Power conversion device and method for controlling same

Abstract

According to the power conversion device and the control method thereof provided by the invention, when a battery management system is in an operation state, a direct current conversion circuit is controlled to start pre-charging work, and then an output instruction is sent to an energy storage battery pack, so that the energy storage battery pack outputs voltage to a battery port according to the output instruction. The electric energy output to the battery port by the energy storage battery pack is provided for the direct current conversion circuit in pre-charging work through the pre-charging circuit, and the direct current conversion circuit performs direct current conversion on the electric energy provided by the energy storage battery pack and then pre-charges the direct current bus, so that the bus voltage of the direct current bus is quickly increased. The pre-charging of the power conversion device is quickly completed, so that the power conversion device can respond to the power supply demand in time. And when the difference value between the bus voltage of the direct-current bus and the battery voltage of the energy storage battery pack is within the preset threshold range, the main control switch circuit is controlled to be switched on, so that the current when the main control switch circuit is switched on can be prevented from being too large, and the power conversion device is further prevented from being damaged.

Description

Technical Field

[0001] The present application belongs to the technical field of power supply, and in particular, relates to a power conversion device and a control method thereof. Background Art

[0002] In the energy storage system, in order to protect the internal devices and the external load of the DC bus, a pre-charging circuit and relay are set between the battery and the DC bus. The pre-charging circuit is used to pre-charge the output before the relay is closed to prevent the relay from directly closing the battery and the DC bus connected devices from causing excessive voltage difference and causing system damage.

[0003] In the related technology, after the battery is connected, the pre-charging circuit pre-charges the DC bus. When the voltage difference between the battery voltage and the bus voltage reaches a certain value, the pre-charging is completed and the relay is attracted. However, for high-power energy storage systems, the pre-charging circuit pre-charges the output slowly, resulting in a long pre-charging time, which makes the energy storage system unable to respond to power supply needs in time. Summary of the invention

[0004] The embodiment of the present application provides a power conversion device and a control method thereof to quickly complete pre-charging, so that the power conversion device can respond to power supply needs in a timely manner, and can prevent the closing current from being too large when the relay is attracted, thereby preventing damage to the power conversion device.

[0005] In a first aspect, the present application provides a control method for a power conversion device, the power conversion device comprising a battery port, a main control switch circuit, a pre-charging circuit, a DC conversion circuit and a DC bus; the battery port is used to connect an energy storage battery pack, a first end of the main control switch circuit is connected to the battery port, a second end of the main control switch circuit is connected to a first end of the DC conversion circuit, a second end of the DC conversion circuit is connected to the DC bus, and the pre-charging circuit is connected in parallel to both ends of the main control switch circuit; the control method comprises: in response to receiving a wake-up feedback signal sent by the energy storage battery pack, controlling the DC conversion circuit to start a pre-charging operation, the wake-up feedback signal is used to indicate that the battery management system of the energy storage battery pack is in an operating state; sending an output instruction to the energy storage battery pack, the output instruction is used to make the energy storage battery pack output a voltage to the battery port; when the difference between the bus voltage of the DC bus and the battery voltage of the energy storage battery pack is within a preset threshold range, controlling the main control switch circuit to be turned on.

[0006] In one possible implementation, in response to receiving a wake-up feedback signal from the energy storage battery pack, before controlling the DC conversion circuit to start working, the control method also includes: when it is detected that the energy storage battery pack is connected to the battery port, sending a wake-up signal to the energy storage battery pack to wake up the battery management system.

[0007] In one possible implementation, the control method also includes: obtaining a pre-charge current of the DC conversion circuit; generating a drive signal based on the pre-charge current and a pre-charge reference current and outputting it to the DC conversion circuit, wherein the drive signal is used to drive the DC conversion circuit to perform a pre-charge operation and adjust the pre-charge current to the pre-charge reference current.

[0008] In one possible implementation, generating a drive signal based on the pre-charge current and the pre-charge reference current and outputting it to the DC conversion circuit includes: obtaining a current deviation value based on the pre-charge current and the pre-charge reference current; generating the drive signal based on the current deviation value, and outputting the drive signal to the DC conversion circuit.

[0009] In a possible implementation, the control method further includes: acquiring the bus voltage of the DC bus and the battery voltage of the energy storage battery pack.

[0010] In a second aspect, the present application provides a power conversion device, which includes a battery port, a main control switch circuit, a pre-charging circuit, a DC conversion circuit, a DC bus and a controller; the battery port is used to connect an energy storage battery pack, a first end of the main control switch circuit is connected to the battery port, a second end of the main control switch circuit is connected to a first end of the DC conversion circuit, a second end of the DC conversion circuit is connected to the DC bus, and the pre-charging circuit is connected in parallel to both ends of the main control switch circuit; the controller is used to: in response to receiving a wake-up feedback signal sent by the energy storage battery pack, control the DC conversion circuit to start a pre-charging operation, the wake-up feedback signal is used to indicate that the battery management system of the energy storage battery pack is in an operating state; send an output instruction to the energy storage battery pack, the output instruction is used to make the energy storage battery pack output a voltage to the battery port; when the difference between the bus voltage of the DC bus and the battery voltage of the energy storage battery pack is within a preset threshold range, control the main control switch circuit to turn on.

[0011] In one possible implementation, the main control switch circuit includes a first switch unit, a first end of the first switch unit is connected to the positive terminal of the battery port, and a second end of the first switch unit is connected to the DC conversion circuit; the pre-charging circuit includes a pre-charging resistor and a pre-charging diode, a first end of the pre-charging resistor is connected to the first end of the first switch unit, a second end of the pre-charging resistor is connected to the anode of the pre-charging diode, and a cathode of the pre-charging diode is connected to the second end of the first switch unit.

[0012] In one possible implementation, the DC conversion circuit includes a DC inductor, a DC diode and a second switch unit; the first end of the DC inductor is connected to the second end of the first switch unit, the second end of the DC inductor is connected to the anode of the DC diode and the first end of the second switch unit, the cathode of the DC diode is connected to the positive DC bus, and the second end of the second switch unit is connected to the negative electrode of the battery port and the negative DC bus.

[0013] In one possible implementation, the power conversion device also includes a bus capacitor, which is connected to the DC bus. When the energy storage battery pack outputs voltage to the battery port, the energy storage battery pack pre-charges the bus capacitor through the pre-charging circuit and the DC conversion circuit.

[0014] In one possible implementation, the energy storage battery pack also includes a battery body and a charge and discharge switch circuit, and the battery body is connected to the battery port through the charge and discharge switch circuit; the battery management system is used to receive the output instruction and control the charge and discharge switch circuit to be turned on according to the output instruction.

[0015] In the embodiment of the present application, when the battery management system of the energy storage battery pack is in operation, the DC conversion circuit is controlled to start the pre-charging operation, and then an output instruction is sent to the energy storage battery pack, so that the energy storage battery pack outputs voltage to the battery port according to the output instruction. The electric energy output from the energy storage battery pack to the battery port is provided to the DC conversion circuit that is already in the pre-charging operation through the pre-charging circuit. The DC conversion circuit performs DC conversion on the electric energy provided by the energy storage battery pack and then pre-charges the DC bus, thereby achieving a rapid increase in the bus voltage of the DC bus, and can quickly complete the pre-charging of the power conversion device, so that the power conversion device can respond to the power supply demand in time. When the difference between the bus voltage of the DC bus and the battery voltage of the energy storage battery pack is within the preset threshold range, the main control switch circuit is controlled to be turned on, which can prevent the current from being too large when the main control switch circuit is turned on, thereby preventing damage to the power conversion device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a module schematic block diagram of a power conversion device provided in an embodiment of the present application.

[0017] Figure 2 It is a schematic diagram of the circuit structure of a power conversion device provided in an embodiment of the present application.

[0018] Figure 3 It is a circuit structure diagram of a power conversion device provided in another embodiment of the present application.

[0019] Figure 4It is a flow chart of a control method for a power conversion device provided in an embodiment of the present application.

[0020] Figure 5 It is a flow chart of a control method for a power conversion device provided in another embodiment of the present application.

[0021] Figure 6 yes Figure 5 Detailed flowchart of step S50 in FIG.

[0022] Figure 7 It is a simulation circuit diagram of the pre-charging process of a power conversion device implemented by the control method of an embodiment of the present application and the pre-charging of a power conversion device implemented only by a pre-charging circuit in the related technology.

[0023] Figure 8 It is a waveform diagram of the bus voltage changing with time during the pre-charging process of the power conversion device achieved only by the pre-charging circuit in the control method of the embodiment of the present application and the related technology. DETAILED DESCRIPTION

[0024] It should be noted that the terms "first" and "second" in the specification, claims and drawings of the present application are used to distinguish similar objects, rather than to describe a specific order or sequence. In the specification, claims and drawings of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "multiple" in the specification, claims and drawings of the present application refers to two or more than two.

[0025] It is understandable that the connection relationship described in the present application refers to direct or indirect connection. For example, A is connected to B or A is electrically connected to B, which can be either A and B are directly connected or A and B are indirectly connected through one or more other electrical components, for example, A and C are directly connected, and C and B are directly connected, so that A and B are connected through C.

[0026] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchangeable with each other, and some of the steps can also be deleted.

[0027] Some embodiments will be described below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0028] In the energy storage system, in order to protect the internal devices and the external load of the DC bus, a pre-charging circuit and relay are set between the battery and the DC bus. The pre-charging circuit is used to pre-charge the output before the relay is closed to prevent the relay from directly closing the battery and the DC bus connected devices from causing excessive voltage difference and causing system damage.

[0029] In the related technology, after the battery is connected, the pre-charging circuit pre-charges the DC bus. When the voltage difference between the battery voltage and the bus voltage reaches a certain value, the pre-charging is completed and the relay is attracted. However, for high-power energy storage systems, the pre-charging circuit pre-charges the output slowly, resulting in a long pre-charging time, which makes the energy storage system unable to respond to power supply needs in time.

[0030] Moreover, since there is still a certain voltage difference between the battery voltage and the bus voltage when the relay is energized, it can only reduce the impact of the current on the system, but does not completely eliminate the hidden danger. As the power level of the energy storage system increases, the bus capacitance and the load required to be connected in the energy storage system also increase, and the closing current generated when the relay is energized will also increase. Excessive closing current will impact the power devices in the energy storage system, damage the power devices, and shorten the life of the devices. If the closing current is higher than the rated current of the device, it may also damage the energy storage system, causing serious losses.

[0031] In view of this, an embodiment of the present application provides a power conversion device and a control method thereof, which can quickly complete the pre-charging of the power conversion device, so that the power conversion device can respond to power supply needs in a timely manner, and can prevent the closing current from being too large when the relay is attracted, thereby preventing damage to the power conversion device.

[0032] Please refer to Figure 1 , Figure 1 A schematic block diagram of a circuit module of a power conversion device 100 provided in an embodiment of the present application. The power conversion device 100 includes a battery port 110, a main control switch circuit 120, a pre-charge circuit 130, a DC conversion circuit 140, a DC bus (BUS+, BUS-) and a controller 150. The battery port 110 is used to connect the energy storage battery pack 200, the first end of the main control switch circuit 120 is connected to the battery port 110, the second end of the main control switch circuit 120 is connected to the first end of the DC conversion circuit 140, the second end of the DC conversion circuit 140 is connected to the DC bus, and the pre-charge circuit 130 is connected in parallel to the two ends of the main control switch circuit 120. The pre-charge circuit 130 is used to pre-charge the DC bus after the energy storage battery pack 200 is connected to the battery port 110 and before the main control switch circuit 120 is turned on. The controller 150 is used to control the operation of the DC conversion circuit 140.

[0033] Specifically, the controller 150 can be used to control the DC conversion circuit 140 to start the pre-charging operation in response to the wake-up feedback signal sent by the energy storage battery pack 200. The wake-up feedback signal is used to indicate that the battery management system (BMS) of the energy storage battery pack 200 is in operation, wherein the battery management system sends a wake-up feedback signal to the controller 150 after waking up. It can be understood that the controller 150 is connected in communication with the battery management system of the energy storage battery pack 200, thereby realizing signal transmission and information interaction between the battery management system and the controller 150. The controller 150 and the battery management system can be connected in communication with the CAN bus.

[0034] After controlling the DC conversion circuit 140 to start the pre-charging operation, the controller 150 sends an output instruction to the energy storage battery pack 200, and the output instruction is used to make the energy storage battery pack 200 output a voltage to the battery port 110. Thus, the voltage output from the energy storage battery pack 200 to the battery port 110 is transmitted to the DC conversion circuit 140 through the pre-charging circuit 130, and the DC conversion circuit 140 in the pre-charging operation converts the voltage into DC and then pre-charges the DC bus.

[0035] That is, when the battery management system of the energy storage battery pack 200 is in operation but the energy storage battery pack 200 has not yet output a voltage, the controller 150 controls the DC conversion circuit 140 to start the pre-charging operation, and then sends an output to the energy storage battery pack 200 so that the energy storage battery pack 200 outputs a voltage to the battery port 110, and then the DC conversion circuit 140 that is already in the pre-charging operation converts the electric energy provided by the energy storage battery pack 200 into DC and pre-charges the DC bus.

[0036] Then, when the difference between the bus voltage of the DC bus and the battery voltage of the energy storage battery pack 200 is within a preset threshold range, the controller 150 controls the main control switch circuit 120 to turn on, completing the pre-charging of the DC bus.

[0037] It can be understood that the DC bus is connected to a bus capacitor C BUS When the energy storage battery pack 200 pre-charges the DC bus through the pre-charging circuit 130, it actually charges the bus capacitor C BUS Charging is carried out, thereby increasing the voltage on the DC bus.

[0038] The preset threshold range can be set according to the voltage sampling error, for example, it can be set to (-100mV, 100mV), (-200mV, 200mV). At this time, when the difference between the bus voltage and the battery voltage is within the preset threshold range, the bus voltage is substantially equal to the battery voltage of the energy storage battery pack 200, and then when the controller 150 controls the main control switch circuit 120 to turn on, since the voltage difference between the DC bus and the battery port 110 is substantially zero, it can be achieved that when the main control switch circuit 120 is turned on, the closed current is zero or close to zero, thereby preventing the impact current from damaging the components in the power conversion device 100, and thus preventing damage to the power conversion device 100.

[0039] It is understandable that the controller 150 can obtain the battery voltage and the bus voltage by performing voltage detection on the battery port 110 and the DC bus.

[0040] In some embodiments, the DC bus can be used to connect external devices and power conversion circuits inside the power conversion device 100. The external device can be, for example, an inverter, a power converter, a DC load, etc., and the energy storage battery pack 200 can power the devices and equipment connected to the DC bus.

[0041] In the embodiment of the present application, when the battery management system of the energy storage battery pack 200 is in operation, the DC conversion circuit 140 is controlled to start the pre-charging operation, and then an output instruction is sent to the energy storage battery pack 200, so that the energy storage battery pack 200 outputs a voltage to the battery port 110 according to the output instruction. The electric energy output from the energy storage battery pack 200 to the battery port 110 is provided to the DC conversion circuit 140 which is already in the pre-charging operation through the pre-charging circuit 130. The DC conversion circuit 140 performs a DC conversion on the electric energy provided by the energy storage battery pack 200 and then pre-charges the DC bus, thereby realizing a rapid increase in the bus voltage of the DC bus, and can quickly complete the pre-charging of the power conversion device 100, so that the power conversion device 100 can respond to the power supply demand in time. When the difference between the bus voltage of the DC bus and the battery voltage of the energy storage battery pack 200 is within the preset threshold range, the controller 150 controls the main control switch circuit 120 to be turned on, which can prevent the current from being too large when the main control switch circuit 120 is turned on, thereby preventing damage to the power conversion device 100.

[0042] See also Figure 2 , Figure 2 A schematic block diagram of the circuit structure of a power conversion device 100 provided in an embodiment of the present application is shown.

[0043] like Figure 2As shown, in some embodiments, the main control switch circuit 120 includes a first switch unit K1, a first end of the first switch unit K1 is connected to the positive terminal of the battery port 110, and a second end of the first switch unit K1 is connected to the DC conversion circuit 140. The pre-charging circuit 130 includes a pre-charging resistor R1 and a pre-charging diode D1, a first end of the pre-charging resistor R1 is connected to the first end of the first switch unit K1, a second end of the pre-charging resistor R1 is connected to the anode of the pre-charging diode D1, and a cathode of the pre-charging diode D1 is connected to the second end of the first switch unit K1. When the difference between the bus voltage and the battery voltage is within a preset threshold range, the controller 150 controls the first switch unit K1 to be turned on, so that the energy storage battery pack 200 and the DC conversion circuit 140 are directly connected.

[0044] The DC conversion circuit 140 includes a DC inductor L1, a DC diode D2, and a second switch unit K2. The first end of the DC inductor L1 is connected to the second end of the first switch unit K1, the second end of the DC inductor L1 is connected to the anode of the DC diode D2 and the first end of the second switch unit K2, the cathode of the DC diode D2 is connected to the positive DC bus (BUS+), and the second end of the second switch unit K2 is connected to the negative electrode of the battery port 110 and the negative DC bus (BUS-). Therefore, the DC conversion circuit 140 is a BOOST boost circuit, which boosts the voltage input by the energy storage battery pack 200 to charge the DC bus, so that the bus voltage of the DC bus is raised faster. In this example, the controller 150 can output a drive signal with a certain duty cycle to the second switch unit K2, so that the second switch unit K2 is turned on and off according to the drive signal, thereby putting the DC conversion circuit 140 in a pre-charge working state.

[0045] Of course, in some other embodiments, the DC conversion circuit 140 is not limited to a BOOST boost circuit, but may also be a BUCK-BOOST circuit. Figure 3As shown, when the DC conversion circuit 140 is a BUCK-BOOST circuit, the DC conversion circuit 140 includes a DC inductor L1, a second switch unit K2 and a third switch unit K3, the first end of the DC inductor L1 is connected to the second end of the first switch unit K1, the second end of the DC inductor L1 is connected to the first end of the second switch unit K2 and the first end of the third switch unit K3, the second end of the third switch unit K3 is connected to the positive DC bus (BUS+), and the second end of the second switch unit K2 is connected to the negative electrode of the battery port 110 and the negative DC bus (BUS-). Thus, the DC conversion circuit 140 can charge the DC bus after boosting the voltage input by the energy storage battery pack 200, so that the bus voltage of the DC bus is raised faster. When the energy storage battery pack 200 needs to be charged, the DC conversion circuit 140 can also convert the voltage on the DC bus to charge the energy storage battery pack 200. In this example, when the DC conversion circuit 140 needs to work in the pre-charging working state, the controller 150 can output a driving signal with a certain duty cycle to the second switch unit K2 and the third switch unit K3 respectively, so that the second switch unit K2 and the third switch unit K3 are switched on and off according to the driving signal, thereby putting the DC conversion circuit 140 in the pre-charging working state.

[0046] Of course, in this application, the specific circuit structure of the DC conversion circuit 140 is not limited to Figure 2 and Figure 3 The specific example can be set according to actual application requirements, and can also be set to other forms of DC / DC conversion circuits.

[0047] The first switch unit K1, the second switch unit K2 and the third switch unit K3 can all be controllable switches, such as relays, contactors, power switch tubes, etc. It can be understood that Figure 2 In the example of , both the first switch unit K1 and the second switch unit K2 can be turned on and off by the controller 150. Figure 3 In the example, the first switch unit K1, the second switch unit K2 and the third switch unit K3 can all be controlled to be on and off by the controller 150.

[0048] In some embodiments, the energy storage battery pack 200 further includes a battery body 210 and a charge and discharge switch circuit (not labeled), and the battery body 210 is connected to the battery port 110 via the charge and discharge switch circuit. The battery management system of the energy storage battery pack 200 is used to control the conduction of the charge and discharge switch circuit.

[0049] When the battery management system receives the output instruction sent by the controller 150 , it controls the charge and discharge switch circuit to be turned on, thereby causing the battery body 210 to output voltage to the battery port 110 .

[0050] The charge and discharge switch circuit may include a charge and discharge switch unit K4, which may also be a controllable switch, such as a relay, a contactor, a power switch tube, etc. When the battery management system receives an output instruction sent by the controller 150, it controls the charge and discharge switch unit K4 to turn on.

[0051] See also Figure 4 , Figure 4 1 is a flow chart of a control method for a power conversion device 100 provided in an embodiment of the present application. In at least one embodiment, the control method is applied to the power conversion device 100 as described above, and the control method can be executed by the controller 150. Figure 1 to Figure 2 The power conversion device 100 shown is taken as an example for description.

[0052] like Figure 4 As shown, the control method specifically includes the following steps:

[0053] S10, in response to receiving a wake-up feedback signal sent by the energy storage battery pack, controlling the DC conversion circuit to start pre-charging operation.

[0054] The feedback wake-up signal is used to indicate that the battery management system of the energy storage battery pack 200 is in operation.

[0055] It is understandable that before step S10 , the control method may include: when it is detected that the energy storage battery pack 200 is connected to the battery port 110 , sending a wake-up signal to the energy storage battery pack 200 to wake up the battery management system.

[0056] The controller 150 can continuously detect the battery port 110. When it is detected that the energy storage battery pack 200 is connected to the battery port 110, the controller 150 sends a wake-up signal to the energy storage battery pack 200, and the energy storage battery pack 200 wakes up its battery management system according to the wake-up signal. After the battery management system wakes up, it returns a feedback wake-up signal to the controller 150, so that the controller 150 confirms that the battery management system is in operation.

[0057] Of course, it can be understood that the awakening method of the battery management system of the energy storage battery pack 200 is not limited to being awakened by the controller 150 sending a wake-up signal, but can also be awakened by other methods, such as the user pressing the power conversion device 100 or the start button set in the energy storage battery pack 200 to generate a wake-up signal to the energy storage battery pack 200 to wake up the battery management system, and for example, sending a wake-up signal to the energy storage battery pack 200 through the user's mobile terminal to wake up the battery management system. The embodiment of the present application is not limited to this and can be set according to user needs.

[0058] S20: Send an output instruction to the energy storage battery pack.

[0059] After controlling the DC conversion circuit 140 to start the pre-charging operation, the controller 150 sends an output instruction to the energy storage battery pack 200. The output instruction is used to make the energy storage battery pack 200 output voltage to the battery port 110, and then the energy storage battery pack 200 outputs voltage to the battery port 110 according to the output instruction.

[0060] When the energy storage battery pack 200 includes a battery body 210 and a charge and discharge switch circuit, the battery management system can receive and control the output instructions sent by it, and the battery management system controls the charge and discharge switch circuit to be turned on according to the output instructions, so that the battery body 210 can output voltage to the battery port 110.

[0061] S30: When the difference between the bus voltage of the DC bus and the battery voltage of the energy storage battery pack is within a preset threshold range, the main control switch circuit is controlled to be turned on.

[0062] That is, when the difference between the bus voltage and the battery voltage of the energy storage battery pack 200 is within the preset threshold range, the DC conversion circuit 140 completes pre-charging of the DC bus, and the controller 150 controls the main control switch circuit 120 to turn on to directly connect the energy storage battery pack 200 and the DC conversion circuit 140, so that the energy storage battery pack 200 can supply power normally.

[0063] It is understandable that the control method may further include: obtaining the bus voltage of the DC bus and the battery voltage of the energy storage battery pack 200 .

[0064] The controller 150 may obtain the bus voltage by detecting the voltage of the DC bus, or may obtain the battery voltage by detecting the voltage of the battery port 110. Of course, the controller 150 may also obtain the battery voltage by communicating with the battery management system of the energy storage battery pack 200.

[0065] like Figure 5 As shown, in some embodiments, the control method may further include:

[0066] S40, obtaining a pre-charge current of the DC conversion circuit.

[0067] The controller 150 may obtain a pre-charge current by performing current detection on the DC conversion circuit 140. The pre-charge current is the current output from the DC conversion circuit 140 to the DC bus.

[0068] S50, generating a driving signal according to the pre-charge current and the pre-charge reference current and outputting it to the DC conversion circuit.

[0069] The pre-charge reference current is a preset value, which is set according to the actual demand for pre-charging the DC bus. The drive signal is used to drive the DC conversion circuit 140 to perform pre-charging and adjust the pre-charging current to the pre-charging reference current.

[0070] Specifically, if Figure 6 As shown, step S50 may include:

[0071] S51. Obtain a current deviation value according to a pre-charge current and a pre-charge reference current.

[0072] The pre-charge current and the pre-charge reference current may be input into a subtractor to obtain a current deviation value. Specifically, the subtractor subtracts the pre-charge current from the pre-charge reference current to obtain the current deviation value. The subtractor may be integrated into the controller 150.

[0073] S52, generating a driving signal according to the current deviation value, and outputting the driving signal to the DC conversion circuit.

[0074] Among them, the current deviation value can be proportionally adjusted to obtain a target control amount, and a drive signal can be generated according to the target control amount. Specifically, the current deviation value can be input into a PI (Proportional Integral) controller for PI adjustment to obtain a target control amount, and then the target control amount is input into a signal modulator to generate a drive signal. It can be understood that the drive signal can be a PWM signal, and the target control amount can be a value related to the duty cycle of the PWM signal.

[0075] In the above process, the controller 150 performs current loop control on the DC conversion circuit 140 according to the pre-charge current and the pre-charge reference current of the DC conversion circuit 140, so as to adjust the current of the DC conversion circuit 140 during the pre-charge operation.

[0076] It can be understood that the pre-charge circuit 130 can limit the pre-charge current, and the controller 150 can adjust the duty cycle of the generated drive signal through the pre-charge current and the pre-charge reference current, thereby limiting the pre-charge current.

[0077] See also Figure 7 , Figure 7 The control method of the embodiment of the present application is used to realize the pre-charging of the power conversion device 100, and the simulation circuit diagram of the pre-charging process of the power conversion device 100 is shown in the related art only through the pre-charging circuit 130, wherein R L To simulate the load. Figure 8 The control method of the embodiment of the present application is used to realize the bus voltage V during the pre-charging process of the power conversion device 100. BUSThe waveform diagram of the change over time, and the bus voltage V during the pre-charging process of the power conversion device 100 realized only by the pre-charging circuit 130 in the related art BUS1 A graph of a waveform changing over time. Figure 8 In the figure, waveform A is the bus voltage V during the pre-charging process of the power conversion device 100 implemented by the control method of the embodiment of the present application. BUS The waveform B is the bus voltage V during the pre-charging process of the power conversion device 100 realized only by the pre-charging circuit 130 in the related art. BUS1 The waveform, V BAT is the battery voltage of the energy storage battery pack 200.

[0078] Combination Figure 7 and Figure 8 It can be seen that when the control method of the embodiment of the present application is used for pre-charging, the energy storage battery pack 200 charges the DC bus through the pre-charging circuit 130 and the DC conversion circuit 140. Figure 8 As shown in waveform A in FIG, the bus voltage of the DC bus can be precharged to be equal to the battery voltage after T1 time. When precharging is performed only through the precharging circuit 130, the energy storage battery pack 200 only charges the DC bus through the precharging circuit 130, such as Figure 8 As shown in waveform B in , the bus voltage of the DC bus needs to be pre-charged to be equal to the battery voltage after T2 time, and T2 time is longer than T1 time.

[0079] Therefore, compared with precharging only through the precharging circuit 130 , the use of the control method of the embodiment of the present application for precharging can effectively shorten the precharging time of the power conversion device 100 .

[0080] It can be understood that the beneficial effects that can be achieved by the control method provided in the embodiment of the present application can refer to the beneficial effects of the corresponding power conversion device 100 provided above, and will not be repeated here.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. In the actual application process, the entire content of the technical solutions described in any embodiment of the present application can be implemented, or some content can be added, or some content can be deleted, or some content can be changed / replaced. Although the present application is described in detail with reference to the preferred embodiments, it should be understood by those of ordinary skill in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A control method for a power conversion device, It is characterized in that The power conversion device includes a battery port, a main control switch circuit, a pre-charging circuit, a DC conversion circuit and a DC bus; the battery port is used to connect to an energy storage battery pack, the first end of the main control switch circuit is connected to the battery port, the second end of the main control switch circuit is connected to the first end of the DC conversion circuit, the second end of the DC conversion circuit is connected to the DC bus, and the pre-charging circuit is connected in parallel to both ends of the main control switch circuit; The control method comprises: In response to receiving a wake-up feedback signal sent by the energy storage battery pack, controlling the DC conversion circuit to start pre-charging operation, wherein the wake-up feedback signal is used to indicate that the battery management system of the energy storage battery pack is in an operating state; Sending an output instruction to the energy storage battery pack, wherein the output instruction is used to make the energy storage battery pack output voltage to the battery port; When the difference between the bus voltage of the DC bus and the battery voltage of the energy storage battery pack is within a preset threshold range, the main control switch circuit is controlled to be turned on.

2. The control method according to claim 1, It is characterized in that Before the DC conversion circuit is controlled to start working in response to receiving the wake-up feedback signal sent by the energy storage battery pack, the control method further includes: When it is detected that the energy storage battery pack is connected to the battery port, a wake-up signal is sent to the energy storage battery pack to wake up the battery management system.

3. The control method according to claim 1 or 2, It is characterized in that The control method further comprises: Obtaining a precharge current of the DC conversion circuit; A drive signal is generated according to the pre-charge current and the pre-charge reference current and output to the DC conversion circuit, wherein the drive signal is used to drive the DC conversion circuit to perform pre-charge operation and adjust the pre-charge current to the pre-charge reference current.

4. The control method according to claim 3, It is characterized in that The method of generating a driving signal according to the pre-charge current and the pre-charge reference current and outputting it to the DC conversion circuit comprises: Obtaining a current deviation value according to the pre-charge current and the pre-charge reference current; The driving signal is generated according to the current deviation value, and the driving signal is output to the DC conversion circuit.

5. The control method according to claim 1, It is characterized in that The control method further includes: acquiring the bus voltage of the DC bus and the battery voltage of the energy storage battery pack.

6. A power conversion device, It is characterized in that The power conversion device includes a battery port, a main control switch circuit, a pre-charging circuit, a DC conversion circuit, a DC bus and a controller; the battery port is used to connect to an energy storage battery pack, the first end of the main control switch circuit is connected to the battery port, the second end of the main control switch circuit is connected to the first end of the DC conversion circuit, the second end of the DC conversion circuit is connected to the DC bus, and the pre-charging circuit is connected in parallel to both ends of the main control switch circuit; The controller is used to: In response to receiving a wake-up feedback signal sent by the energy storage battery pack, controlling the DC conversion circuit to start pre-charging operation, wherein the wake-up feedback signal is used to indicate that the battery management system of the energy storage battery pack is in an operating state; Sending an output instruction to the energy storage battery pack, wherein the output instruction is used to make the energy storage battery pack output voltage to the battery port; When the difference between the bus voltage of the DC bus and the battery voltage of the energy storage battery pack is within a preset threshold range, the main control switch circuit is controlled to be turned on.

7. The power conversion device according to claim 6, It is characterized in that The main control switch circuit includes a first switch unit, a first end of the first switch unit is connected to the positive terminal of the battery port, and a second end of the first switch unit is connected to the DC conversion circuit; the pre-charging circuit includes a pre-charging resistor and a pre-charging diode, a first end of the pre-charging resistor is connected to the first end of the first switch unit, a second end of the pre-charging resistor is connected to the anode of the pre-charging diode, and a cathode of the pre-charging diode is connected to the second end of the first switch unit.

8. The power conversion device according to claim 7, It is characterized in that The DC conversion circuit includes a DC inductor, a DC diode and a second switch unit; the first end of the DC inductor is connected to the second end of the first switch unit, the second end of the DC inductor is connected to the anode of the DC diode and the first end of the second switch unit, the cathode of the DC diode is connected to the positive DC bus, and the second end of the second switch unit is connected to the negative electrode of the battery port and the negative DC bus.

9. The power conversion device according to any one of claims 6 to 8, It is characterized in that It also includes a bus capacitor connected to the DC bus. When the energy storage battery pack outputs voltage to the battery port, the energy storage battery pack pre-charges the bus capacitor through the pre-charging circuit and the DC conversion circuit.

10. The power conversion device according to claim 6, It is characterized in that The energy storage battery pack also includes a battery body and a charge and discharge switch circuit, and the battery body is connected to the battery port through the charge and discharge switch circuit; the battery management system is used to receive the output instruction and control the charge and discharge switch circuit to be turned on according to the output instruction.

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