω 1和ω 2F关系符合以下等式：
ω 1＝K F×ω 2F   等式(1)
其中，K F为正转分频系数且为正整数；
所述电网为三相平衡系统，各相相位差为120°，A相和B相为电网的R、S、T三相中的任意两相，A相的相位角为0°时，B相的相位角符合以下等式：
ω 1×t-(2/3)π＝n 0π   等式(2)
其中，n为整数，t为时间；
所述低速正转分频电网系统，即是软启动器向电机输入的使其低速正转的三相电源系统，也是三相平衡系统，各相相位差为120°，A F相和B F相为低速正转分频电网系统的三相中的任意两相(也即是，A F相和B F为使电机低速正转的U、V、W三相输入电流中的任意两相)，A F相的相位角为0°时，B F相的相位角复位以下等式：
ω 2F×t-(2/3)π＝0   等式(3)
由等式(3)变形得到以下等式：
ω 2F×t＝(2/3)π   等式(4)
将等式(1)带入等式(2)得到以下等式：
K F×ω 2F×t＝(2/3)π+n 0π   等式(5)
将等式(3)带入等式(5)得到以下等式：
Figure PCTCN2022107725-appb-000005
通过以下方法计算电机的低速反转的反转分频系数K R：
工频磁场旋转角速度为ω 1，反转分频后的磁场旋转角速度为ω 2R，ω 1和ω 2关系符合以下等式：
ω 1＝K R×ω 2R   等式(6)
其中，K R为反转分频系数且为正整数；
所述电网为三相平衡系统，各相相位差为120°，A相和B相为电网的R、S、T三相中的任意两相，A相的相位角为0°时，B相的相位角符合以下等式：
ω 1×t-(2/3)π＝n 1π  等式(7)
其中，n为整数，t为时间；
所述低速反转分频电网系统，即是软启动器向电机输入的使其低速反转的三相电源系统，也是三相平衡系统，各相相位差为120°，A R相和B R相分别为低速反转分频电网系统的三相中的任意两相(也即是，A R相和B R相为使电机低速反转的U、V、W三相输入电流中的任意两相)，A R相的相位角为0°时，B R相的相位角复位以下等式：
ω 2R×t+(2/3)π＝0   等式(8)
由等式(8)变形得到以下等式：
ω 2R×t＝-(2/3)π   等式(9)
将等式(6)带入等式(7)得到以下等式：
K R×ω 2R×t＝(2/3)π+n 1π   等式(10)
将等式(9)带入等式(10)得到以下等式：
Figure PCTCN2022107725-appb-000006
本发明控制电机低速正转和低速反转的软启动器控制方法，可以在不改变电网输入相序、电网频率和传动电机软启动器的主电路的前提下，通过改进方法确定电机的低速正转的正转分频系数K F和电机的低速反转的反转分频系数K R，然后通过控制晶闸管的触发时序以及每次向晶闸管输入触发信号的时间点，降低电机的三相输入电流频率和相序，从而控制电机进行转速为V F的低速正转或转速为V R的低速反转。
附图说明
图1是本发明软启动器的电路结构示意图；
图2是本发明4分频低速正转时电机的三相输入电流的基波的波形示 意图；
图3是本发明5分频低速反转时电机的三相输入电流的基波的波形示意图。
具体实施方式
以下结合附图1-3给出的实施例，进一步说明本发明的控制电机低速正转和低速反转的软启动器控制方法的具体实施方式。本发明的控制电机低速正转和低速反转的软启动器控制方法不限于以下实施例的描述。
如图1所示，为本发明软启动器的一个实施例。
所述软启动器包括三相反并联晶闸管，串联在电网的T相和电机的W相输入端之间的反并联晶闸管具有信号端V T+和信号端V T-，串联在电网的S相和电机的V相输入端之间的反并联晶闸管具有信号端V S+和信号端V S-，串联在电网的R相和电机的U相输入端之间的反并联晶闸管具有信号端V R+和信号端V R-。进一步的，串联在电网的T相和电机的W相输入端之间的反并联晶闸管包括T相正向晶闸管SCR5和T相负向晶闸管SCR6，T相正向晶闸管SCR5具有信号端V T+，T相负向晶闸管SCR6具有信号端V T-；串联在电网的S相和电机的V相输入端之间的反并联晶闸管包括S相正向晶闸管SCR3和S相负向晶闸管SCR4，S相正向晶闸管SCR3具有信号端V S+，S相负向晶闸管SCR4具有信号端V S-；串联在电网的R相和电机的U相输入端之间的反并联晶闸管包括R相正向晶闸管SCR1和R相负向晶闸管SCR2，R相正向晶闸管SCR1具有信号端V R+，R相负向晶闸管SCR2具有信号端V R-。进一步的，所述信号端V T+、信号端V T-、信号端V S+、信号端V S-、信号端V R+和信号端V R-分别与T相正向晶闸管SCR5、T相负向晶闸管SCR6、S相正向晶闸管SCR3、S相负向晶闸管SCR4、R相正向晶闸管SCR1和R相负向晶闸管SCR2的G极相连。
本发明控制电机低速正转和低速反转的软启动器控制方法，应用于上述软启动器；
所述电机的低速正转的正转分频系数K F满足以下公式：
Figure PCTCN2022107725-appb-000007
所述电机低速正转的转速
Figure PCTCN2022107725-appb-000008
其中，n 0为整数，K F为正整数，N e为电机的额定转速；
所述电机的低速反转的反转分频系数K R满足以下公式：
Figure PCTCN2022107725-appb-000009
所述电机低速翻转的转速
Figure PCTCN2022107725-appb-000010
其中，n 1为整数，K R为正整数；
控制晶闸管的触发时序及每次向晶闸管输入触发信号的时间点以通过软启动器控制电机进行转速为V F的低速正转或转速为V R的低速反转。
具体的，所述正转分频系数K F可以是4、7、10、13、16等；因此，所述电机的低速正转的转速可以是
Figure PCTCN2022107725-appb-000011
等。所述反转分频系数K R可以是2、5、8、11、14等；因此，所述电机的低速反转的转速可以是
Figure PCTCN2022107725-appb-000012
等。
本发明控制电机低速正转和低速反转的软启动器控制方法，可以在不改变电网输入相序、电网频率和传动电机软启动器的主电路的前提下，通过改进方法确定电机的低速正转的正转分频系数K F和电机的低速反转的反转分频系数K R，然后通过控制晶闸管的触发时序以及每次向晶闸管输入触发信号的时间点，降低电机的三相输入电流频率和相序，从而控制电机进行转速为V F的低速正转或转速为V R的低速反转。
以下为电机的低速正转的正转分频系数K F的计算过程：
工频磁场旋转角速度为ω 1，正转分频后的磁场旋转角速度为ω 2F，ω 1和ω 2F关系符合以下等式：
ω 1＝K F×ω 2F   等式(1)
其中，K F为正转分频系数且为正整数；
所述电网为三相平衡系统，各相相位差为120°，A相和B相为电网的R、S、T三相中的任意两相，A相的相位角为0°时，B相的相位角符合以下等式：
ω 1×t-(2/3)π＝n 0π   等式(2)
其中，n为整数，t为时间；
所述低速正转分频电网系统，即是软启动器向电机输入的使其低速正转的三相电源系统，也是三相平衡系统，各相相位差为120°，A F相和B F相为低速正转分频电网系统的三相中的任意两相(也即是，A F相和B F为使电机低速正转的U、V、W三相输入电流中的任意两相)，A F相和B F相分别对应A相和B相，A相和B相三相电网的频率为A F相和B F相三相电网系统的频率的K F倍，B F相的相位滞后A F相的相位(2/3)π，A F相的相位角为0°时，B F相的相位角符合以下等式：
ω 2F×t-(2/3)π＝0   等式(3)
由等式(3)变形得到以下等式：
ω 2F×t＝(2/3)π   等式(4)
将等式(1)带入等式(2)得到以下等式：
K F×ω 2F×t＝(2/3)π+n 0π   等式(5)
将等式(4)带入等式(5)得到以下等式：
Figure PCTCN2022107725-appb-000013
在n 0为整数的情况下，选取K F为正整数的K F作为正转分频系数。
以下为电机的低速反转的反转分频系数K R的计算过程：
工频磁场旋转角速度为ω 1，反转分频后的磁场旋转角速度为ω 2R，ω 1和ω 2关系符合以下等式：
ω 1＝K R×ω 2R   等式(6)
其中，K R为反转分频系数且为正整数；
所述电网为三相平衡系统，各相相位差为120°，A相和B相为电网的R、S、T三相中的任意两相，A相的相位角为0°时，B相的相位角符合以下等式：
ω 1×t-(2/3)π＝n 1π   等式(7)
其中，n为整数，t为时间；
所述低速反转分频电网系统，即是软启动器向电机输入的使其低速反转的三相电源系统，也是三相平衡系统，各相相位差为120°，A R相和B R相分别为低速反转分频电网系统的三相中的任意两相(也即是，A R相和B R相为使电机低速反转的U、V、W三相输入电流中的任意两相)，A R相和B R相分别与A相和B相对应，A相和B相三相电网的频率为A R相和B R相三相电网系统的频率的K R倍，B R相的相位超前A R相的相位(2/3)π，AR相的相位角为0°时，B R相的相位角符合以下等式：
ω 2R×t+(2/3)π＝0   等式(8)
由等式(8)变形得到以下等式：
ω 2R×t＝-(2/3)π   等式(9)
将等式(6)带入等式(7)得到以下等式：
K R×ω 2R×t＝(2/3)π+n 1π    等式(10)
将等式(9)带入等式(10)得到以下等式：
Figure PCTCN2022107725-appb-000014
在n 1为整数的情况下，选取K R为正整数的K R作为反转分频系数。
参照图2和3所示，所述软启动器控制方法使电机的各相输入电流符合以下条件：
(1)所述电机的各相输入电流的基波均为正弦波。因此，所述电机的各相输入电流波形是三相对称的，相位互差1/3周期，同时电机的各相输入电流的有效值也是平衡的。
(2)基于正转分频系数K F或反转分频系数K R得到所述电机的各相输入
Figure PCTCN2022107725-appb-000015
入电流基波频率的方式改变了电机的转速。
(3)所述电机的各相输入电流的基波相位互差1/3个基波周期。
所述电机的V相输入电流的基波的相位滞后U相输入电流的基波的相位1/3个基波周期且电机的W相输入电流的基波的相位滞后U相输入电流的基波的相位1/3个基波周期时，电机各相输入电流的相序为正相序，电机低速正转；所述电机的V相输入电流的基波的相位滞后U相输入电流的基波的相位2/3个基波周期且W相输入电流的基波的相位滞后U相输入电流的基波的相位1/3个基波周期时，电机各相输入电流的相序为反相序，电机低速反转。
在任何一种分频系数下，合成后的旋转磁场都做圆周运动，三相电流平衡，电机低速正转或低速反转时震动都很小。
优选的，同一时刻只能向不同相的两路晶闸管发送触发信号，而且两路触发信号分别为正向触发信号和反向触发信号，将在以下示例中做具体说明。
本发明控制电机低速正转和低速反转的软启动器控制方法，通过控制晶闸管的触发角度和/或触发信号的宽度，调整电机的输出扭矩。
以下为本发明控制电机低速正转和低速反转的软启动器控制方法的具体控制示例：
示例一：
n 0为2时，所述正转分频系数K F＝4时，通过以下步骤控制晶闸管的触发角度和触发时序以使电机以
Figure PCTCN2022107725-appb-000016
N e的速度低速正转：
所述电网的周期为T pwr，则4分频低速反转状态下的电机的三相输入电流的基波的周期为T1 base＝4×T pwr；
步骤4-1，将检测到所述电网R相电压过零点下降沿信号的时刻记为时间点t 4-1，之后每隔1个T1 base检测一次电网R相电压过零点下降沿信号，从时间点t 4-1延时T pwr/6后的时刻记为时间点t 4-2，在时间点t 4-2同时向输入端V T-、V S+发送触发信号，触发宽度为1.0-3.3ms，T、S相有电流且R相无电流(也即是电机的W、V相有输入电流，U相无输入电流)；
步骤4-2，从时间点t 4-2延时T pwr/6后的时刻记为时间点t 4-3，在时间点t 4-3同时向输入端V R-、V S+发送触发信号，触发宽度为1.0-3.3ms，R、S相有电流且T相无电流(也即是电机的V、U相有输入电流，W相无输入电流)；
步骤4-3，从时间点t 4-3延时T pwr/6后的时刻记为时间点t 4-4，在时间点t 4-4同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms，R、T相有电流且S相无电流(也即是电机的W、U相有输入电流，V相无输入电流)；
步骤4-4，从时间点t 4-4延时T pwr后的时刻记为时间点t 4-5，在时间点t 4-5同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms，R、T相有电流且S相无电流(也即是电机的U、2相有输入电流，V相无输入电流)；
步骤4-5，从时间点t 4-5延时T pwr/6后的时刻记为时间点t 4-6，在时间点t 4-6同时向输入端V S-、V T+发送触发信号，触发宽度为1.0-3.3ms，S、T相有电流且R相无电流(也即是电机的V、W相有输入电流，U相无输入电流)；
步骤4-6，从时间点t 4-6延时T pwr/6后的时刻记为时间点t 4-7，在时间点t 4-7同时向输入端V R+、V S-发送触发信号，触发宽度为1.0-3.3ms，S、R相有电流且T相无电流(也即是电机的V、U相有输入电流，W相无输入电流)；
步骤4-7，从时间点t 4-7延时T pwr后的时刻记为时间点t 4-8，在时间点t 4-8同时向输入端V R+、V S-发送触发信号，触发宽度为1.0-3.3ms，S、R相有电流且T相无电流(也即是电机的V、U相有输入电流，W相无输入电流)；
步骤4-8，从时间点t 4-8延时T pwr/6后的时刻记为时间点t 4-9，在时间点t 4-9同时向输入端V R+、V T-发送触发信号，触发宽度为1.0-3.3ms，R、T相有电流且S相无电流(也即是电机的U、W相有输入电流，V相无输入电流)；
步骤4-9，从时间点t 4-9延时T pwr/6后的时刻记为时间点t 4-10，在时间点t40同时向输入端V T+、V S+发送触发信号，触发宽度为1.0-3.3ms，S、T相有电流且R相无电流(也即是电机的V、W相有输入电流，U相无输入电流)；
步骤4-10，在时间点t 4-10之后，再次检测到所述R相电压过零点下降沿信号，重复步骤4-1至4-9，直至收到停机命令。
如图2所示，为示例一的电机的三相输入电流的基波图形，R、S、T相的基波相位依次互差T1 base/3，各相输入电流平衡，电机以
Figure PCTCN2022107725-appb-000017
N e的速度进行低速正转。
需要指出的，所述正转分频系数K F取其他数值(也即是除4以外的其他数值)时，由于不同的正转分频系数K F对应不同的触发角度和触发时序，因此在示例一的基础上，对触发角度和触发时序做适应性改变，并最终满足以下三个条件即可：(1)产生的三相电流的基波波形互差120°；(2)各相电流波形是对称，也即是各相电流波形为正弦波；(3)电流的基波频率＝电网频率/正转分频系数。
示例二：
n 1为4时，所述反转分频系数K R＝5时，通过以下步骤控制晶闸管的触发角度和触发时序：
所述电网的周期为T pwr，则5分频低速反转状态下的电机的三相输入电流的基波的周期为T2 base＝5×T pwr；
步骤5-1，将检测到所述电网R相电压过零点下降沿信号的时刻记为时间点t 5-1，之后每隔1个T2 base检测一次电网R相电压过零点下降沿信号，从时间点t 5-1延时T pwr/3后的时刻记为时间点t 5-2，在时间点t 5-2同时向输入端V R-、V S+发送触发信号，触发宽度为1.0-3.3ms，R、S相有电流，T相无电流(也即是电机的U和V相有电流输入，W相无电流输入)；
步骤5-2，从时间点t 5-2延时T pwr/6后的时刻记为时间点t 5-3，在时间点t 5-3同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms，R、T相有电流，S相无电流(也即是电机的U和W相有电流输入，V相无电流输入)；
步骤5-3，从时间点t 5-3延时T pwr2/3后的时刻记为时间点t 5-4，在时间点t 5-4同时向输入端V S+、V T-发送触发信号，触发宽度为1.0-3.3ms，S、T相有电流，R相无电流(也即是电机的V和W相有电流输入，U相无电流输入)；
步骤5-4，从时间点t 5-4延时T pwr/6后的时刻记为时间点t 5-5，在时间点t 5-5同时向输入端V R-、V S+发送触发信号，触发宽度为1.0-3.3ms，R、S相有电流，T相无电流(也即是电机的U和V相有电流输入，W相无电流输入)；
步骤5-5，从时间点t 5-5延时T pwr2/3后的时刻记为时间点t 5-6，在时间点t 5-6同时向输入端V R+、V T-发送触发信号，触发宽度为1.0-3.3ms，R、T相有电流，S相无电流(也即是电机的U和W相有电流输入，V相无电流输入)；
步骤5-6，从时间点t 5-6延时T pwr/6后的时刻记为时间点t 5-7，在时间点t 5-7同时向输入端V S+、V T-发送触发信号，触发宽度为1.0-3.3ms，S、T相有电流，R相无电流(也即是电机的V和W相有电流输入，U相无电流输入)；
步骤5-7，从时间点t 5-7延时T pwr2/3后的时刻记为时间点t 5-8，在时间点t 5-8同时向输入端V S-、V R+发送触发信号，触发宽度为1.0-3.3ms，S、R相有电流，T相无电流(也即是电机的V和U相有电流输入，W相无电流输入)；
步骤5-8，从时间点t 5-8延时T pwr/6后的时刻记为时间点t 5-9，在时间点t 5-9同时向输入端V R+、V T-发送触发信号，触发宽度为1.0-3.3ms，R、T相有电流，S相无电流(也即是电机的U和W相有电流输入，V相无电流输入)；
步骤5-9，从时间点t 5-9延时T pwr2/3后的时刻记为时间点t 5-10，在时间点t 5-10同时向输入端V S-、V T+发送触发信号，触发宽度为1.0-3.3ms，S、T相有电流，R相无电流(也即是电机的V和W相有电流输入，U相无电流输入)；
步骤5-10，从时间点t 5-10延时T pwr/6后的时刻记为时间点t 5-11，在时间点t 5-11同时向输入端V S-、V R+发送触发信号，触发宽度为1.0-3.3ms，S、R相有电流，T相无电流(也即是电机的V和U相有电流输入，W相无电流输入)；
步骤5-11，从时间点t 5-11延时T pwr2/3后的时刻记为时间点t 5-12，在时间点t 5-12同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms，T、R相有电流，S相无电流(也即是电机的W和U相有电流输入，V相无电流输入)；
步骤5-12，从时间点t 5-12延时T pwr/6后的时刻记为时间点t 5-13，在时间点t 5-13同时向输入端V S-、V T+发送触发信号，触发宽度为1.0-3.3ms，S、T相有电流，R相无电流(也即是电机的V和W相有电流输入，U相无电流输入)；
步骤5-13，在时间点t 5-13之后，再次检测到所述R相电压过零点下降 沿信号，重复步骤5-1至5-12，直至收到停机命令。
如图3所示，为示例二的电机的三相输入电流的基波图形，R、S、T相的基波相位依次互差T1 base2/3，各相输入电流平衡，电机以
Figure PCTCN2022107725-appb-000018
N e的速度进行低速反转。
需要指出的，所述反转分频系数K R取其他数值(也即是除5以外的其他数值)时，由于不同的反转分频系数K R对应不同的触发角度和触发时序，因此在示例二的基础上，对触发角度和触发时序做适应性改变，并最终满足以下三个条件即可：(1)产生的三相电流的基波波形互差120°；(2)各相电流波形是对称，也即是各相电流波形为正弦波；(3)电流的基波频率＝电网频率/反转分频系数。
结合示例一和示例二可以看出：
1、通过控制晶闸管的触发时序，可以实现对于电机转动方向的控制，也即是控制电机正转或反转；
2、通过控制向晶闸管输入触发信号的时间点，可以实现对于晶闸管导通的时间点的控制，从而通过晶闸管向电机输入与触发信号对应的电流(也即是图2和3中的馒头波形电流信号)，输入电机的电流的基波频率等于电网频率/正转或反转分频系数，也即是输入电机的电流的基波周期等于电网周期×正转或反转分频系数；
3、通过控制晶闸管的初始的触发角度，可以实现对于晶闸管输入电机的电流强度，从而实现对于电机输出转矩的调整。
优选的，本发明控制电机低速正转和低速反转的软启动器控制方法，通过在电机的三相输入电流的基波周期内，同步减小或增大触发角度以增大或减小电机的输出转矩。进一步的，所述触发角度每次减少或增大δ度，9≤δ≤36，δ取值越大则电机的输出转矩的改变值越大，也即是δ取值越大则电机的输出转矩的变化率越大。
以上内容是结合具体的优选实施方式对本发明所作的进一步详细说明，不能认定本发明的具体实施只局限于这些说明。对于本发明所属技术领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干简单推演或替换，都应当视为属于本发明的保护范围。

Claims (11)

  1. 一种控制电机低速正转和低速反转的软启动器控制方法，软启动器包括三相反并联晶闸管，串联在电网的T相和电机的W相输入端之间的反并联晶闸管具有信号端V T+和信号端V T-，串联在电网的S相和电机的V相输入端之间的反并联晶闸管具有信号端V S+和信号端V S-，串联在电网的R相和电机的U相输入端之间的反并联晶闸管具有信号端V R+和信号端V R-；其特征在于：
    所述电机的低速正转的正转分频系数K F满足以下公式：
    Figure PCTCN2022107725-appb-100001
    所述电机低速正转的转速
    Figure PCTCN2022107725-appb-100002
    其中，n 0为整数，K F为正整数，N e为电机的额定转速；
    所述电机的低速反转的反转分频系数K R满足以下公式：
    Figure PCTCN2022107725-appb-100003
    所述电机低速翻转的转速
    Figure PCTCN2022107725-appb-100004
    其中，n 1为整数，K R为正整数；
    通过控制晶闸管的触发时序及每次向晶闸管输入触发信号的时间点以通过软启动器控制电机进行转速为V F的低速正转或转速为V R的低速反转。
  2. 根据权利要求1所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：
    所述软启动器控制方法使电机的各相输入电流符合以下条件：
    (1)所述电机的各相输入电流的基波均为正弦波；
    (2)基于正转分频系数K F或反转分频系数K R得到所述电机的各相输入电流的基波周期T base，所述电机的各相输入电流的基波周期T base＝电网周期T pwr*(K F或K R)；
    (3)所述电机的各相输入电流的基波相位互差1/3个基波周期T base。
  3. 根据权利要求2所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：
    所述电机的V相输入电流的基波的相位滞后U相输入电流的基波的相 位1/3个基波周期且电机的W相输入电流的基波的相位滞后U相输入电流的基波的相位1/3个基波周期时，电机各相输入电流的相序为正相序，电机低速正转；
    所述电机的V相输入电流的基波的相位滞后U相输入电流的基波的相位2/3个基波周期且W相输入电流的基波的相位滞后U相输入电流的基波的相位1/3个基波周期时，电机各相输入电流的相序为反相序，电机低速反转。
  4. 根据权利要求1所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：同一时刻只能向不同相的两路晶闸管发送触发信号，而且两路触发信号分别为正向触发信号和反向触发信号。
  5. 根据权利要求1所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：通过控制晶闸管的触发角度，调整电机的输出扭矩。
  6. 根据权利要求1-5任意一项所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：所述正转分频系数K F＝4时，通过以下步骤控制晶闸管的触发角度和触发时序以及每次向晶闸管输入触发信号的时间点：
    所述电网的周期为T pwr，则4分频低速正转状态下的电机的三相输入电流的基波的周期为T1 base＝4×T pwr；
    步骤4-1，将检测到所述电网R相电压过零点下降沿信号的时刻记为时间点t 4-1，之后每隔1个T1 base检测一次电网R相电压过零点下降沿信号，从时间点t 4-1延时T pwr/6后的时刻记为时间点t 4-2，在时间点t 4-2同时向输入端V T-、V S+发送触发信号，触发宽度为1.0-3.3ms；
    步骤4-2，从时间点t 4-2延时T pwr/6后的时刻记为时间点t 4-3，在时间点t 4-3同时向输入端V R-、V S+发送触发信号，触发宽度为1.0-3.3ms；
    步骤4-3，从时间点t 4-3延时T pwr/6后的时刻记为时间点t 4-4，在时间点t 4-4同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms；
    步骤4-4，从时间点t 4-4延时T pwr后的时刻记为时间点t 4-5，在时间点t 4-5同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms；
    步骤4-5，从时间点t 4-5延时T pwr/6后的时刻记为时间点t 4-6，在时间点t 4-6同时向输入端V S-、V T+发送触发信号，触发宽度为1.0-3.3ms；
    步骤4-6，从时间点t 4-6延时T pwr/6后的时刻记为时间点t 4-7，在时间点t 4-7同时向输入端V R+、V S-发送触发信号，触发宽度为1.0-3.3ms；
    步骤4-7，从时间点t 4-7延时T pwr后的时刻记为时间点t 4-8，在时间点t 4-8同时向输入端V R+、V S-发送触发信号，触发宽度为1.0-3.3ms；
    步骤4-8，从时间点t 4-8延时T pwr/6后的时刻记为时间点t 4-9，在时间点t 4-9同时向输入端V R+、V T-发送触发信号，触发宽度为1.0-3.3ms；
    步骤4-9，从时间点t 4-9延时T pwr/6后的时刻记为时间点t 4-10，在时间点t40同时向输入端V T+、V S+发送触发信号，触发宽度为1.0-3.3ms；
    步骤4-10，检测到所述R相电压过零点下降沿信号，重复步骤4-1至4-9，直至收到停机命令。
  7. 根据权利要求1-5任意一项所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：所述反转分频系数K R＝5时，通过以下步骤控制晶闸管的触发角度和触发时序以及每次向晶闸管输入触发信号的时间点：
    所述电网的周期为T pwr，则5分频低速反转状态下的电机的三相输入电流的基波的周期为T2 base＝5×T pwr；
    步骤5-1，将检测到所述电网R相电压过零点下降沿信号的时刻记为时间点t 5-1，之后每隔1个T2 base检测一次电网R相电压过零点下降沿信号，从时间点t 5-1延时T pwr/3后的时刻记为时间点t 5-2，在时间点t 5-2同时向输入端V R-、V S+发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-2，从时间点t 5-2延时T pwr/6后的时刻记为时间点t 5-3，在时间点t 5-3同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-3，从时间点t 5-3延时T pwr2/3后的时刻记为时间点t 5-4，在时间点t 5-4同时向输入端V S+、V T-发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-4，从时间点t 5-4延时T pwr/6后的时刻记为时间点t 5-5，在时间点t 5-5同时向输入端V R-、V S+发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-5，从时间点t 5-5延时T pwr2/3后的时刻记为时间点t 5-6，在时间点t 5-6同时向输入端V R+、V T-发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-6，从时间点t 5-6延时T pwr/6后的时刻记为时间点t 5-7，在时间点t 5-7同时向输入端V S+、V T-发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-7，从时间点t 5-7延时T pwr2/3后的时刻记为时间点t 5-8，在时间点t 5-8同时向输入端V S-、V R+发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-8，从时间点t 5-8延时T pwr/6后的时刻记为时间点t 5-9，在时间点t 5-9同时向输入端V R+、V T-发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-9，从时间点t 5-9延时T pwr2/3后的时刻记为时间点t 5-10，在时间点t 5-10同时向输入端V S-、V T+发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-10，从时间点t 5-10延时T pwr/6后的时刻记为时间点t 5-11，在时间点t 5-11同时向输入端V S-、V R+发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-11，从时间点t 5-10延时T pwr2/3后的时刻记为时间点t 5-12，在时间点t 5-12同时向输入端V R-、V T+发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-12，从时间点t 5-11延时T pwr/6后的时刻记为时间点t 5-13，在时间点t 5-13同时向输入端V S-、V T+发送触发信号，触发宽度为1.0-3.3ms；
    步骤5-13，检测到所述R相电压过零点下降沿信号，重复步骤5-1至5-12，直至收到停机命令。
  8. 根据权利要求1所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：所述软启动控制方法，通过在电机的三相输入电流的基波周期内，同步减小触发角度以增大电机的输出转矩。
  9. 根据权利要求8所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：所述触发角度每次减少δ度，9≤δ≤36。
  10. 根据权利要求1所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：串联在电网的T相和电机的W相输入端之间的反并联晶闸管包括T相正向晶闸管SCR5和T相负向晶闸管SCR6，T相正向晶闸管SCR5具有信号端V T+，T相负向晶闸管SCR6具有信号端V T-；串联在电网的S相和电机的V相输入端之间的反并联晶闸管包括S相正向晶闸管SCR3和S相负向晶闸管SCR4，S相正向晶闸管SCR3具有信号端V S+，S相负向晶闸管SCR4具有信号端V S-；串联在电网的R相和电机的U相输入端之间的反并联晶闸管包括R相正向晶闸管SCR1和R相负向晶闸管SCR2，R相正向晶闸管SCR1具有信号端V R+，R相负向晶闸管SCR2具有信号端V R-。
  11. 根据权利要求1所述的控制电机低速正转和低速反转的软启动器控制方法，其特征在于：
    通过以下方法计算电机的低速正转的正转分频系数K F：
    工频磁场旋转角速度为ω 1，正转分频后的磁场旋转角速度为ω 2F，ω 1和ω 2F关系符合以下等式：
    ω 1＝K F×ω 2F  等式(1)
    其中，K F为正转分频系数且为正整数；
    所述电网为三相平衡系统，各相相位差为120°，A相和B相为电网的R、S、T三相中的任意两相，A相的相位角为0°时，B相的相位角符合以下等式：
    ω 1×t-(2/3)π＝n 0π  等式(2)
    其中，n为整数，t为时间；
    所述低速正转分频电网系统，即是软启动器向电机输入的使其低速正转的三相电源系统，也是三相平衡系统，各相相位差为120°，A F相和B F相为低速正转分频电网系统的三相中的任意两相(也即是，A F相和B F为使电机低速正转的U、V、W三相输入电流中的任意两相)，A F相的相位角为0°时，B F相的相位角复位以下等式：
    ω 2F×t-(2/3)π＝0  等式(3)
    由等式(3)变形得到以下等式：
    ω 2F×t＝(2/3)π  等式(4)
    将等式(1)带入等式(2)得到以下等式：
    K F×ω 2F×t＝(2/3)π+n 0π  等式(5)
    将等式(3)带入等式(5)得到以下等式：
    Figure PCTCN2022107725-appb-100005
    通过以下方法计算电机的低速反转的反转分频系数K R：
    工频磁场旋转角速度为ω 1，反转分频后的磁场旋转角速度为ω 2R，ω 1和ω 2关系符合以下等式：
    ω 1＝K R×ω 2R  等式(6)
    其中，K R为反转分频系数且为正整数；
    所述电网为三相平衡系统，各相相位差为120°，A相和B相为电网的R、S、T三相中的任意两相，A相的相位角为0°时，B相的相位角符合以下等式：
    ω 1×t-(2/3)π＝n 1π  等式(7)
    其中，n为整数，t为时间；
    所述低速反转分频电网系统，即是软启动器向电机输入的使其低速反转的三相电源系统，也是三相平衡系统，各相相位差为120°，A R相和B R相分别为低速反转分频电网系统的三相中的任意两相(也即是，A R相和B R相为使电机低速反转的U、V、W三相输入电流中的任意两相)，A R相的相位角为0°时，B R相的相位角复位以下等式：
    ω 2R×t+(2/3)π＝0  等式(8)
    由等式(8)变形得到以下等式：
    ω 2R×t＝-(2/3)π  等式(9)
    将等式(6)带入等式(7)得到以下等式：
    K R×ω 2R×t＝(2/3)π+n 1π  等式(10)
    将等式(9)带入等式(10)得到以下等式：
    Figure PCTCN2022107725-appb-100006
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