Dc / dc converter with harmonic injection function and control method

Abstract

The application discloses a DC / DC converter with a harmonic injection function and a control method. The DC / DC converter with the harmonic injection function comprises a boost circuit module, an input side of the boost circuit module is connected with a fuel cell, an output side of the boost circuit module is connected with a power battery, and a control module is used for carrying out closed-loop control according to an instruction issued by an upper computer, realizing constant-voltage input or constant-current input, wherein the instruction issued by the upper computer comprises a target voltage setting instruction or a target current setting instruction, and a harmonic current amplitude setting instruction and a harmonic current frequency setting instruction, and wherein, during the closed-loop control, a harmonic current is generated according to a preset harmonic current amplitude and a harmonic current frequency. The DC / DC converter can superimpose an alternating current harmonic component with a specified frequency on the output current of the fuel cell under the premise of realizing controllable electric energy with constant voltage and constant current.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy vehicles, in particular to a DC / DC converter with harmonic injection function and a control method. BACKGROUND

[0002] Fuel cell system is a key development direction in the field of new energy vehicles. At present, electric vehicles equipped with hydrogen fuel cells and power batteries can solve the problem of insufficient power such as electric vehicle endurance under the support of hydrogen fuel cells. Electrochemical impedance spectroscopy (EIS) is an important indicator of fuel cells. On-line detection can evaluate the running status of the fuel cell in real time, so as to adjust the control measures according to the running status of the fuel cell. In order to detect the EIS of the fuel cell, it is necessary to calculate the alternating current impedance of the specified frequency component of the fuel cell in real time. In order to realize the measurement of alternating current impedance, it is necessary to superimpose an alternating current harmonic component of a specified frequency on the output current of the fuel cell. SUMMARY

[0003] Therefore, the embodiments of the present application provide a DC / DC converter with harmonic injection function and a control method. Under the premise of realizing controllable constant voltage and constant current electric energy, the problem of superimposing an alternating current harmonic component of a specified frequency on the output current of the fuel cell is solved.

[0004] In a first aspect, the embodiments of the present application provide a DC / DC converter with harmonic injection function, which is equipped with a fuel cell and a power battery in a new energy vehicle. The DC / DC converter comprises:

[0005] a boost circuit module, which comprises a boost inductor, a diode, a capacitor and a switch tube;

[0006] The input side of the boost circuit module is connected with the fuel cell, and the output side of the boost circuit module is connected with the power battery;

[0007] a control module, which is used for closed-loop control according to an instruction issued by an upper computer to realize constant voltage input or constant current input, wherein the instruction issued by the upper computer comprises a target voltage setting instruction or a target current setting instruction, and a harmonic current amplitude setting instruction and a harmonic current frequency setting instruction, and wherein a harmonic current is generated according to the preset harmonic current amplitude and harmonic current frequency during closed-loop control.

[0008] According to the above-mentioned aspect and any possible implementation manner, a further implementation manner is provided, wherein the control module is used for closed-loop control according to the instruction issued by the upper computer to realize constant voltage input, comprising:

[0009] According to the target voltage setting instruction, the voltage and current on the input side are sampled to obtain a sample current and a sample voltage;

[0010] The sample current is subjected to a direct-current filtering process to obtain a loop feedback current;

[0011] A loop difference value calculated from the harmonic current and the loop feedback current is input to a PR controller, wherein the PR controller adopts the harmonic current frequency;

[0012] The sample voltage is input to a notch filter to obtain a loop feedback voltage, wherein the notch frequency of the notch filter is the same as the preset harmonic current frequency;

[0013] A loop difference value calculated from a preset target voltage and the loop feedback voltage is input to a PI controller;

[0014] A pulse width modulation signal for the closed-loop control is determined according to the outputs of the PR controller and the PI controller, so as to realize the constant-voltage input.

[0015] According to any possible implementation of the above aspect, an implementation is further provided, wherein the control module is configured to realize the constant-current input according to the instruction issued by the upper computer, and the control module comprises:

[0016] According to the target current setting instruction, the current on the input side is sampled to obtain a sample current;

[0017] A reference current is obtained according to the harmonic current and a preset target current;

[0018] A loop difference value calculated from the reference current and the sample current is input to a PI controller and a PR controller respectively, wherein the PR controller adopts the harmonic current frequency;

[0019] A pulse width modulation signal for the closed-loop control is determined according to the outputs of the PR controller and the PI controller, so as to realize the constant-current input.

[0020] According to any possible implementation of the above aspect, an implementation is further provided, wherein the harmonic current is generated according to a preset harmonic current amplitude and a harmonic current frequency, and the method comprises:

[0021] A sample integrator integrates the preset harmonic current frequency to obtain a harmonic angle;

[0022] A harmonic sine value is obtained according to the harmonic angle;

[0023] The harmonic sine value is multiplied by the preset harmonic current amplitude to obtain the harmonic current.

[0024] As the aspect and any possible implementation manner described above further provides an implementation manner, the instruction issued by the host computer further comprises a control mode instruction and a switch-on / off instruction;

[0025] Wherein, when the value of the control mode instruction is 0, it represents inputting constant current control mode, and when the value of the control mode instruction is 1, it represents inputting constant voltage control mode;

[0026] When the value of the switch-on / off instruction is 0, the DC / DC controller is switched off, and when the value of the switch-on / off instruction is 1, the DC / DC controller is switched on.

[0027] In a second aspect, the embodiments of the present application further provide a DC / DC converter control method, the method comprising:

[0028] Obtaining an instruction issued by a host computer, wherein the instruction issued by the host computer comprises a target voltage setting instruction or a target current setting instruction, and a harmonic current amplitude setting instruction and a harmonic current frequency setting instruction;

[0029] Obtaining a preset harmonic current amplitude according to the harmonic current amplitude setting instruction;

[0030] Obtaining a preset harmonic current frequency according to the harmonic current frequency setting instruction;

[0031] Generating a harmonic current according to the preset harmonic current amplitude and the preset harmonic current frequency;

[0032] When the target voltage setting instruction is received, performing closed-loop control according to the target voltage setting instruction and the harmonic current to realize constant voltage input;

[0033] When the target current setting instruction is received, performing closed-loop control according to the target current setting instruction and the harmonic current to realize constant current input.

[0034] As the aspect and any possible implementation manner described above further provides an implementation manner, the closed-loop control according to the target voltage setting instruction and the harmonic current to realize constant voltage input comprises:

[0035] According to the target voltage setting instruction, sampling to obtain a sample current and a sample voltage;

[0036] Performing direct current filtering processing on the sample current to obtain a loop feedback current;

[0037] Inputting a loop difference value calculated from the harmonic current and the loop feedback current into a PR controller, wherein the PR controller adopts the harmonic current frequency;

[0038] inputting the sample voltage into a notch filter to obtain a loop feedback voltage, wherein a notch frequency of the notch filter is the same as the preset harmonic current frequency;

[0039] obtaining a target voltage according to the target voltage setting instruction;

[0040] inputting a loop difference value calculated from the target voltage and the loop feedback voltage into a PI controller;

[0041] determining a pulse width modulation signal of the closed-loop control according to outputs of the PR controller and the PI controller, to realize the constant voltage input.

[0042] According to the aspect and any possible implementation manner described above, an implementation manner is further provided, and the closed-loop control according to the target current setting instruction and the harmonic current to realize the constant current input comprises:

[0043] sampling to obtain a sample current according to the target current setting instruction;

[0044] obtaining a target current according to the target current setting instruction;

[0045] obtaining a reference current according to the harmonic current and the target current;

[0046] inputting a loop difference value calculated from the reference current and the sample current into a PI controller and a PR controller respectively, wherein the PR controller adopts the harmonic current frequency;

[0047] determining a pulse width modulation signal of the closed-loop control according to outputs of the PR controller and the PI controller, to realize the constant current input.

[0048] According to the aspect and any possible implementation manner described above, an implementation manner is further provided, and the generation of the harmonic current according to the preset harmonic current amplitude and the preset harmonic current frequency comprises:

[0049] According to the aspect and any possible implementation manner described above, an implementation manner is further provided, and the instruction issued by the host computer further comprises a control mode instruction and a switch instruction;

[0050] When the value of the control mode instruction is 0, it represents inputting a constant current control mode, and when the value of the control mode instruction is 1, it represents inputting a constant voltage control mode.

[0051] When the value of the switch instruction is 0, the DC / DC controller is powered off, and when the value of the switch instruction is 1, the DC / DC controller is powered on.

[0052] In the embodiment of the present application, a DC / DC converter is taken as a basic device for controlling the output of electric energy, which is mounted on a new energy vehicle with a fuel cell and a power battery; the DC / DC converter comprises a boost circuit module and a control module, the input side of the boost circuit module is connected with the fuel cell, and the output side of the boost circuit module is connected with the power battery, so that the control of the output of electric energy of the fuel cell or the switching to the charging of the power battery can also support the control of the output of electric energy; the control module is used for closed-loop control according to the instruction issued by the upper computer, to realize constant voltage input or constant current input, wherein the instruction issued by the upper computer comprises a target voltage setting instruction or a target current setting instruction, and a harmonic current amplitude setting instruction and a harmonic current frequency setting instruction, during the closed-loop control, a harmonic current can be generated according to the preset harmonic current amplitude and harmonic current frequency, so that under the premise of realizing controllable constant voltage control or constant current control, an alternating current harmonic component of a specified frequency can also be generated. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0054] Figure 1 is a circuit schematic diagram of a DC / DC converter in the embodiment of the present application;

[0055] Figure 2 is a closed-loop control schematic diagram of an input constant current control mode in the embodiment of the present application;

[0056] Figure 3 is a closed-loop control schematic diagram of an input constant voltage control mode in the embodiment of the present application. DETAILED DESCRIPTION

[0057] In order to better understand the technical solutions of the present application, the embodiments of the present application will be described in detail below with reference to the drawings.

[0058] It should be clear that the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0059] The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in the description of the embodiments of the present application and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0060] It should be understood that the term "and / or" used herein is merely used to describe associated objects, and / or can represent three relationships, for example, A and / or B can represent three cases of A alone, A and B, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0061] It should be understood that although the terms first, second, third, etc. may be used in the embodiments of the present application to describe the preset ranges, etc., these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from each other. For example, the first preset range can also be referred to as the second preset range, and similarly, the second preset range can also be referred to as the first preset range without departing from the scope of the embodiments of the present application.

[0062] Depending on the context, the word "if" as used herein can be interpreted to mean "when" or "while" or "in response to determining" or "in response to detecting". Similarly, the phrase "if it is determined" or "if (a stated condition or event) is detected" can be interpreted to mean "when it is determined" or "in response to determining" or "when (a stated condition or event) is detected" or "in response to detecting (a stated condition or event)".

[0063] In addition to electric vehicles containing only power batteries, electric vehicles equipped with fuel cells (such as hydrogen fuel cells) and power batteries are also a key development direction in the field of new energy vehicles. Electric vehicles equipped with fuel cells can solve some inherent problems of pure electric vehicles. In order to evaluate the operating condition of the fuel cell in real time and adjust the control measures according to the operating condition of the fuel cell, a specified frequency of alternating current harmonic component is superimposed on the output current of the fuel cell.

[0064] In the present application, in order to achieve better effect of fuel cell power output, a DC / DC converter can be used as a basic device for controlling power output, and on the basis of the DC / DC converter, generation of a specified frequency of alternating current harmonic component is realized to evaluate the operating condition of the fuel cell in real time and adjust the control measures according to the operating condition of the fuel cell.

[0065] The present application proposes a DC / DC converter with harmonic injection function, which is applied to new energy vehicles equipped with fuel cells and power batteries. The DC / DC converter comprises:

[0066] The boost circuit module includes a boost inductor, diode, capacitor, and switching transistor.

[0067] Specifically, this boost circuit module can be a boost circuit in which a boost inductor and diode are connected in series, and in parallel with a capacitor and a switching transistor. The capacitor is also connected in parallel with the switching transistor. When the switching transistor (such as a MOSFET) is turned on, the input current flows through the boost inductor, while the diode prevents the capacitor from discharging to ground. As time changes, the inductor current increases, storing magnetic energy within the inductor. Later, when the switching transistor is turned off, due to the inductor's current-holding characteristic, the current flowing through the inductor does not immediately become zero, but rather slowly decreases to zero. During this time, the inductor converts the magnetic energy into electrical energy to charge the capacitor, increasing the voltage across the capacitor. At this point, the capacitor voltage is higher than the input voltage. Thus, this boost circuit module, composed of a boost inductor, diode, capacitor, and switching transistor, achieves the effect of voltage boosting.

[0068] Furthermore, the input side of the boost circuit module is connected to the fuel cell, and the output side of the boost circuit module is connected to the power battery.

[0069] This application incorporates a DC / DC converter between the fuel cell and the power battery. The input and output sides of the DC / DC converter's boost circuit module are connected to the fuel cell and the power battery, respectively, linking them together. Thus, during fuel cell operation, the output voltage and current can be controlled via the DC / DC converter, enabling the fuel cell to achieve optimal power generation under different operating conditions. Furthermore, when the power battery requires charging, the boost circuit of the DC / DC converter can also stabilize the voltage and current output, achieving efficient and stable charging.

[0070] The DC / DC converter also includes a control module, which is used to perform closed-loop control according to the instructions issued by the host computer to achieve constant voltage input or constant current input. The instructions issued by the host computer include target voltage setting instructions or target current setting instructions, as well as harmonic current amplitude setting instructions and harmonic current frequency setting instructions. During the closed-loop control, harmonic current is generated according to the preset harmonic current amplitude and harmonic current frequency.

[0071] In one embodiment, the control module can control the on and off states of the switching transistor to achieve constant voltage or constant current input. Furthermore, based on the DC / DC converter boost circuit module, it can generate AC current harmonic components (hereinafter referred to as harmonic current) according to preset harmonic current amplitude and frequency. Specifically, after receiving a target voltage setting command or a target current setting command, the control module will acquire the target voltage or target current according to the command. If the acquired value is a target voltage, the control module is used to implement closed-loop control for constant voltage input; if the acquired value is a target current, the control module is used to implement closed-loop control for constant current input. The control module also receives harmonic current amplitude setting instructions and harmonic current frequency setting instructions, and obtains the preset harmonic current amplitude and frequency according to these instructions, thereby generating harmonic current. That is, in this embodiment, based on the DC / DC converter boost circuit module, constant voltage input or constant current input is achieved through instructions issued by the control module from the host computer. Furthermore, when implementing closed-loop control of constant voltage input or constant current input, a harmonic current of a specified frequency can be generated to evaluate the fuel cell operating status in real time based on the harmonic current of the specified frequency, thereby implementing voltage and current adjustment control measures according to the operating status of the fuel cell.

[0072] Furthermore, the instructions issued by the host computer in this application also include control mode instructions and power on / off instructions.

[0073] The control mode command is used to determine whether the DC / DC converter uses constant current control mode or constant voltage control mode. Specifically, a value of 0 indicates constant current control mode, and a value of 1 indicates constant voltage control mode.

[0074] Power-on / off commands are used to control the DC / DC converter to turn on or off. Specifically, when the power-on / off command value is 0, the DC / DC controller is off, and when the power-on / off command value is 1, the DC / DC controller is on.

[0075] Understandably, the control module can control the operating mode of the DC / DC converter. Users can control the DC / DC converter to turn on or off by issuing commands from the host computer, as well as input constant current control mode or input constant voltage control mode, and achieve dynamic adjustment of the fuel cell by generating harmonic current of a specified frequency.

[0076] Furthermore, in this application, harmonic current is generated based on a preset harmonic current amplitude and harmonic current frequency, specifically including:

[0077] The sampling integrator integrates the preset harmonic current frequency to obtain the harmonic angle.

[0078] Obtain the harmonic sine value based on the harmonic angle.

[0079] The harmonic current is obtained by multiplying the harmonic sine value by the preset harmonic current amplitude.

[0080] In this application, an integrator is a component whose output signal is the integral of the input signal over time. Specifically, an integrator is used to integrate the frequency of the input harmonic current over time and output the result as a trigonometric function angle of the AC current harmonic components, which can be simply referred to as the harmonic angle.

[0081] In this application, the harmonic sine value is obtained by taking the sine of the harmonic angle. Then, the harmonic sine value is multiplied by a preset harmonic current amplitude to obtain the harmonic current. For example, if the harmonic angle is θ, the harmonic sine value is sinθ, and the preset harmonic current amplitude is D, then the harmonic current can be expressed as Dsinθ, which is the harmonic component of the alternating current. It should be noted that, in addition to using the sine of the harmonics, trigonometric function values ​​expressed using the cosine of the harmonics, etc., should also be within the scope of protection of this application.

[0082] In this application, harmonics can be injected into the constant current control mode and the constant voltage control mode, and the normal operation of the constant current control mode and the constant voltage control mode is guaranteed.

[0083] Specifically, the constant current input control mode can be achieved using the following closed-loop control method:

[0084] 1-1: Based on the target current setting command, sample the current on the input side to obtain the sample current.

[0085] In one embodiment, the control module first receives a power-on / off command with a value of 1 and a control mode command with a value of 0, thus activating the DC / DC controller and preparing to enter the input constant current control mode. Then, it receives a target current setting command from the host computer and samples the current output from the fuel cell side connected to the boost circuit module to obtain a sample current.

[0086] 1-2: The reference current is obtained based on the harmonic current and the preset target current.

[0087] The reference current includes the harmonic components of the AC current and the DC current input to the boost circuit module. Specifically, the target current can be obtained according to the target current setting command issued by the host computer. This target current is the DC component current required by the boost circuit module to achieve the input constant current control mode. In this application, since harmonic current is also injected in the input constant current control mode, the DC and AC components of the current are combined as the reference current under the closed-loop control of the input constant current control mode. It can be understood that the closed-loop control needs to compare the set expected value with the sample value of the actual output of the circuit to obtain the loop difference. The loop difference is used to optimize the loop so that the sample value of the actual output of the circuit is close to the set expected value. For example, in the embodiment of this application, in order to achieve the input constant current control mode under the input constant voltage control mode, the sample current will be made close to the reference current, thereby achieving the effect of closed-loop control and input constant current.

[0088] 1-3: Input the loop difference calculated from the reference current and the sample current into the PI controller and the PR controller respectively. The PR controller uses the harmonic current frequency.

[0089] The PI controller is a linear controller that uses the control deviation between the given value and the actual output value to linearly combine the proportional and integral parts of the deviation to form the control quantity, thereby controlling the controlled object. In this application, the PI controller is used to control the loop output based on the loop difference calculated from the reference current and the sample current, so that the sample current is close to the reference current. Furthermore, since the loop error includes an AC component, and given that the PI controller is suitable for tracking DC current signals without steady-state error but cannot achieve zero steady-state error tracking in the tracking of sinusoidal current signals, this application also incorporates a PR controller to track the AC component. The PR controller uses the harmonic current frequency to track the AC component at a specified frequency, and combined with the output of the PI controller, makes the sample current closer to the reference current, thereby achieving the purpose of constant current input.

[0090] 1-4: Determine the pulse width modulation signal for closed-loop control based on the outputs of the PR controller and PI controller to achieve constant current input.

[0091] In one embodiment, by regulating the closed-loop circuit through the PR controller and PI controller, the DC and AC components of the loop error can be effectively controlled, enabling the closed-loop circuit to operate in constant current input control mode. Specifically, the outputs of the PR controller and PI controller can be converted into PWM (Pulse Width Modulation) signal control, maintaining the DC / DC converter in constant current input control mode by controlling the on / off state of the switching transistors.

[0092] In addition to supporting harmonic injection in the constant current input control mode, this application can also support harmonic injection in the constant voltage input control mode. Specifically, the constant voltage input control mode can be implemented using the following closed-loop control method:

[0093] 2-1: According to the target voltage setting command, the voltage and current on the input side are sampled to obtain sample current and sample voltage.

[0094] In this embodiment, the constant voltage input control mode consists of two closed-loop control loops: an input voltage control loop for controlling the input voltage and a current control loop for generating harmonic current. It can be seen that the closed-loop control loop used in the constant voltage input control mode differs significantly from that used in the constant current input control mode; the constant voltage input control mode employs two closed-loop control loops for control.

[0095] In one embodiment, the control module first receives a power-on / off command with a value of 1 and a control mode command with a value of 1, thereby activating the DC / DC controller and preparing to enter the input constant voltage control mode. Then, it receives a target voltage setting command from the host computer and samples the current and voltage output from the fuel cell side connected to the boost circuit module to obtain sample current and sample voltage.

[0096] 2-2: The sample current is subjected to DC blocking filtering to obtain the loop feedback current.

[0097] 2-3: Input the loop difference calculated from the harmonic current and the loop feedback current into the PR controller, where the PR controller uses the harmonic current frequency.

[0098] In one embodiment, under constant voltage input control mode, the DC component of the input circuit is no longer controlled; only the harmonic current corresponding to the AC component needs to be generated. This harmonic current is specifically tracked and loop-controlled using a PR controller. Further, as a loop control comparison item for the harmonic current, since only the harmonic current corresponding to the AC component is controlled under constant voltage input control mode, the sampled current is filtered by a DC blocking filter, and the sampled current with the DC component removed is used as the current feedback value of the loop to be compared with the harmonic current, thereby calculating the loop error. The PR controller uses the harmonic current frequency to track the AC component at a specified frequency, achieving better closed-loop control for the AC component.

[0099] 2-4: Input the sample voltage into the notch filter to obtain the loop feedback voltage, wherein the notch frequency of the notch filter is the same as the preset harmonic current frequency.

[0100] In the voltage control loop of the constant input voltage control mode, this application also incorporates a notch filter. This notch filter uses the same frequency as the harmonic current, effectively filtering out the AC signal with the same frequency. In other words, the notch filter can remove harmonic components from the sample voltage. This avoids the PI controller suppressing harmonic components of the input voltage at a specified frequency without affecting the control performance of the voltage control loop.

[0101] 2-5: Input the loop difference calculated from the preset target voltage and the loop feedback voltage into the PI controller.

[0102] The preset target voltage is the voltage value that the user expects to input as a constant voltage, while the loop feedback voltage is used as a comparison item to calculate the loop difference. In one embodiment, because harmonic components in the sample voltage are filtered out, the PI controller will not be affected by the AC harmonic components in the originally acquired sample voltage when performing control calculations, thereby achieving more accurate closed-loop control.

[0103] 2-6: Determine the pulse width modulation signal for closed-loop control based on the outputs of the PR controller and PI controller to achieve constant voltage input.

[0104] In one embodiment, the outputs of the PR controller and the PI controller jointly influence the input constant voltage control mode. Based on the closed-loop control of the voltage control loop and the current control loop, the combination of the two can yield the final control strategy. The DC / DC converter is kept in the input constant voltage control mode by means of pulse width modulation signal control.

[0105] Figure 1 This is a circuit diagram of a DC / DC converter according to an embodiment of this application. Figure 1 As shown, the DC / DC converter uses a Boost circuit as the boost circuit module, which includes a boost inductor L, a diode D, a capacitor C, and a switching transistor Q. The boost inductor L and diode D are connected in series, and the capacitor C and switching transistor Q are connected in parallel. The input side of this Boost circuit is connected to the fuel cell, and the output side is connected to the power battery or other loads. The fuel cell, power battery, other loads, and the other end of the switching transistor are grounded, represented as GND in the figure. The DC / DC converter also includes a control module, which receives commands from a host computer via a CAN (Controller Area Network) bus. Based on these commands, it samples the input current and input voltage from the input side. Depending on whether the input is in constant current or constant voltage mode, it outputs a PWM control signal to the switching transistor to control its on / off state, thus achieving closed-loop control of the circuit.

[0106] Specifically, the instructions issued by the host computer may include:

[0107] Target voltage setting command Vset: Input the target value of the input voltage in constant voltage control mode. The control module samples the actual input voltage and adjusts the PWM through closed loop to make the actual input voltage close to Vset.

[0108] Target current setting instruction Iset: Input the target value of the input current in constant current control mode. The control module samples the actual input current and adjusts the PWM through closed loop to make the actual input current close to Iset.

[0109] Harmonic current amplitude setting instruction IacSet: The target value of AC harmonic amplitude superimposed on the input current. Combined with the harmonic current frequency control instruction iFreqSet, the harmonic current IHarmonicSet can be calculated. The control module samples the actual input current and extracts the AC component. Through closed-loop adjustment of PWM, the harmonic amplitude of the input current is made close to IHarmonicSet.

[0110] Harmonic current frequency control command IFreqSet: AC harmonic frequency superimposed on the input current.

[0111] Control Mode Set: 0 indicates constant current control mode, 1 indicates constant voltage control mode.

[0112] PowerOnSet command: 0 indicates DC / DC power off, 1 indicates DC / DC power on.

[0113] This application supports the injection of harmonics in either constant current control mode or constant voltage control mode.

[0114] Figure 2 This is a schematic diagram of closed-loop control of an input constant current control mode in an embodiment of this application.

[0115] like Figure 2As shown, the harmonic current frequency control command IFreqSet is input to the integrator to obtain the harmonic angle θ. The value of the harmonic current amplitude setting command IacSet is multiplied by the sine of the harmonic angle θ to obtain the harmonic current IHarmonicSet, thus obtaining the AC component required for this constant current control mode. Next, it is added to the target current setting command Iset, representing the DC component, to obtain the reference current Iref, which contains both the DC and AC components of the current in the loop. Then, the sampling current Isamp is obtained, representing the actual sampled current, which also contains both the DC and AC components. The difference between the reference current Iref and the sampling current Isamp yields the corresponding loop difference value. Similarly, since the loop difference includes both DC and AC components, to make the loop control more efficient and accurate, a PI controller will be used to process the DC component of the loop difference, and a PR controller will be used to process the AC component (wherein, the PR controller uses the same frequency as the harmonic current frequency control instruction IFreqSet). Finally, the control calculations are combined to obtain the PWM control signal. Figure 2 The closed-loop control flow shown can realize the constant current control mode of the DC / DC converter input.

[0116] Figure 3 This is a closed-loop control diagram of an input constant pressure control mode in an embodiment of this application.

[0117] like Figure 3 As shown, the constant voltage input control mode consists of two closed-loop control loops: an input voltage control loop for controlling the input voltage and a current control loop for generating harmonic current.

[0118] First, looking at the control loop that generates harmonic current, we can see that the harmonic current frequency control command IFreqSet is input to the integrator to obtain the harmonic angle θ. The harmonic current amplitude setting command IacSet is multiplied by the sine of the harmonic angle θ to obtain the harmonic current IHarmonicSet. Then, considering that in the constant voltage input control mode, the DC component of the input current is no longer subject to closed-loop control, and only the AC component of the harmonic current needs to be generated, the sampled current Isamp can be input to the DC blocking filter to remove the DC component before being used as the current feedback value Ifb of the loop. The difference between the current feedback value Ifb and the harmonic current IHarmonicSet is calculated to obtain the loop difference of the current control loop. Then, the PR controller using the IFreqSet frequency can perform control calculation processing on the loop difference, and the output of the PR controller is used as one of the control conditions of the PWM control signal.

[0119] Looking at the input voltage control loop, a notch filter with the same frequency as the harmonic current frequency control command IFreqSet is first set. The sampled voltage is then input to this notch filter, effectively filtering out harmonic components in the sample voltage vsamp. This avoids the PI controller suppressing harmonic components of the input voltage without affecting the control performance of the input voltage control loop. Next, the output of the notch filter is used as the voltage feedback value Vfb, and the difference between this output and the value of Vset is calculated to obtain the loop difference for the input voltage control loop. Through processing by the PI controller, its output, combined with the output of the PI controller, determines the PWM control signal.

[0120] In this application, harmonic current can be directly generated based on the DC / DC converter circuit module. Furthermore, this application can also inject harmonics while implementing either constant current control mode or constant voltage control mode.

[0121] In this embodiment, a DC / DC converter is used as the basic device for controlling the output of electrical energy. This DC / DC converter is installed in a new energy vehicle equipped with a fuel cell and a power battery. The DC / DC converter includes a boost circuit module and a control module. The input side of the boost circuit module is connected to the fuel cell, and the output side of the boost circuit module is connected to the power battery. In this way, it can also support the control of electrical energy output when controlling the output of electrical energy from the fuel cell or when switching to charging the power battery. The control module is used to perform closed-loop control according to the instructions issued by the host computer to achieve constant voltage input or constant current input. The instructions issued by the host computer include target voltage setting instructions or target current setting instructions, as well as harmonic current amplitude setting instructions and harmonic current frequency setting instructions. During the closed-loop control, harmonic current can be generated according to the preset harmonic current amplitude and harmonic current frequency. In this way, under the premise of achieving controllable constant voltage input or constant current input, it is also possible to generate AC current harmonic components of a specified frequency.

[0122] This application also provides a DC / DC converter control method, which includes:

[0123] Obtain instructions issued by the host computer, including target voltage setting instructions or target current setting instructions, as well as harmonic current amplitude setting instructions and harmonic current frequency setting instructions.

[0124] The preset harmonic current amplitude is obtained according to the harmonic current amplitude setting command.

[0125] The preset harmonic current frequency is obtained according to the harmonic current frequency setting command.

[0126] Harmonic currents are generated based on preset harmonic current amplitudes and preset harmonic current frequencies.

[0127] When a target voltage setting command is received, closed-loop control is performed according to the target voltage setting command and harmonic current to achieve constant voltage input.

[0128] And / or, when the received instruction is a target current setting instruction, closed-loop control is performed according to the target current setting instruction and harmonic current to achieve constant current input.

[0129] The embodiments of the above-described DC / DC converter control method and its extensions can be referred to the embodiments of the DC / DC converter with harmonic injection function described above, and will not be repeated here.

[0130] Furthermore, closed-loop control is performed based on the target voltage setting command and harmonic current to achieve constant voltage input, including:

[0131] Based on the target voltage setting command, the sample current and sample voltage are sampled and obtained.

[0132] The sample current is subjected to DC blocking filtering to obtain the loop feedback current.

[0133] The loop difference calculated from the harmonic current and the loop feedback current is input into the PR controller, where the PR controller uses the harmonic current frequency.

[0134] The sample voltage is input to the notch filter to obtain the loop feedback voltage, wherein the notch frequency of the notch filter is the same as the preset harmonic current frequency.

[0135] Obtain the target voltage according to the target voltage setting command.

[0136] The loop difference calculated from the target voltage and the loop feedback voltage is input to the PI controller.

[0137] The pulse width modulation signal for closed-loop control is determined based on the outputs of the PR controller and PI controller to achieve constant voltage input.

[0138] Furthermore, closed-loop control is performed based on the target current setting command and harmonic current to achieve constant current input, including:

[0139] The sample current is obtained by sampling according to the target current setting command.

[0140] Obtain the target current according to the target current setting command.

[0141] The reference current is obtained based on the harmonic current and the target current.

[0142] The loop difference calculated from the reference current and the sample current is input to the PI controller and the PR controller, respectively, where the PR controller uses the harmonic current frequency.

[0143] The pulse width modulation signal for closed-loop control is determined based on the outputs of the PR controller and PI controller to achieve constant current input.

[0144] Furthermore, harmonic currents are generated based on preset harmonic current amplitudes and preset harmonic current frequencies, including:

[0145] The sampling integrator integrates the preset harmonic current frequency to obtain the harmonic angle.

[0146] Obtain the harmonic sine value based on the harmonic angle.

[0147] The harmonic current is obtained by multiplying the harmonic sine value by the preset harmonic current amplitude.

[0148] Furthermore, the instructions issued by the host computer also include control mode instructions and power on / off instructions.

[0149] When the value of the control mode command is 0, it indicates that the constant current control mode is input; when the value of the control mode command is 1, it indicates that the constant voltage control mode is input.

[0150] When the power-on / off command value is 0, the DC / DC controller is powered off; when the power-on / off command value is 1, the DC / DC controller is powered on.

[0151] In this embodiment, a DC / DC converter is used as the basic device for controlling the output of electrical energy. This DC / DC converter is installed in a new energy vehicle equipped with a fuel cell and a power battery. The DC / DC converter includes a boost circuit module and a control module. The input side of the boost circuit module is connected to the fuel cell, and the output side of the boost circuit module is connected to the power battery. In this way, it can also support the control of electrical energy output when controlling the output of electrical energy from the fuel cell or when switching to charging the power battery. The control module is used to perform closed-loop control according to the instructions issued by the host computer to achieve constant voltage input or constant current input. The instructions issued by the host computer include target voltage setting instructions or target current setting instructions, as well as harmonic current amplitude setting instructions and harmonic current frequency setting instructions. During the closed-loop control, harmonic current can be generated according to the preset harmonic current amplitude and harmonic current frequency. In this way, under the premise of achieving controllable constant voltage input or constant current input, it is also possible to generate AC current harmonic components of a specified frequency.

[0152] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0153] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0154] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A DC / DC converter with harmonic injection function, applied to new energy vehicles equipped with fuel cells and power batteries, characterized in that, The DC / DC converter includes: A boost circuit module, comprising a boost inductor, a diode, a capacitor, and a switching transistor; The input side of the boost circuit module is connected to the fuel cell, and the output side of the boost circuit module is connected to the power battery. The control module is used to perform closed-loop control according to the instructions issued by the host computer to achieve constant voltage input or constant current input. The instructions issued by the host computer include target voltage setting instructions or target current setting instructions, as well as harmonic current amplitude setting instructions and harmonic current frequency setting instructions. During the closed-loop control, harmonic current is generated according to the preset harmonic current amplitude and harmonic current frequency.

2. The DC / DC converter according to claim 1, characterized in that, The control module is used to perform closed-loop control according to instructions issued by the host computer to achieve constant voltage input, including: According to the target voltage setting command, the voltage and current on the input side are sampled to obtain sample current and sample voltage; The sample current is subjected to DC blocking filtering to obtain the loop feedback current; The loop difference calculated from the harmonic current and the loop feedback current is input to the PR controller, wherein the PR controller uses the frequency of the harmonic current. The sample voltage is input to a notch filter to obtain a loop feedback voltage, wherein the notch frequency of the notch filter is the same as the preset harmonic current frequency. The preset target voltage and the loop difference calculated from the loop feedback voltage are input to the PI controller; The pulse width modulation signal for closed-loop control is determined based on the outputs of the PR controller and the PI controller to achieve the constant voltage input.

3. The DC / DC converter according to claim 1, characterized in that, The control module is used to perform closed-loop control according to instructions issued by the host computer to achieve constant current input, including: According to the target current setting command, the current on the input side is sampled to obtain the sample current; The reference current is obtained based on the harmonic current and the preset target current; The loop difference calculated from the reference current and the sample current is input to the PI controller and the PR controller, respectively, wherein the PR controller uses the harmonic current frequency; The pulse width modulation signal for closed-loop control is determined based on the outputs of the PR controller and the PI controller to achieve the constant current input.

4. The DC / DC converter according to any one of claims 1-3, characterized in that, The process of generating harmonic current based on preset harmonic current amplitude and harmonic current frequency includes: The sampling integrator integrates the preset harmonic current frequency to obtain the harmonic angle; The harmonic sine value is obtained based on the harmonic angle; The harmonic current is obtained by multiplying the harmonic sine value and the preset harmonic current amplitude.

5. The DC / DC converter according to claim 1, characterized in that, The instructions issued by the host computer also include control mode instructions and power on / off instructions; Wherein, when the value of the control mode instruction is 0, it indicates that the constant current control mode is input, and when the value of the control mode instruction is 1, it indicates that the constant voltage control mode is input. When the power-on / off command value is 0, the DC / DC controller is powered off; when the power-on / off command value is 1, the DC / DC controller is powered on.

6. A DC / DC converter control method, characterized in that, The method includes: Obtain instructions sent by the host computer, wherein the instructions sent by the host computer include a target voltage setting instruction or a target current setting instruction, as well as a harmonic current amplitude setting instruction and a harmonic current frequency setting instruction. The preset harmonic current amplitude is obtained according to the harmonic current amplitude setting command; The preset harmonic current frequency is obtained according to the harmonic current frequency setting command. Harmonic current is generated according to the preset harmonic current amplitude and the preset harmonic current frequency. When a target voltage setting command is received, closed-loop control is performed based on the target voltage setting command and the harmonic current to achieve constant voltage input. When a target current setting command is received, closed-loop control is performed based on the target current setting command and the harmonic current to achieve constant current input.

7. The method according to claim 6, characterized in that, The method of achieving constant voltage input by performing closed-loop control based on the target voltage setting command and the harmonic current includes: According to the target voltage setting command, sample current and sample voltage are obtained by sampling; The sample current is subjected to DC blocking filtering to obtain the loop feedback current; The loop difference calculated from the harmonic current and the loop feedback current is input to the PR controller, wherein the PR controller uses the frequency of the harmonic current. The sample voltage is input to a notch filter to obtain a loop feedback voltage, wherein the notch frequency of the notch filter is the same as the preset harmonic current frequency. The target voltage is obtained according to the target voltage setting command; The loop difference calculated from the target voltage and the loop feedback voltage is input to the PI controller; The pulse width modulation signal for closed-loop control is determined based on the outputs of the PR controller and the PI controller to achieve the constant voltage input.

8. The method according to claim 6, characterized in that, The step of performing closed-loop control based on the target current setting command and the harmonic current to achieve constant current input includes: The sample current is obtained by sampling according to the target current setting command; The target current is obtained according to the target current setting command; The reference current is obtained based on the harmonic current and the target current; The loop difference calculated from the reference current and the sample current is input to the PI controller and the PR controller, respectively, wherein the PR controller uses the harmonic current frequency; The pulse width modulation signal for closed-loop control is determined based on the outputs of the PR controller and the PI controller to achieve the constant current input.

9. The method according to any one of claims 6-8, characterized in that, The step of generating harmonic current based on the preset harmonic current amplitude and the preset harmonic current frequency includes: The sampling integrator integrates the preset harmonic current frequency to obtain the harmonic angle; The harmonic sine value is obtained based on the harmonic angle; The harmonic current is obtained by multiplying the harmonic sine value and the preset harmonic current amplitude.

10. The method according to claim 6, characterized in that, The instructions issued by the host computer also include control mode instructions and power on / off instructions; Wherein, when the value of the control mode instruction is 0, it indicates that the constant current control mode is input, and when the value of the control mode instruction is 1, it indicates that the constant voltage control mode is input. When the power-on / off command value is 0, the DC / DC controller is powered off; when the power-on / off command value is 1, the DC / DC controller is powered on.

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