New energy automobile charging control method and system

Abstract

The invention provides a new energy automobile charging control method and system, and the method comprises the steps: collecting the relative static position of a rotor and a stator of a three-phase power motor in a static state, obtaining a rotor magnetic pole and one or two windings adjacent to the rotor magnetic pole as target windings according to the relative static position, and determining a target angle; and the target current of the target winding is obtained according to the target angle, so that the direction of a combined magnetic field generated by the target winding under the driving of the target current is consistent with the magnetic pole direction of the rotor, and rotation caused by torque generated during charging is avoided. According to the new energy automobile charging control method, the three-phase power motor is reused as the direct current booster circuit, only one or two windings adjacent to the magnetic pole of the static rotor are selected for loading, the number of parallel currents can be effectively reduced, switching loss is reduced, the ripple frequency and amplitude of high-frequency current are reduced, iron loss is reduced, and the service life of the three-phase power motor is prolonged. And the radiation disturbance of high-frequency ripple current is reduced while the system efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a new energy vehicle charging control method and system. Background Art

[0002] The development of the new energy vehicle industry has pushed the voltage platform of power batteries towards the high voltage era, so that the motor can obtain stronger power and more efficiently convert electrical energy and mechanical energy.

[0003] However, the charging piles configured before this are mainly adapted to power batteries with lower voltages, and cannot be directly adapted to newly produced high-voltage power batteries, and cannot charge power batteries with higher voltage levels. In order to resolve the contradiction in this charging scenario, the solution of the prior art is: using the inverter circuit of the three-phase power motor, combined with the windings of the three-phase power motor, to reuse it as a DC boost circuit, which can effectively reduce the boost cost, but in order to improve the quality of the output DC, it will use the three-phase current ripple with a phase difference of 120 degrees in parallel to cancel the superposition to reduce the current ripple of the output DC, but at the same time it also greatly increases the frequency of the current ripple. This high-frequency current ripple component is very easy to generate iron loss in the stator and rotor of the motor, and the three-phase switch loss of the inverter circuit is large, which reduces the system efficiency. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide a new energy vehicle charging control method and system to solve the problem that in the prior art, in which a three-phase power motor is reused as a DC boost circuit to realize the charging of a high-voltage power battery by a low-voltage charging pile, the three-phase switch loss of the inverter circuit is large, and the current ripple component is prone to iron loss, thereby reducing the system efficiency.

[0005] One aspect of the present invention provides a new energy vehicle charging control method, comprising:

[0006] Acquiring a relative static position of a rotor and a stator of a three-phase power motor in a static state, and obtaining a target angle between a rotor magnetic pole and a target winding adjacent to the rotor magnetic pole according to the relative static position;

[0007] Obtaining a target current of the target winding according to the target angle, so that the direction of the resultant magnetic field generated by the target winding driven by the target current is consistent with the direction of the rotor magnetic pole;

[0008] Wherein, the number of the target windings is one or two.

[0009] Optionally, the input power supply of the three-phase power motor in the charging mode is direct current, and the output end of each winding is connected to an output capacitor through a half-bridge circuit to provide a charging power output at both ends of the output capacitor.

[0010] Optionally, it also includes: obtaining a target output duty cycle of the half-bridge circuit corresponding to the target winding according to the target current, so as to control the working state of the half-bridge circuit corresponding to the target winding according to the target output duty cycle, so that the target winding operates under the target current.

[0011] Optionally, when the number of the target windings is two, the phase difference between the output modulation cycles corresponding to the two target currents is 180 degrees.

[0012] Optionally, it also includes:

[0013] Obtaining a voltage control value according to a real-time error between a target input voltage and an actual input voltage, and obtaining a first initial duty cycle of a first target winding and a second initial duty cycle of a second target winding of the two target windings according to the voltage control value;

[0014] Obtaining a current control value according to a real-time error between a target current of a first target winding of the two target windings and an actual phase current of a corresponding phase, and obtaining a duty cycle control value according to the current control value, so as to obtain a first target output duty cycle of the first target winding in combination with the first initial duty cycle;

[0015] The second initial duty cycle is used as the second target output duty cycle, and combined with the first target output duty cycle and the phase difference, a first pulse width modulation signal and a second pulse width modulation signal are obtained, so as to control the working states of the two half-bridge circuits corresponding to the first target winding and the second target winding according to the first pulse width modulation signal and the second pulse width modulation signal, so that the target winding operates at the target current.

[0016] The present invention also provides a new energy vehicle charging control system, comprising:

[0017] A collection module, used for collecting the relative static position of the rotor and the stator of the three-phase power motor in a static state, and obtaining the target angle between the rotor magnetic pole and the target winding adjacent to the rotor magnetic pole according to the relative static position;

[0018] a control module, configured to obtain a target current of the target winding according to the target angle, and control a working state of an inverter circuit of the three-phase power motor according to the target current, so that the target winding of the three-phase power motor operates at the target current, and a direction of a resultant magnetic field generated by the target winding driven by the target current is consistent with a direction of a rotor magnetic pole;

[0019] Wherein, the number of the target windings is one or two.

[0020] Optionally, the control module includes:

[0021] A first control link, for obtaining a voltage control value according to a real-time error between a target input voltage and an actual input voltage, and obtaining a first initial duty cycle of a first target winding and a second initial duty cycle of a second target winding of the two target windings according to the voltage control value;

[0022] a second control link, for obtaining a current control value according to a real-time error between a target current of a first target winding of the two target windings and an actual phase current of a corresponding phase, and obtaining a duty cycle control value according to the current control value, so as to obtain a first target output duty cycle of the first target winding in combination with the first initial duty cycle;

[0023] A driving modulation unit is used to use the second initial duty cycle as the second target output duty cycle, combine the first target output duty cycle and the phase difference, obtain a first pulse width modulation signal and a second pulse width modulation signal, and control the working states of the two half-bridge circuits corresponding to the first target winding and the second target winding according to the first pulse width modulation signal and the second pulse width modulation signal, so that the target winding operates at the target current.

[0024] Optionally, the first control link further includes a first proportional-integral-differential controller, configured to obtain the first initial duty cycle and the second initial duty cycle according to the voltage control value;

[0025] The second control link also includes a second proportional-integral-derivative controller, which is used to obtain the duty cycle control value according to the current control value.

[0026] The new energy vehicle charging control method provided by the present invention collects the relative static position of the rotor and stator of the three-phase power motor in a static state, and obtains the target angle of the rotor pole and the target winding adjacent to the rotor pole according to the relative static position. According to the static state of the three-phase power motor, one or two target windings are selected, and then the target current of the target winding is obtained according to the target angle, so that the direction of the combined magnetic field generated by the target winding under the drive of the target current is consistent with the direction of the rotor pole, avoiding the rotation caused by the torque generated during charging. At the same time, the loaded target winding is one or two. Compared with the three-phase load in the prior art, it can effectively reduce the number of parallel currents, reduce switching losses, reduce the frequency and amplitude of high-frequency current ripples, reduce iron losses, improve system efficiency and reduce the radiation interference of high-frequency ripple currents. The new energy vehicle charging control method provided by the present invention reuses the three-phase power motor as a DC boost circuit, and only selects one or two windings adjacent to the stationary rotor poles to carry loads, which can effectively reduce the number of parallel currents, reduce switching losses, reduce the frequency and amplitude of high-frequency current ripples, and reduce iron losses. Overall, while improving system efficiency, it can effectively reduce the radiation interference of high-frequency ripple currents. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of a three-phase power motor reused for DC boost in the prior art;

[0028] Figure 2 It is a schematic diagram of the main process of the new energy vehicle charging control method in an embodiment of the present invention;

[0029] Figure 3 A schematic diagram of current space vector allocation of a new energy vehicle charging control method in an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of the generation principle of a pulse width modulation signal of a new energy vehicle charging control method in an embodiment of the present invention;

[0031] Figure 5 It is a schematic diagram of the main architecture of a new energy vehicle charging control system in an embodiment of the present invention;

[0032] Figure 6 It is a structural schematic diagram of a control module of a new energy vehicle charging control system in an embodiment of the present invention.

[0033] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0035] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0037] In order to solve the problem that in the prior art, when a three-phase power motor is reused as a DC boost circuit to realize charging of a high-voltage power battery by a low-voltage charging pile, the three-phase switching loss of the inverter circuit is large, the frequency of the current ripple is high, iron loss is easily generated, and the system efficiency is reduced, the present invention provides a new energy vehicle charging control method, which only selects one or two windings adjacent to the stationary rotor poles to carry load, can effectively reduce the number of parallel currents, reduce switching losses, reduce the frequency and amplitude of high-frequency current ripples, reduce iron losses, improve system efficiency, and reduce the radiation interference of high-frequency ripple current.

[0038] See also Figure 1 , shows a schematic diagram of the structure of a three-phase power motor reused as a DC boost. When the three-phase power motor is reused as a DC boost circuit, the intermediate node of its three-phase winding is connected to the DC power supply of the low-voltage charging pile, and the upper bridge arm of the three-phase inverter circuit is disconnected. By controlling the duty cycle of the lower bridge arm, the output voltage can be adjusted to achieve DC boost and provide a high-voltage DC charging voltage for the high-voltage power battery.

[0039] In the prior art, in order to make full use of the resources of the three-phase motor, the three-phase inverter bridges are all put into operation to provide three-phase current output, and at the same time, the three-phase current ripples are controlled to have a phase difference of 120 degrees, which can reduce the amplitude of the total current ripple, but will increase the current slope change frequency of the parallel output current, generating high-frequency current ripples. The ripples flow through the motor windings, generating iron losses in the stator and rotor cores of the motor, reducing the boost conversion efficiency, and the three-phase switch losses when the inverter circuit is fully put into operation are also large.

[0040] For this reason, Figure 2 As shown, the embodiment of the present invention provides a new energy vehicle charging control method including:

[0041] Step S01: The relative static position of the rotor and the stator of the three-phase power motor in a static state is collected, and a target angle between a rotor pole and a target winding adjacent to the rotor pole is obtained according to the relative static position.

[0042] Step S02: obtaining a target current of the target winding according to the target angle, so that the direction of the resultant magnetic field generated by the target winding driven by the target current is consistent with the direction of the rotor magnetic poles.

[0043] Among them, considering the randomness when the motor stops, when the direction of the rotor pole coincides with a certain phase winding, the number of target windings is one, and in other cases, the number of target windings is two.

[0044] like Figure 3 As shown, taking the rotor magnetic pole direction when the rotor is stationary, the electrical angle θ is located between the A-phase winding and the B-phase winding as an example, θ is between 0 and 2π / 3, i s is the space current vector synthesized by the currents of phase A and phase B, i a is the electric vector of the first target current corresponding to the A-phase winding, i b It is the electric vector of the second target current corresponding to the B-phase winding, and the C-phase winding has no current. After the electric vectors of the first target current and the second target current are superimposed, they are consistent with the direction of the rotor pole. Therefore, when the A-phase winding and the B-phase winding operate under the first target current and the second target current, the direction of the combined magnetic field they generate is consistent with the direction of the rotor pole. Therefore, no torque is generated by the interaction with the rotor magnetic field, and the three-phase power motor remains stationary to avoid the conversion of electrical energy into mechanical energy, so as to ensure that the vehicle does not occur during boosting.

[0045] This embodiment is mainly suitable for DC input. The input power supply of the three-phase power motor in the charging mode is DC power, and the output end of each winding is connected in parallel to the output capacitor through the corresponding half-bridge circuit in the inverter circuit to provide a high-voltage charging power output at both ends of the output capacitor to charge the power battery.

[0046] In this embodiment, connecting the positive pole of a DC power supply to the star point (or neutral point) of the three-phase winding of the three-phase motor is equivalent to passing a zero-sequence current into the motor.

[0047] In order to realize the input and working current control of the selected target winding, in this embodiment, the PWM (Pulse width modulation) control scheme is mainly selected, specifically, it also includes: obtaining the target output duty cycle of the half-bridge circuit corresponding to the target winding according to the target current, and controlling the duty cycle of the half-bridge circuit corresponding to the target winding according to the target output duty cycle, so that the target winding works at the target current. Under the PWM control scheme, the target winding is a pulsed current at the target current, and the output modulation period of the pulsed current is consistent with the period of the corresponding PWM signal, and any modulation method that can generate a pulsed current can be used, for example, pulse amplitude modulation (PAM) or pulse frequency modulation (PFM) and other modulation methods can also be used.

[0048] by Figure 3 Taking the space current vector relationship of the motor in a stationary state as an example, the magnitudes of the two target currents can be solved based on the relationship of the vector triangle. If the rotor pole is at a certain position, the required first target current is smaller than the second target current, and correspondingly, the first target output duty cycle is larger than the second target output duty cycle, such as Figure 4 As shown, based on the first target output duty cycle α A and the second target output duty cycle α B Get the first pulse width modulation signal PWM A and a second pulse width modulation signal PWM B In order to improve the quality of the parallel output current, in this embodiment, the phase difference of the output modulation period of the two target currents is 180 degrees, so that the peaks and valleys of the first target current and the second target current are staggered and aligned to maximize the cancellation of the current ripple. Among them, the generation of the pulse width modulation signal is based on the comparison of the triangular wave signal and the duty cycle signal. The triangular wave signal with the same frequency and amplitude and a phase difference of 180 degrees can be used as a reference benchmark, which is convenient for unified regulation and ensures the quality of the provided pulse width modulation signal.

[0049] In order to further improve the output quality, in the present embodiment, a feedback control loop is also used to regulate the output, specifically including: obtaining a voltage control value according to a real-time error between a target input voltage and an actual input voltage, and obtaining a first initial duty cycle of a first target winding and a second initial duty cycle of a second target winding of the two target windings according to the voltage control value; obtaining a current control value according to a real-time error between a target current of the first target winding of the two target windings and an actual phase current of a corresponding phase, and obtaining a duty cycle control value according to the current control value, so as to obtain a first target output duty cycle of the first target winding in combination with the first initial duty cycle; using the second initial duty cycle as the second target output duty cycle, and combining the first target output duty cycle and the phase difference, obtaining a first pulse width modulation signal and a second pulse width modulation signal, so as to control the working states of the two half-bridge circuits corresponding to the first target winding and the second target winding according to the first pulse width modulation signal and the second pulse width modulation signal, so as to make the target windings work at the target current.

[0050] Through feedback loop control, the output voltage and current can be effectively guaranteed to be stable at the target value, the boost reliability can be guaranteed, and then the charging reliability can be guaranteed. In addition, different target windings are selected for voltage control and current control, and the control loops are linked through duty cycle, which can effectively reduce the complexity of control implementation and reduce control costs.

[0051] The present invention also provides a new energy vehicle charging control system, such as Figure 5 As shown, it mainly includes an acquisition module and a control module. The acquisition module is used to acquire the relative static position of the rotor and the stator of the three-phase power motor in a static state, and obtain the target angle of the rotor pole and the target winding adjacent to the rotor pole according to the relative static position. On the other hand, the real-time value of the three-phase current can also be acquired; the control module is used to obtain the target current of the target winding according to the target angle, and control the working state of the inverter circuit of the three-phase power motor according to the target current, so that the target winding of the three-phase power motor works under the target current, and the direction of the combined magnetic field generated by the target winding under the drive of the target current is consistent with the direction of the rotor pole; according to the actual static state of the three-phase power motor, the number of the target winding is one or two.

[0052] Specifically, Figure 6 The example shown is that the electrical angle θ of the rotor magnetic pole direction is between the A-phase winding and the B-phase winding, θ is between 0 and 2π / 3, and the control module includes a first control link and a second control link, both of which are feedback loop control chains to ensure that the actual output is consistent with the target.

[0053] The first control link is used to control the target input voltage u ref And the actual input voltage u dcInThe real-time error (in terms of input voltage u dcIn The sampling voltage u fb For logic operation reference) to obtain the voltage control value u err , and according to the voltage control value u err Obtain a first initial duty cycle α0 of the first target winding and a second initial duty cycle of the second target winding in the two target windings, and the second initial duty cycle is directly used as the second target output duty cycle α B .

[0054] The second control link is used to control the target current i of the first target winding of the two target windings according to the target current i aref The actual phase current i of phase A a The real-time error (the actual phase current i of phase A) a The sampling current is referenced by i afb ) to obtain the current control value i aerr , and obtain a duty cycle control value Δα according to the current control value, so as to obtain a first target output duty cycle α of the first target winding in combination with the first initial duty cycle α0 A .

[0055] Among them, for the actual phase current i of phase B b In this embodiment, the actual input charging current i0 and the actual phase current i of phase A are used. a The difference is obtained.

[0056] The outputs of the first control link and the second control link are provided to the driving modulation unit 210, which is used to output a duty cycle α according to a first target based on a preset 180-degree phase difference. A and the second target output duty cycle α B Perform phase difference modulation to obtain a first pulse width modulation signal PWM A and a second pulse width modulation signal PWM B , according to the first pulse width modulation signal PWM A and a second pulse width modulation signal PWM B Control the working states of two half-bridge circuits corresponding to the first target winding and the second target winding in the three-phase inverter circuit.

[0057] To ensure the control efficiency, in this embodiment, the first control link also includes a first proportional integral differential controller PID1, which is used to obtain the first initial duty cycle and the second initial duty cycle according to the voltage control value; the second control link also includes a second proportional integral differential controller PID2, which is used to obtain the duty cycle control value according to the current control value.

[0058] Proportional-integral-derivative control (PID) can effectively guarantee the control efficiency of the control loop, improve the accuracy and stability of the boost output, and ensure the working efficiency of the system. According to actual needs, any combination of proportional, integral, and differential can be selected for control. The two proportional-integral-derivative controllers are mainly based on Figure 3 The current vector relationship shown, as well as the circuit parameter configuration and system stability requirements of the three-phase power motor multiplexed as a boost circuit, are used to calculate the first initial duty cycle, the second initial duty cycle and the duty cycle control value. In fact, other controllers that can achieve the algorithm requirements are applicable to the present invention.

[0059] The new energy vehicle charging control method and system provided by the present invention is based on the relative static position of the rotor and stator of the three-phase power motor in a static state, selects one or two windings adjacent to the rotor poles as the target windings of the boost circuit, and controls the direction of the combined magnetic field generated by the target winding to be consistent with the direction of the rotor poles, so as to avoid the torque generated during charging and rotation, and ensure charging safety. When the three-phase power motor is reused as a DC boost circuit, only one or two windings adjacent to the static rotor poles are selected to carry the load, which can effectively reduce the number of parallel currents, reduce switching losses, reduce the frequency and amplitude of high-frequency current ripples, reduce iron losses, improve system efficiency, and reduce the radiation interference of high-frequency ripple currents.

[0060] The actual input voltage and the actual phase current of the input phase are monitored through the voltage control loop and the current control loop to ensure that the system operates in the target state and the reliability of charging is guaranteed. The current control loop only selects one phase and obtains the phase current of the other phase through the relationship between the charging input current and the current space vector, which can reduce the control cost and improve the control efficiency.

[0061] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0062] The above-mentioned embodiments only express several specific implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A new energy vehicle charging control method, characterized in that: include: Acquiring a relative static position of a rotor and a stator of a three-phase power motor in a static state, and obtaining a target angle between a rotor magnetic pole and a target winding adjacent to the rotor magnetic pole according to the relative static position; Obtaining a target current of the target winding according to the target angle, so that the direction of the resultant magnetic field generated by the target winding driven by the target current is consistent with the direction of the rotor magnetic pole; Wherein, the number of the target windings is one or two.

2. The new energy vehicle charging control method according to claim 1, characterized in that: The input power source of the three-phase power motor in the charging mode is direct current, and the output end of each winding is connected to the output capacitor through a half-bridge circuit to provide a charging power output at both ends of the output capacitor.

3. The new energy vehicle charging control method according to claim 2, characterized in that: Also includes: A target output duty cycle of a half-bridge circuit corresponding to the target winding is obtained according to the target current, so as to control a working state of the half-bridge circuit corresponding to the target winding according to the target output duty cycle, so that the target winding operates at the target current.

4. The new energy vehicle charging control method according to claim 3, characterized in that: When the number of the target windings is two, the phase difference between the output modulation cycles corresponding to the two target currents is 180 degrees.

5. The new energy vehicle charging control method according to claim 4, characterized in that: Also includes: Obtaining a voltage control value according to a real-time error between a target input voltage and an actual input voltage, and obtaining a first initial duty cycle of a first target winding and a second initial duty cycle of a second target winding of the two target windings according to the voltage control value; Obtaining a current control value according to a real-time error between a target current of a first target winding of the two target windings and an actual phase current of a corresponding phase, and obtaining a duty cycle control value according to the current control value, so as to obtain a first target output duty cycle of the first target winding in combination with the first initial duty cycle; The second initial duty cycle is used as the second target output duty cycle, and combined with the first target output duty cycle and the phase difference, a first pulse width modulation signal and a second pulse width modulation signal are obtained, so as to control the working states of the two half-bridge circuits corresponding to the first target winding and the second target winding according to the first pulse width modulation signal and the second pulse width modulation signal, so that the target winding operates at the target current.

6. A new energy vehicle charging control system, characterized in that: include: A collection module, used for collecting the relative static position of the rotor and the stator of the three-phase power motor in a static state, and obtaining the target angle between the rotor magnetic pole and the target winding adjacent to the rotor magnetic pole according to the relative static position; a control module, configured to obtain a target current of the target winding according to the target angle, and control a working state of an inverter circuit of the three-phase power motor according to the target current, so that the target winding of the three-phase power motor operates at the target current, and a direction of a resultant magnetic field generated by the target winding driven by the target current is consistent with a direction of a rotor magnetic pole; Wherein, the number of the target windings is one or two.

7. The new energy vehicle charging control system according to claim 6, characterized in that: The control module comprises: A first control link, for obtaining a voltage control value according to a real-time error between a target input voltage and an actual input voltage, and obtaining a first initial duty cycle of a first target winding and a second initial duty cycle of a second target winding of the two target windings according to the voltage control value; a second control link, for obtaining a current control value according to a real-time error between a target current of a first target winding of the two target windings and an actual phase current of a corresponding phase, and obtaining a duty cycle control value according to the current control value, so as to obtain a first target output duty cycle of the first target winding in combination with the first initial duty cycle; A driving modulation unit is used to use the second initial duty cycle as the second target output duty cycle, combine the first target output duty cycle and the phase difference, obtain a first pulse width modulation signal and a second pulse width modulation signal, and control the working states of the two half-bridge circuits corresponding to the first target winding and the second target winding according to the first pulse width modulation signal and the second pulse width modulation signal, so that the target winding operates at the target current.

8. The new energy vehicle charging control system according to claim 6, characterized in that: The first control link further includes a first proportional-integral-differential controller, configured to obtain the first initial duty cycle and the second initial duty cycle according to the voltage control value; The second control link also includes a second proportional-integral-derivative controller, which is used to obtain the duty cycle control value according to the current control value.

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