A voltage stabilization control method for reconstructing the DC bus current of a dual-three-phase permanent magnet synchronous generator

Abstract

The invention discloses a voltage stabilization control method for reconstructing the DC bus current of a dual three-phase permanent magnet synchronous generator. The control method comprises the following steps: Based on the maximum four-vector space vector pulse width modulation (SVPWM) of the dual three-phase permanent magnet synchronous generator, the relationship between the phase current and the bus current is deduced, and the six-phase current is sampled by the motor digital control system to reconstruct the bus current; Since the reconstructed current is a stepped discrete signal sequence, a second-order low-pass filter is required to process the ripple to obtain a smooth reconstructed current curve; The reconstructed bus current is fed forward to the voltage outer loop with the capacitor energy storage as the control quantity, and the capacitor energy storage proportional integral (PI) controller is combined with the feedforward control quantity to quickly output the given value of the current loop. The invention can accurately reconstruct the DC bus current and perform filtering optimization, saves current sensors in the feedforward control, realizes the observation of the DC bus current, and improves the voltage control performance of the DTP-PMSG system.

Description

Technical Field

[0001] The present invention relates to the field of dual three-phase permanent magnet synchronous generators, and particularly to the field of DC bus current reconstruction observation and voltage control. Specifically, it is a voltage stabilization control method for DC bus current reconstruction of a dual three-phase permanent magnet synchronous generator, which is beneficial to saving the current sensor of the DC bus, accelerating the response speed of the bus voltage, reducing the amplitude of voltage fluctuation, and realizing high-performance voltage stabilization control without a current sensor for the DC bus. Background Art

[0002] The dual three-phase permanent magnet synchronous generator (DTP-PMSG) has characteristics such as strong fault tolerance performance and high power density, and has broad application prospects in high-end equipment such as special vehicles, warships and aircraft. Due to the complex and changeable load conditions of the equipment, more stringent constraints are imposed on the medium and low voltage DC power system. In the DC power pulse width modulation rectification system with the dual three-phase permanent magnet synchronous generator as the core, in harsh working conditions such as complex electromagnetic environment, severe mechanical vibration, high temperature and high humidity, it is easy to cause abnormal operation of the internal components of the sensor, resulting in the failure of the DC bus current sensor, thus losing the accurate monitoring of the bus current, causing misoperation of the overload protection, and reducing the reliability of the DC bus voltage stabilization control.

[0003] In the DC power PWM rectification system, the multi-phase AC voltage output by the mechanical device driving the generator to rotate is subjected to voltage stabilization control by the PWM rectifier to obtain the DC bus voltage. For the traditional outer-loop voltage stabilization control, taking the DC bus voltage as the controlled quantity, although it does not require a current sensor for the DC bus or the load, and only a PI controller can be used to adjust the DC voltage, the control effect is poor. In the case of load mutation, there are problems such as long recovery time and large fluctuation amplitude of the bus voltage. In addition, monitoring the bus current requires an additional current sensor, which will increase the cost and volume of the rectifier.

[0004] Based on space vector pulse width modulation, the present invention deduces the relationship between the phase current and the bus current, reconstructs the bus current and filters it. A mathematical model of the rectifier system is established to analyze the non-linear relationship between the voltage and the quadrature-axis current. A voltage outer-loop controller with capacitor energy storage as the control quantity is designed, the reconstructed bus current is fed forward, and the parameters are designed according to the transfer function of the control system. Comparing with the actual bus current and the voltage stabilization effect of the traditional PI control, it can accurately realize the reconstruction and effectively suppress the influence of load mutation on the bus voltage. Summary of the Invention

[0005] In view of the disadvantages of long voltage recovery time and large fluctuation amplitude in the PI control of the bus voltage in the traditional dual-three-phase permanent magnet synchronous generator system, especially for improving the control performance, it is necessary to add a current sensor to measure the load current for feedforward, which increases the hardware complexity of the control system. By analyzing the working principle of the dual-three-phase PWM rectifier, the relationship between the phase current and the bus current is deduced, and the DC bus current is reconstructed. Then, the reconstructed current is filtered and directly fed forward to the voltage outer loop control with the capacitor energy storage as the feedback quantity to achieve the voltage stabilization control without a current sensor, which can not only observe the DC bus current but also effectively improve the control performance of the DC bus voltage.

[0006] To achieve the above invention purpose, the present invention adopts the following technical solutions:

[0007] Step 1: Based on the space vector pulse width modulation of the dual-three-phase permanent magnet synchronous generator, the relationship between the phase current and the bus current is deduced, and the bus current is reconstructed by sampling the six-phase current using the motor digital control system;

[0008] Step 2: The reconstructed current is a set of stepped discrete signal sequences with equal time intervals of the switching period T s and needs to be processed by a second-order low-pass filter to obtain a smooth reconstructed current curve;

[0009] Step 3: The reconstructed bus current is fed forward to the voltage outer loop with the capacitor energy storage as the control quantity, and the capacitor energy storage feedback quantity is combined with the feedforward control quantity to quickly output the given value of the current loop.

[0010] Furthermore, in the above step 1,

[0011] The maximum four-vector SVPWM modulation method, that is, in the α-β subspace, the four outermost large vectors closest to the target vector are selected for synthesis, and the selected vectors have zero effect in the z1-z2 subspace. According to the volt-second balance, the action time of the selected vectors is calculated as

[0012]

[0013] where T n represents the action time of the nth voltage vector in a switching period, n = 1, 2, 3, 4; T s represents the switching period; U mn represents the projection of the nth voltage vector on the m axis, m = α, β, z1, z2; u α , u β , u z1 and u z2 represent the projections of the target voltage vector on the corresponding axes.

[0014] Appropriately selecting zero vectors can reduce switching actions. After determining the action time of the effective vectors, the remaining time is attributed to the action of zero vectors. Usually, the action time of zero vectors is evenly distributed to obtain

[0015]

[0016] where T0 represents the action time of zero vectors; T 00 represents the action time of the voltage vector when all upper bridge arms of the six phases are turned off; T 77 represents the action time of the voltage vector when all upper bridge arms of the six phases are turned on.

[0017] The neutral points of the two sets of stator windings of DTP - PMSG are isolated, and the constraint relationship among the phase currents is

[0018]

[0019] where i p represents the current of the p - th phase, and p = a, b, c, d, e, f.

[0020] Taking the first sector as an example, in each switching period, the bus current is reconstructed by measuring the instantaneous value of the phase current. Four non - zero voltage vectors u 45 , u 55 , u 64 , u 44 are used as effective vectors, and the corresponding bridge arms will be turned on within their respective action times. The phase current forms a current on the bus through the rectifier. The zero vector u 77 represents that all upper bridge arms of each phase are turned on. According to the constraint relationship of the phase currents in the above formula, the equivalent current on the bus is zero, so the action of the zero vector is not included in the reconstruction calculation. In summary, the expression of the bus current reconstruction in the first sector within a unit switching period can be deduced as

[0021]

[0022] where i all is the bus current.

[0023] The bus currents of the remaining 11 sectors can be reconstructed by referring to the above formula. Based on the maximum four - vector SVPWM modulation, it can be deduced in sequence to realize the monitoring of the DC bus without a current sensor.

[0024] Furthermore, in step 2:

[0025] When reconstructing the bus current, the bus current at the current moment is calculated according to the selected vector in each switching period T s . The switching period T s of this article is set to 100 μs. In the time domain, the reconstructed current is a set of values with a period of T sAn equal-time-interval, stepped discrete signal sequence is equivalent to a ripple current with a frequency of 10 kHz superimposed on a direct current pp ;

[0026] In order to obtain a smoother reconstructed current, a second-order low-pass filter with a narrow passband and stopband is used to process the ripple; the filter transfer function is

[0027]

[0028] where ω c is the cut-off frequency of the filter, and ξ is the damping ratio, usually set to 1.

[0029] Furthermore, in step 3:

[0030] Ignoring the power losses in the motor system and the PWM rectifier, taking the DC-link capacitor as the node, the instantaneous power balance equation on both sides of the capacitor is obtained:

[0031]

[0032] where i q is the quadrature-axis current in the inner current loop of the motor, ψ f is the amplitude of the permanent magnet flux linkage, ω e is the electrical angular velocity of the motor, U dc is the DC bus voltage, C is the bus capacitor, and i dc is the DC-side load current.

[0033] The motor system usually designs the inner current loop according to the typical type-I system, which is tuned to a first-order inertia link with a time constant of T iq . Considering the non-linear relationship between the quadrature-axis current and the bus voltage in the above formula, the voltage outer loop is designed with the capacitor energy storage as the control variable. The proposed method converts the reconstructed bus current into the quadrature-axis current feedforward according to the power balance relationship, combines the capacitor energy storage feedback, and quickly outputs the reference of the quadrature-axis current inner loop, which can effectively reduce the response time and improve the anti-load disturbance ability of the system.

[0034] The control method with the capacitor energy storage as the feedback has an open-loop transfer function as follows:

[0035]

[0036] where K P_Ec , K I_Ec are the PI parameters of the voltage outer loop of the generator system respectively, E C is the energy stored in the capacitor, and E* C is the given capacitor stored energy.

[0037] The beneficial effects of the present invention are:

[0038] 1. By analyzing the relationship between the phase current and the bus current under the maximum four-vector SVPWM modulation strategy, the present invention deduces the calculation formula required for current reconstruction. The voltage outer loop adopts capacitor energy storage feedback and bus current feedforward control, with a simple controller structure and convenient parameter design. The feedforward bus reconstructed current not only includes the load current but also the capacitor charging current, which can better reflect the actual output power demand of the PWM rectifier system. The physical meaning of the algorithm is clear and the calculation amount is small.

[0039] 2. Compared with the traditional voltage PI control, the present invention can quickly output the desired quadrature-axis current given value, achieve power balance on both sides of the bus capacitor, and improve the ability to resist load disturbances. The present invention can accurately reconstruct the bus current, save current sensors, and has a fast recovery speed and small voltage fluctuation in voltage stabilization control. It is suitable for high-performance control occasions of bus voltage and has good engineering significance.

[0040] 3. The control method proposed by the present invention can meet the high-reliability and high-performance operation requirements of equipment fields such as special vehicles, warships, and aircraft. It not only provides a way to reduce the volume and cost of the rectifier, but also can increase the analytical redundancy of the bus current, avoid being unable to measure the load state due to the failure of the current sensor, and improve the status of the dual three-phase permanent magnet synchronous generator rectifier system in the above fields. Description of the Drawings

[0041] Figure 1 is the control block diagram of a dual three-phase permanent magnet synchronous generator for a voltage stabilization control method based on DC bus current reconstruction;

[0042] Figure 2 is the topology structure diagram of the generator and the rectifier system;

[0043] Figure 3 is the voltage vector distribution diagram of the six-phase rectifier; (a) is the voltage vector distribution diagram in the α-β subspace; (b) is the voltage vector distribution diagram in the z1-z2 subspace;

[0044] Figure 4 is the PWM waveform diagram of the maximum four-vector SVPWM in the first sector;

[0045] Figure 5 is the phase current flow diagram under the action of the basic voltage vector u 44 ;

[0046] Figure 6 is the current reconstruction diagram within a unit switching period;

[0047] Figure 7 is the voltage outer loop control block diagram of the generator rectifier system;

[0048] Figure 8 is the waveform diagram of the reconstructed bus current during loading;

[0049] Figure 9 It is a comparison chart of the bus voltage response waveform during loading.

[0050] Specific implementation method

[0051] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described.

[0052] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0053] As Figure 1 shown in the structural block diagram, the present invention is a voltage stabilization control method for the DC bus current reconstruction of a dual three-phase permanent magnet synchronous generator, mainly including DC bus current reconstruction and a feedforward voltage stabilization control method. The specific measures are as follows:

[0054] 1. Construct the controlled system: The controlled system consists of a dual three-phase permanent magnet synchronous generator and a PWM rectifier.

[0055] The control object of the present invention is a neutral-point isolated dual three-phase surface-mounted permanent magnet synchronous generator. The electrical angles of the motor windings ABC and DEF are 30° out of phase with each other and the neutral point is isolated. The rectifier adopts a two-level structure and is connected to each phase on the generator side. The topological structures of the motor and the dual three-phase voltage source PWM rectifier are as Figure 2 shown. The PWM signal controls each phase bridge arm, and the upper and lower switching tubes conduct complementarily.

[0056] 2. Define the switching vector matrix S = [S a , S b , S c , S d , S e , S f . For example, when the upper bridge arm of phase a conducts, S a = 1, and when the lower bridge arm conducts, S a = 0. The same applies to the other phase bridge arms. Then, according to different switching combination methods, the dual three-phase rectifier is divided into 60 effective vectors and 4 zero vectors. According to the division of the vector space, the voltage vectors in the α-β subspace and the z1-z2 subspace can be expressed as:

[0057]

[0058] In the formula, a = e jπ / 6 . To facilitate writing the relationship between the voltage vector number and the switching state, the subscript of each vector is represented by a two-digit octal number. For example: u64 Indicates that the switch state S = [1, 1, 0, 1, 0, 0].

[0059] The effective vectors can be divided into the outermost large vector U according to the voltage amplitude L = 0.644U dc 、the medium-large vector U in the second outermost layer ML = 0.471U dc 、the medium vector U in the inner layer M = 0.333U dc and the innermost small vector U S = 0.173U dc . Figure 3 The distribution diagram of voltage vectors in two subspaces is shown. All voltage vectors are divided into 12 sectors in two orthogonal subspaces. To control the harmonic current of the dual three-phase motor to reduce motor losses and improve the utilization level of the bus voltage, this paper adopts the maximum four-vector SVPWM, that is, four outermost large vectors U closest to the target vector are selected in the α-β subspace L for synthesis, and the selected vectors have zero effect in the z1-z2 subspace. Taking the first sector as an example, as Figure 3 shown by the voltage vectors within the black frame, four non-zero voltage vectors u 64 、u 44 、u 45 、u 55 are selected to synthesize the target voltage vector. According to the volt-second balance, the action time of the selected vectors is calculated as

[0060]

[0061] where T n represents the action time of the nth voltage vector within a switching period, n = 1, 2, 3, 4; T s represents the switching period; U mn represents the projection of the nth voltage vector on the m axis, m = α, β, z1, z2; u α 、u β 、u z1 and u z2 represent the projections of the target voltage vector on the corresponding axes.

[0062] Appropriately selecting the zero vector can reduce the switching actions. After determining the action time of the effective vectors, the remaining time is attributed to the action of the zero vector. Usually, the action time of the zero vector is evenly distributed to obtain

[0063]

[0064] where T0 represents the action time of the zero vector; T 00 represents the action time of the voltage vector when all six-phase upper bridge arms are turned off; T 77Indicates the action time of the voltage vector when all the upper-bridge arms of the six-phase are conducting.

[0065] 3. The neutral points of the two sets of stator windings of the motor are isolated, and the constraint relationship among the phase currents is

[0066]

[0067] In the formula, i p represents the current of the p-th phase, where p = a, b, c, d, e, f.

[0068] As Figure 4 shown, the rectifier is modulated by the maximum four-vector SVPWM. Taking the first sector as an example, in each switching period, the bus current is reconstructed by measuring the instantaneous value of the phase current. Four non-zero voltage vectors u 45 , u 55 , u 64 , u 44 are used as effective vectors, and the corresponding bridge arms will conduct within their respective action times. The phase currents form a current on the bus through the rectifier. The zero vector u 77 represents that all the upper-bridge arms of each phase are conducting. According to the constraint relationship of the phase currents, the equivalent current on the bus is zero, so the action of the zero vector is not included in the reconstruction calculation. As Figure 5 shown, the figure shows the six-phase current flow under the action of the basic voltage vector u 44 . At this time, the switching state of each phase bridge arm of the rectifier is S = [1, 0, 0, 1, 0, 0]. The currents of phase A and phase D flow through the upper-bridge arm through the DC bus, providing electrical energy for the bus capacitor and the DC load, and then flowing back to the motor winding through the lower-bridge arm. According to the action time of the voltage vector u 44 , the bus current in the current state can be reconstructed.

[0069] For the remaining effective vectors u 45 , u 55 , u 64 in the first sector, the phase current flow can also be analyzed according to Figure 5 to obtain the current reconstruction within a unit period, as Figure 6 shown. In summary, the expression of the bus current reconstruction in the first sector within a unit switching period can be derived as

[0070]

[0071] In the formula, i all is the bus current.

[0072] The bus currents of the remaining 11 sectors can be referred to the above formula and reconstructed on the basis of the maximum four-vector SVPWM modulation by analogy to achieve the DC bus monitoring without current sensors. For the convenience of realizing by triangular carrier modulation digital control, the PWM waveform is usually centralized. After the centralization processing, the action time of some vectors will change, but the conduction time of each phase current will not change, which will not affect the reconstruction of the bus current.

[0073] 4. When reconstructing the bus current, in each switching period T s the bus current at the current moment will be calculated according to the selected vector. The switching period T of this paper s is set to 100 μs. In the time domain, the reconstructed current is a set of stepped discrete signal sequences with equal time intervals of T s equivalent to a ripple i with a frequency of 10 kHz superimposed on the DC current pp . In order to obtain a relatively smooth reconstructed current, a second-order low-pass filter with a narrow passband and stopband is used to process the ripple. The transfer function of the filter is

[0074]

[0075] where ω c is the cut-off frequency of the filter, and ξ is the damping ratio, usually set to 1.

[0076] 5. Ignoring the loss power in the motor system and the PWM rectifier, taking the DC side capacitor as the node, the instantaneous power balance equation on both sides of the capacitor can be obtained:

[0077]

[0078] where i q is the quadrature-axis current of the inner loop of the motor, ψ f is the amplitude of the permanent magnet flux linkage, ω e is the electrical angular velocity of the motor, U dc is the DC bus voltage, C is the bus capacitor, and i dc is the DC side load current.

[0079] The inner current loop of the motor system is usually designed as a typical type-I system and tuned to a first-order inertial link with a time constant of T iq . Considering the non-linear relationship between the quadrature-axis current and the bus voltage in the above formula, the outer voltage loop is designed with the capacitor energy storage as the control variable. As Figure 7 shown in the outer voltage loop control block diagram of the present invention, the reconstructed bus current is converted into the quadrature-axis current feedforward according to the power balance relationship, combined with the capacitor energy storage feedback, and the given value of the quadrature-axis current inner loop is quickly output, which can effectively reduce the response time and improve the anti-load disturbance ability of the system.

[0080] A control method using capacitor energy storage as feedback, whose open-loop transfer function is:

[0081]

[0082] In the formula, K P_Ec and K I_Ec are the voltage outer-loop PI parameters of the generator system respectively, E C is the energy stored in the capacitor, is the given energy stored in the capacitor.

[0083] Figure 8 This is the waveform of the bus current reconstruction in the loading experiment of the method of the present invention. Among them, after the reconstructed bus current i rec is calculated in the digital controller, it is output to the oscilloscope through the digital-to-analog conversion unit, and the remaining quantities are measured by the voltage isolation probe and the current clamp. It can be seen from the figure that in the steady state before and after the load change, the bus currents i all and the bus current i rec are close in value. Their trends are the same during the dynamic change of loading and unloading. The bus current i all can be well reconstructed by the bus current i rec , and can be used for the feedforward control of the outer loop and the observation of the DC bus without current sensors. The reconstructed bus current i rec includes the charging current i C of the capacitor, and is slightly larger than the load current i dc in value, increasing the feedforward quantity, which better meets the actual power output requirements of the rectifier and is beneficial to improving the outer-loop control effect.

[0084] Figure 9 The experimental waveform of the bus voltage response under sudden load is given. Under the condition of sudden load with the same resistance, according to the changes of capacitor energy storage and bus current, the method of the present invention can quickly obtain the expected given value of the inner loop of the quadrature-axis current, meet the requirements of power balance when the load changes, save current sensors, realize the observation of the DC bus current, improve the voltage control performance of the dual three-phase permanent magnet synchronous generator system, effectively shorten the recovery time, and reduce the fluctuation amplitude of the bus voltage.

[0085] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0086] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A voltage stabilization control method for reconstructing the DC bus current of a dual-three-phase permanent magnet synchronous generator, characterized in that It includes the following steps: Step 1: Based on space vector pulse width modulation of a dual three-phase permanent magnet synchronous generator, the relationship between phase current and bus current is derived, and the bus current is reconstructed by sampling six-phase current using a motor digital control system; Step 2: The reconstructed current is a stepped discrete signal sequence with equal time intervals within a switching period T s and a second-order low-pass filter is required to process the ripple to obtain a smooth reconstructed current curve; Step 3: Feed forward the reconstructed bus current to the voltage outer loop with capacitor energy storage as the control variable. Combine the capacitor energy storage feedback quantity and the feed forward control quantity to quickly output the given value of the current loop; In the said Step 1: The maximum four-vector SVPWM modulation method, that is, select the four outermost large vectors closest to the target vector in the α-β subspace for synthesis, and the selected vectors have zero effect in the z1-z2 subspace. According to volt-second balance, calculate the action time of the selected vectors as where, T n represents the action time of the nth voltage vector within a switching period, n = 1, 2, 3, 4; T s represents the switching period; U mn represents the projection of the nth voltage vector on the m axis, m = α, β, z1, z2; u α , u β , u z1 and u z2 represent the projections of the target voltage vector on the corresponding axes; Appropriately select zero vectors to reduce switching actions. After determining the action time of the effective vectors, assign the remaining time to the action of zero vectors and evenly distribute the action time of zero vectors to obtain Wherein, T0 represents the time when the zero vector acts; T 00 represents the action time of the voltage vector when all the upper bridge arms of the six-phase are turned off; T 77 represents the action time of the voltage vector when all the upper bridge arms of the six-phase are turned on; The neutral points of the two sets of stator windings of the dual three-phase permanent magnet synchronous generator DTP-PMSG are isolated, and the constraint relationship existing between phase currents is where i p represents the current of the p-th phase, where p = a, b, c, d, e, f; In the first sector, during each switching period, the bus current is reconstructed by measuring the instantaneous value of the phase current. Four non-zero voltage vectors u 45 , u 55 , u 64 , u 44 are used as effective vectors and will conduct the corresponding bridge arms during their respective action times. The phase current forms a current on the bus through the rectifier. The zero vector u 77 represents that the upper bridge arms of each phase are all conducting. According to the constraint relationship of the phase currents in the above formula, the equivalent current on the bus is zero. Therefore, the action of the zero vector is not included in the reconstruction calculation. In summary, the expression of the bus current reconstruction in the first sector within a unit switching period can be derived as Where, i all is the busbar current; The bus currents of the remaining 11 sectors can be reconstructed by referring to the above formula and by analogy on the basis of the maximum four-vector SVPWM modulation to achieve current sensorless DC bus monitoring.

2. The voltage stabilization control method for reconstructing the DC bus current of a dual-three-phase permanent magnet synchronous generator according to claim 1, wherein In the said Step 2: When reconstructing the bus current, at each switching period T s the bus current at the current moment is calculated according to the selected vector. The switching period T in this paper s is set to 100 μs. In the time domain, the reconstructed current is a set of stepped discrete signal sequences with equal time intervals of T s , equivalent to a ripple current i with a frequency of 10 kHz superimposed on the DC current pp ; In order to obtain a relatively smooth reconstructed current, use a second-order low-pass filter with a narrow passband and stopband to process the ripple, and the filter transfer function is where ω c is the filter cut-off frequency, and ξ is the damping ratio, which is set to 1.

3. A voltage stabilization control method for reconstructing the DC bus current of a dual-three-phase permanent magnet synchronous generator according to claim 1, characterized in that In the said Step 3: Neglect the loss power in the motor system and PWM rectifier, and take the DC side capacitor as the node to obtain the instantaneous power balance equation on both sides of the capacitor: where, i q is the inner-loop quadrature-axis current of the motor, ψ f is the amplitude of the permanent magnet flux linkage, ω e is the electrical angular velocity of the motor, U dc is the DC bus voltage, C is the bus capacitor, i dc is the DC-side load current; The motor system usually designs the inner current loop according to the typical type-I system, which is set as a first-order inertia link with a time constant of T iq ; Considering the non-linear relationship between the quadrature-axis current and the bus voltage in the above formula, the outer voltage loop is designed with the capacitor energy storage as the control variable. The proposed method converts the reconstructed bus current into the quadrature-axis current feedforward according to the power balance relationship, and combines the capacitor energy storage feedback to quickly output the given value of the quadrature-axis current inner loop, which can effectively reduce the response time and improve the anti-load disturbance ability of the system; For the control method with capacitor energy storage as feedback, its open-loop transfer function is: Where K P_Ec and K I_Ec are the voltage outer-loop PI parameters of the generator system, E C is the energy stored in the capacitor, is the given energy stored in the capacitor.

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