A position-free control system and method for a double-salient-pole generator

Abstract

The present invention discloses a method for identifying the rotor position of a double-salient pole generator under current optimization control with minimum copper loss. The method specifically comprises the following steps: based on an electrically excited double-salient pole generator under current optimization control with minimum copper loss, utilizing the unsaturated magnetic circuit characteristic of the double-salient pole generator rotor pole sliding into the phase, using the phase winding current and bus voltage to calculate the phase winding flux, and further calculating the phase inductance, and finally obtaining a position signal through the phase inductance, thereby realizing position sensorless control of the electrically excited double-salient pole generator.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric drive, and in particular relates to a method for identifying the rotor position of a double-salient-pole generator under current optimization control with minimum copper loss. Background Art

[0002] DC motors, synchronous motors and asynchronous motors generally move based on the principle that a current-carrying conductor is subjected to force in a magnetic field. Reluctance motors are a special type of motor that use the minimum reluctance theorem to generate reluctance torque with the help of the salient pole structure of the stator and rotor. Both switched reluctance motors and double salient pole motors belong to reluctance motors.

[0003] The stator and rotor of the switched reluctance motor are both salient pole structures with simple structure and the advantage of being able to operate reliably in harsh environments. They are widely used in wind power generation, tram drive, aerospace, and household appliances.

[0004] The doubly salient pole motor is based on the switched reluctance motor, with permanent magnets or DC excitation windings added to the stator. Depending on the excitation method, it can also be divided into permanent magnet doubly salient pole motor, electrically excited doubly salient pole motor and hybrid excitation doubly salient pole motor.

[0005] In the starting and generating system composed of a double-salient-pole motor, accurate rotor position information is required for phase change during electric operation in the starting phase and motor speed detection during PWM rectifier power generation operation in the power generation phase. In traditional double-salient-pole motor systems, rotor position information is generally obtained by installing mechanical position sensors, mainly including photoelectric, Hall, and rotary transformers. The first two types of position sensors detect rotor position by detecting optical signals and magnetic signals respectively, which are easily affected by high temperature and vibration, prone to failure, and are not suitable for the harsh working environment of aviation starting and power generation. The rotary transformer is suitable for harsh working conditions and has high reliability, but its processing and assembly are complex and large in size, which reduces the power density of the starting and power generation system. It can be seen that the installation of mechanical position sensors in the starting and power generation system increases the volume and cost of the system and reduces the power density on the one hand, and on the other hand, it is very easy to fail in harsh environments such as high temperature, high pressure, and vibration in aviation, reducing the reliability of the system.

[0006] The position sensorless technology estimates the motor rotor position by detecting physical quantities such as voltage, current, and magnetic flux when the motor is running. This technology can abandon the system's mechanical position sensor, reduce the size and cost of the motor drive system, increase the power density, and improve the reliability of the system. Therefore, it has received widespread attention from many scholars.

[0007] At present, the position sensorless control method for doubly salient motors is still in its infancy. According to the applicable speed range, it can be divided into initial rotor position estimation technology, low-speed position sensorless technology and medium- and high-speed position sensorless control technology. The initial position estimation methods for electrically excited doubly salient motors mainly include pulse injection method and initial position detection method during excitation voltage building process; the low-speed position sensorless method is currently mainly pulse injection method; and the main position sensorless control methods for motors running at medium and high speeds include: back-EMF detection method, flux linkage detection method, observer method, and other additional component methods.

[0008] Zhou Xingwei et al. published a "position sensorless commutation method for electrically excited double-pole motor based on neutral point" (China, publication number: 110829907A), which calculates the difference between the motor neutral point voltage and the bus midpoint voltage to obtain the characteristic quantity for position sensorless commutation control, compares it with the position sensorless commutation threshold to estimate the sector where the rotor is located, and determines the current conducting phase to achieve position sensorless operation.

[0009] The patent "Position sensorless method for three-phase electrically excited double-pole motor based on line flux" (China, publication number: 106100499A) disclosed by Liu Weifeng et al. determines the commutation point information through the zero-crossing point of the line-line flux characteristic quantity.

[0010] Chen Xu et al. published “A hybrid excitation double-pole motor position-free control method based on pulse response” (China, publication number: 113037178A) which obtains the commutation point by detecting the pulse response of the non-conducting phase and comparing it with a set threshold.

[0011] The above control methods need to add additional voltage sensors or change the original control mode and add pulse control, which increases the complexity of the system; and can only obtain a limited number of characteristic position points, and cannot obtain the specific real-time position of the motor, and need to cooperate with a phase-locked loop to realize the advance angle control of the double-salient-pole motor. Based on the original current optimization control with minimal copper loss, the present invention can calculate the continuous real-time position of the motor without adding additional hardware, injecting pulses, or using a phase-locked loop, which is convenient for realizing advance angle control. Summary of the invention

[0012] Purpose of the invention: In order to solve the problems existing in the above-mentioned prior art, the present invention provides a positionless control system and method for an electrically excited double-pole generator, which only requires one voltage sensor to obtain continuous rotor position, thereby facilitating the implementation of advance angle control.

[0013] A double salient pole motor position-free control system comprises a double salient pole motor, an excitation current detection module, a hysteresis comparison module, a position signal estimation module, an excitation drive module, a drive logic operation module, a PI adjustment module, an armature current detection module and a current distribution module; wherein the generator winding of the double salient pole motor is connected to the AC side of a PWM rectifier to obtain the PWM rectifier output voltage; the real-time excitation current and armature current are respectively detected by the excitation current detection module and the armature current detection module; the position signal estimation module is based on the real-time armature current, excitation current and P The real-time rotor position θ is calculated by the WM rectifier output voltage; the PI adjustment module obtains the excitation current reference value based on the PWM rectifier output voltage and the preset voltage, and inputs the excitation current reference value into the current distribution module to obtain the armature current reference value; the hysteresis comparison module compares the reference value and the real-time value of the excitation current, and the reference value and the real-time value of the armature current respectively to obtain the chopping signal; the drive logic operation module and the excitation drive module obtain the control signal of the PWM rectifier bridge arm switch tube and the control signal of the excitation current based on the chopping signal and the real-time rotor position θ, so as to realize the control of the double-pole motor.

[0014] Preferably, the armature current includes an armature positive current and an armature negative current, and the armature current reference value includes an armature positive current reference value and an armature negative current reference value. The armature positive and negative currents are compared with the armature positive and negative current reference values ​​respectively, and the drive is generated by the drive logic operation module to control the upper and lower tube drive signals of the PWM rectifier bridge arm respectively.

[0015] The present invention also discloses a position-free control method for a double-salient-pole motor, comprising the following steps: Step 1: Real-time acquisition of the phase current of the double-salient-pole motor and the output voltage signal U of the PWM rectifier o , calculate the phase winding flux in combination with the PWM rectifier control signal; collect the real-time excitation current i f and the real-time armature current i x , combined with the phase winding flux, the phase winding inductance L is calculated x ; Step 2: Obtain the inductance L of each phase winding in turn x And thus obtain the position information rotor real-time position θ; Step 3: Compare the PWM rectifier output voltage with the preset voltage to obtain the excitation current reference value, and obtain the armature current reference value based on the excitation current reference value; Step 4: Compare the reference value of the armature current with the real-time value to obtain the chopping signal P; Compare the reference value of the excitation current with the real-time value to obtain the excitation current converter control signal P f ; Step 5: Perform a logical operation on the chopping signal P and the real-time rotor position θ to obtain the control signal C of the bridge arm switch tube; convert the excitation current converter control signal P f Input the excitation regulator to control the excitation current.

[0016] Preferably, step 1 includes the following steps: Step 1.1, calculating the phase winding flux: ψ x =∫(U x -i x ·R x )dt+ψ0, where ψ x is the flux linkage of the xth phase of the doubly salient motor, i x is the armature current of phase x, R x is the winding resistance, U x is the voltage at the end of the x-phase winding of the doubly salient motor, ψ0 is the initial value of the phase winding flux; Step 1.2, calculate the phase winding inductance L x : Where k is the turns ratio between the field winding and the phase winding, N f is the number of turns of the excitation winding, N x is the number of turns of the phase winding; step 1.3, based on the inductance value obtained in step 1.2, determine whether the position representation is correct, and correct it if it is not correct.

[0017] As a preference, in step 1.1, for the complementary controlled H-bridge topology, when current flows through the winding, U x It is expressed as:

[0018]

[0019] Among them, U o is the output voltage, R on is the on-resistance of the switch tube, C x1 It is the switch tube control signal that controls the forward current flowing into the winding.

[0020] As a preferred method, in step 1.2, it is first determined whether the armature winding has a negative current. If the determination is no, the flux linkage ψ x With inductance L x The output is zero, and the flag bit Busy = 0; if the judgment is yes, then judge whether the flag bit Busy is equal to 1. If the judgment is no, the current magnetic flux is assigned an initial value ψ x = k·i f ·L int , inductance L x =L int , otherwise start integrating Δψ x =(U x -r x i x )·t, and then calculate the ψ at the next moment x is x =ψ x +Δψ x , and further calculate the inductance L x =ψx / (i x +k·i f ).

[0021] As a preference, in step 1.3, when the calculated inductance L x Less than the minimum value L int When , it indicates a position error, that is, the calculated position does not match the actual position; at this time, the inductance value is corrected based on the flux clamping method, and the estimated inductance is limited by limiting the flux, so that negative current is continuously injected into one-phase winding when the position is wrong, until the estimated position tracks the actual position and normal commutation is performed.

[0022] As a preferred method, the flux clamping method is as follows: when L x <L int And when the flag bit Busy = 1, let ψ x =(i x +k·i f )·L int .

[0023] As a preferred embodiment, in step 4, the positive and negative current chopping signals P of the xth phase of the N-phase doubly salient motor are defined respectively. x1 and P x2 , the position signals within a certain angle range of positive and negative currents are S x1 , S x2 , then the control signal C of the x-phase H-bridge 1 and 4 tubes x1 And the control signal C of tubes 2 and 3 x2 They are:

[0024]

[0025]

[0026] If θ is in S x1 Within the corresponding position angle range, S x1 =1, otherwise S x1 =0;P x1 is the chopping signal of the x-phase forward current of the N-phase electrically excited doubly salient generator, P x2 It is the chopping signal of negative current.

[0027] Beneficial effects:

[0028] Compared with the traditional double-pole speed control system, the present invention lacks a position sensor, which reduces the cost; the position estimation algorithm adopted by the present invention only needs one voltage sensor, and uses the output voltage and the switch signal to obtain the winding end voltage, and does not require a phase-locked loop and an injected pulse, so that a continuous rotor position can be obtained, which is convenient for realizing advance angle control. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A working principle diagram of an embodiment of the present invention;

[0030] Figure 2 A system structure diagram of an embodiment of the present invention;

[0031] Figure 3 A schematic structural diagram of a four-phase electrically excited doubly salient pole generator according to an embodiment of the present invention;

[0032] Figure 4 A control circuit for a single-phase H-bridge rectifier according to an embodiment of the present invention;

[0033] Figure 5 is a flow chart of inductance calculation according to an embodiment of the present invention;

[0034] Figure 6 A comparison between an estimated inductance waveform and an actual inductance waveform according to an embodiment of the present invention;

[0035] Figure 7 A flow chart of a flux clamping algorithm according to an embodiment of the present invention;

[0036] Figure 8 A flow chart of position calculation according to an embodiment of the present invention;

[0037] Fig. 9 This is a waveform comparison between the calculated position and the actual position according to an embodiment of the present invention.

[0038] Figure numerals: 1-stator, 2-rotor, 3-armature winding, 4-excitation winding, ①-first hysteresis control module, ②-second hysteresis control module, ③-third hysteresis control module. DETAILED DESCRIPTION

[0039] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0040] The following is combined with Figure 1 To Attachment Fig. 9 The present invention is further described as follows:

[0041] like Figure 1 As shown in 2, this embodiment provides an electrically excited double-pole generator position-free control system based on copper loss minimum current, including an excitation current detection module, first to third hysteresis control modules, a position signal estimation module, an excitation drive module, a drive logic operation module, an excitation current regulator, a PI regulation module, an armature current detection module and a current distribution module.

[0042] The winding of the electrically excited double-salient-pole generator is connected to the AC side of the PWM rectifier, and the excitation current detection module detects the excitation current i of the electrically excited double-salient-pole generator in real time. f The armature current detection module detects the actual armature current of the electrically excited double-pole motor in real time. The actual armature current includes the positive and negative armature currents of each phase. The position calculation module calculates the real-time rotor position θ through the armature current, excitation current and PWM rectifier output voltage.

[0043] The PI regulation module calculates the excitation current reference value i according to the current output voltage and the preset reference voltage. fref The excitation current reference value is sent to the current distribution module, and the armature forward reference current i is further calculated. pref , armature negative current reference value i nref , the actual armature forward current of each phase of the N-phase excitation doubly salient motor and i pref The comparison is performed and the comparison result is transmitted to the first hysteresis control module ①, and the actual armature negative current of each phase of the N-phase excitation double-salient pole motor and I nref The comparison is performed and the comparison result is transmitted to the second hysteresis control module ②, which compares the actual excitation current of the electrically excited double-salient-pole motor with I fref The first hysteresis control module ① and the second hysteresis control module ② transmit the calculation results to the drive logic operation module, and the drive logic operation module generates a drive signal for driving the upper and lower tubes of each bridge arm; the third hysteresis control module ③ transmits the calculation results to the excitation drive module, and the excitation drive module adjusts the excitation current of the N-phase excitation double-pole motor through the excitation current converter.

[0044] In this embodiment, the system further includes a DC load and an excitation power supply; the DC load consumes the energy generated by the motor, and the excitation power supply supplies power to the excitation current regulator.

[0045] The present invention also discloses a method for position-free control of an electrically excited double-salient-pole motor. The control idea can be briefly described as estimating the motor rotor position through the armature current, the excitation current and the rectifier output voltage, comparing the actual rectifier output voltage with the reference voltage and sending it to the PI regulator to obtain the excitation current reference value i fref , and then the armature forward reference current i is obtained through the copper loss minimum current distribution module pref and armature negative current reference value i nref Then, the control signal of the rectifier switch tube is obtained through the hysteresis control logic to realize that the actual positive current of the motor armature tracks the armature positive current reference value, the actual negative current of the armature tracks the armature negative current reference value, and the excitation current tracks the excitation current reference value, thereby realizing voltage closed-loop control. The specific steps are:

[0046] Step 1: Real-time acquisition of the phase current of the doubly salient motor and the PWM rectifier output voltage signal U o , calculate the phase winding flux in combination with the output switch signal; collect the real-time excitation current i f and the real-time armature current i x , combined with the phase winding flux, the phase winding inductance L is calculated x , specifically,

[0047] Step 1.1, the position estimation algorithm is as follows:

[0048] ψ x =∫(U x -i x ·R x )dt+ψ0

[0049] where ψ x is the flux linkage of the xth phase of the doubly salient motor, i x is the armature current of phase x, R x is the winding resistance, U x is the voltage at the end of the x-phase winding of the doubly salient motor. For the complementary controlled H-bridge topology, when current flows through the winding, U x It can be expressed as:

[0050]

[0051] Among them U o is the output voltage, R on is the on-resistance of the switch tube, C x1 It is the switch control signal that controls the forward current flowing into the winding:

[0052] ψ0=ki f ·L int

[0053] Where L int is the inductance value when the rotor teeth are aligned with the stator slots, which is given according to the minimum value actually measured by the motor, i f is the field current and k is the turns ratio between the field winding and the phase winding.

[0054]

[0055] Where N f is the number of turns of the excitation winding, N x is the number of turns of the phase winding.

[0056] Step 1.2: Collect the actual excitation current i f , and the armature current i x , combined with the phase winding flux calculation to get the phase winding inductance L x :

[0057]

[0058] When current flows through the winding, its terminal voltage can be determined by the switch state; when no current flows through, its voltage value is uncertain and is discarded. The specific algorithm is as follows: Figure 5 First, determine whether the armature winding has a negative current. If not, set the flux ψ x With inductance L x The output is zero, and the flag bit Busy = 0; if it is judged to be yes, then judge whether the flag bit Busy is equal to 1. If it is judged to be no, the current magnetic flux is assigned an initial value ψ x = k·i f ·L int , inductance L x =L int , otherwise start integrating Δψ x =(U x -r x i x )·t, and then calculate the ψ at the next moment x is x =ψ x +Δψ x , and further calculate the inductance L x =ψ x / (i x +k·i f ). The Busy flag is used to determine whether it is the first time to enter the integral condition.

[0059] Step 1.3, based on the inductance value obtained in step 1.2, determine whether the position representation is correct, and make corrections if it is incorrect.

[0060] When the calculated inductance L x Less than the minimum value L int When , it indicates a position error, that is, the calculated position does not match the actual position. At this time, based on the flux clamp correction inductance value, by limiting the flux limit estimated inductance, so that when the position is wrong, the negative current is continuously injected into one phase winding until the estimated position tracks the actual position and the phase is normally switched. The specific process is as follows Figure 7 As shown, when L x <L int And when the flag bit Busy = 1, it is judged as a position error. x =(i x +k·i f )·L int And L x =L intBy limiting the flux linkage and thus limiting the estimated inductance from being calculated below the minimum inductance value, it is possible to continuously inject negative current into one phase winding when the position is wrong, and to switch phases normally when the calculated position is the same as the actual position. The comparison results of the inductance estimated waveform and the actual waveform are shown in the figure below. Figure 6 shown.

[0061] The optimized current algorithm adopted in the present invention can ensure that when a negative current is passed through the winding, the magnetic flux generated by the armature winding can offset a part of the magnetic flux generated by the excitation winding, thereby making the magnetic circuit in an unsaturated state.

[0062] Step 2: Using the state machine program, the phase winding inductance L x Get the real-time position of the rotor θ, specifically,

[0063] like Figure 8 As shown, based on the above method, the inductance of each phase of the motor is obtained in turn, L a , L b , ..., through the corresponding algorithm, the position information can be obtained: θ = f (L a ,L b ,...).

[0064] In this embodiment, a four-phase motor is taken as an example, and the inductance L of the four states a, b, c, and d are obtained in sequence. a , L b , L c , L d ,θ=f(L a ,L b ,L c ,L d ).

[0065] Step 3: Compare the PWM rectifier output voltage with the preset voltage to obtain an excitation current reference value, and obtain an armature current reference value based on the excitation current reference value.

[0066] Step 4: Compare the reference value of the armature current with the real-time value to obtain the chopping signal P; compare the reference value of the excitation current with the real-time value to obtain the control signal P of the excitation regulator f .

[0067] Step 5: Perform a logical operation on the chopping signal P and the real-time rotor position θ to obtain the control signal C of the bridge arm switch tube; f The signal is input into the excitation regulator to control the excitation current. Specifically,

[0068] The generator winding of the N-phase excited doubly salient motor is connected to the AC side of the PWM rectifier, and S is defined x1 is the position angle signal of the forward current flowing into the xth phase of the N-phase excitation doubly salient motor, S x2It is the position signal of the negative current flowing into the xth phase of the N-phase electrically excited double-salient-pole generator. The control signal C of the xth phase H-bridge 1 and 4 is calculated according to the following formula x1 And the control signal C of tubes 2 and 3 x2 :

[0069]

[0070]

[0071] If θ is in S x1 Within the corresponding position angle range, S x1 =1, otherwise S x1 = 0. x1 is the chopping signal of the x-phase forward current of the N-phase electrically excited doubly salient generator, P x2 It is the chopping signal of negative current.

[0072] The simulation results are as follows Fig. 9 As shown, it can be seen that the position estimation waveform can track the actual position waveform very well.

[0073] An embodiment of the present invention:

[0074] Taking a four-phase electrically excited double-salient-pole generator as an example, a four-phase electrically excited double-salient-pole generator is Figure 3 As shown, the motor body is composed of a stator 1 and a rotor 2, and there are an excitation winding 4 and an armature winding 3 on the stator. The excitation magnetic field of the electrically excited double-pole motor can be directly adjusted by adjusting the excitation current. In the presence of an excitation magnetic field of the electrically excited double-pole motor, as long as a negative current is passed when the magnetic flux of the four-phase armature winding is in the rising interval, and a positive current is passed when the magnetic flux is in the falling interval, the motor can be controlled to rectify and generate electricity.

[0075] The motor controller drives the excitation current regulator to control the excitation current, thereby adjusting the excitation magnetic field of the electrically excited double-pole motor, that is, the excitation current regulator provides the electrically excited double-pole motor with excitation current to generate an excitation magnetic field. The DC power supply is connected to the excitation current regulator to supply power to the excitation current regulator.

[0076] The DC side of the rectifier is connected to the DC load through a filter capacitor. When the electrically excited double-salient-pole generator is running, the rectifier rectifies the current emitted by the four-phase winding of the electrically excited double-salient-pole generator into DC to provide energy for the load.

[0077] H-bridge control topology such as Figure 4 As shown, the DC side is connected to the DC load, and the AC side is connected to both ends of the motor winding. The direction of the arrow is the positive direction of the current. When tubes 1 and 4 are turned on, the winding current increases, and when tubes 2 and 3 are turned on, the current decreases.

[0078] The control method of the A, B, C, and D phase H bridges is as follows:

[0079] Define the position signal of the mechanical angle 20-35° when the forward current is passed as S A1 , the position signal of 35-50° is S B1 , the position signal of 50-60° and 0-5° is S C1 , the position signal of 5-20° is S D1 ; Define the position signal of the mechanical angle 0-15° when the negative current is passed as S A2 , the position signal of 15-30° is S B2 , 30-45°S C2 , 45-60° is S D2 . S A1 , S B1 , S C1 , S D1 , S A2 , S B2 , S C2 , S D2 All are logic signals.

[0080] The four-phase current sampling values ​​are compared with the armature positive current reference value and the armature negative current reference value respectively and sent to the first hysteresis chopping module ① and the second hysteresis chopping module ② to obtain the four-phase positive current chopping signal P A1 , P B1 , P C1 , P D1 And the four-phase negative current chopping signal P A2 , P B2 , P C2 , P D2 The above signals can be logically operated with the position signal to obtain the control signal C of the four-phase bridge arm switch tube. A1 , C A2 , C B1 , C B2 , C C1 , C C2 , C D1 , C D2 ,Right now:

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] Therefore, the voltage at the ends of the four-phase winding can be expressed as:

[0090]

[0091]

[0092]

[0093]

[0094] The four-phase flux can be expressed as:

[0095]

[0096] The four-phase winding inductance can be calculated by flux linkage. The calculation process is as follows:

[0097]

[0098] Calculate the motor rotor position:

[0099]

[0100] Among them, f1-f4 are the fitting formulas of the linear region and position of each phase inductance respectively.

[0101] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for controlling a doubly salient motor without position, characterized in that: The following steps are involved: Step 1: Real-time acquisition of the phase current of the doubly salient motor and the PWM rectifier output voltage signal U o , calculate the phase winding flux in combination with the PWM rectifier control signal; collect the real-time excitation current i f and the real-time armature current i x , combined with the phase winding flux, the phase winding inductance L is calculated x , specifically including: Step 1.1, calculate the phase winding flux: ψ x =∫(U x -i x ·R x )dt+ψ0, Among them, ψ x is the flux linkage of the xth phase of the doubly salient motor, i x is the armature current of phase x, R x is the winding resistance, U x is the voltage at the end of the x-th phase winding of the doubly salient motor, ψ0 is the initial value of the phase winding flux; Step 1.2, calculate the phase winding inductance L x : Where k is the turns ratio between the field winding and the phase winding, N f is the number of turns of the excitation winding, N x is the number of turns of the phase winding. First, determine whether the armature winding has a negative current. If not, then set the flux linkage ψ x With inductance L x The output is zero, and the flag bit Busy = 0; if the judgment is yes, then judge whether the flag bit Busy is equal to 1. If the judgment is no, the current magnetic flux is assigned an initial value ψ x = k·i f ·L int , inductance L x =L int , otherwise start integrating Δψ x =(U x -r x i x )·t, and then calculate the ψ at the next moment x is x =ψ x +Δψ x , and further calculate the inductance L x =ψ x / (i x +k·i f ); Step 1.3, based on the inductance value obtained in step 1.2, determine whether the position representation is correct. If it is not correct, make corrections. Specifically, when the calculated inductance L x Less than the minimum value L int When L x <L int And when the flag bit Busy = 1, let ψ x =(i x +k·i f )·L int , by limiting the flux linkage to limit the estimated inductance, so that when the position is wrong, negative current is continuously injected into one phase winding until the estimated position tracks the actual position and the phase is normally commutated; Step 2: Obtain the inductance L of each phase winding in turn x And thereby obtain the position information rotor real-time position θ; Step 3: Compare the PWM rectifier output voltage with the preset voltage to obtain an excitation current reference value, and obtain an armature current reference value based on the excitation current reference value; Step 4: Compare the reference value of the armature current with the real-time value to obtain the chopping signal P; compare the reference value of the excitation current with the real-time value to obtain the excitation current converter control signal P f ; Step 5: Perform a logical operation on the chopping signal P and the real-time rotor position θ to obtain the control signal C of the bridge arm switch tube; convert the excitation current converter control signal P f Input the excitation regulator to control the excitation current.

2. The method for position-free control of a doubly salient motor according to claim 1, characterized in that: In step 1.1, for the complementary controlled H-bridge topology, when current flows through the winding, U x It is expressed as: Among them, U o is the output voltage, R on is the on-resistance of the switch tube, C x1 It is the switch tube control signal that controls the forward current flowing into the winding.

3. The method for position-free control of a doubly salient motor according to claim 2, characterized in that: In step 4, the positive and negative current chopping signals P of the xth phase of the N-phase doubly salient motor are defined respectively. x1 and P x2 , the position signals within a certain angle range of positive and negative currents are S x1 , S x2 , then the control signal C of the x-phase H-bridge 1 and 4 tubes x1 And the control signal C of tubes 2 and 3 x2 They are: If θ is in S x1 Within the corresponding position angle range, S x1 =1, otherwise S x1 =0;P x1 is the chopping signal of the x-phase forward current of the N-phase electrically excited doubly salient generator, P x2 It is the chopping signal of negative current.

4. A double salient pole motor position-free control system, comprising a double salient pole motor, characterized in that: Based on the position-free control method of a doubly salient motor according to any one of claims 1 to 3, the system further comprises an excitation current detection module, a hysteresis comparison module, a position signal estimation module, an excitation drive module, a drive logic operation module, a PI adjustment module, an armature current detection module and a current distribution module; The generator winding of the double-salient-pole motor is connected to the AC side of the PWM rectifier to obtain the PWM rectifier output voltage; the real-time excitation current and armature current are respectively detected by the excitation current detection module and the armature current detection module; The position signal estimation module calculates the real-time rotor position θ based on the real-time armature current, excitation current and PWM rectifier output voltage; The PI adjustment module obtains an excitation current reference value based on the PWM rectifier output voltage and the preset voltage, and inputs the excitation current reference value into the current distribution module to obtain an armature current reference value; the hysteresis comparison module compares the reference value and the real-time value of the excitation current and the reference value and the real-time value of the armature current respectively to obtain a chopping signal; The drive logic operation module and the excitation drive module obtain the control signal of the PWM rectifier bridge arm switch tube and the control signal of the excitation current based on the chopping signal and the real-time rotor position θ, so as to realize the control of the double-salient-pole motor.

5. The doubly salient motor position-free control system according to claim 4, characterized in that: The armature current includes an armature positive current and an armature negative current, and the armature current reference value includes an armature positive current reference value and an armature negative current reference value. The armature positive and negative currents are compared with the armature positive and negative current reference values ​​respectively, and the drive is generated by the drive logic operation module to control the upper and lower tube drive signals of the PWM rectifier bridge arm respectively.

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