CN117526799B - Dynamic control method of electric excitation doubly salient generator based on excitation current feedforward - Google Patents

Abstract

The application discloses a dynamic control method of an electro-magnetic doubly salient generator based on excitation current feedforward, which relates to the field of electro-magnetic doubly salient generators, and is characterized in that a target conduction angle value is determined based on the change condition of the operation working condition of the electro-magnetic doubly salient generator, a switching tube of a main power converter is controlled to be on-off based on the target conduction angle value, a given excitation current value is determined based on the target conduction angle value, and the given excitation current value is fed forward to an excitation current inner loop to control the on-off of the switching tube in the excitation power converter. According to the application, the difference between the output voltage value after the change of the operation working condition and the given voltage value is minimized by changing the conduction angle value, and the cooperative control is realized by feeding the given excitation current value forward to the excitation current inner ring, so that the dynamic response time is reduced, and the dynamic control performance of the electrically excited doubly salient generator is effectively improved.

Description

Dynamic Control Method of Electrically Excited Doubly Salient Generator Based on Excitation Current Feedforward

Technical Field

The present application relates to the field of electrically excited double-salient-pole generators, and in particular to a dynamic control method of electrically excited double-salient-pole generators based on excitation current feedforward.

Background technique

The stator and rotor of the electrically excited double-salient-pole generator are both salient-pole tooth-slot structures. The armature winding is centrally wound on the stator, the excitation winding is embedded in the stator slot, and there is no winding on the rotor. It has the advantages of simple structure, flexible control, and good fault tolerance. It has broad application prospects in aviation, wind power and other fields. The traditional electrically excited double-salient-pole generator uses an uncontrolled rectifier power generation system composed of six diodes, which has the advantages of simple structure and low cost. However, since its output voltage can only be adjusted by the excitation current, and the traditional excitation current inner loop has the inherent problem of a large time constant, its dynamic performance is poor and it cannot respond quickly when the working conditions change.

Summary of the invention

In view of the technical problem and technical demand of poor dynamic performance of the existing electrically excited double-salient-pole generator mentioned above, the applicant proposes a dynamic control method of an electrically excited double-salient-pole generator based on excitation current feedforward. The technical solution of this application is as follows:

According to the change of the operating condition of the electrically excited double-pole generator, the target conduction angle value θ _c that minimizes the difference between the output voltage value and the given voltage value U _ref while keeping the current actual value of the excitation current if unchanged under the current operating condition of the electrically excited double-pole generator is determined, and the given excitation current value _ifc when the electrically excited double-pole generator reaches the given voltage value U _ref at the target conduction angle value θ _c under the _current operating condition is determined.

The on-off of the switch tube in the main power converter is controlled according to the target conduction angle value θ _c , the given excitation current value _ifc is fed forward to the excitation current inner loop to determine the excitation current reference value _ifref , and the excitation current inner loop is used to control the on-off of the switch tube in the excitation power converter according to the excitation current reference value _ifref and the excitation current actual value _if .

A further technical solution is that determining the conduction angle value θ _c includes:

When it is determined that the operating condition of the electrically excited double-pole generator is loaded or the speed is reduced, the target conduction angle value θ _c is determined to be the maximum conduction angle θ _max under the current condition. The maximum conduction angle θ _max under the current condition is calculated using the rotor speed n and the load value R of the electrically excited double-pole generator under the current condition according to a predetermined estimation formula.

When it is determined that the operating condition of the electrically excited double-salient-pole generator is in a state of load reduction or speed increase, the target conduction angle value θ _c is determined to be 0.

A further technical solution is that the method for dynamic control of an electrically excited double-salient-pole generator further includes:

The change of the operating condition of the electrically excited double-pole generator is determined based on the rotor speed n, load value R and actual value _if of the excitation current of the electrically excited double-pole generator under the current operating condition.

A further technical solution is to determine the change of the operating condition of the electrically excited double-salient-pole generator, including:

The output voltage range of the electrically excited doubly salient pole generator under the current operating condition is estimated based on the rotor speed n, load value R and actual value of excitation current _if of the electrically excited doubly salient pole generator under the current operating condition.

According to the degree of deviation of the output voltage range of the electrically excited doubly salient pole generator under the current operating condition relative to the given voltage value U _ref , the change of the operating condition of the electrically excited doubly salient pole generator is determined.

A further technical solution is to determine the change of the operating condition of the electrically excited double-salient-pole generator, including:

When the maximum value U _max of the output voltage range of the electrically excited doubly salient generator under the current operating condition is less than the given voltage value U _ref and U _ref -U _max ≥δ ₁ , it is determined that the operating condition of the electrically excited doubly salient generator is loaded or the speed is reduced.

When the minimum value U _min of the output voltage range of the electrically excited double-pole generator under the current operating condition is greater than the given voltage value U _ref and U _min -U _ref ≥δ ₂ , it is determined that the operating condition of the electrically excited double-pole generator has a load reduction or a speed increase;

Among them, δ ₁ and δ ₂ are two thresholds.

A further technical solution is to estimate the output voltage range of the electrically excited double-pole generator under the current working condition based on the rotor speed n, load value R and actual value of excitation current _if of the electrically excited double-pole generator under the current working condition, including:

A first decoupling coefficient Z _{uf — max} is calculated using the rotor speed n and the load value R of the electrically excited double-pole generator under the current operating condition according to a first fitting formula, and a second decoupling coefficient Z _uf — 0 is calculated using the rotor speed n and the load value R of the electrically excited double-pole generator under the current operating condition according to a second fitting formula; an output voltage range of the electrically excited double-pole generator under the current operating condition is determined to be [i _f × Z _{uf — 0} , _if × Z _{uf — max} ].

A further technical solution is that determining a given excitation current value _ifc when the electrically excited double-salient-pole generator reaches a given voltage value _Uref at a target conduction angle value θc under the current working condition _includes :

When the conduction angle value θ _c =θ _max , it is determined that _ifc =U _ref /Z _{uf — max} , wherein Z _{uf — max} is a first decoupling coefficient calculated according to a first fitting formula using a rotor speed n and a load value R of the electrically excited doubly salient generator under a current working condition.

When the conduction angle value θ _c =0, it is determined that _ifc =U _ref /Z _{uf — 0} , wherein Z _{uf — 0} is a second decoupling coefficient calculated according to the first fitting formula using the rotor speed n and the load value R of the electrically excited doubly salient generator under the current working condition.

Its further technical solution is:

Z _{uf — max} = -0.002058R ² -7.638×10 ^-5 R·n-13.81+0.832R+0.01503n.

Z _{uf — 0} = -21.94 + 0.4752 R + 0.03579 n - 0.004091 R ² + 0.0002274 R·n - 0.09n ² .

Its further technical solution is:

θ _max = -11.74 + 0.5232R + 0.03119n - 0.002191R ² + 0.011134R·n - 0.34n ² .

A further technical solution is that the given excitation current value _ifc is fed forward to the excitation current inner loop to determine the excitation current reference value _ifref , including:

The difference U _ref -U _dc between the given voltage value U _ref and the output voltage U _dc of the electrically excited doubly salient generator under the current working condition is input into the voltage PI regulator to obtain the excitation current error value _ie ; and the excitation current reference value _ifref = _ifc +i _e is determined.

The beneficial technical effects of this application are:

The dynamic control method of the electrically excited double-salient-pole generator of the present application determines the target conduction angle value based on the change of the operating condition of the electrically excited double-salient-pole generator, and controls the on-off of the switch tube of the main power converter based on the target conduction angle value. By changing the conduction angle value, the difference between the output voltage value after the operating condition changes and the given voltage value is minimized, thereby reducing the dynamic response time and effectively improving the dynamic control performance of the electrically excited double-salient-pole generator.

The present application also determines a given excitation current value based on the target conduction angle value, and feeds the given excitation current value forward to the excitation current inner loop to control the on and off of the switch tube in the excitation power converter, thereby cooperatively controlling the electrically excited double-pole generator so that the output voltage value can quickly and accurately reach the given voltage value.

The present application decouples the control of the conduction angle value and the actual value of the excitation current on the output voltage value by designing a decoupling coefficient, so that the decoupling coefficient can be obtained according to the rotor speed and load fitting under the current operating conditions when the actual value of the excitation current remains unchanged, and the output voltage range and the given excitation current value are calculated, thereby performing corresponding control on the main power converter and the excitation power converter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a control block diagram of a dynamic control method for an electrically excited doubly salient pole generator in one embodiment of the present application.

FIG. 2 is a circuit diagram of an electrically excited double-salient-pole generator system in one embodiment of the present application.

FIG3 is a graph showing an external characteristic curve of the output voltage of an electrically excited double-salient-pole generator when the operating conditions change in one embodiment of the present application.

FIG4 is a three-phase mutual inductance curve of an electrically excited double-pole generator and a conduction logic diagram of a switch tube in a main power converter in one embodiment of the present application.

FIG5 is a schematic diagram of loading simulation results of an output voltage-excitation current dual closed-loop fixed conduction angle control strategy in one embodiment of the present application.

FIG. 6 is a schematic diagram of loading simulation results of a minimum excitation current trajectory tracking strategy in one embodiment of the present application.

FIG. 7 is a schematic diagram of loading simulation results of an excitation current feedforward control strategy in one embodiment of the present application.

FIG8 is a schematic diagram of load shedding simulation results of an output voltage-excitation current dual closed-loop fixed conduction angle control strategy in one embodiment of the present application.

FIG. 9 is a schematic diagram of load shedding simulation results of a minimum excitation current trajectory tracking strategy in an embodiment of the present application.

FIG. 10 is a schematic diagram of load shedding simulation results of an excitation current feedforward control strategy in one embodiment of the present application.

Detailed ways

The specific implementation of the present application is further described below in conjunction with the accompanying drawings.

As shown in FIG1 , the dynamic control method of the electrically excited doubly salient pole generator based on excitation current feedforward of the present application includes:

According to the change of the operating condition of the electrically excited double-pole generator, the target conduction angle value θ _c that minimizes the difference between the output voltage value and the given voltage value U _ref while keeping the current actual value of the excitation current if unchanged under the current operating condition of the electrically excited double-pole generator is determined, and the given excitation current value _ifc when the electrically excited double-pole generator reaches the given voltage value U _ref at the target conduction angle value θ _c under the _current operating condition is determined.

The on-off of the switch tube in the main power converter is controlled according to the target conduction angle value θ _c , the given excitation current value _ifc is fed forward to the excitation current inner loop to determine the excitation current reference value _ifref , and the excitation current inner loop is used to control the on-off of the switch tube in the excitation power converter according to the excitation current reference value _ifref and the excitation current actual value _if .

This scheme of the present application changes the conduction angle value so that the difference between the output voltage value after the operating condition changes and the given voltage value U _ref is minimized, thereby reducing the dynamic response time, and controls the switch tube in the excitation power converter by feeding forward the given excitation current value to the excitation current inner loop, thereby cooperatively controlling the electrically excited double-pole generator, effectively improving the dynamic control performance of the electrically excited double-pole generator.

In order to more clearly illustrate the dynamic control method of the electrically excited double-pole generator of the present application, another embodiment of the present application is described in detail below in conjunction with the accompanying drawings.

In this embodiment, the A, B, and C three-phase armature windings of the electrically excited double-pole generator are connected to the main power converter, and the excitation winding is connected to the excitation power converter. As shown in FIG2 , the main power converter includes three groups of bridge arms connected in parallel; each group of bridge arms includes two switch tubes, and each switch tube is anti-parallel connected to a diode; the midpoint of the bridge arm where the first switch tube _T1 and the fourth switch tube _T4 are located is connected to the A-phase armature winding, the midpoint of the bridge arm where the third switch tube _T3 and the sixth switch tube _T6 are located is connected to the B-phase armature winding, and the midpoint of the bridge arm where the fifth switch tube _T5 and the second switch tube _T2 are located is connected to the C-phase armature winding, and the three-phase armature windings are star-connected. The two ends of the DC side output of the main power converter are connected in parallel with the load energy storage capacitor C and the load R. The excitation power converter includes an asymmetric half-bridge circuit, a capacitor and a power supply U _f in parallel; each bridge arm of the asymmetric half-bridge circuit includes a switch tube and a diode in series, and each switch tube is anti-parallel connected to a diode; the midpoints of the two bridge arms of the asymmetric half-bridge circuit are respectively connected to the two ends of the excitation winding.

In this embodiment, the dynamic control method of the electrically excited doubly salient pole generator includes:

1. According to the change of the operating condition of the electrically excited doubly salient generator, determine the target conduction angle value θ _c that minimizes the difference between the output voltage value and the given voltage value U _ref while keeping the current actual value of the excitation current _if unchanged under the current operating condition.

(1) Determine the change in the operating condition of the electrically excited doubly salient pole generator based on the rotor speed n, load value R and actual value of excitation current _if of the electrically excited doubly salient pole generator under the current operating condition.

In this embodiment, the output voltage range of the electrically excited double-pole generator under the current operating condition is estimated based on the rotor speed n, load value R and actual value of excitation current _if of the electrically excited double-pole generator under the current operating condition; according to the degree of deviation of the output voltage range of the electrically excited double-pole generator under the current operating condition relative to the given voltage value U _ref , the change of the operating condition of the electrically excited double-pole generator is determined.

Exemplarily, when the maximum value U _max of the output voltage range of the electrically excited double-pole generator under the current operating condition is less than the given voltage value U _ref and U _ref -U _max ≥δ ₁ , it is determined that the operating condition of the electrically excited double-pole generator is loaded or the speed is reduced; when the minimum value U _min of the output voltage range of the electrically excited double-pole generator under the current operating condition is greater than the given voltage value U _ref and U _min -U _ref ≥δ ₂ , it is determined that the operating condition of the electrically excited double-pole generator is unloaded or the speed is increased; wherein δ ₁ and δ ₂ are two thresholds respectively.

The output voltage value is affected by both the actual value of the controlled excitation current _if and the target conduction angle value _θc , and when the operating condition of the electrically excited double-pole generator remains unchanged, the actual value of the excitation current _if will not affect the maximum conduction angle _θmax . Based on this principle, the present application designs a first decoupling coefficient Z _{uf_max} and a second decoupling coefficient Z _{uf_0} , and divides the output voltage value in the experimental data by the actual value of the excitation current _if to obtain the decoupling coefficient, thereby removing the influence of the actual value of the excitation current _if on the output voltage value, and obtains the first decoupling coefficient Z _{uf_max} and the second decoupling coefficient Z _{uf_0} by nonlinear fitting using the rotor speed n and the load value R of the electrically excited double-pole generator under the current working condition.

In this embodiment, estimating the output voltage range of the electrically excited double-pole generator under the current operating condition includes: using the rotor speed n and the load value R of the electrically excited double-pole generator under the current operating condition to calculate the first decoupling coefficient Z _{uf_max} according to the first fitting formula, and using the rotor speed n and the load value R of the electrically excited double-pole generator under the current operating condition to calculate the second decoupling coefficient Z _{uf_0} according to the second fitting formula; determining that the output voltage range of the electrically excited double-pole generator under the current operating condition is [i _f ×Z _{uf_0} , _if ×Z _{uf_max} ].

In one embodiment, the first fitting formula is:

Z _{uf — max} = -0.002058R ² -7.638×10 ^-5 R·n-13.81+0.832R+0.01503n.

In one embodiment, the second fitting formula is:

Z _{uf — 0} = -21.94 + 0.4752 R + 0.03579 n - 0.004091 R ² + 0.0002274 R·n - 0.09n ² .

(2) Determine the target conduction angle value θ _c according to the change of the operating condition of the electrically excited doubly salient pole generator.

a) When it is determined that the operating condition of the electrically excited double-pole generator is loaded or the speed is reduced, the target conduction angle value θ _c is determined to be the maximum conduction angle θ _max under the current condition. The maximum conduction angle θ _max under the current condition is calculated using the rotor speed n and the load value R of the electrically excited double-pole generator under the current condition according to a predetermined estimation formula.

The maximum conduction angle θ _max corresponds to the maximum output voltage when the actual value of the excitation current remains unchanged under the current working condition. Taking the sectors corresponding to the armature windings of phases A and C as an example, the output voltage formula is It can be seen that the output voltage formula is in a differential relationship with the conduction angle θ _c . From the continuous differentiable theorem, it can be seen that there is a maximum value that makes the output voltage maximum. As shown in Figure 3, the curve of the output voltage changing with the conduction angle is a convex curve, so there is a maximum conduction angle θ _max under each working condition. Wherein, _Laf is the mutual inductance of the A-phase armature winding, _La is the self-inductance of the A-phase armature winding, _Lc is the self-inductance of the C-phase armature winding, ω is the rotation angular velocity of the electrically excited double-pole generator, _ia is the A-phase current, and r is the internal resistance of each phase armature winding.

In one embodiment, the predetermined estimation formula for calculating the maximum conduction angle θ _max by the rotor speed n and the load value R under the current working condition is:

θ _max = -11.74 + 0.5232R + 0.03119n - 0.002191R ² + 0.011134R·n - 0.34n ² .

As shown in FIG3 , when the rotor speed of the electrically excited double-pole generator changes from n ₀ to n ₁ and the load value changes from R ₀ to R ₁ , the output voltage curve when the actual value of the excitation current remains unchanged changes from L1 to L2. Since the maximum value U _max of the output voltage range under the current working condition is less than the given voltage value U _ref and U _ref -U _max = ΔU ₁ , ΔU ₁ ≥ δ ₁ , it is determined that the operating condition is loaded or the speed is reduced, and the target conduction angle value θ _c is determined to be the maximum conduction angle θ _max under the current working condition. Assume that the electrically excited double-pole generator works at point S ₀ before the working condition changes, and the target conduction angle value θ _c is changed to the maximum conduction angle θ _max after the working condition changes, and the electrically excited double-pole generator works at point Y _1. To make the output voltage value of the current working condition reach the given voltage value U _ref , the output voltage value that needs to be changed is ΔU ₁ , and the actual value of the excitation current that needs to be changed is Δ _f1 . If the conventional solution without changing the conduction angle value is adopted, the electrically excited double-pole generator operates at point _Y0 after the operating condition changes. To make the output voltage value of the current operating condition reach the given voltage value U _ref , the output voltage value that needs to be changed is ΔU ₂ , and the actual value of the excitation current that needs to be changed is Δ _f2 . It can be seen from the diagram that ΔU ₂ >ΔU ₁ , Δ _f2 >Δ _f1 . The technical solution of the present application has the smallest difference between the output voltage value and the given voltage value U _ref when loading or speed reduction occurs in the operating condition, and the actual value of the changed excitation current is also the smallest, thereby achieving the fastest dynamic response.

b) When it is determined that the operating condition of the electrically excited double-pole generator is a load reduction or a speed increase, the target conduction angle value θ _c is determined to be 0.

As shown in FIG3 , when the rotor speed of the electrically excited double-pole generator changes from n ₀ to n ₂ and the load value changes from R ₀ to R ₂ , the output voltage curve when the actual value of the excitation current remains unchanged changes from L1 to L3. Since the minimum value U _min of the output voltage range under the current working condition is greater than the given voltage value U _ref and U _min -U _ref = ΔU ₄ , ΔU ₄ ≥ δ ₂ , it is determined that the operating condition has a load reduction or a speed increase, and the target conduction angle value θ _c is determined to be 0. Assume that the electrically excited double-pole generator works at point S ₀ before the working condition changes, and the target conduction angle value θ _c is changed to 0 after the working condition changes, and the electrically excited double-pole generator works at point W _1. To make the output voltage value of the current working condition reach the given voltage value U _ref , the output voltage value that needs to be changed is ΔU ₄ , and the actual value of the excitation current that needs to be changed is Δ _f4 . If the traditional solution of not changing the conduction angle value is adopted, the electrically excited double-pole generator operates at point _W0 after the operating condition changes. To make the output voltage value of the current operating condition reach the given voltage value U _ref , the output voltage value that needs to be changed is ΔU ₃ , and the actual value of the excitation current that needs to be changed is Δ _f3 . Combined with the diagram, it can be seen that ΔU ₃ >ΔU ₄ , Δ _f3 >Δ _f4 . The technical solution of the present application has the smallest difference between the output voltage value and the given voltage value U _ref when the load is reduced or the speed increases during the operating condition, and the actual value of the changed excitation current is also the smallest, thereby achieving the fastest dynamic response.

2. Determine a given excitation current value _ifc when the electrically excited doubly salient pole generator reaches a given voltage value U _ref at a target conduction angle value θ _c under the current operating condition.

When the conduction angle value θ _c =θ _max , _ifc =U _ref /Z _{uf — max} is determined, wherein Z _{uf — max} is a first decoupling coefficient calculated according to a first fitting formula using a rotor speed n and a load value R of the electrically excited doubly salient generator under a current working condition;

When the conduction angle value θ _c =0, it is determined that _ifc =U _ref /Z _{uf — 0} , wherein Z _{uf — 0} is a second decoupling coefficient calculated according to the first fitting formula using the rotor speed n and the load value R of the electrically excited doubly salient generator under the current working condition.

3. Control the on and off of the switch tube in the main power converter according to the target conduction angle value _θc .

In this embodiment, 360° is taken as the rotor electrical angle period, and the rotor electrical angle period is evenly divided into three sectors for control. Each sector corresponds to a two-phase armature winding, and the two-phase armature windings are respectively in the inductance rising area and the inductance falling area. The armature winding in the inductance rising area turns on the upper tube of the corresponding bridge arm, and the phase winding in the inductance falling area turns on the lower tube of the corresponding bridge arm.

The three-way mutual inductance curve of the electrically excited double-pole generator is shown in Figure 4. When the rotor electrical angle is in the range of 0° to 120°, the A-phase armature winding is in the inductance rising area with a positive induced kinetic potential, and the C-phase winding is in the inductance falling area with a reverse induced kinetic potential; when the rotor electrical angle is in the range of 120° to 240°, the B-phase armature winding is in the inductance rising area with a positive induced kinetic potential, and the A-phase winding is in the inductance falling area with a reverse induced kinetic potential; when the rotor electrical angle is in the range of 240° to 360°, the C-phase armature winding is in the inductance rising area with a positive induced kinetic potential, and the B-phase winding is in the inductance falling area with a reverse induced kinetic potential. In Figure 4, _Laf is the mutual inductance between the A-phase armature winding and the excitation winding, _Lbf is the mutual inductance between the B-phase armature winding and the excitation winding, _Lcf is the mutual inductance between the C-phase armature winding and the excitation winding, _eaf is the induced electromotive force between the A-phase armature winding and the excitation winding, _ebf is the induced electromotive force between the B-phase armature winding and the excitation winding, and _ecf is the induced electromotive force between the C-phase armature winding and the excitation winding.

After determining the target conduction angle value θ _c , the on and off of the switch tube in the main power converter is controlled in combination with the current electrical angle θ of the rotor. The conduction logic of the switch tube in the main power converter is shown in FIG4 . When the rotor electrical angle is in the range of 0° to θ _c , the first switch tube T ₁ and the second switch tube T ₂ are turned on, and the remaining switch tubes are turned off; when the rotor electrical angle is in the range of 120° to 120° + θ _c , the third switch tube T ₃ and the fourth switch tube T ₄ are turned on, and the remaining switch tubes are turned off; when the rotor electrical angle is in the range of 240° to 240° + θ _c , the fifth switch tube T ₅ and the sixth switch tube T ₆ are turned on, and the remaining switch tubes are turned off; when the rotor electrical angle is in other ranges, all switch tubes are turned off.

4. Feed forward the given excitation current value _ifc to the excitation current inner loop to determine the excitation current reference value _ifref , and use the excitation current inner loop to control the on and off of the switch tube in the excitation power converter according to the excitation current reference value _ifref and the excitation current actual value _if .

In this embodiment, the difference U _ref -U _dc between the given voltage value U _ref and the output voltage U _dc of the electrically excited double-salient-pole generator under the current working condition is input into the voltage PI regulator to obtain the excitation current error value _ie ; the excitation current reference value _ifref = _ifc + _ie is determined. The difference between the excitation current reference value _ifref and the actual excitation current value _if is input into the excitation current regulator, and the current PI regulator outputs a PWM duty cycle signal d to control the on and off of the switch tube in the excitation power converter.

The above technical solution of the present application is mainly to dynamically control the operating conditions of the electrically excited double-salient-pole generator when the operating conditions change greatly. In another embodiment, in order to ensure that the electrically excited double-salient-pole generator can be controlled at any time, a strategy switching module is designed. The control method of the strategy switching module includes:

When it is determined that the operating condition of the electrically excited double-pole generator is loaded or the speed is reduced, the target conduction angle value θ _c is determined to be the maximum conduction angle θ _max under the current condition; when it is determined that the operating condition of the electrically excited double-pole generator is unloaded or the speed is increased, the target conduction angle value θ _c is determined to be 0; when it is determined that the operating condition of the electrically excited double-pole generator is neither loaded or the speed is reduced, nor unloaded or the speed is increased, other control strategies are used to control the electrically excited double-pole generator. Optionally, the other control strategies are any one of the traditional output voltage-excitation current dual closed-loop fixed conduction angle control strategies or the minimum excitation current trajectory tracking strategies. The minimum excitation current tracking strategy is to keep the excitation current change amount to the minimum when the operating conditions change.

In order to better illustrate the beneficial effects of the present application, the excitation current feedforward control strategy of the present application is compared with the traditional output voltage-excitation current dual closed-loop fixed conduction angle control strategy and the minimum excitation current trajectory tracking strategy through simulation. The simulation results are shown in Figures 5-10 and Table 1.

Table 1 Comparison of simulation results of three control strategies

It can be seen from Figures 5-7 and Table 1 that the voltage change ΔU ₀ of the excitation current feedforward control strategy of the present application during loading is smaller than that of the other two control strategies, and the adjustment time Δt during loading is also much smaller than that of the other two control strategies, which proves that the technical solution of the present application significantly improves the dynamic control performance of the electrically excited double-pole generator during working condition loading.

It can be seen from Figures 8-10 and Table 1 that the voltage change _ΔU0 of the excitation current feedforward control strategy of the present application during load reduction is smaller than that of the other two control strategies, and the adjustment time Δt during load reduction is also much smaller than that of the other two control strategies, which proves that the technical solution of the present application significantly improves the dynamic control performance of the electrically excited double-pole generator during load reduction.

The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the scope of protection of the present application.

Claims (8)

1. The dynamic control method of the electro-magnetic doubly salient generator based on the excitation current feedforward is characterized by comprising the following steps of:

According to the change condition of the operation working condition of the electro-magnetic doubly salient generator, determining a target conduction angle value theta _c with the smallest difference value between an output voltage value and a given voltage value U _ref under the condition that the current excitation current actual value i _f of the electro-magnetic doubly salient generator is kept unchanged under the current working condition, and determining a given excitation current value i _fc when the electro-magnetic doubly salient generator reaches the given voltage value U _ref at the target conduction angle value theta _c under the current working condition;

Controlling the on-off of a switching tube in the main power converter according to a target conduction angle value theta _c, feeding the given excitation current value i _fc forward to an excitation current inner loop to determine an excitation current reference value i _fref, and controlling the on-off of the switching tube in the excitation power converter by utilizing the excitation current inner loop according to the excitation current reference value i _fref and an excitation current actual value i _f;

Determining the conduction angle value θ _c includes:

When the condition that the loading or the rotation speed is reduced under the operation working condition of the electro-magnetic doubly salient generator is determined, determining a target conduction angle value theta _c as a maximum conduction angle theta _max under the current working condition, and calculating the maximum conduction angle theta _max under the current working condition by using the rotor rotation speed n and the load value R of the electro-magnetic doubly salient generator under the current working condition according to a preset estimation formula;

When the condition that load shedding or rotating speed rising occurs in the operation working condition of the electro-magnetic doubly salient generator is determined, determining a target conduction angle value theta _c to be 0;

The determining a given excitation current value i _fc when the electro-magnetic doubly salient generator reaches a given voltage value U _ref at a target conduction angle value θ _c under the current working condition includes:

When the conduction angle value theta _c＝θ_max is over, determining i _fc＝U_ref/Z_{uf_max}, wherein Z _{uf_max} is a first decoupling coefficient calculated by using the rotor rotating speed n and the load value R of the electrically excited doubly salient generator under the current working condition according to a first fitting formula;

when the conduction angle value θ _c =0, determining i _fc＝U_ref/Z_{uf_0}, wherein Z _{uf_0} is a second decoupling coefficient calculated by using the rotor rotating speed n and the load value R of the electrically excited doubly salient generator under the current working condition according to a second fitting formula.

2. The method for dynamically controlling an electrically-excited doubly salient generator according to claim 1, further comprising:

And determining the change condition of the operation working condition of the electric excitation doubly salient generator based on the rotor rotating speed n, the load value R and the exciting current actual value i _f of the electric excitation doubly salient generator under the current working condition.

3. The method for dynamically controlling an electrically-excited doubly salient generator according to claim 2, wherein said determining a change in operating conditions of said electrically-excited doubly salient generator comprises:

estimating the output voltage range of the electro-magnetic doubly salient generator under the current working condition based on the rotor rotating speed n, the load value R and the exciting current actual value i _f of the electro-magnetic doubly salient generator under the current working condition;

And determining the change condition of the operation working condition of the electro-magnetic doubly salient generator according to the deviation degree of the output voltage range of the electro-magnetic doubly salient generator under the current working condition relative to the given voltage value U _ref.

4. A method of dynamically controlling an electrically-excited doubly salient generator according to claim 3, wherein said determining a change in operating conditions of said electrically-excited doubly salient generator comprises:

when the maximum value U _max of the output voltage range of the electro-magnetic doubly salient generator under the current working condition is smaller than the given voltage value U _ref and U _ref-U_max≥δ₁, determining that the running working condition of the electro-magnetic doubly salient generator has loading or rotation speed reduction;

when the minimum value U _min of the output voltage range of the electro-magnetic doubly salient generator under the current working condition is larger than the given voltage value U _ref and U _min-U_ref≥δ₂, determining that the condition of load shedding or rotating speed rising occurs in the operation working condition of the electro-magnetic doubly salient generator;

Wherein δ ₁ and δ ₂ are two thresholds, respectively.

5. The method for dynamically controlling an electrically-excited doubly salient generator according to claim 4, wherein estimating the output voltage range of the electrically-excited doubly salient generator under the current working condition based on the rotor speed n, the load value R and the exciting current actual value i _f of the electrically-excited doubly salient generator under the current working condition comprises:

Calculating a first decoupling coefficient Z _{uf_max} according to a first fitting formula by using the rotor rotating speed n and the load value R of the electric excitation doubly salient generator under the current working condition, and calculating a second decoupling coefficient Z _{uf_0} according to a second fitting formula by using the rotor rotating speed n and the load value R of the electric excitation doubly salient generator under the current working condition; and determining the output voltage range of the electro-magnetic doubly salient generator under the current working condition as [ i _f×Z_{uf_0},i_f×Z_{uf_max} ].

6. The method for dynamically controlling an electrically excited doubly salient generator according to claim 1 or 5,

Z_{uf_max}＝-0.002058R²-7.638×10^-5R·n-13.81+0.832R+0.01503n；

Z_{uf_0}＝-21.94+0.4752R+0.03579n-0.004091R²+0.0002274R·n-0.09n²。

7. The method for dynamically controlling an electrically excited doubly salient generator as claimed in claim 1,

θ_max＝-11.74+0.5232R+0.03119n-0.002191R²+0.011134R·n-0.34n²。

8. The method of claim 1, wherein said feeding forward the given excitation current value i _fc to an excitation current inner loop to determine an excitation current reference value i _fref comprises:

Inputting a difference value U _ref-U_dc between a given voltage value U _ref and an output voltage U _dc of the electrically excited doubly salient generator under the current working condition into a voltage PI regulator to obtain an excitation current error value i _e;

The excitation current reference value i _fref＝i_fc+i_e is determined.