Vehicle-mounted charger and control method of DC-DC converter

Abstract

The invention provides a vehicle-mounted charger and a control method of a DC-DC converter, and the control method of the DC-DC converter comprises the steps: carrying out the sampling of a signal of an AC power grid, carrying out the frequency recognition and calculation of the sampled signal, obtaining a corresponding order harmonic wave, carrying out the amplification of the corresponding order harmonic wave, and then carrying out the superposition processing; and a processing result is injected into a DC-DC control loop so as to suppress disturbance of harmonic waves of corresponding orders, and power factor correction is realized. The control method of the DC-DC converter can ensure that the DC-DC converter realizes a stable power factor correction function under the condition of a distorted power grid or external interference.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a control method for an on-board charger and a DC-DC converter. Background Art

[0002] An on-board charger (OBC) is an energy conversion device that connects to the AC power grid and converts grid-side energy into electrical energy for charging power batteries. Traditional on-board chargers usually consist of two parts: an AC-DC converter and a DC-DC converter. Figure 1 . Among them, the AC-DC converter realizes the power factor correction function, called PFC circuit, which converts the alternating voltage into DC bus voltage; the DC-DC converter realizes the controllable constant current or constant voltage output function, such as the dual active full bridge converter (DAB, DualActive Bridge). In the traditional on-board charger structure, the DC bus capacitor connecting the AC-DC converter and the DC-DC converter plays the role of rectification and buffering, which is used to reduce the input voltage ripple on the AC side and avoid the charger from malfunctioning when the power on the input and output sides suddenly changes. In this solution, the AC-DC converter and the DC-DC converter respectively realize two functions, and the control system is easy to design, but the DC bus capacitor has a high capacitance, many high-frequency switching devices, and a high cost.

[0003] In order to reduce costs, researchers in this field have proposed a light bus OBC, which means that the power factor correction function originally performed by PFC is completely implemented by the subsequent DC-DC converter. Under the light bus OBC solution, the DC-DC converter must not only achieve power factor correction but also achieve convenient and adjustable power output, which puts higher requirements on the control method of the DC-DC converter. The existing DC-DC converter control method is mainly implemented through the DC-DC control loop, such as Figure 2 The present invention shows a control method of an existing DAB converter, which may specifically include the following steps:

[0004] Step S01: subtracting the output instruction of the DC-DC converter from the actual output signal of the DC-DC converter to obtain an error;

[0005] Step S02: sending the error to a proportional-integral controller to obtain a duty cycle;

[0006] Step S03: The duty cycle is modulated by PWM to generate an actual driving signal which is applied to the controlled load.

[0007] Figure 3 The control waveform of the existing DC-DC converter control method on the light bus OBC is shown. Figure 3It can be seen that the output command of the DC-DC converter is inconsistent with the waveform of the actual output signal of the DC-DC converter. In other words, the existing DC-DC converter control method cannot quickly track the power frequency signal command and cannot achieve power factor correction. In the existing DC-DC converter control method, modulation is achieved by the internal and external phase shift angles of the primary and secondary sides, and the output power is adjusted by the proportional integral (PI) controller. However, the loop bandwidth is limited and can only be used to control low-frequency or DC signals, making it difficult to achieve power factor correction. Due to nonlinear factors such as distorted power grids and PWM modulation, a large number of sideband harmonics are also generated in the loop. Especially when the power grid quality is poor, very high control frequency and bandwidth are required to achieve stable and high-quality power conversion. However, higher control frequency and bandwidth require switching devices and control chips with higher switching frequencies. Summary of the Invention

[0008] The object of the present invention is to provide a vehicle-mounted charger and a control method for a DC-DC converter, so as to ensure that the DC-DC converter can achieve a stable power factor correction function in the case of a distorted power grid or external interference.

[0009] In order to achieve the above-mentioned object and other related objects, the present invention provides a control method of a DC-DC converter, comprising:

[0010] Sampling the signal of the AC power grid, obtaining the corresponding order harmonics by frequency identification and calculation of the sampled signal, and amplifying and superimposing the corresponding order harmonics;

[0011] The processed results are injected into the DC-DC control loop to suppress the disturbance of the corresponding order harmonics and achieve power factor correction.

[0012] Optionally, in the control method of the DC-DC converter, the signal of the AC power grid includes the voltage of the AC power grid and the current of the AC power grid, and the fundamental frequency is obtained by frequency identification and calculation of the sampled voltage; and the current fundamental of the AC power grid is obtained by calculation of the sampled current.

[0013] Optionally, in the control method of the DC-DC converter, the fundamental frequency is transmitted to a harmonic injection controller; at the same time, the current harmonics of the AC grid obtained by subtracting the current fundamental of the AC grid from the current of the AC grid are also transmitted to the harmonic injection controller. Through calculation by the harmonic injection controller, the corresponding order harmonics in the current harmonics of the AC grid can be obtained, and the result of amplification and superposition processing can be obtained.

[0014] Optionally, in the control method of the DC-DC converter, the harmonic injection controller is composed of a plurality of resonant controllers with different resonant frequencies connected in parallel.

[0015] Optionally, in the control method of the DC-DC converter, the method of performing frequency identification on the sampled voltage includes: taking the voltage of the AC power grid as input, performing frequency identification on the voltage of the AC power grid through a phase-locked loop or discrete Fourier transform method to obtain the fundamental frequency.

[0016] Optionally, in the control method of the DC-DC converter, the method of performing frequency identification on the voltage of the AC power grid through a phase-locked loop includes:

[0017] The input AC grid voltage is processed by the orthogonal signal generator to obtain sine and cosine signals with a phase difference of 90 degrees.

[0018] The sine signal and the cosine signal are subjected to Park transformation to obtain a Q-axis DC signal;

[0019] The Q-axis DC signal is processed by a low-pass filter to obtain speed and frequency information;

[0020] The obtained rotation speed and fundamental frequency information are integrated to obtain phase information.

[0021] Optionally, in the control method of the DC-DC converter, a result obtained by amplifying and superimposing corresponding order harmonics is the first duty cycle.

[0022] Optionally, in the control method of the DC-DC converter, injecting the processed result into the DC-DC control loop includes:

[0023] Subtracting the output command of the DC-DC converter from the actual output signal of the DC-DC converter to obtain an error;

[0024] delivering the obtained error to a proportional-integral controller to obtain a second duty cycle;

[0025] Adding the second duty cycle to the first duty cycle to obtain an addition result;

[0026] The addition result is subjected to PWM modulation to generate an actual driving signal which is applied to the controlled load.

[0027] Optionally, in the control method of the DC-DC converter, the DC-DC converter includes a dual active full-bridge converter.

[0028] Optionally, in the control method of the DC-DC converter, the output instruction of the DC-DC converter includes one of a DC-DC converter output current instruction, a DC-DC converter output voltage instruction, and a DC-DC converter output power instruction.

[0029] In order to achieve the above-mentioned and other related purposes, the present invention further provides a vehicle-mounted charger, comprising:

[0030] An AC-DC converter, connected to an AC power grid, for converting an AC signal of the AC power grid into a DC bus signal;

[0031] The DC bus capacitor is connected to the AC-DC converter and plays the role of rectification and buffering;

[0032] A DC-DC converter is connected between the DC bus capacitor and the vehicle power battery to realize a controllable constant signal output function and a power factor correction function, and the above-mentioned DC-DC converter control method is applied to the DC-DC converter.

[0033] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0034] The present invention provides a control method for a DC-DC converter. This method samples signals from an AC power grid, identifies the frequencies of the sampled signals, calculates corresponding harmonics, amplifies the corresponding harmonics, and then adds them together. The resulting signal is then injected into a DC-DC control loop to suppress disturbances caused by the corresponding harmonics and achieve power factor correction. Specifically, the present invention actively injects corresponding harmonics for disturbance suppression, ensuring that the DC-DC converter achieves stable power factor correction even in the presence of a distorted power grid or external interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a topological diagram of a traditional on-board charger;

[0036] Figure 2 is a block diagram of an existing DAB control loop;

[0037] Figure 3 This is the control waveform diagram of the existing DAB control method on the light bus OBC;

[0038] Figure 4 1 is a topological diagram of a vehicle-mounted charger according to an embodiment of the present invention;

[0039] Figure 5a This is the bus voltage waveform of a traditional on-board charger;

[0040] Figure 5b This is a bus voltage waveform diagram of an on-board charger according to an embodiment of the present invention;

[0041] Figure 6 is a block diagram of a control method for a DC-DC converter according to an embodiment of the present invention;

[0042] Figure 7 is a block diagram of a phase-locked loop based on an orthogonal signal generator according to an embodiment of the present invention;

[0043] Figure 8 This is an implementation of the resonant controller according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following is a detailed description of the vehicle charger and DC-DC converter control method proposed in the present invention, with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clarify the purpose of illustrating the embodiments of the present invention.

[0045] See Figure 4 The present invention provides a new on-board charger (OBC), which adopts a light bus OBC and is mainly composed of a front-stage AC-DC converter and a rear-stage DC-DC converter. The AC-DC converter is connected between the AC power grid and the DC bus capacitor, and is used to convert the AC signal of the AC power grid into a DC bus signal, mainly used to convert the electric energy of the AC power grid into the electric energy of the bus capacitor.

[0046] The on-board charger structure of this embodiment reduces the DC bus capacitor value and simultaneously converts the traditional on-board charger ( Figure 1 The high-frequency switching PFC converter of the AC-DC converter in the ) is replaced by a 50Hz power frequency synchronous rectification circuit, and the traditional on-board charger ( Figure 1 The power factor correction function of the PFC in the embodiment is fully realized by the DC-DC converter of this embodiment. Compared with the traditional on-board charger ( Figure 1 ), the vehicle charger of this embodiment has different AC-DC converters, and the DC bus capacitor input voltage (U) of the DC-DC converter in the two solutions is very different. Figure 5a and Figure 5b .

[0047] The DC-DC converter is connected between the DC bus capacitor and the on-board power battery, and is used to convert the electrical energy of the DC bus capacitor into the electrical energy of the on-board power battery. The DC-DC converter is preferably a DAB converter, but is not limited thereto. For example, it can also be a dual bridge series resonant DC-DC converter (Dual Bridge Series Resonant DC-DC Converter, DBSRC), LLC converter, CLLC converter, etc. This embodiment is described by taking the DC-DC converter as a DAB converter as an example. The DAB converter can be composed of two full-bridge circuits and a transformer connecting the two full-bridge circuits. The purpose of isolation is achieved by the transformer, and the output voltage is controlled by adjusting the on-off state of the switch tubes in the two full-bridge circuits.

[0048] In the on-board charger scheme of this embodiment, the DC-DC converter must achieve both power factor correction and convenient and adjustable power output, which places higher requirements on the control method of the DC-DC converter. Figure 2 ) Modulation is achieved through the internal and external phase shift angles of the original secondary side, and the output power is adjusted by the proportional integral (PI) controller. However, the loop bandwidth is limited and can only be used to control low-frequency or DC signals, making it difficult to achieve power factor correction. Due to nonlinear factors such as distorted power grids and PWM modulation, a large number of sideband harmonics will also be generated in the loop. Especially when the power grid quality is poor, very high control frequency and bandwidth are required to achieve stable and high-quality power conversion, but higher control frequency and bandwidth require switching devices and control chips with higher switching frequencies.

[0049] To this end, the present invention also provides a control method for a DC-DC converter to ensure that the DC-DC converter can achieve a stable power factor correction function under the condition of a distorted power grid or external interference. The control method for a DC-DC converter provided by the present invention may specifically include the following steps: Figure 6 :

[0050] Step S1: sampling the signal of the AC power grid, identifying the frequency of the sampled signal and calculating the corresponding order harmonics, and amplifying and superimposing the corresponding order harmonics;

[0051] Step S2: Inject the processed result into the DC-DC control loop to suppress the disturbance of the corresponding order harmonics and achieve power factor correction.

[0052] In this embodiment, the control method of the DC-DC converter adds a ripple suppression process of active harmonic injection, namely step S1. In step S1, the signal of the AC power grid includes the voltage of the AC power grid (i.e., AC voltage) and the current of the AC power grid (i.e., AC current). The voltage of the AC power grid is sampled, and the frequency of the sampled voltage is identified and calculated to obtain the fundamental frequency. While sampling the voltage of the AC power grid, the current of the AC power grid is also sampled, and the current fundamental wave of the AC power grid (i.e., AC current fundamental wave) is calculated. In this embodiment, the current fundamental wave can be calculated using conventional software.

[0053] The frequency identification of this embodiment is implemented in software. The method for frequency identification of the sampled voltage can be: using the voltage of the AC power grid as input, performing frequency identification on the voltage of the AC power grid through a phase-locked loop or discrete Fourier transform method to obtain the fundamental frequency. The phase-locked loop of this embodiment can be various phase-locked loops, and the Fourier transform can be various Fourier transforms. For example Figure 7 A method for frequency identification of the voltage of an AC power grid using a phase-locked loop is shown, which may specifically include:

[0054] The input AC grid voltage is processed by the orthogonal signal generator to obtain sine and cosine signals with a phase difference of 90 degrees.

[0055] The sine signal and the cosine signal are subjected to Park transformation to obtain a Q-axis DC signal;

[0056] The Q-axis DC signal is processed by a low-pass filter to obtain speed and frequency information;

[0057] The obtained rotation speed and fundamental frequency information are integrated to obtain phase information.

[0058] In this embodiment, the sampled AC grid voltage (uAc) is first transmitted to an orthogonal signal generator, and processed by the orthogonal signal generator to obtain a sine signal [U×sin(θ)] and a cosine signal [U×cos(θ)] with a phase difference of 90°. The orthogonal signal generator is implemented in conventional software and will not be described in detail here. Then, the obtained sine signal [U×sin(θ)] and cosine signal [U×cos(θ)] are subjected to Park transformation to obtain a Q-axis DC signal. The Q-axis component obtained after Park transformation is equal to the AC voltage amplitude (U Q=U). The Park transform is a conventional software algorithm and will not be described in detail here. Next, the Q-axis DC signal is fed into a low-pass filter (LPF). After processing by the LPF, speed and frequency information (AC grid angular frequency ω, i.e., fundamental frequency) is obtained. The LPF is a conventional software algorithm and will not be described in detail here. Finally, the speed and frequency information is fed into an integrator (VCO) for integration to obtain phase information, namely, the AC grid phase angle θ. The integrator is also a conventional software algorithm and will not be described in detail here. When phase lock is achieved, the Q-axis DC signal is zero. The AC grid phase angle θ identified by the VCO output is also fed back to the Park transform to meet the Park transform requirements.

[0059] In this embodiment, the fundamental frequency obtained by frequency identification of the sampled voltage is transmitted to the harmonic injection controller. The error obtained by subtracting the fundamental current wave of the AC grid from the current of the AC grid is also transmitted to the harmonic injection controller. The error obtained by subtracting the fundamental current wave of the AC grid from the current of the AC grid is the current harmonics of the AC grid (AC current harmonics), which include harmonics of various orders. In this embodiment, corresponding harmonic orders of the AC grid current harmonics can be selected and input into a calculation containing the fundamental frequency to obtain corresponding harmonic orders of the AC grid current harmonics, which are amplified and added. The final processing result is the first duty cycle, which can be used to suppress ripple.

[0060] The harmonic injection controller of this embodiment can amplify and add the harmonic signals of the current corresponding to the order of the AC power grid, and inject them into the DC-DC control loop. The harmonic injection controller can be composed of a plurality of resonant (R) controllers with different resonant frequencies in parallel, and it is required to amplify only the signal at the resonant frequency. The resonant controller of this embodiment is preferably a quasi-resonant controller. In other embodiments, the resonant controller can also be a resonant controller of other forms, such as an ideal resonant controller. The harmonic injection controller can be set according to process requirements to select which order harmonics (i.e., select the corresponding order harmonics) in the current harmonics of the AC power grid to amplify and superimpose, preferably common order harmonics, such as the 3rd, 5th and 7th harmonics, but not limited to this. For example, it can also be expanded to higher odd harmonics such as 9, 11, 13 and even harmonics such as 2, 6, 8.

[0061] For example Figure 8 The corresponding order harmonics in the current harmonics of the AC power grid include the 3rd, 5th and 7th harmonics, so the 3rd, 5th and 7th harmonics are amplified and superimposed. In the process of amplifying and superimposing the 3rd, 5th and 7th harmonics, 2K r3 ω c3 s / [s 2 +2ω c3s+(3ω f ) 2 ] represents the amplification of the third harmonic, K r3 represents the gain coefficient of the injected third harmonic; ω c3 represents the resonant bandwidth angular frequency of the resonant controller injected with the third harmonic; s represents the Laplace operator, which is the operator symbol; ω f Represents the resonant angular frequency of the resonant controller, that is, the fundamental frequency obtained by frequency identification; K r3 and ω c3 is the fixed value of calibration. Similarly, 2K r5 ω c5 s / [s 2 +2ω c5 s+(5ω f ) 2 ] represents the amplification of the fifth harmonic, where K r5 represents the gain coefficient of the injected fifth harmonic, ω c5 K represents the resonant bandwidth angular frequency of the resonant controller with injected fifth harmonic. r5 and ω c5 It is a fixed value for calibration; 2K r7 ω c7 s / [s 2 +2ω c7 s+(7ω f ) 2 ] represents the amplification of the seventh harmonic, where K r7 represents the gain coefficient of the injected seventh harmonic, ω c7 K represents the resonant bandwidth angular frequency of the resonant controller with seventh harmonic injection. r7 and ω c7 It is a fixed value for calibration.

[0062] In step S2, the processed result is injected into the DC-DC control loop to achieve power factor correction. In this embodiment, injecting the processed result into the DC-DC control loop may include:

[0063] Step S21: subtracting the output command of the DC-DC converter from the actual output signal of the DC-DC converter to obtain an error;

[0064] Step S22: transmitting the obtained error to a proportional-integral controller to obtain a second duty cycle;

[0065] Step S23: adding the second duty cycle to the first duty cycle to obtain an addition result;

[0066] Step S24: the addition result is subjected to PWM modulation to generate an actual driving signal which is applied to the controlled load.

[0067] In step S21, the output instruction of the DC-DC converter can be one of a DC-DC converter output current instruction, a DC-DC converter output voltage instruction, and a DC-DC converter output power instruction, but is not limited thereto. For example, it can also be a parameter such as total harmonic distortion. The output instruction of the DC-DC converter is an instruction input in software. The actual output signal of the DC-DC converter corresponds to the output instruction of the DC-DC converter, that is, if the output instruction of the DC-DC converter is a DC-DC converter output current instruction, then the actual output signal of the DC-DC converter is the actual output current of the DC-DC converter.

[0068] In step S22, the error obtained by subtracting the output command of the DC-DC converter from the actual output signal of the DC-DC converter is processed by a proportional-integral controller to obtain a second duty cycle. The processing of the proportional-integral controller adopts the existing DAB control method ( Figure 2 ) can be processed by the proportional-integral controller in .

[0069] In step S23, the second duty cycle is added to the first duty cycle to obtain an addition result. In this embodiment, the first duty cycle is used to suppress ripples, that is, to suppress disturbances; the second duty cycle is used to control the output signal of the DC-DC converter. Therefore, after the second duty cycle is added to the first duty cycle, the control loop of the DC-DC converter can suppress ripples (that is, suppress disturbances of corresponding harmonics) and control the output signal.

[0070] In step S24, the summation result is PWM-modulated to generate an actual drive signal, which is applied to the controlled load. The load may include the entire controlled object, including a DC-DC converter, an onboard power battery, or a resistive load. The load outputs the actual output signal of the DC-DC converter, which is fed back into the subtraction operation in step S21. Its dimension is the same as the instruction. The load also outputs iAc (i.e., the charging current of the onboard power battery).

[0071] In summary, the present invention samples the voltage of the AC power grid, identifies the frequency of the sampled voltage, calculates and obtains corresponding harmonic orders, amplifies and then superimposes the corresponding harmonic orders, and injects the processed results into the DC-DC control loop to suppress the disturbance of the corresponding harmonic orders and achieve power factor correction. That is, the present invention actively injects corresponding harmonic orders to suppress disturbances, thereby ensuring that the DC-DC converter can achieve stable power factor correction in the presence of a distorted power grid or external interference. This solves the problem of odd harmonics of various orders generated by distorted power grids and PWM modulation under existing DAB control methods, and also eliminates the need for switching devices and control chips with higher switching frequencies.

[0072] Furthermore, the control method of the DC-DC converter of the present invention can quickly track the power frequency signal instruction (the instruction and the actual output are highly consistent) and simultaneously achieve the suppression of sideband harmonics near the power frequency.

[0073] In addition, it is understood that although the present invention has been disclosed above with reference to preferred embodiments, the above embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or to modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of protection of the technical solution of the present invention.

[0074] It should also be understood that the present invention is not limited to the specific methods, compounds, materials, manufacturing techniques, uses, and applications described herein, which may vary. It should also be understood that the terminology described herein is used only to describe specific embodiments and is not intended to limit the scope of the present invention. It should be noted that the singular forms "a," "an," and "the" as used herein and in the appended claims include plural references unless the context clearly indicates otherwise. Thus, for example, a reference to "a step" means a reference to one or more steps, and may include secondary steps. All conjunctions used should be understood in their broadest sense. Thus, the word "or" should be understood to have the definition of a logical "or," not a logical "exclusive or," unless the context clearly indicates otherwise. Structures described herein are to be understood to also refer to functional equivalents of that structure. Language that can be interpreted as approximating should be so interpreted unless the context clearly indicates otherwise.

Claims

1. A control method for a DC-DC converter, characterized in that: include: Sampling the signal of the AC power grid, obtaining the corresponding order harmonics by frequency identification and calculation of the sampled signal, and amplifying and superimposing the corresponding order harmonics; The processed results are injected into the DC-DC control loop to suppress the disturbance of the corresponding order harmonics and achieve power factor correction.

2. The control method of the DC-DC converter according to claim 1, wherein: The AC grid signal includes the voltage and current of the AC grid. The fundamental frequency is obtained by frequency identification and calculation of the sampled voltage; the current fundamental of the AC grid is obtained by calculation of the sampled current.

3. The control method of the DC-DC converter according to claim 2, wherein: The fundamental frequency is transmitted to the harmonic injection controller; at the same time, the current harmonics of the AC grid obtained by subtracting the current fundamental of the AC grid from the current of the AC grid are transmitted to the harmonic injection controller. Through the calculation of the harmonic injection controller, the corresponding order harmonics in the current harmonics of the AC grid can be obtained, and the results of the amplification and superposition processing can be obtained.

4. The control method of the DC-DC converter according to claim 3, wherein: The harmonic injection controller is composed of a plurality of resonance controllers with different resonance frequencies connected in parallel.

5. The control method of the DC-DC converter according to claim 2, wherein: The method for frequency identification of the sampled voltage includes: taking the voltage of the AC grid as input, performing frequency identification on the voltage of the AC grid by a phase-locked loop or discrete Fourier transform method to obtain a fundamental frequency.

6. The control method of the DC-DC converter according to claim 5, wherein: Methods for frequency identification of AC grid voltage using a phase-locked loop include: The input AC grid voltage is processed by the orthogonal signal generator to obtain sine and cosine signals with a phase difference of 90 degrees. The sine signal and the cosine signal are subjected to Park transformation to obtain a Q-axis DC signal; The Q-axis DC signal is processed by a low-pass filter to obtain speed and frequency information; The obtained rotation speed and fundamental frequency information are integrated to obtain phase information.

7. The control method of the DC-DC converter according to claim 1, wherein: The result obtained by amplifying and superimposing the corresponding order harmonics is the first duty cycle.

8. The control method of the DC-DC converter according to claim 7, wherein: The injecting the processed result into the DC-DC control loop comprises: Subtracting the output command of the DC-DC converter from the actual output signal of the DC-DC converter to obtain an error; delivering the obtained error to a proportional-integral controller to obtain a second duty cycle; Adding the second duty cycle to the first duty cycle to obtain an addition result; The addition result is subjected to PWM modulation to generate an actual driving signal which is applied to the controlled load.

9. The control method of the DC-DC converter according to claim 1, wherein: The DC-DC converter includes a dual active full-bridge converter.

10. The control method of the DC-DC converter according to claim 1, wherein: The output instruction of the DC-DC converter includes one of a DC-DC converter output current instruction, a DC-DC converter output voltage instruction, and a DC-DC converter output power instruction.

11. A vehicle-mounted charger, characterized in that: include: An AC-DC converter, connected to an AC power grid, for converting an AC signal of the AC power grid into a DC bus signal; The DC bus capacitor is connected to the AC-DC converter and plays the role of rectification and buffering; A DC-DC converter is connected between a DC bus capacitor and an on-board power battery to realize a controllable constant signal output function and a power factor correction function, and the control method of the DC-DC converter according to any one of claims 1 to 10 is applied to the DC-DC converter.

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