Two-stage power converter, bus voltage adjusting method and related device

Abstract

The invention provides a two-stage power converter, a bus voltage adjusting method and a related device. The two-stage power converter comprises an AC-DC conversion circuit and a DC-DC conversion circuit. The input end of the AC-DC conversion circuit is connected with an AC power supply, and the output end of the AC-DC conversion circuit is connected with the input end of the DC-DC conversion circuit so as to output bus BUS voltage to the DC-DC conversion circuit; the output end of the DC-DC conversion circuit is connected with a load so as to output the required voltage of the load to the load; and the DC-DC conversion circuit is used for adjusting the BUS voltage according to the change of the output frequency of the DC-DC conversion circuit, so that the output frequency of the DC-DC conversion circuit is within a rated output frequency range. The BUS voltage is dynamically adjusted according to the change of the output power of the DC-DC conversion circuit, so that the output frequency of the DC-DC conversion circuit is always kept within a rated output frequency range. Not only is the power conversion efficiency in the light-load and no-load states optimized, but also the switching loss of the DC-DC conversion module is reduced; and moreover, the increase of output voltage ripples and the reduction of the overall efficiency caused by entering the hiccup mode are avoided.

Description

Technical Field

[0001] The present application relates to the field of electronic power technology, and in particular to a two-stage power converter, a bus voltage regulation method, and related devices. Background Art

[0002] In related technologies, most two-stage charge and discharge modules are composed of an AC-DC converter module and a DC-DC converter module. The output of the AC-DC converter module is the bus voltage, which is also the input of the DC-DC converter module.

[0003] Traditional BUS voltage control methods only ensure that the DC-DC converter module's output power reaches full load when the module outputs a specific voltage value, but they cannot guarantee output power at light loads or no loads. When the DC-DC converter module's output power is in a light load or no load state, the DC-DC converter module's operating frequency increases to maintain its output voltage, increasing switching losses. This requires intermittently switching the power on and off in hiccup mode to reduce the DC-DC converter module's continuous operating time.

[0004] However, after entering hiccup mode, the ripple of the DC-DC converter module's output voltage increases significantly, causing output voltage fluctuations. Furthermore, although the switching frequency is relatively low in hiccup mode, the periodic switching action still results in certain switching losses, reducing overall system efficiency. Summary of the Invention

[0005] In view of this, the present application provides a two-stage power converter, a bus voltage regulation method and related devices.

[0006] In a first aspect, the present application provides a two-stage power converter, comprising an AC-DC conversion circuit and a DC-DC conversion circuit;

[0007] The input end of the AC-DC conversion circuit is connected to an AC power supply, and the output end of the AC-DC conversion circuit is connected to the input end of the DC-DC conversion circuit to output a bus voltage BUS to the DC-DC conversion circuit; the output end of the DC-DC conversion circuit is connected to a load to output a required voltage of the load to the load;

[0008] The DC-DC conversion circuit is used to adjust the magnitude of the BUS voltage output by the AC-DC conversion circuit according to the extent to which the output frequency of the DC-DC conversion circuit exceeds the rated output frequency range, so that the output frequency of the DC-DC conversion circuit is within the rated output frequency range.

[0009] In one possible implementation, the DC-DC conversion circuit is used to instruct the AC-DC conversion circuit to reduce the BUS voltage when the output power is greater than the rated output frequency range; and is used to instruct the AC-DC conversion circuit to increase the BUS voltage when the output power is less than the rated output frequency range.

[0010] In one possible implementation, the DC-DC conversion circuit is configured to generate a PWM signal based on a given BUS voltage value and send the PWM signal to the AC-DC conversion circuit. The AC-DC conversion circuit is configured to receive the PWM signal and adjust the BUS voltage to the given BUS voltage value based on the PWM signal, so that the output frequency of the DC-DC conversion circuit is within the rated output frequency range.

[0011] In a possible implementation, the DC-DC conversion circuit is configured to determine the BUS voltage set value according to a difference between the output frequency and the rated output frequency range.

[0012] In a possible implementation, the converter further includes a low-speed isolation device connected between the AC-DC conversion circuit and the DC-DC conversion circuit;

[0013] The DC-DC conversion circuit sends the PWM signal to the AC-DC conversion circuit through the low-speed isolation device.

[0014] In a possible implementation, the process of the DC-DC conversion circuit generating the PWM signal according to the BUS voltage given value is as follows:

[0015] According to the mapping relationship between the BUS voltage and the duty cycle, the PWM signal duty cycle corresponding to the given BUS voltage value is determined, and the PWM signal is generated according to the PWM signal duty cycle; the mapping relationship between the BUS voltage and the duty cycle is obtained by mapping the BUS voltage adjustable range and the duty cycle range.

[0016] In a possible implementation, the DC-DC conversion circuit is an LLC resonant conversion circuit or a CLLC resonant conversion circuit.

[0017] In a second aspect, the present application provides a charge and discharge circuit, characterized in that the charge and discharge include a two-stage power converter as described in any one of the first aspects.

[0018] In a third aspect, the present application provides a charging pile, characterized in that the charging pile includes a two-stage power converter as described in any one of the first aspects.

[0019] In a fourth aspect, the present application provides a bus voltage regulation method, which is applied to the two-stage power converter according to any one of the first aspects above, wherein the two-stage power converter includes an AC-DC conversion circuit and a DC-DC conversion circuit;

[0020] The input end of the AC-DC conversion circuit is connected to an AC power supply, and the output end of the AC-DC conversion circuit is connected to the input end of the DC-DC conversion circuit to output a bus voltage BUS to the DC-DC conversion circuit; the output end of the DC-DC conversion circuit is connected to a load to output a required voltage of the load to the load;

[0021] The method comprises:

[0022] The magnitude of the BUS voltage output by the AC-DC conversion circuit is adjusted according to the change of the output frequency of the DC-DC conversion circuit, so that the output frequency of the DC-DC conversion circuit is within the rated output frequency range.

[0023] In the fifth aspect, the present application provides a control device, characterized in that it includes a processor and a memory, the memory is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the memory to complete the bus voltage regulation method as described in the fourth aspect.

[0024] In a sixth aspect, the present application provides a computer-readable storage medium, characterized in that a computer program is stored therein, and the computer program is loaded by a processor to execute the bus voltage regulation method as described in the fourth aspect.

[0025] The present application provides a two-stage power converter, a bus voltage regulation method, and related devices. The two-stage power converter includes an AC-DC converter circuit and a DC-DC converter circuit. The input of the AC-DC converter circuit is connected to an AC power source, and the output of the AC-DC converter circuit is connected to the input of the DC-DC converter circuit to output a bus voltage to the DC-DC converter circuit. The output of the DC-DC converter circuit is connected to a load to output a required voltage to the load. The DC-DC converter circuit is configured to adjust the bus voltage output by the AC-DC converter circuit according to changes in the output frequency of the DC-DC converter circuit, so that the output frequency of the DC-DC converter circuit is within the rated output frequency range. The circuit dynamically adjusts the bus voltage output by the AC-DC converter circuit according to changes in the output power of the DC-DC converter circuit, so that the output frequency of the DC-DC converter circuit always remains within the rated output frequency range. This not only optimizes the power conversion efficiency under light load and no-load conditions, but also reduces the switching loss of the DC-DC converter module. Furthermore, it avoids the increase in output voltage ripple and the decrease in overall efficiency caused by entering hiccup mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a two-stage power converter provided in an embodiment of the present application;

[0027] Figure 2 A schematic diagram of another two-stage power converter provided in an embodiment of the present application;

[0028] Figure 3 A schematic diagram of another two-stage power converter provided in an embodiment of the present application;

[0029] Figure 4 A schematic diagram of a control device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In traditional bus voltage control strategies, the bus voltage output by the AC-DC converter circuit is strongly correlated with the output voltage of the DC-DC converter circuit. When the output voltage is determined, the bus voltage is also determined, and this bus voltage can satisfy the DC-DC converter circuit's operation at the rated output frequency under full load. During the operation of the AC-DC converter circuit and the DC-DC converter circuit, the AC-DC converter circuit continuously outputs a fixed bus voltage. When the output power of the DC-DC converter circuit changes, such as from full load to light load, the output frequency of the DC-DC converter circuit needs to be changed to ensure that the DC-DC converter circuit continues to provide output voltage to the load.

[0031] However, this control strategy has problems such as high switching loss, high output voltage ripple due to entering the hiccup mode, and low conversion efficiency, as mentioned in the background art.

[0032] To address the above technical issues, the present invention provides a two-stage power converter. This circuit dynamically adjusts the BUS voltage output by the AC-DC converter circuit based on the output power of the DC-DC converter circuit, maintaining the output frequency of the DC-DC converter circuit within the rated output frequency range under various load conditions (such as full load, light load, or no load). This eliminates the need to adjust the output frequency of the DC-DC converter circuit, and the DC-DC converter circuit does not need to enter hiccup mode to optimize the output frequency. This reduces switching losses and eliminates the negative effects of entering hiccup mode.

[0033] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0034] like Figure 1 As shown, Figure 1 A schematic diagram of a two-stage power converter provided in an embodiment of the present application. The two-stage power converter includes an AC-DC conversion circuit (front-stage conversion circuit) and a DC-DC conversion circuit (back-stage conversion circuit).

[0035] The input end of the AC-DC conversion circuit is connected to the AC power supply, and the output end of the AC-DC conversion circuit is connected to the input end of the DC-DC conversion circuit to output the BUS voltage to the DC-DC conversion circuit; the output end of the DC-DC conversion circuit is connected to the load to output the required voltage of the load to the load.

[0036] A load is an electrical device or energy storage device, such as an electric vehicle's battery. The load's required voltage can be either its operating voltage or its charging voltage. For example, an electric vehicle using a 400-volt (V) charging platform has a battery required voltage of 400V. The AC power source connected to the input of the AC-DC converter circuit can be the grid or another power source capable of providing AC power.

[0037] The two-stage power converter provided in the embodiment of the present application can provide a wide range of output voltages. In this way, when the output end of the DC-DC conversion circuit is connected to a load, it can adaptively provide the load with a voltage required by the load.

[0038] The AC-DC converter circuit is used to output the BUS voltage to the DC-DC converter circuit. The AC-DC is also used to adjust the BUS voltage based on the signal from the DC-DC converter circuit. The DC-DC converter circuit is used to adjust the BUS voltage output by the AC-DC converter circuit based on changes in the output frequency of the DC-DC converter circuit, so that the output frequency of the DC-DC converter circuit is within the rated output frequency range.

[0039] The output frequency refers to the switching frequency of the DC-DC conversion circuit, that is, the number of switching actions per unit time. In the embodiment of the present application, the output frequency can be the current switching frequency of the DC-DC conversion circuit. The rated output frequency is the preferred switching frequency of the DC-DC conversion circuit. The minimum value of the rated output frequency range is the rated output frequency minus the fluctuation frequency Δf, and the maximum value of the rated output frequency range is the rated output frequency plus the fluctuation frequency Δf. If the output frequency of the DC-DC conversion circuit is within the rated output frequency range, that is, the output frequency is greater than or equal to the minimum value of the rated output frequency range, and the output frequency is less than or equal to the maximum value of the rated output frequency range, the switching loss of the DC-DC conversion circuit is low and the conversion efficiency is high.

[0040] In the embodiments of the present application, the fluctuation frequency Δf can be set by a technician based on experience, and the set fluctuation frequency Δf only needs to ensure that the rated output frequency range meets the requirements. That is, when the DC-DC converter circuit performs switching at an output frequency within the rated output frequency range, the switching loss is low and the conversion efficiency is high.

[0041] When the output end of the DC-DC conversion circuit is connected to the load, the output voltage of the DC-DC conversion circuit is the required voltage of the load. The DC-DC conversion circuit needs to continuously output the required voltage of the load to the load.

[0042] In related technologies, the BUS voltage is strongly correlated with the output voltage of the DC-DC converter circuit. Once the output voltage is determined, the BUS voltage that supports the DC-DC converter circuit's output of that output voltage at full load can be determined. At this point, the AC-DC converter circuit outputs this BUS voltage to the DC-DC converter circuit, which, at full load, can deliver this output voltage to the load.

[0043] If the load state of the DC-DC converter circuit changes, such as from full load to light load, the output power of the DC-DC converter circuit decreases. In this case, to continuously provide the output voltage to the load, the DC-DC converter circuit needs to increase the output frequency, that is, increase the switching frequency of the DC-DC converter circuit, which will lead to switching losses.

[0044] Through the two-stage power converter provided in the embodiment of the present application, the BUS voltage is adjusted according to the extent to which the output frequency of the DC-DC conversion circuit exceeds the rated output frequency range, so that the DC-DC conversion circuit can perform switching at an output frequency within the rated output frequency range under various load conditions and continuously provide the load with the output voltage required by the load.

[0045] It should be noted that the above Figure 1 This is only an exemplary topology provided in the embodiment of the present application. Specifically, the two-stage power converter can be as follows: Figure 2 As shown. Figure 2 As shown in a and b, the DC-DC conversion circuit can be a single-channel DC-DC conversion circuit, and the AC-DC conversion circuit and the DC-DC conversion circuit can be connected through a two-level bus ( Figure 2 In a), the AC-DC conversion circuit and the DC-DC conversion circuit can also be connected via a three-level bus ( Figure 2 b). Figure 2 As shown in c and d, the DC-DC conversion circuit can be a two-way DC-DC conversion circuit, and the AC-DC conversion circuit and the DC-DC conversion circuit can be connected through a two-level bus ( Figure 2 In c), the AC-DC conversion circuit and the DC-DC conversion circuit can also be connected via a three-level bus ( Figure 2 (d)

[0046] In an embodiment of the present application, the DC-DC conversion circuit may be a resonant conversion circuit, such as an LLC resonant conversion circuit and a CLLC resonant conversion circuit.

[0047] The rated output frequency of the resonant converter circuit is the resonant frequency, and the minimum value of the rated output frequency range is the resonant frequency f 谐振 Subtract the fluctuation frequency Δf, the maximum value of the rated output frequency range is the resonant frequency f 谐振 Add the fluctuation frequency Δf.

[0048] Below, a DC-DC conversion circuit is used as an example to illustrate the resonant conversion circuit. The DC-DC conversion circuits described below all represent LLC resonant conversion circuits or CLLC resonant conversion circuits.

[0049] The embodiment of the present application controls the BUS voltage according to the change of the output frequency f of the DC-DC converter circuit so that the output frequency f of the DC-DC converter circuit is within the rated output frequency range. The specific control method is as follows:

[0050] When the output frequency f of the DC-DC converter circuit is greater than the rated output frequency range, that is, the output frequency f> the resonant frequency f 谐振+ Fluctuation frequency Δf, it is necessary to instruct the AC-DC converter circuit to reduce the BUS voltage; when the output frequency f of the DC-DC converter circuit is less than the rated output frequency range, that is, the output frequency f<resonant frequency f 谐振 -Frequency Δf, it is necessary to instruct the AC-DC converter circuit to increase the BUS voltage. The control of the BUS voltage in the embodiment of the present application is to make the output frequency f of the DC-DC converter circuit within the rated output frequency range, that is, to meet the "resonance frequency f 谐振 - Fluctuation frequency Δf≤output frequency f≤resonant frequency f 谐振 + fluctuation frequency Δf”.

[0051] This regulation method allows the DC-DC converter circuit to operate within the rated output frequency range under various load conditions (such as full load, light load, or no load) while providing a continuous and stable output voltage to the load. This reduces switching losses in the DC-DC converter circuit and eliminates the need for the DC-DC converter circuit to enter hiccup mode for regulation, thereby improving output voltage stability.

[0052] In the embodiment of the present application, the DC-DC conversion circuit can determine the BUS voltage set value according to the frequency difference between the output frequency f and the rated output frequency range.

[0053] The frequency difference between the output frequency f and the rated output frequency range can be the difference between the output frequency f and the endpoint value or the median value in the rated output frequency range. Specifically, the endpoint value in the rated output frequency range is the "resonant frequency f 谐振 + Fluctuation frequency Δf" and "resonance frequency f 谐振 - Fluctuation frequency Δf", the median value in the rated output frequency range is the resonant frequency f 谐振 .

[0054] Correspondingly, the frequency difference can be “|output frequency f-resonant frequency f 谐振 - Fluctuation frequency Δf|", "output frequency f-resonance frequency f 谐振 + Fluctuation frequency Δf||" or "| Output frequency f - Resonant frequency f 谐振 |".

[0055] In one possible implementation, the DC-DC conversion circuit may calculate a frequency adjustment amount based on the frequency difference using a PID control algorithm (proportional (P), integral (I), and differential (D) control algorithm). Then, the BUS voltage adjustment amount may be determined based on a conversion coefficient between the frequency adjustment amount and the BUS voltage adjustment amount. Finally, a set BUS voltage value may be determined based on the BUS voltage adjustment amount and the current BUS voltage.

[0056] The unit of the conversion factor may be volts per kilohertz (V / kHz), indicating the BUS voltage value that needs to be adjusted to adjust the output frequency to kilohertz.

[0057] It should be noted that the DC-DC converter circuit can also use other methods to determine the BUS voltage setpoint based on the frequency difference. Furthermore, the aforementioned adjustment process is performed in real time, with the DC-DC converter circuit adjusting the BUS voltage in real time based on the output frequency to ensure that the DC-DC converter circuit continuously operates within the rated output frequency range.

[0058] After determining the BUS voltage set value, the DC-DC conversion circuit needs to send the BUS voltage set value to the AC-DC conversion circuit so that the AC-DC conversion circuit adjusts the BUS voltage to the BUS voltage set value.

[0059] When the output frequency f is greater than the rated output frequency range, you can select the upper limit value of the rated output frequency range (resonant frequency f 谐振 + ripple frequency Δf), lower limit (resonance frequency f 谐振 - Fluctuation frequency Δf) and median (resonance frequency f 谐振 Of course, you can also choose to compare with any value within the rated output frequency range.

[0060] As an example, if the difference is calculated as the difference between the output frequency f and the upper limit, the difference can directly reflect the extent to which the output frequency exceeds the rated output frequency range. The larger the difference, the further the output frequency deviates from the upper limit. This is suitable for scenarios where the output frequency needs to be quickly reduced to return to the rated output frequency range. The PID control algorithm can quickly adjust the output frequency based on the difference. If the difference is calculated as the difference between the output frequency f and the midpoint, the PID control algorithm can adjust the output frequency based on the difference to maintain the output frequency near the resonant frequency.

[0061] Similarly, when the output frequency f is less than the rated output frequency range, the upper limit value of the rated output frequency range (resonant frequency f 谐振 + ripple frequency Δf), lower limit (resonance frequency f 谐振 - Fluctuation frequency Δf) and median (resonance frequency f 谐振 Of course, you can also choose to compare with any value within the rated output frequency range.

[0062] As an example, if the difference is calculated as the difference between the output frequency f and the lower limit, the difference can directly reflect the extent to which the output frequency exceeds the rated output frequency range. The larger the difference, the further the output frequency deviates from the lower limit. This is suitable for scenarios where the output frequency needs to be quickly increased to return to the rated output frequency range. When rapid response and correction of low-frequency deviations are required, comparing the output frequency f with the lower limit is more appropriate. The PID control algorithm can quickly adjust the output frequency accordingly. If the difference is calculated as the difference between the output frequency f and the median, the PID control algorithm can adjust the output frequency based on the difference to maintain the output frequency near the resonant frequency.

[0063] In one implementation, the DC-DC conversion circuit can transmit the BUS voltage set value to the AC-DC conversion circuit via data communication. For example, the BUS voltage set value is transmitted to the AC-DC conversion circuit using a message or signaling as a carrier. However, the communication rate between the DC-DC conversion circuit and the DC-DC conversion circuit is low, the delay in transmitting the BUS voltage set value via communication is long, and the BUS voltage update speed is slow. When the output frequency of the DC-DC conversion circuit changes dynamically, the DC-DC conversion circuit may have certain switching losses due to the limitation of the BUS voltage update speed.

[0064] In order to increase the adjustment speed of the BUS voltage, the embodiment of the present application uses a pulse width modulation (PWM) signal to transmit the BUS voltage set value, so as to increase the transmission speed of the BUS voltage set value.

[0065] Specifically, the DC-DC converter circuit generates a PWM signal based on a given bus voltage value and transmits the PWM signal to the AC-DC converter circuit. After receiving the PWM signal, the AC-DC converter circuit adjusts the bus voltage to the given bus voltage value based on the PWM signal, so that the output frequency of the DC-DC converter circuit is within the rated output frequency range.

[0066] In the embodiments of the present application, the duty cycle of a PWM signal is used to represent a given bus voltage value. The DC-DC converter circuit transmits the PWM signal to the AC-DC converter circuit via a hardware line, thereby improving the bus voltage adjustment speed. The PWM signal is directly transmitted via the hardware line, eliminating the need for complex protocol parsing and processing. Therefore, compared to traditional communication transmission, the PWM signal transmission speed is faster. Furthermore, the PWM signal transmitted via the hardware line has strong anti-interference capabilities, making it suitable for use in scenarios with complex electrical environments.

[0067] In the two-stage power converter provided in the embodiment of the present application, a low-speed isolation device is further provided between the AC-DC conversion circuit and the DC-DC conversion circuit, such as Figure 3shown.

[0068] The DC-DC converter circuit sends a PWM signal to the AC-DC converter circuit via a low-speed isolation device. After receiving the PWM signal, the AC-DC converter circuit uses its internal capture module to measure the PWM signal's duty cycle and decode it to obtain the bus voltage setting. Based on the decoded bus voltage setting, the AC-DC converter circuit adjusts the bus voltage output by the AC-DC converter circuit to keep the DC-DC converter circuit's output frequency within the rated output frequency range.

[0069] The AC-DC conversion circuit and the DC-DC conversion circuit can realize PWM transmission and capture (CAP) reception by using low-speed isolation devices.

[0070] The circuit provided in the embodiment of the present application utilizes existing hardware resources without requiring additional hardware modifications, and can achieve improvements in signal transmission methods without changing the hardware layout. This fully utilizes the circuit's hardware resources and reduces the complexity of circuit design.

[0071] In the above embodiment, the duty cycle of the PWM signal can be used to represent the BUS voltage set value. The specific process of the DC-DC conversion circuit generating the PWM signal according to the BUS voltage set value is as follows:

[0072] According to the mapping relationship between BUS voltage and duty cycle, the PWM signal duty cycle corresponding to the given BUS voltage value is determined, and the PWM signal is generated according to the PWM signal duty cycle.

[0073] The mapping relationship between BUS voltage and duty cycle is obtained by mapping the BUS voltage adjustable range to the duty cycle range. By mapping the BUS voltage adjustable range to the duty cycle range one-to-one, the BUS voltage value and the duty cycle value are aligned one-to-one. A unique BUS voltage value can be determined using a specific duty cycle value.

[0074] The BUS voltage adjustable range refers to the adjustable BUS voltage value. The minimum value of the BUS voltage adjustable range is the minimum BUS voltage value that the AC-DC conversion circuit can adjust. min The maximum value of the BUS voltage adjustable range is the maximum BUS voltage value that the AC-DC conversion circuit can adjust, that is, BUS max The duty cycle range refers to the range of the duty cycle in the PWM signal, such as 20% to 80%, or 0% to 100%. The minimum value of the duty cycle range can be expressed as Duty min , the maximum value of the duty cycle range can be expressed as Duty max .

[0075] In a possible implementation, the mapping relationship between the BUS voltage and the duty cycle may be a linear mapping relationship. min Corresponding Duty min , BUS max Corresponding Duty max .

[0076] The linear mapping relationship can be expressed as a linear equation: BUS voltage = slope × duty cycle + intercept. The slope can be expressed as: The intercept can be expressed as: Intercept = BUS min -Slope×Duty min .

[0077] Take the duty cycle range of 20% to 80% and the BUS voltage adjustable range of 10V to 20V as an example. min =20%, Duty max =80%, BUS min =10V, BUS max = 20 V. The slope is 16.76, and the intercept is 6.67. Therefore, the linear mapping equation between BUS voltage and duty cycle is: BUS voltage = 16.76 × duty cycle + 6.67.

[0078] After determining the set BUS voltage value, the DC-DC converter circuit determines the PWM signal duty cycle corresponding to the set BUS voltage value based on the mapping relationship between BUS voltage and duty cycle, and then generates a corresponding PWM signal based on this PWM signal duty cycle value. The DC-DC converter circuit transmits the PWM signal to the AC-DC converter circuit via a hardware line. After receiving the PWM signal, the AC-DC converter circuit determines the BUS voltage corresponding to the PWM signal duty cycle based on the mapping relationship between BUS voltage and duty cycle, obtains the set BUS voltage value, and then adjusts the BUS voltage output by the AC-DC converter circuit to the set BUS voltage value. The DC-DC converter circuit and the AC-DC converter circuit utilize the PWM signal to rapidly transmit the set BUS voltage value and precisely control the BUS voltage, thereby maintaining the output frequency of the DC-DC converter circuit within the rated output frequency range.

[0079] Based on the above embodiments, the present application also provides a bus voltage regulation method, which is applied to the two-stage power converter described in any of the above embodiments. The method includes:

[0080] The BUS voltage output by the AC-DC conversion circuit is adjusted according to the change of the output frequency of the DC-DC conversion circuit, so that the output frequency of the DC-DC conversion circuit is within the rated output frequency range.

[0081] In one possible implementation, adjusting the magnitude of the BUS voltage output by the AC-DC conversion circuit according to a change in the output frequency of the DC-DC conversion circuit includes:

[0082] When the output power is greater than the rated output frequency range, the AC-DC converter circuit is instructed to reduce the BUS voltage; and when the output power is less than the rated output frequency range, the AC-DC converter circuit is instructed to increase the BUS voltage.

[0083] In one possible implementation, adjusting the magnitude of the BUS voltage output by the AC-DC conversion circuit according to a change in the output frequency of the DC-DC conversion circuit includes:

[0084] A PWM signal is generated according to a given BUS voltage value, and the PWM signal is sent to the AC-DC conversion circuit. The AC-DC conversion circuit is configured to receive the PWM signal and adjust the BUS voltage to the given BUS voltage value according to the PWM signal, so that the output frequency of the DC-DC conversion circuit is within the rated output frequency range.

[0085] In a possible implementation, the BUS voltage set value is determined by: determining the BUS voltage set value according to a difference between the output frequency and the rated output frequency range.

[0086] In a possible implementation, generating the PWM signal according to the BUS voltage given value includes:

[0087] According to the mapping relationship between the BUS voltage and the duty cycle, the PWM signal duty cycle corresponding to the given BUS voltage value is determined, and the PWM signal is generated according to the PWM signal duty cycle; the mapping relationship between the BUS voltage and the duty cycle is obtained by mapping the BUS voltage adjustable range and the duty cycle range.

[0088] Based on the above embodiments, the present application further provides a charging and discharging circuit, which includes the two-stage power converter described in any of the above embodiments.

[0089] The present application also provides a charging pile, which includes the two-stage power converter described in any of the above embodiments. The input end of the charging pile is used to connect to the power grid, and the output end of the charging pile is used to connect to the charging port of the electric vehicle.

[0090] This application also provides a control device, see Figure 4 , which is a schematic diagram of a control device provided in an embodiment of the present application.

[0091] The control device may include a memory 401 and a processor 402. The processor 402 may be connected to the power converter and may drive switches in various power conversion circuits in the power converter. The memory may be a random access memory (RAM), a flash memory, a read-only memory (ROM), an EPROM memory, an electronic programmable ROM (EPROM), a register, a hard disk, a removable disk, or the like.

[0092] The memory 401 may store computer instructions. When the computer instructions stored in the memory 401 are executed by the processor 402, the processor 402 may be configured to execute the bus voltage regulation method. The memory 401 may also store data, such as information such as the mapping relationship between the bus voltage and the duty cycle involved in the above-mentioned embodiments.

[0093] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0094] The present application also provides a readable storage medium for storing the methods provided in the above embodiments, such as a random access memory (RAM), flash memory, read-only memory (ROM), EPROM, electronic programmable ROM (EPROM), register, hard disk, removable disk, or any other form of storage medium known in the art.

[0095] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from the other embodiments. Similar or identical parts between the various embodiments can be referred to in conjunction with each other. The methods disclosed in the embodiments are described briefly because they correspond to the product embodiments disclosed in the embodiments. For relevant details, refer to the description of the product embodiments.

[0096] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A two-stage power converter, characterized in that: Including AC-DC conversion circuit and DC-DC conversion circuit; The input end of the AC-DC conversion circuit is connected to an AC power source, and the output end of the AC-DC conversion circuit is connected to the input end of the DC-DC conversion circuit to output a bus voltage to the DC-DC conversion circuit; the output end of the DC-DC conversion circuit is connected to a load to output a required voltage of the load to the load; The DC-DC conversion circuit is used to adjust the magnitude of the BUS voltage output by the AC-DC conversion circuit according to the magnitude by which the output frequency of the DC-DC conversion circuit exceeds the rated output frequency range, so that the output frequency of the DC-DC conversion circuit is within the rated output frequency range.

2. The converter according to claim 1, characterized in that The DC-DC conversion circuit is used to instruct the AC-DC conversion circuit to reduce the BUS voltage when the output power is greater than the rated output frequency range; and is used to instruct the AC-DC conversion circuit to increase the BUS voltage when the output power is less than the rated output frequency range.

3. The converter according to claim 1, characterized in that The DC-DC conversion circuit is used to generate a PWM signal according to a given value of a BUS voltage, and send the PWM signal to the AC-DC conversion circuit. The AC-DC conversion circuit is used to receive the PWM signal and adjust the BUS voltage to the given value of the BUS voltage according to the PWM signal, so that the output frequency of the DC-DC conversion circuit is within the rated output frequency range.

4. The converter according to claim 3, characterized in that The DC-DC conversion circuit is used to determine the BUS voltage given value according to the difference between the output frequency and the rated output frequency range.

5. The converter according to claim 3, characterized in that: The converter further comprises a low-speed isolation device connected between the AC-DC conversion circuit and the DC-DC conversion circuit; The DC-DC conversion circuit sends the PWM signal to the AC-DC conversion circuit through the low-speed isolation device.

6. The converter according to claim 3, characterized in that The process of the DC-DC conversion circuit generating the PWM signal according to the BUS voltage given value is as follows: According to the mapping relationship between the BUS voltage and the duty cycle, the PWM signal duty cycle corresponding to the given value of the BUS voltage is determined, and the PWM signal is generated according to the PWM signal duty cycle; the mapping relationship between the BUS voltage and the duty cycle is obtained by mapping the adjustable range of the BUS voltage with the duty cycle range.

7. The converter according to claim 1, characterized in that The DC-DC conversion circuit is an LLC resonant conversion circuit or a CLLC resonant conversion circuit.

8. A charging and discharging circuit, characterized in that: The charging and discharging includes a two-stage power converter as described in any one of claims 1-7.

9. A charging pile, characterized in that: The charging pile comprises a two-stage power converter as described in any one of claims 1-7.

10. A method for adjusting bus voltage, characterized in that: Applicable to a two-stage power converter, the two-stage power converter comprising an AC-DC conversion circuit and a DC-DC conversion circuit; The input end of the AC-DC conversion circuit is connected to an AC power supply, and the output end of the AC-DC conversion circuit is connected to the input end of the DC-DC conversion circuit to output a bus BUS voltage to the DC-DC conversion circuit; The output end of the DC-DC conversion circuit is connected to a load to output a required voltage of the load to the load; The method comprises: The magnitude of the BUS voltage output by the AC-DC conversion circuit is adjusted according to the change of the output frequency of the DC-DC conversion circuit, so that the output frequency of the DC-DC conversion circuit is within the rated output frequency range.

11. A control device, characterized in that: It comprises a processor and a memory, wherein the memory is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the memory to complete the bus voltage regulation method as claimed in claim 10.

12. A computer-readable storage medium, characterized in that: A computer program is stored, and the computer program is loaded by a processor to execute the bus voltage regulation method as claimed in claim 10.

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