Energy storage module open circuit detection method and device and power conversion equipment

Abstract

The invention provides an energy storage module open circuit detection method and device and power conversion equipment, and relates to the technical field of charging. The method is applied to a control unit in the power conversion equipment, the power conversion equipment further comprises a power module and an energy storage module, the control unit is connected with the power module, the direct current end of the power module is connected with the energy storage module, and the method comprises the steps that whether the power module is in a constant voltage state or not is judged; when the power module enters the constant-voltage state, adjusting the reference voltage of the direct-current voltage loop so as to control the power module by adopting the direct-current voltage detection parameter of the power module and the adjusted reference voltage; obtaining a direct current detection parameter of the power module under the control of the adjusted reference voltage; according to the direct current detection parameters, open circuit detection is carried out on the energy storage module to obtain an open circuit detection result, and the open circuit detection result is used for indicating whether the energy storage module and the power module are in an open circuit state. Whether the energy storage module is open-circuited can be effectively identified, and safe operation of the system is ensured.

Description

Technical Field

[0001] The present application relates to the field of charging technology, and in particular to a method and device for detecting open circuit of an energy storage module and a power conversion device. Background Art

[0002] In the field of charging technology, general power modules are equipped with anti-reverse diodes, which monitor the energy storage module by monitoring the communication status with the battery management system (BMS) in the vehicle, and determine the insertion and connection status of the gun line based on the node signal detection of the charging gun.

[0003] For power modules without anti-reverse diodes, the connection status cannot be determined based on the communication status and gun line detection. When the power module enters the constant voltage state, the current value between the power module and the energy storage module gradually decreases and eventually approaches 0A. In this case, it is impossible to detect whether an open circuit occurs directly between the energy storage module and the power module, affecting the safe operation of the system. Summary of the invention

[0004] The purpose of the present application is to provide a method, device and power conversion equipment for detecting open circuit of energy storage module in view of the above-mentioned deficiencies in the prior art, so as to effectively identify whether an open circuit occurs in the energy storage module and ensure the safe operation of the system.

[0005] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] In a first aspect, an embodiment of the present application provides a method for detecting an open circuit of an energy storage module, which is applied to a control unit in a power conversion device, wherein the power conversion device further includes: a power module and an energy storage module, wherein the control unit is connected to the power module, and the DC end of the power module is connected to the energy storage module, and the method includes:

[0007] Determining whether the power module is in a constant voltage state;

[0008] When the power module enters a constant voltage state, adjusting the reference voltage of the DC voltage loop, so as to control the power module using the DC voltage detection parameter of the power module and the adjusted reference voltage;

[0009] Acquiring a DC detection parameter of the power module under control of the adjusted reference voltage;

[0010] According to the DC detection parameter, an open circuit detection is performed on the energy storage module to obtain an open circuit detection result, and the open circuit detection result is used to indicate whether the energy storage module and the power module are in an open circuit state.

[0011] Optionally, performing an open circuit detection on the energy storage module according to the DC detection parameter to obtain an open circuit detection result includes:

[0012] If the DC current detection parameter is equal to the target current parameter output by the DC voltage loop according to the adjusted reference voltage, determining that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state;

[0013] If the DC current detection parameter is equal to a preset small current value, it is determined that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

[0014] Optionally, performing an open circuit detection on the energy storage module according to the DC detection parameter to obtain an open circuit detection result includes:

[0015] If the DC current detection parameter exits the current range of the constant voltage state, determining that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state;

[0016] If the DC current detection parameter does not exit the current range of the constant voltage state, it is determined that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

[0017] Optionally, determining whether the power module is in a constant voltage state includes:

[0018] Whether the power module enters a constant voltage state is determined according to the working states of the DC current loop and the DC voltage loop.

[0019] Optionally, the power module is a bidirectional power converter, and when the power module enters a constant voltage state, adjusting the reference voltage of the DC voltage loop includes:

[0020] Determining a voltage adjustment direction according to the type of the constant voltage state;

[0021] According to a preset voltage adjustment amplitude, the reference voltage of the DC voltage loop is adjusted in the voltage adjustment direction.

[0022] Optionally, the DC voltage loop includes a high-voltage DC voltage loop, and determining the voltage adjustment direction according to the type of the constant voltage state includes:

[0023] If the type of the constant voltage state is a constant voltage charging state, determining that the voltage adjustment direction is a downward adjustment direction;

[0024] The step of adjusting the reference voltage of the DC voltage loop in the voltage adjustment direction according to the preset voltage adjustment amplitude includes:

[0025] According to the preset voltage adjustment amplitude, the reference voltage of the DC voltage loop is adjusted downward.

[0026] Optionally, the DC voltage loop further includes: a low voltage DC current loop, and the determining of the voltage adjustment direction according to the type of the constant voltage state includes:

[0027] If the type of the constant voltage state is a constant voltage discharge state, determining that the voltage adjustment direction is an upward adjustment direction;

[0028] The step of adjusting the reference voltage of the DC voltage loop in the voltage adjustment direction according to the preset voltage adjustment amplitude includes:

[0029] According to the preset voltage adjustment amplitude, the reference voltage of the DC voltage loop is increased.

[0030] Optionally, the method further comprises:

[0031] If the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state, the reference voltage of the DC voltage loop is restored.

[0032] In a second aspect, an embodiment of the present application further provides an energy storage module open circuit detection device, which is applied to a control unit in a power conversion device, wherein the power conversion device also includes: a power module and an energy storage module, wherein the control unit is connected to the power module, and the DC end of the power module is connected to the energy storage module, and the device includes:

[0033] A judging module, used for judging whether the power module is in a constant voltage state;

[0034] An adjustment module, used for adjusting the reference voltage of the DC voltage loop when the power module enters a constant voltage state, so as to control the power module by using the DC voltage detection parameter of the power module and the adjusted reference voltage;

[0035] An acquisition module, used for acquiring a DC detection parameter of the power module under the control of the adjusted reference voltage;

[0036] The detection module is used to perform an open circuit detection on the energy storage module according to the DC detection parameter to obtain an open circuit detection result, wherein the open circuit detection result is used to indicate whether the energy storage module and the power module are in an open circuit state.

[0037] Optionally, the detection module is specifically used to determine that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state if the DC current detection parameter is equal to the target current parameter output by the DC voltage loop according to the adjusted reference voltage; if the DC current detection parameter is equal to 0, determine that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

[0038] Optionally, the detection module is specifically used to determine that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state if the DC current detection parameter exits the current range of the constant voltage state; if the DC current detection parameter does not exit the current range of the constant voltage state, determine that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

[0039] Optionally, the judgment module is specifically used to determine whether the power module enters a constant voltage state according to the working states of the DC current loop and the DC voltage loop.

[0040] Optionally, the power module is a bidirectional power converter, and the adjustment module is specifically used to determine the voltage adjustment direction according to the type of the constant voltage state; and adjust the reference voltage of the DC voltage loop in the voltage adjustment direction according to the preset voltage adjustment amplitude.

[0041] Optionally, the DC voltage loop includes a high-voltage DC voltage loop, and the adjustment module is specifically used to determine that the voltage adjustment direction is a downward direction if the type of the constant voltage state is a constant voltage charging state; and to lower the reference voltage of the DC voltage loop according to the preset voltage adjustment amplitude.

[0042] Optionally, the DC voltage loop also includes: a low-voltage DC current loop, and the adjustment module is also used to determine that the voltage adjustment direction is an upward direction if the type of the constant voltage state is a constant voltage discharge state; and increase the reference voltage of the DC voltage loop according to the preset voltage adjustment amplitude.

[0043] Optionally, the adjustment module is further used to restore the reference voltage of the DC voltage loop if the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state.

[0044] In a third aspect, an embodiment of the present application further provides a power conversion device, comprising: a control unit, a power module and an energy storage module, the control unit being connected to the power module, the DC end of the power module being connected to the energy storage module, and the control unit being used to execute the steps of the energy storage module open circuit detection method described in any one of the first aspects.

[0045] In a fourth aspect, an embodiment of the present application further provides a control unit, comprising: a processor, a storage medium and a bus, wherein the storage medium stores program instructions executable by the processor, and when the control unit is running, the processor communicates with the storage medium through the bus, and the processor executes the program instructions to perform the steps of the energy storage module open circuit detection method as described in any one of the first aspects.

[0046] In a fifth aspect, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the energy storage module open circuit detection method as described in any one of the first aspects are executed.

[0047] The beneficial effects of this application are:

[0048] The energy storage module open circuit detection method, device and power conversion equipment provided in the present application adjust the reference voltage of the DC voltage loop when the power module enters a constant voltage state, and detect the DC detection parameters of the power module under the adjusted reference voltage control to determine whether the energy storage module and the power module are in an open circuit state, and determine whether the energy storage module is offline or online, so as to effectively identify whether the energy storage module has an offline fault in the constant voltage state, and ensure the safe operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0050] Figure 1 A schematic diagram of the structure of a power conversion device provided in an embodiment of the present application;

[0051] Figure 2 Schematic diagram of the process of the energy storage module open circuit detection method provided in the embodiment of the present application Figure 1 ;

[0052] Figure 3 Schematic diagram of the process of the energy storage module open circuit detection method provided in the embodiment of the present application Figure 2 ;

[0053] Figure 4 A loop block diagram of a dual voltage and current loop provided in an embodiment of the present application;

[0054] Figure 5 The open circuit detection disturbance waveform diagram provided in the embodiment of the present application;

[0055] Figure 6 A schematic diagram of the structure of an energy storage module open circuit detection device provided in an embodiment of the present application;

[0056] Figure 7 A schematic diagram of a control unit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0058] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0059] In addition, the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0060] It should be noted that, in the absence of conflict, the features in the embodiments of the present application may be combined with each other.

[0061] Figure 1 A schematic diagram of the structure of a power conversion device provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the power conversion device includes: a control unit 10, a power module 20 and an energy storage module 30, wherein the power module 20 can be an AC / DC power module or a DC / DC power module, the AC side or one DC side of the power module 20 is connected to the input source, and the other DC side is connected to the bus capacitor Cdc and the energy storage module 30, and the circuit breaker, contactor, switch, and connecting line between the power module 20 and the energy storage module 30 are equivalent to an equivalent switch S1.

[0062] If the input source is a DC source, the current provided to the power module 20 is I1. If the input end is an AC source, the current provided to the power module 20 is a three-phase AC current, whose active component determines the energy flow. The DC voltage of the power module 20 on the energy storage module 30 side is Vdc, and the current is Idc.

[0063] The specific implementation of the energy storage module open circuit detection method executed by the control unit is described below in conjunction with the embodiments.

[0064] Figure 2 Schematic diagram of the process of the energy storage module open circuit detection method provided in the embodiment of the present application Figure 1 ,like Figure 2 As shown, the energy storage module open circuit detection method may include:

[0065] S101: Determine whether the power module is in a constant voltage state.

[0066] In this embodiment, when energy is transmitted between the power module and the energy storage module, it includes a constant current state and a constant voltage state, wherein the constant current state provides a large current to realize rapid energy transmission between the power module and the energy storage module, and automatically enters the constant voltage state when the DC voltage for energy transmission between the power module and the energy storage module reaches a constant voltage value, and the current value for energy transmission between the power module and the energy storage module gradually decreases from a constant voltage large current value, and finally decreases to a constant voltage small current value close to 0A.

[0067] In some embodiments, whether the power module is in a constant voltage state can be determined by detecting whether the DC voltage for energy transmission between the power module and the energy storage module reaches a constant voltage value.

[0068] In other embodiments, it can be determined whether the power module is in the constant voltage state or the constant current state according to the state flag of the power module.

[0069] S102: When the power module enters a constant voltage state, adjusting a reference voltage of a DC voltage loop, so as to control the power module by using a DC voltage detection parameter of the power module and the adjusted reference voltage.

[0070] In this embodiment, the control unit includes a DC voltage loop and a DC current loop. The DC voltage loop performs proportional integration (PI) according to the difference between the DC voltage detection parameter of the power module and the reference voltage to generate a first control current. The DC current loop performs PI output according to the difference between the DC current detection parameter of the power module and the reference current to generate a second control current. The first control current and the second control current compete for the smaller one to obtain a target control current. The control unit generates a PWM control signal according to the target control current to control the power module.

[0071] The DC voltage loop and the DC current loop may be loops formed by hardware devices or loops formed by software algorithms, which is not limited in this embodiment.

[0072] When the power module is in a constant current state, the DC voltage loop and the DC current loop compete with each other to minimize the control current, and the second control current of the DC current loop is used as the target control current. When the power module is in a constant voltage state, the DC voltage loop and the DC current loop compete with each other to minimize the control current, and the first control current of the DC voltage loop is used as the target control current.

[0073] When the power module enters the constant voltage state, the DC voltage detection parameter of the power module is infinitely close to or equal to the reference voltage, and the difference between the DC voltage detection parameter and the reference voltage is close to 0. Through the proportional integration of the DC voltage loop, a first control current close to 0A is output.

[0074] When the power module is in a constant voltage state, since the current between the power module and the energy storage module is close to 0A, when an open circuit occurs between the power module and the energy storage module, the current between the power module and the energy storage module is also close to 0A. At this time, it is impossible to determine whether an open circuit occurs between the power module and the energy storage module based on the current value.

[0075] In order to detect whether an open circuit occurs between the power module and the energy storage module, this solution adjusts the reference voltage of the DC voltage loop to change the difference between the DC voltage detection parameter of the power module and the reference voltage. After proportional integration based on the difference, the first control current output by the DC voltage loop is no longer 0A. At this time, the power module is controlled according to the PWM signal generated by the first control current.

[0076] S103: Obtaining a DC detection parameter of the power module under control based on the adjusted reference voltage.

[0077] In this embodiment, after the PWM signal corresponding to the first control current generated based on the adjusted reference voltage controls the power module, the control unit obtains the DC detection parameter of the power module through the detection module. The DC detection parameter can be a DC current detection parameter or a DC voltage detection parameter.

[0078] S104: performing an open circuit detection on the energy storage module according to the DC detection parameter to obtain an open circuit detection result, where the open circuit detection result is used to indicate whether the energy storage module and the power module are in an open circuit state.

[0079] In some embodiments, after the power module is controlled by a PWM signal corresponding to a first control current generated based on an adjusted reference voltage, if there is no open circuit between the power module and the energy storage module, energy can be transferred between the power module and the energy storage module, and the current value will change. Therefore, the energy storage module can be open-circuited according to the DC current detection parameters between the power module and the energy storage module.

[0080] Specifically, it is determined whether the DC current detection parameters have changed to determine whether the power module and the energy storage module are in an open circuit state. If the DC current detection parameters have not changed, it is determined that the power module and the energy storage module are in an open circuit state. If the DC current detection parameters have changed, it is determined that the power module and the energy storage module are in a non-open circuit state.

[0081] In other embodiments, after the power module is controlled by a PWM signal corresponding to a first control current generated based on an adjusted reference voltage, if no open circuit occurs between the power module and the energy storage module, then energy can be transferred between the power module and the energy storage module to maintain a stable voltage value; if an open circuit occurs between the power module and the energy storage module, energy cannot be transferred between the power module and the energy storage module to maintain a stable voltage value; therefore, the energy storage module can be detected for an open circuit based on a DC voltage detection parameter between the power module and the energy storage module.

[0082] Specifically, it is determined whether the DC voltage detection parameters have changed to determine whether the power module and the energy storage module are in an open circuit state. If the DC voltage detection parameters have changed, it is determined that the power module and the energy storage module are in an open circuit state. If the DC voltage detection parameters have not changed, it is determined that the power module and the energy storage module are in a non-open circuit state.

[0083] The energy storage module open circuit detection method provided in the above embodiment adjusts the reference voltage of the DC voltage loop when the power module enters a constant voltage state, and detects the DC detection parameters of the power module under the control of the adjusted reference voltage to determine whether the energy storage module and the power module are in an open circuit state, and determines whether the energy storage module is offline or online, so as to effectively identify whether the energy storage module has an offline fault in the constant voltage state, thereby ensuring the safe operation of the system.

[0084] In a possible implementation, open circuit detection of the energy storage module based on a DC current detection parameter between the power module and the energy storage module is more accurate than open circuit detection of the energy storage module based on a DC voltage detection parameter between the power module and the energy storage module.

[0085] In some embodiments, the process of performing open circuit detection on the energy storage module according to the DC detection parameter in S104 to obtain the open circuit detection result may include:

[0086] If the DC current detection parameter is equal to the target current parameter output by the DC voltage loop according to the adjusted reference voltage, it is determined that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state; if the DC current detection parameter is equal to the preset small current value, it is determined that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

[0087] In this embodiment, after the DC voltage loop generates the first control current by performing proportional integration according to the difference between the adjusted reference voltage and the DC voltage detection parameter of the power module, the first control current is used as the target current parameter to determine whether the DC current detection parameter between the power module and the energy storage module is equal to the target current parameter. If the DC current detection parameter between the power module and the energy storage module can be adjusted to the target current parameter, it is determined that the energy storage module is online and the power module and the energy storage module are in a non-open circuit state. If the DC current detection parameter between the power module and the energy storage module is still maintained at a preset small current value, such as 0A, it is determined that the energy storage module is offline and the power module and the energy storage module are in an open circuit state.

[0088] In some other embodiments, the process of performing open circuit detection on the energy storage module according to the DC detection parameter in S104 to obtain the open circuit detection result may include:

[0089] If the DC current detection parameter exits the current range of the constant voltage state, it is determined that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state; if the DC current detection parameter does not exit the current range of the constant voltage state, it is determined that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

[0090] In this embodiment, a current range of a constant voltage state is preset, within which the power module is determined to be in a constant voltage state, the DC voltage loop generates a first control current by performing proportional integration according to the difference between the adjusted reference voltage and the DC voltage detection parameter of the power module, and after the power module is controlled to perform power conversion according to the PWM signal corresponding to the first control current, it is determined whether the DC current detection parameter between the power module and the energy storage module is still in the current range of the constant voltage state, if the DC current detection parameter exits the current range of the constant voltage state, it indicates that the power module can transfer energy with the energy storage module based on the PWM signal, it is determined that the energy storage module is online, and the power module and the energy storage module are in a non-open circuit state. If the DC current detection parameter does not exit the current range of the constant voltage state, it indicates that the power module cannot transfer energy with the energy storage module based on the PWM signal, it is determined that the energy storage module is offline, and the power module and the energy storage module are in an open circuit state.

[0091] For example, in the constant voltage state, the DC current detection parameter between the power module and the energy storage module is close to 0A, and the current range of the constant voltage state can be set to 0±3A. If the power module is a unidirectional charging power module, the current range of the constant voltage state is 0~3A. If the power module is a bidirectional charging power module, the current range of the constant voltage state is -3A~3A.

[0092] The energy storage module open circuit detection method provided in the above embodiment determines whether the power module and the energy storage module are in an open circuit state according to whether the DC current detection parameter is equal to the target current parameter output by the DC voltage loop according to the adjusted reference voltage, or whether the current range of the constant voltage state is exited, so as to accurately identify whether the energy storage module has an offline fault in the constant voltage state to ensure the safe operation of the system.

[0093] In a possible implementation, the process of determining whether the power module is in a constant voltage state in S101 may include:

[0094] Whether the power module enters a constant voltage state is determined according to the working states of the DC current loop and the DC voltage loop.

[0095] In this embodiment, the working state of the power module is divided into a constant current state and a constant voltage state. The constant current state or the constant voltage state is determined by the competition between the DC current loop and the DC voltage loop. When the power module and the energy storage module are controlled to transfer energy based on the competition output of the DC current loop, the power module is in a constant current state. When the power module and the energy storage module are controlled to transfer energy based on the competition output of the DC voltage loop, the power module is in a constant voltage state. Therefore, whether the power module enters the constant voltage state can be determined based on the competition result between the DC current loop and the DC voltage loop.

[0096] In some embodiments, the control unit determines the competition result of the DC current loop and the DC voltage loop according to the flag bit of the competition between the DC current loop and the DC voltage loop, thereby determining whether the power module enters the constant voltage state. If the DC current loop competition is successful, the power module is controlled according to the output of the DC current loop to determine that the power module is in the constant current state; if the DC voltage loop competition is successful, the power module is controlled according to the output of the DC voltage loop to determine that the power module is in the constant voltage state.

[0097] In a possible implementation, the power module is a bidirectional power converter, that is, the input source can charge the energy storage module through the power module, and the energy storage module can also discharge to the input source through the power module.

[0098] Figure 3 Schematic diagram of the process of the energy storage module open circuit detection method provided in the embodiment of the present application Figure 2 ,like Figure 3As shown, the process of adjusting the reference voltage of the DC voltage loop in the above S102 when the power module enters the constant voltage state may include:

[0099] S201: Determine a voltage adjustment direction according to the type of constant voltage state.

[0100] S202: Adjusting a reference voltage of a DC voltage loop in a voltage adjustment direction according to a preset voltage adjustment amplitude.

[0101] In this embodiment, during the process of the input source charging the energy storage module through the power module, the constant voltage state of the power module is a constant voltage floating charge state, and during the process of the energy storage module discharging to the input source through the power module, the constant voltage state of the power module is a constant voltage floating discharge state. The voltage adjustment direction can be determined according to the type of the constant voltage state, wherein the voltage adjustment direction of the constant voltage floating charge state and the voltage adjustment direction of the constant voltage floating discharge state are in opposite directions.

[0102] If the power module is in a constant voltage floating charge state, the voltage adjustment direction is determined to be the first adjustment direction, and the reference voltage of the DC voltage loop is adjusted in the first adjustment direction according to the preset voltage adjustment amplitude, so that the DC voltage loop is proportionally integrated according to the difference between the adjusted reference voltage and the DC current detection parameter, and then the PWM signal controls the energy storage module to discharge through the power module. If the discharge current parameter is detected, it is determined that the energy storage module is online and the energy storage module and the power module are in a non-open circuit state; if 0A is detected, it is determined that the energy storage module is offline and the energy storage module and the power module are in an open circuit state.

[0103] If the power module is in a constant voltage floating state, the voltage adjustment direction is determined to be the second adjustment direction, and the reference voltage of the DC voltage loop is adjusted in the second adjustment direction according to the preset voltage adjustment amplitude, so that after the DC voltage loop is proportionally integrated according to the difference between the adjusted reference voltage and the DC current detection parameter, the PWM signal controls the energy storage module to charge through the power module. If the charging current parameter is detected, it is determined that the energy storage module is online and the energy storage module and the power module are in a non-open circuit state; if 0A is detected, it is determined that the energy storage module is offline and the energy storage module and the power module are in an open circuit state.

[0104] In some embodiments, the DC voltage loop includes a high-voltage DC voltage loop, and the process of determining the voltage adjustment direction according to the type of the constant voltage state in S201 may include:

[0105] If the type of the constant voltage state is a constant voltage charging state, it is determined that the voltage adjustment direction is a downward adjustment direction.

[0106] The process of adjusting the reference voltage of the DC voltage loop in the voltage adjustment direction according to the preset voltage adjustment amplitude in S202 may include:

[0107] The reference voltage of the DC voltage loop is adjusted downward according to the preset voltage adjustment amplitude.

[0108] In this embodiment, Figure 4 A loop block diagram of a dual voltage and current loop provided in an embodiment of the present application, such as Figure 4 As shown, the reference voltage of the high-voltage DC voltage loop is Vdc_max*, and the DC voltage detection parameter is Vdc. When the power module charges the energy storage module, the high-voltage DC voltage loop and the DC current loop compete to obtain the smaller one, and the limiters of the high-voltage DC voltage loop and the DC current loop are respectively used to limit the control current corresponding to the PI output.

[0109] When the power module charges the energy storage module, when the DC voltage detection parameter Vdc is close to Vdc_max*, the power module enters a constant voltage charging state, which can also be called a constant voltage floating charging state, and the DC current detection parameter Idc is close to 0A. At this time, according to the preset voltage adjustment amplitude ΔV, the reference voltage Vdc_max* is lowered to Vdc_max*-ΔV, so that the high-voltage DC voltage loop is negatively saturated, that is, the energy storage module is controlled to discharge to the power module.

[0110] For example, Vdc_max* is set to 1000V. After the power module enters the constant voltage charging state, Vdc_max* is controlled to be lowered to 990V. After proportional integration is performed based on the difference between the lowered Vdc_max* and Vdc, a control current of -10A is output through the limiter. If the DC current detection parameter Idc between the power module and the energy storage module is detected to be -10A at this time, and the DC voltage detection parameter Vdc is approximately unchanged, it is determined that the energy storage module is online, and the energy storage module and the power module are in a non-open circuit state. If it is detected that the DC current detection parameter Idc is still maintained within the current range of the constant voltage charging state, or the DC voltage detection parameter Vdc is adjusted to 990V, it is determined that the bus capacitor Cdc on the DC side of the power module is discharged, the energy storage module is offline, and the energy storage module and the power module are in an open circuit state.

[0111] In some other embodiments, the DC voltage loop further includes a low voltage DC voltage loop, and the process of determining the voltage adjustment direction according to the type of the constant voltage state in S201 may include:

[0112] If the type of the constant voltage state is the constant voltage discharge state, it is determined that the voltage adjustment direction is an upward adjustment direction.

[0113] The process of adjusting the reference voltage of the DC voltage loop in the voltage adjustment direction according to the preset voltage adjustment amplitude in S202 may include:

[0114] The reference voltage of the DC voltage loop is adjusted upward according to a preset voltage adjustment amplitude.

[0115] In this embodiment, if Figure 4 As shown, the reference voltage of the low-voltage DC voltage loop is Vdc_min*, and the DC voltage detection parameter is Vdc. When the energy storage module discharges to the power module, the low-voltage DC voltage loop and the DC current loop compete to obtain the larger one, and the limiters of the low-voltage DC voltage loop and the DC current loop are respectively used to limit the control current corresponding to the PI output.

[0116] When the energy storage module discharges electricity to the power module, when the DC voltage detection parameter Vdc is close to Vdc_min*, the power module enters a constant voltage discharge state, which can also be called a constant voltage floating state, and the DC current detection parameter Idc is close to 0A. At this time, according to the preset voltage adjustment amplitude ΔV, the reference voltage Vdc_min* is increased to Vdc_min*+ΔV, so that the low-voltage DC voltage loop is forward saturated, that is, the power module is controlled to charge the energy storage module.

[0117] For example, Vdc_min* is set to 700V. After the power module enters the constant voltage discharge state, Vdc_min* is controlled to be increased to 710V. After proportional integration is performed based on the difference between the increased Vdc_min* and Vdc, a control current of 10A is output through the limiter. If it is detected that the DC current detection parameter Idc between the power module and the energy storage module is 10A and the DC voltage detection parameter Vdc is approximately unchanged at this time, it is determined that the energy storage module is online and the energy storage module and the power module are in a non-open circuit state. If it is detected that the DC current detection parameter Idc is still maintained within the current range of the constant voltage discharge state, or the DC voltage detection parameter Vdc is adjusted to 710V, it is determined that the bus capacitor Cdc on the DC side is charged by the power module, the energy storage module is offline, and the energy storage module and the power module are in an open circuit state.

[0118] The energy storage module open circuit detection method provided in the above embodiment can perform open circuit detection on the situation where the bidirectional power converter and the energy storage module are charging or discharging, so as to effectively identify whether the energy storage module has an offline fault in the constant voltage charging state or the constant voltage discharging state, thereby ensuring the safe operation of the system.

[0119] In a possible implementation, the method may further include:

[0120] If the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state, the reference voltage of the DC voltage loop is restored.

[0121] In this embodiment, if it is detected that the energy storage module is online, that is, the energy storage module and the power module are in a non-open circuit state, the reference voltage of the DC voltage loop can be restored to a value between 20 and 25, so that the open circuit detection can be performed again after a period of time, thereby realizing disturbance detection of the open circuit state of the energy storage module.

[0122] In some embodiments, Figure 5 The open circuit detection disturbance waveform diagram provided in the embodiment of the present application is as follows: Figure 5 As shown, the specific working principle of open circuit detection and amplification of the energy storage module provided by this solution is:

[0123] 1) In the time period of 0 to t0, detect whether the dual voltage current loop enters the high voltage limiting loop state or the low voltage limiting loop state, that is, the constant voltage charging state or the constant voltage discharging state. If so, it is determined that the energy storage module enters the blind area of ​​online and offline detection, that is, it is impossible to determine whether the energy storage module is open based on the DC current detection parameters.

[0124] 2) In the time period t0-t1, when the dual voltage current loop enters the high-voltage voltage limiting loop state, Vdc_max* is adjusted to Vdc_max*-ΔV, where ΔV can be 10V, for example. After a delay of a period of time to ensure that the power module enters a steady state, the DC current detection parameter Idc is detected to be the target current parameter, or whether it exits the current parameter range of the constant voltage charging state. If the DC current detection parameter Idc is 0A, or does not exit the current parameter range of the constant voltage charging state, it is determined that the energy storage module is offline, and the energy storage module and the power module are in an open circuit state; if the DC current detection parameter Idc is -10A, or exits the current parameter range of the constant voltage charging state, it is determined that the energy storage module is online, and the energy storage module and the power module are not in an open circuit state.

[0125] Similarly, when the dual voltage current loop enters the low voltage limiting loop state, Vdc_min* is adjusted to Vdc_min*+ΔV, where ΔV can be 10V, for example. After a delay of a period of time to ensure that the power module enters a steady state, the DC current detection parameter Idc is detected to be the target current parameter, or whether it exits the current parameter range of the constant voltage discharge state. If the DC current detection parameter Idc is 0A, or has not exited the current parameter range of the constant voltage discharge state, it is determined that the energy storage module is offline, and the energy storage module and the power module are in an open circuit state; if the DC current detection parameter Idc is 10A, or has exited the current parameter range of the constant voltage charging state, it is determined that the energy storage module is online, and the energy storage module and the power module are not in an open circuit state.

[0126] If the energy storage module is online normally, Vdc_max*-ΔV is readjusted to Vdc_max*, and Vdc_min*+ΔV is readjusted to Vdc_min*.

[0127] It should be noted that no matter whether the dual voltage current loop enters the high-voltage voltage-limiting loop state or the low-voltage voltage-limiting loop state, it can actually only be in one of the loop states, and the difference between the high-voltage reference voltage adjustment range and the low-voltage reference voltage adjustment range is large, which is much larger than the preset voltage adjustment amplitude ΔV, that is, Vdc_max*-ΔV is greater than Vdc_min*+ΔV. Therefore, after entering the constant voltage state, you can choose to adjust Vdc_max* to Vdc_max*-ΔV and Vdc_min* to Vdc_min*+ΔV at the same time, and then detect the DC current detection parameter Idc to determine whether the energy storage module is online or offline, thereby determining whether the energy storage module and the power module are in an open circuit state.

[0128] 3) During the time period t1-t2, if the energy storage module is detected to be online during the time period t0-t1, and the reference voltage of the DC voltage loop is restored, in order not to frequently disturb the energy transmission between the power module and the energy storage module, a dead time t1-t2 is set, and the energy storage module is not open-circuited during this time period. This time period can be, for example, 5 minutes.

[0129] 4) After the time period t2, the open circuit detection of the energy storage module is entered again.

[0130] On the basis of the above method embodiment, the embodiment of the present application further provides an energy storage module open circuit detection device, which is applied to a control unit in a power conversion device, wherein the power conversion device also includes: a power module and an energy storage module, wherein the control unit is connected to the power module, and the DC end of the power module is connected to the energy storage module. Figure 6 A schematic diagram of the structure of the energy storage module open circuit detection device provided in the embodiment of the present application is shown in FIG. Figure 6 As shown, the device may include:

[0131] A judging module 301 is used to judge whether the power module is in a constant voltage state;

[0132] The adjustment module 302 is used to adjust the reference voltage of the DC voltage loop when the power module enters the constant voltage state, so as to control the power module by using the DC voltage detection parameter of the power module and the adjusted reference voltage;

[0133] An acquisition module 303 is used to acquire a DC detection parameter of the power module under control based on the adjusted reference voltage;

[0134] The detection module 304 is used to perform an open circuit detection on the energy storage module according to the DC detection parameter to obtain an open circuit detection result, and the open circuit detection result is used to indicate whether the energy storage module and the power module are in an open circuit state.

[0135] Optionally, the detection module 304 is specifically used to determine that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state if the DC current detection parameter is equal to the target current parameter output by the DC voltage loop according to the adjusted reference voltage; if the DC current detection parameter is equal to 0, determine that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

[0136] Optionally, the detection module 604 is specifically used to determine that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state if the DC current detection parameter exits the current range of the constant voltage state; if the DC current detection parameter does not exit the current range of the constant voltage state, determine that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

[0137] Optionally, the judgment module 301 is specifically configured to determine whether the power module enters a constant voltage state according to the working states of the DC current loop and the DC voltage loop.

[0138] Optionally, the power module is a bidirectional power converter, and the adjustment module 302 is specifically used to determine the voltage adjustment direction according to the type of constant voltage state; and adjust the reference voltage of the DC voltage loop in the voltage adjustment direction according to a preset voltage adjustment amplitude.

[0139] Optionally, the DC voltage loop includes a high-voltage DC voltage loop, and the adjustment module 302 is specifically used to determine that the voltage adjustment direction is a downward direction if the type of the constant voltage state is a constant voltage charging state; and to reduce the reference voltage of the DC voltage loop according to a preset voltage adjustment amplitude.

[0140] Optionally, the DC voltage loop also includes: a low voltage DC current loop, an adjustment module 302, and is also used to determine that the voltage adjustment direction is an upward direction if the constant voltage state type is a constant voltage discharge state; and increase the reference voltage of the DC voltage loop according to a preset voltage adjustment amplitude.

[0141] Optionally, the adjustment module 302 is further configured to restore the reference voltage of the DC voltage loop if the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state.

[0142] The above-mentioned device is used to execute the method provided by the aforementioned embodiment, and its implementation principle and technical effect are similar, which will not be repeated here.

[0143] The above modules may be one or more integrated circuits configured to implement the above methods, such as one or more application specific integrated circuits (ASICs), or one or more microprocessors, or one or more field programmable gate arrays (FPGAs). For another example, when a module is implemented in the form of a processing element scheduling program code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0144] Figure 7 A schematic diagram of a control unit provided in an embodiment of the present application, such as Figure 7 As shown, the control unit 10 includes: a processor 11, a storage medium 12 and a bus, the storage medium 12 stores program instructions executable by the processor 11, when the control unit 10 is running, the processor 11 and the storage medium 12 communicate through the bus, and the processor 11 executes the program instructions to execute the above method embodiment. The specific implementation method and technical effect are similar and will not be repeated here.

[0145] Optionally, the present application further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the above method embodiment is executed.

[0146] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0147] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0148] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0149] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (English: processor) to perform some steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (English: Read-Only Memory, abbreviated: ROM), random access memory (English: Random Access Memory, abbreviated: RAM), disk or optical disk and other media that can store program codes.

[0150] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for detecting an open circuit of an energy storage module, characterized in that: A control unit applied to a power conversion device, wherein the power conversion device further comprises: a power module and an energy storage module, wherein the control unit is connected to the power module, and the DC end of the power module is connected to the energy storage module, and the method comprises: Determining whether the power module is in a constant voltage state; When the power module enters a constant voltage state, adjusting the reference voltage of the DC voltage loop, so as to control the power module using the DC voltage detection parameter of the power module and the adjusted reference voltage; Acquiring a DC detection parameter of the power module under control of the adjusted reference voltage; According to the DC detection parameter, an open circuit detection is performed on the energy storage module to obtain an open circuit detection result, and the open circuit detection result is used to indicate whether the energy storage module and the power module are in an open circuit state.

2. The method according to claim 1, characterized in that The step of performing an open circuit detection on the energy storage module according to the DC detection parameter to obtain an open circuit detection result includes: If the DC current detection parameter is equal to the target current parameter output by the DC voltage loop according to the adjusted reference voltage, determining that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state; If the DC current detection parameter is equal to a preset small current value, it is determined that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

3. The method according to claim 1, characterized in that The step of performing an open circuit detection on the energy storage module according to the DC detection parameter to obtain an open circuit detection result includes: If the DC current detection parameter exits the current range of the constant voltage state, determining that the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state; If the DC current detection parameter does not exit the current range of the constant voltage state, it is determined that the open circuit detection result indicates that the energy storage module and the power module are in an open circuit state.

4. The method according to claim 1, characterized in that The determining whether the power module is in a constant voltage state includes: Whether the power module enters a constant voltage state is determined according to the working states of the DC current loop and the DC voltage loop.

5. The method according to claim 1, characterized in that The power module is a bidirectional power converter, and when the power module enters a constant voltage state, adjusting the reference voltage of the DC voltage loop includes: Determining a voltage adjustment direction according to the type of the constant voltage state; According to a preset voltage adjustment amplitude, the reference voltage of the DC voltage loop is adjusted in the voltage adjustment direction.

6. The method according to claim 5, characterized in that The DC voltage loop includes a high-voltage DC voltage loop, and the voltage adjustment direction is determined according to the type of the constant voltage state, including: If the type of the constant voltage state is a constant voltage charging state, determining that the voltage adjustment direction is a downward adjustment direction; The step of adjusting the reference voltage of the DC voltage loop in the voltage adjustment direction according to the preset voltage adjustment amplitude includes: According to the preset voltage adjustment amplitude, the reference voltage of the DC voltage loop is adjusted downward.

7. The method according to claim 5, characterized in that The DC voltage loop further includes: a low voltage DC current loop, and the voltage adjustment direction is determined according to the type of the constant voltage state, including: If the type of the constant voltage state is a constant voltage discharge state, determining that the voltage adjustment direction is an upward adjustment direction; The step of adjusting the reference voltage of the DC voltage loop in the voltage adjustment direction according to the preset voltage adjustment amplitude includes: According to the preset voltage adjustment amplitude, the reference voltage of the DC voltage loop is increased.

8. The method according to claim 1, characterized in that The method further comprises: If the open circuit detection result indicates that the energy storage module and the power module are in a non-open circuit state, the reference voltage of the DC voltage loop is restored.

9. An energy storage module open circuit detection device, characterized in that: A control unit applied to a power conversion device, wherein the power conversion device further includes: a power module and an energy storage module, wherein the control unit is connected to the power module, and the DC end of the power module is connected to the energy storage module, and the device includes: A judging module, used for judging whether the power module is in a constant voltage state; An adjustment module, used for adjusting the reference voltage of the DC voltage loop when the power module enters a constant voltage state, so as to control the power module by using the DC voltage detection parameter of the power module and the adjusted reference voltage; An acquisition module, used for acquiring a DC detection parameter of the power module under the control of the adjusted reference voltage; The detection module is used to perform an open circuit detection on the energy storage module according to the DC detection parameter to obtain an open circuit detection result, wherein the open circuit detection result is used to indicate whether the energy storage module and the power module are in an open circuit state.

10. A power conversion device, characterized in that: The power conversion device includes: a control unit, a power module and an energy storage module, the control unit is connected to the power module, the DC end of the power module is connected to the energy storage module, and the control unit is used to execute the steps of the energy storage module open circuit detection method as described in any one of claims 1-8.

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