Source-carrier integrated machine and current equalization method thereof, and bidirectional source-carrier system

Abstract

The present application discloses a source-load integrated machine and a current balancing method thereof, and a bidirectional source-load system. The source-load integrated machine includes a bidirectional AC-DC circuit, multiple DC-DC modules, a PFC controller, and a DC-DC controller. The DC-DC controller includes a master controller and a slave controller. The master controller is used to perform PID operation according to the total output voltage sampling value, the total output current sampling value, and the total output voltage setting value to obtain a current balancing current reference value. The master controller is respectively connected to multiple slave controllers to send the current balancing current reference value. The slave controllers are respectively connected to the control end and the sampling end of the corresponding DC-DC module for current balancing control according to the current balancing current reference value and the output current of the DC-DC module. The master controller is respectively connected to multiple slave controllers through FSI modules. The present application can improve the scalability of power output, and can simultaneously meet the requirements of high voltage accuracy and fast dynamic response of current balancing.

Description

Technical Field

[0001] The present application relates to the field of source-carrying equipment, and in particular to a source-carrying integrated machine and a current equalization method thereof, and a bidirectional source-carrying system. Background Art

[0002] The current source-load integrated machine adopts a single module design, that is, it consists of a bidirectional AC-DC circuit and a DC-DC module. The DC-DC module includes a resonant converter and a buck-boost circuit connected in series. When used as a DC source, AC380 AC power is corrected for power factor and outputs DC voltage stability through a bidirectional AC-DC circuit. The resonant converter plays the role of electrical isolation and buck-boost. The output of the resonant converter is adjusted over a wide range of voltage through a buck-boost circuit to achieve the required voltage output. When used as a load, it is a reverse process. The DC voltage acts on the capacitor and is converted into a corresponding DC voltage through a buck-boost circuit. The resonant converter plays the role of electrical isolation and buck-boost. Its output is converted into an inverter through a bidirectional AC-DC circuit, and finally the energy is fed back to the power grid.

[0003] The disadvantages of existing source-load integrated machines are that the scalability of power output is poor, and if fast current sharing is to be achieved, it will affect the setting or feedback of the total voltage, resulting in low voltage accuracy. Therefore, it is difficult to simultaneously meet the requirements of high voltage accuracy and fast dynamic response of current sharing. Summary of the invention

[0004] The present application proposes a source-load integrated machine and a current balancing method thereof, as well as a bidirectional source-load system, which can improve the scalability of power output and can simultaneously meet the requirements of high voltage accuracy and fast dynamic response of current balancing.

[0005] According to the first aspect of the present application, the source-load integrated machine includes: multiple DC-DC modules, all of which are connected to the DC end of the bidirectional AC-DC circuit; a PFC controller, the PFC controller is connected to the control end and the sampling end of the bidirectional AC-DC circuit; a DC-DC controller, the DC-DC controller includes a main controller and multiple slave controllers corresponding to the DC-DC modules one by one, the main controller is used to perform PID operation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain a current sharing current reference value, the main controller is respectively connected to the multiple slave controllers for calculating and sending the current sharing current reference value, the slave controllers are respectively connected to the control end and the sampling end of the corresponding DC-DC module for realizing current sharing control according to the current sharing current reference value and the output current of the DC-DC module; the main controller is respectively connected to the multiple slave controllers through the FSI module.

[0006] According to some embodiments of the present application, a first CLA module is provided in the master controller, and a second CLA module is provided in the slave controller. The first CLA module performs PID operation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain a current sharing current reference value. The first CLA module sends the current sharing current reference value to the second CLA module through the FSI module, and the second CLA module implements current sharing control according to the current sharing current reference value and the output current of the DC-DC module.

[0007] According to some embodiments of the present application, the slave controller implements current sharing control according to the current sharing current reference value and the output current of the DC-DC module, including:

[0008] The slave controller obtains a current sharing control signal according to the current sharing current reference value and the output current of the DC-DC module;

[0009] The slave controller obtains the pulse width value to be compensated through the output voltage sampling value, the bus voltage setting value and the maximum pulse width value;

[0010] The slave controller compensates the current sharing control signal by using the pulse width value to be compensated to obtain a PWM pulse width signal, and controls the current of the corresponding DC-DC module according to the PWM pulse width signal.

[0011] According to some embodiments of the present application, each of the DC-DC modules includes a series-connected resonant converter and a buck-boost circuit, one end of each of the multiple resonant converters is connected to the DC end of the bidirectional AC-DC circuit, and the other ends of each of the multiple resonant converters are respectively connected to the corresponding buck-boost circuit; the slave controller is respectively connected to the control end of the corresponding resonant converter and the buck-boost circuit;

[0012] The PFC controller controls the bidirectional AC-DC circuit in a closed loop, the slave controller controls the corresponding buck-boost circuit in a closed loop, and the slave controller controls the corresponding resonant converter in an open loop.

[0013] According to some embodiments of the present application, the PFC controller uses a CCM mode closed-loop control of a bidirectional AC-DC circuit.

[0014] According to the first aspect of the present application, the current balancing method includes the following steps:

[0015] The main controller obtains the total output voltage sampling value, the total output current sampling value and the total output voltage setting value of the source-load integrated machine;

[0016] The main controller performs PID calculation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain the current sharing current reference value;

[0017] The master controller sends the current sharing current reference value to each slave controller;

[0018] Obtain the corresponding DC-DC module output current from the controller;

[0019] The slave controller performs PID operation according to the DC-DC module output current and the current sharing current reference value to obtain a current sharing control signal;

[0020] The slave controller controls the current of the corresponding DC-DC module according to the current sharing control signal.

[0021] According to some embodiments of the present application, the main controller performs PID operation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain the current sharing current reference value, including:

[0022] The main controller simultaneously performs a current PID operation and a power PID operation according to the total output voltage sampling value and the total output current sampling value to obtain a first PID operation result;

[0023] The main controller obtains a total output voltage setting value of the source-load integrated machine, adds the first PID operation result and the total output voltage setting value, and obtains a total output voltage reference value;

[0024] The main controller performs a current PID operation according to the total output voltage reference value and the total output voltage sampling value to obtain a current sharing current reference value.

[0025] According to some embodiments of the present application, the DC-DC modules all include a resonant converter and a buck-boost circuit connected in series;

[0026] The slave controller controls the current of the corresponding DC-DC module according to the current sharing control signal, including:

[0027] Obtaining the output voltage sampling value, bus voltage setting value and maximum pulse width value of the corresponding resonant converter from the controller;

[0028] The slave controller obtains the pulse width value to be compensated according to the output voltage sampling value, the bus voltage setting value and the maximum pulse width value;

[0029] The slave controller adds the current sharing control signal to the pulse width value to be compensated to obtain a PWM pulse width signal;

[0030] The slave controller controls the current of the corresponding DC-DC module according to the PWM pulse width signal.

[0031] According to some embodiments of the present application, after the master controller sends the current sharing current reference value to each slave controller, the method further includes:

[0032] The master controller sends heartbeat signals to all slave controllers at a fixed time. If a slave controller receives a heartbeat signal within the target time, it remains in working mode. If a slave controller does not receive a heartbeat signal within the target time, it enters shutdown mode.

[0033] The bidirectional source-carrier system according to the third aspect of the present application includes the above-mentioned source-carrier integrated machine.

[0034] The source-carrier integrated machine and current equalization method thereof, and the bidirectional source-carrier system according to the embodiments of the present application have at least the following beneficial effects:

[0035] In the implementation mode of the present application, multiple parallel DC-DC modules are arranged at the DC end of the bidirectional AC-DC circuit, and the multiple DC-DC modules all extract power from the DC end of the bidirectional AC-DC circuit, so that effective expansion of power can be achieved. In addition, the controller of the source-load integrated machine is divided into a PFC controller and a DC-DC controller. The PFC controller controls the bidirectional AC-DC circuit alone, and the DC-DC controller is divided into a main controller and multiple slave controllers corresponding to the DC-DC controller. The main controller directly collects the total voltage output by the source-load integrated machine of multiple DC-DC modules in parallel, avoiding the influence of the output voltage difference of each DC-DC module caused by the difference of the current sharing of each DC-DC module on the total output voltage, and using the voltage loop of the main controller to perform PID operation to achieve high-precision control of the output voltage; the current sharing current reference value output by the main controller is used as the current setting of each slave controller, and the output current of each DC-DC module is guaranteed to be consistent through the slave controller, and the main controller is connected to the slave controller through the FSI module, which improves the response speed, and realizes both the fast dynamic response of the current sharing and the high voltage accuracy.

[0036] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present application is further described below with reference to the accompanying drawings and embodiments, wherein:

[0038] Figure 1 This is a principle block diagram of the source-carrier integrated machine in the embodiment of the present application;

[0039] Figure 2 for Figure 1 The principle block diagram of the DC-DC module;

[0040] Figure 3 This is a control loop schematic diagram of the master controller and the slave controller in the embodiment of the present application;

[0041] Figure 4 This is a flow chart of the current balancing method in an embodiment of the present application;

[0042] Figure 5 It is a principle block diagram of a single-module source-load integrated machine in the related technology. DETAILED DESCRIPTION

[0043] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0044] In the description of the present application, it should be understood that the descriptions involving orientation, such as the orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0045] In the description of this application, "a plurality" means more than two. If there is a description of "first" or "second", it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0046] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0047] The following first introduces the specific structure of the source-load integrated machine in the related technology. Figure 5 As shown, the source-load integrated machine in the related art adopts a single-module design, which is composed of a bidirectional AC-DC circuit and a DC-DC module. The DC-DC module includes a resonant converter and a buck-boost circuit connected in series.

[0048] It should be noted that when the source-load integrated machine is used as a DC source, it converts AC power into DC power. The AC220 AC power is subjected to power factor correction and DC regulated output through a bidirectional AC-DC circuit. The resonant converter plays the role of electrical isolation and buck-boost. The output of the resonant converter is then subjected to a wide range of voltage regulation through a buck-boost circuit to achieve the required voltage output. When the source-load integrated machine is used as a load, it converts DC power into AC power. The process is opposite to that of the DC source. The DC voltage acts on capacitor C2 and is converted into the corresponding DC voltage through a buck-boost circuit. The resonant converter plays the role of electrical isolation and buck-boost. Its output is subjected to inversion output through a bidirectional AC-DC, and finally the energy is fed back to the power grid.

[0049] Of course, the source-load integrated machine also includes a corresponding control unit to control the MOS tubes in the bidirectional AC-DC circuit, the resonant converter and the buck-boost circuit to achieve the regulation of voltage, current and other states.

[0050] The disadvantages of existing source-load integrated machines are that the scalability of power output is poor, and if fast current sharing is to be achieved, it will affect the setting or feedback of the total voltage, resulting in low voltage accuracy. Therefore, it is difficult to simultaneously meet the requirements of high voltage accuracy and fast dynamic response of current sharing.

[0051] To solve the above problems, refer to Figure 1 As shown, the present application relates to a source-load integrated machine, including: a bidirectional AC-DC circuit, a plurality of DC-DC modules, a PFC controller and a DC-DC controller. Specifically, the bidirectional AC-DC circuit is used for the conversion of AC and DC, and the plurality of DC-DC modules are all connected to the DC end of the bidirectional AC-DC circuit, that is, the plurality of DC-DC modules are connected in parallel to the DC end of the bidirectional AC-DC circuit, and the PFC controller is connected to the control end and the sampling end of the bidirectional AC-DC circuit; the DC-DC controller includes a main controller and a plurality of slave controllers corresponding to the DC-DC modules one by one, the main controller is used to perform PID operation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain the current sharing current reference value, the main controller is respectively connected to the plurality of slave controllers for calculating and sending the current sharing current reference value, and the slave controllers are respectively connected to the control end and the sampling end of the corresponding DC-DC module for current sharing control according to the current sharing current reference value and the output current of the DC-DC module.

[0052] The master controller is connected to a plurality of slave controllers through FSI modules.

[0053] In this implementation, the master controller is connected to a plurality of slave controllers respectively through FSI modules, and the master controller transmits real-time loop information through fast serial port communication, thereby improving the speed of the entire system control.

[0054] It should be noted that the FSI module is a serial communication module that enables reliable high-speed communication between isolated devices. It provides variable packet sizes and enables reliable high-speed communication between isolated devices using only a small number of signals. The FSI module consists of an independent FSITX module (transmitter) and FSIRX module (receiver), which are independently configured and operated. The FSI module can achieve high-speed and robust communication between the master controller and the slave controller.

[0055] In this embodiment, the master controller and the PFC controller use low-speed serial communication to transmit slow voltage, current, status and command information; the master controller and multiple slave controllers use FSI modules to communicate and transmit real-time loop information, which improves the speed of the entire system control and can control costs. The master controller and multiple slave controllers can be connected to the interface using FSI modules in various ways such as star or daisy chain.

[0056] It should be noted that in the embodiment of the present application, a star topology is adopted between the master controller and multiple slave controllers, that is, all slave controllers are connected to the master controller, which can improve the maximum operable frequency. The master controller broadcasts messages through its FSITX port, which is connected to all FSIRX ports of all slave controllers in turn. All slave controllers respond through their FSITX ports, and each port is connected to a different FSIRX port on the master controller. In this embodiment, 4 FSIRX ports and 2 FSITX ports are set on the master controller, which can meet the star connection topology when three DC-DC modules are connected in parallel. The advantages of the star topology are: the slave controller is point-to-point connected to the master controller, and the master controller broadcasts messages to all slave controllers, and the communication delay is minimized when the slave controller directly responds to the master controller. The FSI module includes a clock clk and two data lines. When TCLK is set to 50MHz, for 64-bit data, when one data line is used, the transmission between two adjacent nodes requires 1.04μS, and when two data lines are used, the transmission between two adjacent nodes requires 0.64uS. In addition to this, each MCU will have a delay of about 2µS for sending data. Therefore, when the star mode is adopted, the delay in sending and receiving data between the master controller and any slave controller will be the same. For one data line, this delay is 1x1.04µS+1x2µS=3.04µS. Therefore, when using one data line, the master controller and any slave controller can operate at a maximum frequency of about 328kHz. For 2 data lines, the same loop delay is 1x0.64µS+1x2µS=2.64µS. Therefore, in this case, the master controller and any DC-DC slave controller can operate at a maximum frequency of about 378kHz. The operating frequency of the power device of the high-power source-carrier integrated machine is basically around 100k, which meets the ability to adjust the pulse width or frequency once in one control cycle, and realizes the fast dynamic response of current sharing.

[0057] In this implementation, a low-speed serial port is used for communication between the master controller and the PFC controller to transmit slow voltage, current, status and command information; an FSI module is used for communication between the master controller and multiple slave controllers to transmit real-time loop information, thereby improving the speed of the entire system control.

[0058] In the embodiment of the present application, the main controller completes the control of the total voltage, total current, and total power; the slave controller mainly completes the current sharing control; such a setting is conducive to achieving high-voltage precision control, and at the same time utilizes the communication of the FSI module to achieve fast current sharing control through the slave controller.

[0059] In this configuration, the slave controller can also send its voltage, current, temperature, and status information to the master controller and offload some slower control tasks to the master controller, such as running fan control or calculating the panel voltage control loop output.

[0060] In an embodiment of the present application, the main controller directly collects the total output voltage of the source-load integrated system in which multiple modules are connected in parallel, thereby avoiding the influence of the output voltage differences of each sub-module caused by the differences in the current sharing current of each module on the total output voltage, and utilizing the voltage loop of the main controller to achieve high-precision control of the output voltage; the output of the main controller is used as the current given by each slave controller, and the output current of each sub-module is guaranteed to be consistent through the current sharing current loop of the slave controller, further ensuring the stability of the total output voltage; the present invention applies the FSI module to the communication between the main controller and the slave controller, so that the loop information can be transmitted quickly and can be controlled at the us level, effectively ensuring that the current sharing is realized quickly and stably, thereby improving the dynamic and steady-state performance of the source-load integrated system.

[0061] In the implementation mode of the present application, multiple parallel DC-DC modules are arranged at the DC end of the bidirectional AC-DC circuit, and the multiple DC-DC modules all extract power from the DC end of the bidirectional AC-DC circuit, so that effective expansion of power can be achieved. In addition, the controller of the source-load integrated machine is divided into a PFC controller and a DC-DC controller. The PFC controller controls the bidirectional AC-DC circuit alone, and the DC-DC controller is divided into a main controller and multiple slave controllers corresponding to the DC-DC controller. The main controller directly collects the total voltage output by the source-load integrated machine of multiple DC-DC modules in parallel, avoiding the influence of the output voltage difference of each DC-DC module caused by the difference of the current sharing of each DC-DC module on the total output voltage, and using the voltage loop of the main controller to perform PID operation to achieve high-precision control of the output voltage; the current sharing current reference value output by the main controller is used as the current setting of each slave controller, and the output current of each DC-DC module is guaranteed to be consistent through the slave controller, and the main controller is connected to the slave controller through the FSI module, which improves the response speed, and realizes both the fast dynamic response of the current sharing and the high voltage accuracy.

[0062] In some embodiments of the present application, a first CLA (Control Law Accelerator) module is provided in the main controller, and a second CLA module is provided in the slave controller. The first CLA module performs PID operation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain a current sharing current reference value. The first CLA module sends the current sharing current reference value to the second CLA module through the FSI module, and the second CLA module implements current sharing control according to the current sharing current reference value and the output current of the DC-DC module.

[0063] In this embodiment, the main controller performs loop operation through the first CLA, and then the first CLA directly sends the current sharing reference value to the second CLA module through the FSI module. There is no need for CPU intervention of the main controller and the slave controller, which saves data reading time and further improves the rapid response of current sharing.

[0064] It should be noted that the main controller is provided with a data interface and a buffer corresponding to the first CLA module. The ADC module of the main controller collects the total output voltage in real time and directly and quickly transmits the sampled data to the data interface and the buffer corresponding to the first CLA module. The main controller uses the first CLA to directly read the ADC data through the direct memory, without the intervention of the CPU of the main controller, thus saving the time of data reading. At the same time, the loop operation of the voltage loop is completed through the first CLA, thus improving the operation speed. The given current equalization result calculated by the first CLA loop is no longer fed back to the CPU of the main controller, but is directly sent to the data buffer of the FSI sending interface by using the direct memory again. The entire sampling, loop operation and data transmission are real-time and efficient, and can be guaranteed to be completed within 2us.

[0065] The current-sharing data transmission between the master and slave controllers adopts FSI mode, which has ultra-small data delay. With a 50MHz CLK setting, 64-bit data can be completed within 2.64us, and the time can be further shortened at 200MHz.

[0066] After receiving the given current sharing data from the FSI receiving interface of the slave control, the data is quickly transferred to the data interface and buffer specified by the second CLA in the slave controller by direct storage; the CLA is used to directly read the data of the FSI receiving interface by direct storage, without the intervention of the CPU of the slave controller, saving the time of data reading, and at the same time, the loop operation of the current sharing loop is completed by the second CLA, which improves the operation speed; the entire data transmission and loop operation are real-time and efficient, and can be guaranteed to be completed within 2us; the slave control is configured with a 10us PWM cycle, and the duty cycle result calculated by the CLA loop is directly updated to the comparator memory by direct storage, and finally the duty cycle is updated;

[0067] The entire data processing, loop operation, and data transmission can be completed within a switching cycle of 10us, realizing a fast current sharing method and improving the system response speed.

[0068] Therefore, in this embodiment, both the master controller and the slave controller implement loop calculations through CLA, and data is transferred between the first CLA and the second CLA through FSI without CPU intervention, further improving the calculation speed and system response speed.

[0069] In some embodiments of the present application, the slave controller implements current sharing control according to the current sharing current reference value and the output current of the DC-DC module, including:

[0070] The slave controller obtains a current sharing control signal according to a current sharing current reference value and an output current of the DC-DC module;

[0071] The slave controller obtains the pulse width value to be compensated through the output voltage sampling value, the bus voltage setting value and the maximum pulse width value;

[0072] The slave controller compensates the current sharing control signal by the pulse width value to be compensated to obtain a PWM pulse width signal, and controls the current of the corresponding DC-DC module according to the PWM pulse width signal.

[0073] The output current of the DC-DC module is collected from the controller and PID operation is performed with the module current sharing current reference value. The calculated result is a PWM pulse width signal. The DC-DC current sharing control can be directly performed according to the PWM pulse width signal. However, in order to speed up the dynamic response and improve the current sharing accuracy, the input bus voltage feedforward compensation is added in this application, that is, the sampling value of the resonant converter output voltage is compared with the set bus voltage value, and then multiplied by the designed maximum pulse width value to obtain the pulse width value that needs to be compensated, and then the calculated PWM pulse width is added to obtain the final PWM pulse width to be output, which is assigned to the comparison register CMPR to generate the corresponding PWM waveform to control the MOS tube in the resonant converter. The resonant converter works in the BUCK step-down mode when in the forward direction and in the BOOST step-up mode when in the reverse direction, so as to realize bidirectional energy flow and realize continuous adjustment of voltage and current over a wide range.

[0074] In this embodiment, reference Figure 2 As shown, the source-load integrated machine includes a bidirectional AC-DC circuit and multiple DC-DC modules. Each DC-DC module consists of a resonant converter and a three-phase interleaved buck-boost circuit, and has the characteristics of small size and high power density. The front-end bidirectional AC-DC circuit realizes power factor correction and grid feeding functions, and provides a high-voltage DC bus for the DC-DC module. Multiple DC-DC modules extract power from the high-voltage DC bus, which can achieve effective power expansion.

[0075] In this implementation, the PFC controller is connected to the control end and the sampling end of the bidirectional AC-DC circuit, which means that the PFC controller obtains the input and output current and voltage of the bidirectional AC-DC circuit through the sampling end. It should be understood that one end of the bidirectional AC-DC circuit is the AC side and the other end is the DC side. Therefore, the input and output current and voltage of the bidirectional AC-DC circuit include the voltage and current on the DC side and the voltage and current on the AC side.

[0076] It should be noted that when the source-carrier integrated machine is used as a DC source, the PFC controller collects the AC input current through the Hall current sensor, samples the AC input voltage through the differential signal, and samples the DC750V bus voltage at the DC output end through the differential signal. The DSP in the PFC controller performs phase-locked loop calculations through the sampled input AC voltage to obtain the phase value θ, which is used for abc-dq coordinate transformation.

[0077] In order to make the inductor current close to a sine wave and reduce the current ripple, the PFC controller in the embodiment of the present application adopts a continuous conduction mode (CCM) double closed-loop PI control algorithm, and generates an output voltage error signal according to the comparison between the collected output voltage and the reference voltage, as the reference current signal of the rotating coordinate system dq axis, and obtains the current feedback signal of the dq axis after the collected inductor current of L1-L3 is transformed, and then compared with the reference current signal, and a three-phase voltage signal is generated by the current loop PI controller built into the DSP, and the three-phase voltage signal is transformed by coordinates, sector judgment, and vector action time calculation to obtain each phase modulation wave, and then compared with the carrier to obtain SVPWM drive, and finally the 100KHz frequency SVPWM waveform is used to drive the MOS tubes Q1, MOS tube Q2, MOS tube Q3, MOS tube Q4, MOS tube Q5 and MOS tube Q6 in the bidirectional AC-DC circuit, and finally the AC current and AC voltage of the bidirectional AC-DC circuit are in the same phase, and the output voltage is stable at DC750V, which can achieve unity power factor. Therefore, the three-phase PWM converter can realize bidirectional energy flow.

[0078] It should be noted that, in addition to adopting the CCM mode, the PFC controller may also adopt the DCM mode or other control algorithms to control the bidirectional AC-DC circuit.

[0079] In this embodiment, the DC-DC controller includes a main controller and a plurality of slave controllers corresponding to the DC-DC modules one by one, which means that the control unit of the DC-DC module is divided into a main controller and a plurality of slave controllers, each slave controller controls a DC-DC module respectively, and in the embodiment of the present application, there are n DC-DC modules, so there are also n slave controllers, and each slave controller is connected to the main controller through a communication port. Taking the source-carrier integrated machine as a DC source as an example, the main controller is used to perform PID calculation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain the current sharing current reference value. Among them, the total output voltage sampling value and the total output current sampling value are the total output voltage and current of all DC-DC modules obtained by the main controller through the sampling circuit, that is, the total output voltage and current of the source-carrier integrated machine. The main controller is also connected to a firmware board, which provides an external communication interface to connect to the host computer, and an interface to connect to the LCD display screen. The main controller communicates with the firmware board through the SCI / CAN / SPI communication port. The user sends the total output voltage setting value to the main controller through the host computer.

[0080] Specifically, refer to Figure 3 As shown, the main controller obtains the total output voltage sampling value and the total output current sampling value and then performs PID operation. The PID operation in the embodiment of the present application refers to simultaneously performing positive current PID operation, negative current PID operation, positive power PID operation, and negative power PID operation, and then adding the results of the four PID operations and the total output voltage setting value as the reference value of the total output voltage; then the PID operation is performed according to the reference value of the total output voltage and the total output voltage sampling value, and its output is used as the current sharing current reference value Iavg of each slave controller.

[0081] It should be noted that, in the present embodiment, the slave controller is respectively connected to the control end and the sampling end of the corresponding DC-DC module, the slave controller obtains the output current sampling value of the corresponding DC-DC module through the sampling end, controls the output current of the DC-DC module through the control end, and performs current sharing control according to the current sharing current reference value and the output current of the DC-DC module, which means that after the slave controller receives the current sharing current reference value from the main controller, it performs PID operation with the output current sampling value of the DC-DC module, and controls each MOS tube in the DC-DC module according to the calculated PWM pulse width signal.

[0082] In some embodiments of the present application, the PFC controller controls the bidirectional AC-DC circuit in a closed loop, the slave controller controls the corresponding buck-boost circuit in a closed loop, and the slave controller controls the corresponding resonant converter in an open loop.

[0083] In the above implementation, the PFC controller controls the bidirectional AC-DC circuit in a closed loop, the slave controller controls the corresponding buck-boost circuit in a closed loop, and the slave controller controls the corresponding resonant converter in an open loop. This can ensure the stability of the output of the source-load integrated machine, reduce the resources of the voltage and current detection circuit and the controller, and reduce the software and hardware costs.

[0084] Since the source-load integrated machine in the present application has a three-stage circuit structure, if each stage adopts closed-loop control, the algorithm will be complicated, occupy a large amount of resources, and the software and hardware costs are too high. Based on the voltage quality goals measured on the user side and the power grid, the present application effectively optimizes the loop control method. The optimized control loop mode is two-stage closed-loop control + one-stage open-loop control. There are two closed-loop controls, one open-loop control, one closed-loop control is a bidirectional AC-DC closed-loop control, and the main control targets are power factor, harmonic content and output voltage value; one closed-loop control is a closed-loop control of the buck-boost circuit, and the main control targets are forward and reverse constant power, forward and reverse constant current and constant voltage, etc.; the resonant converter adopts open-loop control, which can reduce the resources of the voltage and current detection circuit and the controller, the algorithm is simple, and the software and hardware costs are reduced.

[0085] refer to Figure 4 As shown, the present application also relates to a current balancing method applied to the above embodiment, comprising the following steps:

[0086] S101, the main controller obtains a total output voltage sampling value, a total output current sampling value and a total output voltage setting value of the source-load integrated machine;

[0087] S102, the main controller performs PID calculation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain a current sharing current reference value;

[0088] S103, the master controller sends the current sharing current reference value to each slave controller;

[0089] S104, obtaining the corresponding DC-DC module output current from the controller;

[0090] S105, the slave controller performs PID operation according to the DC-DC module output current and the current sharing current reference value to obtain a current sharing control signal;

[0091] S106 , the slave controller controls the current of the corresponding DC-DC module according to the current sharing control signal.

[0092] In this embodiment, the total output voltage sampling value, the total output current sampling value and the total output voltage setting value of the source-load integrated machine are obtained by the main controller; the main controller performs PID operation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain the current sharing current reference value; the main controller sends the current sharing current reference value to each slave controller; the slave controller obtains the corresponding DC-DC module output current; the slave controller performs PID operation according to the DC-DC module output current and the current sharing current reference value to obtain the current sharing control signal; the slave controller controls the current of the corresponding DC-DC module according to the current sharing control signal. The main controller directly collects the total voltage output by the source-load integrated machine of multiple DC-DC modules in parallel, avoiding the influence of the output voltage difference of each DC-DC module caused by the difference of the current sharing current of each DC-DC module on the total output voltage, and uses the voltage loop of the main controller to perform PID operation to achieve high-precision control of the output voltage; the current sharing current reference value output by the main controller is used as the current setting of each slave controller, and the output current of each DC-DC module is guaranteed to be consistent through the slave controller, that is, the fast dynamic response of the current sharing is achieved and the high voltage accuracy is guaranteed.

[0093] In some embodiments of the present application, in step S102, the main controller performs PID operation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain the current sharing current reference value, which may include:

[0094] S201, the main controller simultaneously performs current PID calculation and power PID calculation according to the total output voltage sampling value and the total output current sampling value to obtain a first PID calculation result;

[0095] S202, the main controller obtains a total output voltage setting value of the source-load integrated machine, adds the first PID operation result and the total output voltage setting value, and obtains a total output voltage reference value;

[0096] S203: The main controller performs a current PID operation according to the total output voltage reference value and the total output voltage sampling value to obtain a current sharing current reference value.

[0097] In this embodiment, the current PID operation and the power PID operation include the rectifier current PID operation, the inverter current PID operation, the rectifier power PID operation, and the inverter power PID operation, so the first PID operation result is the result obtained by these four PID operations. The main controller obtains the total output voltage setting value of the source-load integrated machine, adds the first PID operation result and the total output voltage setting value, and obtains the total output voltage reference value, which means that the results of the four PID operations and the total output voltage setting value are added as the total output voltage reference value. The effect of current sharing can be improved.

[0098] In some embodiments of the present application, controlling the current of the corresponding DC-DC module from the controller according to the current sharing control signal may include:

[0099] S301, obtaining an output voltage sampling value, a bus voltage setting value and a maximum pulse width value of a corresponding resonant converter from a controller;

[0100] S302, the slave controller obtains a pulse width value to be compensated according to the output voltage sampling value, the bus voltage setting value and the maximum pulse width value;

[0101] S303, the slave controller adds the current sharing control signal to the pulse width value to be compensated to obtain a PWM pulse width signal;

[0102] S304 , the slave controller controls the current of the corresponding DC-DC module according to the PWM pulse width signal.

[0103] In this embodiment, the output voltage sampling value, bus voltage setting value and maximum pulse width value of the corresponding resonant converter are obtained from the slave controller; the pulse width value to be compensated is obtained from the slave controller according to the output voltage sampling value, bus voltage setting value and maximum pulse width value; the slave controller adds the current sharing control signal to the pulse width value to be compensated to obtain a PWM pulse width signal; and the slave controller controls the current of the corresponding DC-DC module according to the PWM pulse width signal. This can speed up the dynamic response and improve the accuracy of the current sharing.

[0104] In this embodiment, the output current of the DC-DC module is collected from the controller, and a PID operation is performed with the module current sharing current reference value. The calculated result is a PWM pulse width signal, and the DC-DC current sharing control can be directly performed according to the PWM pulse width signal. However, in order to speed up the dynamic response and improve the current sharing current accuracy, the input bus voltage feedforward compensation is added through steps S301-S304 in this application, that is, the sampled value of the output voltage of the resonant converter is compared with the set bus voltage value, and then multiplied by the designed maximum pulse width value to obtain the pulse width value that needs to be compensated, and then the calculated PWM pulse width is added to obtain the final PWM pulse width to be output, which is assigned to the comparison register CMPR to generate the corresponding PWM waveform to control the MOS tube in the resonant converter. The resonant converter works in the BUCK step-down mode when in the forward direction and in the BOOST step-up mode when in the reverse direction, so as to realize bidirectional energy flow and realize continuous adjustment of voltage and current over a wide range.

[0105] In some embodiments of the present application, after the master controller sends the current sharing current reference value to each slave controller, the method further includes:

[0106] The master controller sends heartbeat signals to all slave controllers at a fixed time. If a slave controller receives a heartbeat signal within the target time, it remains in working mode. If a slave controller does not receive a heartbeat signal within the target time, it enters shutdown mode.

[0107] In this embodiment, the master controller timers all slave controllers to send heartbeat signals, and if a slave controller receives a heartbeat signal within a target time, it maintains the working mode, and if a slave controller does not receive a heartbeat signal within the target time, it enters the shutdown mode. This can achieve fast shutdown control of the slave controller and the corresponding DC-DC module and occupy less communication resources.

[0108] It should be noted that the master controller timers all slave controllers to send heartbeat signals. As long as the slave controllers continue to receive heartbeat signals, they work normally. If they do not receive heartbeat signals within the allocated time, they enter shutdown mode.

[0109] The present application also relates to a bidirectional source-carrier system, including the above-mentioned source-carrier integrated machine.

[0110] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present application.

Claims

1. A source-carrier integrated machine, characterized in that: include: Bidirectional AC-DC circuit, used for conversion between AC and DC; A plurality of DC-DC modules, wherein the plurality of DC-DC modules are all connected to the DC end of the bidirectional AC-DC circuit; A PFC controller, the PFC controller is connected to a control terminal and a sampling terminal of the bidirectional AC-DC circuit; A DC-DC controller, the DC-DC controller comprises a main controller and a plurality of slave controllers corresponding to the DC-DC modules one by one, the main controller is used to perform PID operation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain a current sharing current reference value, the main controller is respectively connected to the plurality of slave controllers for calculating and sending the current sharing current reference value, the slave controllers are respectively connected to the control end and the sampling end of the corresponding DC-DC module for realizing current sharing control according to the current sharing current reference value and the output current of the DC-DC module; the main controller is respectively connected to the plurality of slave controllers through the FSI module; The master controller is provided with a first CLA module, and the slave controller is provided with a second CLA module. The first CLA module performs PID operation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain a current sharing current reference value. The first CLA module sends the current sharing current reference value to the second CLA module through the FSI module. The second CLA module implements current sharing control according to the current sharing current reference value and the output current of the DC-DC module. The slave controller implements current sharing control according to the current sharing current reference value and the output current of the DC-DC module, including: The slave controller obtains a current sharing control signal according to the current sharing current reference value and the output current of the DC-DC module; The slave controller obtains the pulse width value to be compensated through the output voltage sampling value, the bus voltage setting value and the maximum pulse width value; The slave controller compensates the current sharing control signal by the pulse width value to be compensated to obtain a PWM pulse width signal, and controls the current corresponding to the DC-DC module according to the PWM pulse width signal; The main controller is used to perform PID calculation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain the current sharing current reference value, including: The main controller simultaneously performs a current PID operation and a power PID operation according to the total output voltage sampling value and the total output current sampling value to obtain a first PID operation result; The main controller obtains a total output voltage setting value of the source-load integrated machine, adds the first PID operation result and the total output voltage setting value, and obtains a total output voltage reference value; The main controller performs a current PID operation according to the total output voltage reference value and the total output voltage sampling value to obtain a current sharing current reference value.

2. The source-carrier integrated machine according to claim 1, characterized in that: Each of the DC-DC modules comprises a resonant converter and a buck-boost circuit connected in series, one end of each of the resonant converters is connected to the DC end of the bidirectional AC-DC circuit, and the other ends of each of the resonant converters are connected to the corresponding buck-boost circuits; the slave controllers are connected to the control ends of the corresponding resonant converters and the buck-boost circuits respectively; The PFC controller controls the bidirectional AC-DC circuit in a closed loop, the slave controller controls the corresponding buck-boost circuit in a closed loop, and the slave controller controls the corresponding resonant converter in an open loop.

3. The source-carrier integrated machine according to claim 1, characterized in that: The PFC controller adopts CCM mode to close the loop and control the bidirectional AC-DC circuit.

4. A current balancing method applied to the source-carrier integrated machine according to any one of claims 1 to 3, characterized in that: The following steps are involved: The main controller obtains the total output voltage sampling value, the total output current sampling value and the total output voltage setting value of the source-load integrated machine; The main controller performs PID calculation according to the total output voltage sampling value, the total output current sampling value and the total output voltage setting value to obtain the current sharing current reference value; The master controller sends the current sharing current reference value to each slave controller; Obtain the corresponding DC-DC module output current from the controller; The slave controller performs PID operation according to the DC-DC module output current and the current sharing current reference value to obtain a current sharing control signal; The slave controller controls the current of the corresponding DC-DC module according to the current sharing control signal.

5. The current balancing method according to claim 4, characterized in that: The DC-DC modules all include a series-connected resonant converter and a buck-boost circuit; The slave controller controls the current of the corresponding DC-DC module according to the current sharing control signal, including: Obtaining the output voltage sampling value, bus voltage setting value and maximum pulse width value of the corresponding resonant converter from the controller; The slave controller obtains the pulse width value to be compensated according to the output voltage sampling value, the bus voltage setting value and the maximum pulse width value; The slave controller adds the current sharing control signal to the pulse width value to be compensated to obtain a PWM pulse width signal; The slave controller controls the current of the corresponding DC-DC module according to the PWM pulse width signal.

6. The current equalization method according to claim 4, characterized in that: After the master controller sends the current sharing current reference value to each slave controller, the method further includes: The master controller sends heartbeat signals to all slave controllers at a fixed time. If a slave controller receives a heartbeat signal within the target time, it remains in working mode. If a slave controller does not receive a heartbeat signal within the target time, it enters shutdown mode.

7. A bidirectional source-carrier system, characterized in that: It comprises the source-carrier integrated machine as described in any one of claims 1 to 3.

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