A DC-side starting control circuit and method for a power conversion device

Abstract

An embodiment of the present application provides a DC-side starting control circuit, method, and control unit for a power conversion device, which relates to the technical field of charge and discharge power conversion. The method includes: when it is detected that the outer voltage value is in a first interval, controlling the output voltage value of the power conversion device to softly rise to the outer voltage value, where the lower limit of the first interval is a positive value close to 0V, and the upper limit is the highest voltage allowed by the power conversion device; after the output voltage value of the power conversion device reaches the outer voltage value through soft start, first turn off the drive of the power conversion device, and then control the main switch module to close; start a delay when the control signal for controlling the main switch module to close is issued, delay for a set first time, and then control the output current of the power conversion device to softly rise. By detecting the outer voltage, controlling the inner soft start to charge the output capacitor, and then closing the main switch module, it is possible to adapt to higher-voltage charge and discharge starting without the need to equip a current-limiting resistor.

Description

Technical Field

[0001] The present application relates to the technical field of charging and discharging power conversion, and particularly to a starting control circuit and method for the DC side of a power conversion device. Background Art

[0002] The prior art provides a charging and discharging circuit, as Figure 1 shown, which can be used for electric vehicle charging and discharging. On the left side is the input voltage Vin. After passing through the power conversion device, electrical energy is stored in the battery Vbat; or the energy of Vbat is released to the Vin side.

[0003] In order to avoid excessive charging current at the moment of closing the relay contact switch S1, which affects the service life of the output capacitor C1; and to avoid damage to the contacts due to arcing when the S1 contacts are attracted with voltage, or negative impacts on the relay life or surrounding functional circuits, the prior art usually connects a soft start resistor R1 in parallel at both ends of S1. Vbat first charges the output capacitor C1 through R1, causing the voltage of the output capacitor C1 to rise slowly and reducing the current magnitude at the moment of starting charging; in addition, when the output is short-circuited, R1 can also play a certain current-limiting role; after the voltage of C1 is stable, S1 is closed. At this time, the voltage difference across the contacts is very small, and there is no negative impact on the relay life. However, when Vbat is reverse-connected, the battery will form a path through Vbat+—>C1—>R1—>Vbat-. Since C1 is generally an electrolytic capacitor and can withstand very little negative voltage, C1 will be damaged when reverse-connected. For this reason, the prior art provides another charging and discharging circuit, as Figure 2 , a diode D1 is connected in series in the path of the soft start resistor R1 to prevent C1 from being damaged when reverse-connected.

[0004] However Figure 1 and Figure 2 both charging and discharging circuits still have the following problems:

[0005] 1. The power conversion device and the battery are always connected. When the power converter is in the standby state, if an internal short circuit occurs, the battery can only be protected by burning out R1 or D1;

[0006] 2. Both C1 and the power conversion device have equivalent internal resistances. Therefore, when the system is in the standby state, if Vbat always exists, it will always be in a small current discharge state, causing energy loss;

[0007] 3. Although the slow charging of C1 can be achieved through R1, the current at the moment of Vbat access = Vbat / R1. At this time, the magnitude of the current is highly related to the battery voltage and the current-limiting resistor. With the continuous popularization of high-voltage fast charging technology and the increasing voltage level, in order to limit the instantaneous current, only the resistance value and power of the current-limiting resistor can be increased.

[0008] Therefore, how to adapt to the soft start function of charging and discharging at a higher voltage is a technical problem to be solved. Summary of the Invention

[0009] The purpose of this application is to provide a starting control circuit, method, and control unit for the DC side of a power conversion device to solve the technical problem of adapting to the soft start function of charging and discharging at a higher voltage in the prior art.

[0010] To achieve the above purpose, the embodiments of this application have taken the following technical solutions.

[0011] In a first aspect, the embodiments of this application provide a starting control circuit for the DC side of a power conversion device, including a power conversion device, a positive line, a negative line, an inner voltage sampling module, an outer voltage sampling module, an output current sampling module, an output capacitor, a main switch module, and a control unit.

[0012] The connection relationship is described as follows: The input end of the power conversion device is used to connect to an input power supply;

[0013] The positive line is electrically connected to the positive output end of the power conversion device, the positive electrode of the output capacitor, the positive electrode of the inner voltage sampling module, and the positive electrode of the outer voltage sampling module, and the positive line is used to be electrically connected to the positive electrode of the battery;

[0014] The negative line is electrically connected to the negative output end of the power conversion device, the negative electrode of the output capacitor, the negative electrode of the inner voltage sampling module, and the negative electrode of the outer voltage sampling module, and the negative line is used to be electrically connected to the negative electrode of the battery;

[0015] The output current sampling module is located in the positive line or the negative line;

[0016] The main switch module is located in the positive line or the negative line and is located between the outer voltage sampling module and the inner voltage sampling module;

[0017] The input end of the control unit is electrically connected to the sampling ends of the output current sampling module, the inner voltage sampling module, and the outer voltage sampling module respectively.

[0018] Among them, the outer voltage sampling module is used to detect the outer voltage, the inner voltage sampling module is used to detect the output voltage of the power conversion device, and the control unit is used to control the output voltage value of the power conversion device to softly rise to the outer voltage value when the detected outer voltage value is in a first interval. The lower limit of the first interval is a positive value close to 0V, and the upper limit is the highest voltage allowed by the power conversion device.

[0019] Optionally, the starting control circuit on the DC side of the power conversion device further includes a soft-start resistor and a soft-start switch module. The soft-start resistor and the soft-start switch module are connected in series to form a soft-start module, and both ends of the soft-start module are connected in parallel with the main switch module.

[0020] In a second aspect, an embodiment of the present application provides a starting control method for the DC side of a power conversion device, which is applied to the starting control circuit on the DC side of the power conversion device in the first aspect. The method includes:

[0021] S1-1. When it is detected that the external voltage value is in the first interval, control the output voltage value of the power conversion device to soft-start to the external voltage value. The lower limit of the first interval is a positive value close to 0V, and the upper limit is the highest voltage allowed by the power conversion device;

[0022] S1-2. After the output voltage value of the power conversion device reaches the external voltage value through soft-start, first turn off the drive of the power conversion device, and then control the main switch module to close;

[0023] S1-3. Start a delay when the control signal for controlling the main switch module to close is issued. When the delay reaches the set first time, then control the output current of the power conversion device to soft-start. The first time is used to ensure that the main switch module completes the closing action.

[0024] Optionally, the method further includes:

[0025] S2-1. When it is detected that the external voltage value is in the second interval, assign and set the target output voltage value of the power conversion device to the first external voltage value, and control the main switch module to close. The upper limit of the second interval is a positive value close to 0V, and the lower limit is a negative value close to 0V;

[0026] S2-2. Start a delay when the control signal for controlling the main switch module to close is issued. When the delay reaches the set second time, control the output current of the power conversion device to soft-start, and control the output voltage of the power conversion device to soft-start to the target output voltage value. The second time is used to ensure that the main switch module completes the closing action.

[0027] Optionally, the method further includes:

[0028] When it is detected that the external voltage value is greater than the preset maximum voltage value or less than the preset reverse connection voltage value, report an output terminal fault to avoid starting up.

[0029] Optionally, the starting control circuit on the DC side of the power conversion device further includes a soft-start resistor and a soft-start switch module. The soft-start resistor and the soft-start switch module are connected in series to form a soft-start module, and both ends of the soft-start module are connected in parallel with the main switch module. Step S1-2 includes: when the output voltage value of the power conversion device reaches the outer voltage value through soft start, first turn off the drive of the power conversion device, then control the soft-start switch module to close, start a delay when the control signal for controlling the soft-start switch module to close is issued, and when the delay reaches the set soft-start time, then control the main switch module to close.

[0030] Optionally, the battery is located in the battery terminal device, and the control unit is communicatively connected to the battery terminal device; the method includes: S3. Comparing the signals collected inside the battery terminal device with at least one of the detected inner voltage value, outer voltage value, and output current value to determine whether a fault has occurred.

[0031] Optionally, in the battery terminal device, a connected relay is provided at at least one end of the battery; step S3 includes: determining whether the relay has a sticking fault according to the comparison result between the signal collected inside the battery terminal device and the inner voltage value or the outer voltage value.

[0032] In a third aspect, a computer-readable storage medium stores a computer program or instruction, and when the computer program or instruction is executed by a computing device, the starting control method for the DC side of the power conversion device in the second aspect is implemented.

[0033] In a fourth aspect, an embodiment of the present application provides a control unit, including a memory and a processor, the memory is electrically connected to the processor, the memory stores an executable program, and when the processor executes the executable program, the starting control method for the DC side of the power conversion device in the second aspect is implemented.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] The starting control circuit, method, and control unit for the DC side of the power conversion device provided by the embodiments of the present application can, when the outer voltage sampling module detects the voltage of the connected battery, control the power conversion device by the control unit to gradually increase the inner voltage to the voltage of the battery. At this time, when the main switch module is closed again, excessive current and contact arcs will not be generated due to too large a voltage difference, and it is possible to adapt to the soft-start requirements for charging and discharging at higher voltages without the need to equip a current-limiting resistor. Description of the Drawings

[0036] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as a limitation of the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0037] Figure 1 It is a schematic diagram of a charge and discharge circuit in the prior art;

[0038] Figure 2 It is a schematic diagram of a charge and discharge circuit with reverse connection prevention in the prior art;

[0039] Figure 3 It is a schematic diagram of a starting control circuit for the DC side of a power conversion device provided by an embodiment of the present application;

[0040] Figure 4 It is a schematic diagram of an operational amplifier module provided by an embodiment of the present application;

[0041] Figure 5 It is a schematic diagram of a peripheral circuit connected to the DC side of the system provided by an embodiment of the present application;

[0042] Figure 6 It is a schematic diagram of a starting control circuit for the DC side of a power conversion device with a soft start module provided by an embodiment of the present application;

[0043] Figure 7 It is a schematic diagram of a starting control method for the DC side of a power conversion device under the condition of having an external voltage provided by an embodiment of the present application;

[0044] Figure 8 It is a schematic diagram of a starting control method for the DC side of a power conversion device under the condition of not having an external voltage provided by an embodiment of the present application;

[0045] Figure 9 It is a schematic diagram of a starting control method for the DC side of a power conversion device with more comprehensive functions provided by an embodiment of the present application;

[0046] Figure 10 It is a schematic diagram of a starting control method for the DC side of a power conversion device with a soft start module provided by an embodiment of the present application.

[0047] Description of reference numerals:

[0048] 10 - Power conversion device

[0049] 20 - Inner voltage sampling module

[0050] 30 - Outer voltage sampling module

[0051] 40 - Output current sampling module

[0052] 50 - Control unit Detailed implementation manners

[0053] To make the objectives, 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 with reference to the accompanying drawings in the embodiments of the present application. The described embodiments are some but not all of the embodiments of the present application. Usually, the components of the embodiments of the present application described in the accompanying drawings here can be arranged and designed in various different configurations.

[0054] 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 claimed, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0055] In the description of the present application, it should be noted that relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. The term "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium.

[0056] The existing power startup circuit needs to be equipped with a current-limiting resistor with a large resistance value and high power to achieve a smooth startup of high-voltage charge and discharge.

[0057] To overcome the above problems, refer to Figure 3 , the embodiment of the present application provides a DC-side starting control circuit for a power conversion device, including a power conversion device 10, a positive line, a negative line, an inner voltage sampling module 20, an outer voltage sampling module 30, an output current sampling module 40, an output capacitor C1, a main switch module S1, and a control unit 50. The connection relationship is as follows:

[0058] The input end of the power conversion device 10 is used to connect to an input power source;

[0059] The positive line is electrically connected to the positive output end of the power conversion device 10, the positive pole of the output capacitor C1, the positive pole of the inner voltage sampling module 20, and the positive pole of the outer voltage sampling module 30 respectively, and the positive line is used to be electrically connected to the positive pole of the battery;

[0060] The negative electrode line is electrically connected to the negative output terminal of the power conversion device 10, the negative electrode of the output capacitor, the negative electrode of the inner voltage sampling module 20, and the negative electrode of the outer voltage sampling module 30 respectively. The negative electrode line is used to be electrically connected to the negative electrode of the battery;

[0061] The output current sampling module 40 is located in the positive electrode line or the negative electrode line;

[0062] The main switch module S1 is located in the positive electrode line or the negative electrode line, and is located between the outer voltage sampling module 30 and the inner voltage sampling module 20;

[0063] The input terminals of the control unit 50 are electrically connected to the sampling terminals of the output current sampling module 40, the sampling terminal of the inner voltage sampling module 20, and the sampling terminal of the outer voltage sampling module 30 respectively.

[0064] The starting control circuit on the DC side of this power conversion device can disconnect the main switch module S1 through control, and can achieve a complete disconnection of the output capacitor C1 and the battery in the standby state, thereby solving problems 1 and 2 described in the background technology. That is, if a short - circuit problem occurs, the control unit 50 can detect that the current is too large according to the output current sampling module 40, and then disconnect the main switch module S1 to solve problem 1. In the standby state, the main switch module S1 can be directly disconnected, and there is no loop operation, so there is no small - current discharge, solving problem 2.

[0065] The voltage of the connected battery is detected by the outer voltage sampling module 30, and then the inner voltage is controlled to gradually rise to the voltage of the battery. When the inner voltage sampling module 20 detects that the inner voltage reaches the voltage of the battery, the main switch module S1 is then closed. In this way, excessive current and contact arc will not be generated due to too large a voltage difference, and it can adapt to charging and discharging at higher voltages without being equipped with a current - limiting resistor, solving problem 3 described in the background technology. The output capacitor plays a filtering role.

[0066] For the specific way of controlling the gradual rise of the inner voltage, it can be set according to the specific circuit principle. For example, there is a BUCK circuit with an output voltage of 0 - 200V inside the power conversion device, and the duty ratio of the BUCK circuit can be controlled to step - by - step rise within a certain period of time. When it is necessary to output 100V, the duty ratio can be stepped up from 0 to 50% within 1s. It can be specifically set according to needs.

[0067] In addition, the outer voltage sampling module can also be used to judge whether the externally connected voltage is too large or reversed. This circuit can realize the detection function of over - voltage and reverse - connection faults at the outer port.

[0068] Figure 3A implementation manner of the inner voltage sampling module and the outer voltage sampling module is given. It can be seen that the inner voltage sampling module and / or the outer voltage sampling module includes at least two resistors connected in series, and the connection point of the two resistors is the sampling terminal.

[0069] The sampling terminal of the inner voltage sampling module 20 and the sampling terminal of the outer voltage sampling module 30 can both be electrically connected to the control unit 50 through an operational amplifier module. For example, Figure 4 , it can be set that the operational amplifier module includes an operational amplifier, a non-inverting resistor R 1,1 , an inverting resistor R 1,2 , a grounding resistor R 2,1 , a feedback resistor R 2,2 , an output resistor R 3,1 , an output power supply resistor R 4,1 , a reference power supply V ref and an output capacitor. Among them, it can be set that the resistance values of the non-inverting resistor R 1,1 and the inverting resistor R 1,2 are equal, and the resistance values of the grounding resistor R 2,1 and the feedback resistor R 2,2 are equal.

[0070] In addition to the connection and amplification functions, the operational amplifier module can also play the following roles:

[0071] Function 1: Set in the outer voltage sampling module. If a positive voltage is sampled, it is determined that the external connection state is normal, and then the function of starting the device with voltage is realized;

[0072] Function 2: Set in the outer voltage sampling module. When the external voltage exceeds the maximum voltage allowed by the device, protection can also be realized to avoid damaging the components inside the starting control circuit of the DC side of the power conversion device;

[0073] Function 3: Set in the outer voltage sampling module. If a negative voltage is sampled, reverse connection protection of the external voltage can be realized;

[0074] Function 4: As Figure 5 shown, the left box 100 is the starting control circuit of the DC side of the power conversion device, and the right box 200 is the circuit in the battery terminal device. After adding this operational amplifier module to the inner or outer voltage sampling module, the upper monitoring unit or power distribution unit in the battery terminal device can directly obtain the sampling value through communication and compare it with its own battery voltage sampling value to realize the adhesion detection of the relays S3 and S4 on the battery side (relay adhesion faults are divided into two types: cannot be attracted and cannot be disconnected). The circuit in the battery terminal device can omit this operational amplifier module.

[0075] Figure 5The control unit 50 is communicatively connected to the battery terminal device, and compares the signals collected inside the battery terminal device with at least one of the detected inner voltage value, outer voltage value, and output current value to determine whether a fault has occurred. The comparison can be performed by the control unit 50, or by the upper monitoring unit or power distribution unit in the battery device.

[0076] According to the comparison result between the signal collected inside the battery terminal device and the inner voltage value or outer voltage value, it is determined whether the relay in the battery terminal device has an adhesion fault. When the battery voltage sampled by the battery terminal device has a large difference from the inner voltage value or outer voltage value, that is, when the difference reaches the threshold, it can be determined that the relay has an adhesion fault.

[0077] Figure 6 An embodiment with a soft start resistor and a soft start switch module is given, that is, on the basis of Figure 3 a soft start resistor R3 and a soft start switch module S2 are added to form Figure 6 , the soft start resistor R3 and the soft start switch module S2 are connected in series to form a soft start module, and both ends of the soft start module are connected in parallel with the main switch module. The soft start module and the main switch module can be relays.

[0078] The embodiment with a soft start module can better ensure that the current at the moment of closing is not too large and avoid arcs, etc. Specifically, the current at the moment of closing S2 = (Vbat - Vo) / R1. If Vo is controlled to approach Vbat, the current will approach 0.

[0079] The embodiment of the present application also provides a method for controlling the starting of the DC side of a power conversion device, which is applied to the control unit in the control circuit for starting the DC side of the above-mentioned power conversion device, such as Figure 7 , the method includes:

[0080] S1-1. When it is detected that the outer voltage value is in the first interval, control the output voltage value of the power conversion device to soft start to the outer voltage value;

[0081] S1-2. After the output voltage value of the power conversion device reaches the outer voltage value through soft start, first turn off the drive of the power conversion device, and then control the main switch module to close;

[0082] S1-3. Start a delay when the control signal for controlling the closing of the main switch module is issued, and when the delay reaches the set first time, then control the output current of the power conversion device to soft start. The first time is used to ensure that the main switch module completes the closing action.

[0083] The lower limit of the first interval is a positive value close to 0V, and the upper limit is the highest voltage allowed by the power conversion device. Here, the first interval represents that a normal battery to be charged is externally connected, that is, starting up with voltage on the outside. To start charging, first slowly raise the output voltage value to be the same as the voltage of the battery, and use this process to charge the output capacitor C1, and then close the main switch module to avoid generating too large a current instantaneously.

[0084] When there is no externally connected battery to be charged, that is, starting up without voltage on the outside, which is different from the above starting process. Refer to Figure 8 and the following steps can be set:

[0085] S2-1. When it is detected that the outside voltage value is in the second interval, assign and set the target output voltage value of the power conversion device to be the first outside voltage value, and control the main switch module to close. The upper limit of the second interval is a positive value close to 0V, and the lower limit is a negative value close to 0V;

[0086] S2-2. Control the main switch module to close and delay for a set second time, control the output current of the power conversion device to soft start, and control the output voltage of the power conversion device to soft start to the target output voltage value.

[0087] In this way, charging of the output capacitor can also be achieved. The first voltage value can be a value preset in the control unit, which can be used to prepare for connecting the battery, or can be used to connect a load without voltage such as a resistor to test devices such as the power conversion device.

[0088] To prevent overvoltage or reverse connection on the outside, when it is detected that the outside voltage value is greater than the preset maximum voltage value or less than the preset reverse connection voltage value, report a fault at the output end and avoid starting up.

[0089] Figure 9 An implementation manner without a soft start module is given. It is preset that V1 < V2 < V3, where V1 is a negative value close to 0V (the V1 voltage is selected as a negative value as close to 0V as possible according to the negative voltage sampling range and accuracy of the sampling circuit), V2 is a positive value close to 0V, and V3 is the highest voltage allowed by the power conversion device. The first interval can be from V2 to V3, the second interval can be from V1 to V2, the preset maximum voltage value can refer to V3, and the preset reverse connection voltage value can refer to V1. Set the first time as t2, and the second time can also be set as t2 (it can also be set differently from t2, Figure 9 and in

[0090] the second time is the same as the first time).

[0091] Step 1. When receiving the monitored power-on command, the control unit initializes the relevant power-on status bits;

[0092] Step 2: By judging the magnitude of the voltage sampling value of the outer voltage sampling module, different control logics are selected, which are divided into the following four cases A, B, C, and D:

[0093] A. When the outer voltage > V3 value, the control unit issues an output port reverse connection fault, or reports an output port overvoltage fault to the host computer or monitoring unit, and the module does not perform the relevant logic for subsequent starting;

[0094] B. When V2 < outer voltage ≤ V3 value, it is considered that there is voltage on the outside. At this time, the corresponding logic needs to be executed, reducing the current at the moment when S1 is closed and increasing the service life of the output capacitor C1 (if the soft start switch module S2 and soft start resistor R1 are set, their service lives will also be increased);

[0095] C. When V1 < outer voltage ≤ V2 value, it is considered that there is no voltage on the outside, and the control unit executes the relevant starting logic according to the output no-load or resistive load mode;

[0096] D. When the outer voltage < V1, the control unit issues an output port reverse connection fault, or reports an output port reverse connection fault to the host computer or monitoring unit, and the module does not perform the relevant logic for subsequent starting.

[0097] For B, that is, the starting process with voltage on the outside:

[0098] Step B1: Assign the actually measured outer voltage to the output voltage given value, and the output voltage given value is used as the target output voltage value of the power conversion device;

[0099] Step B2: The internal switching devices of the power conversion device can be controlled to switch, and the output voltage Vo is gradually released in a certain step to realize the soft start process of the output voltage, that is, the output voltage Vo rises slowly;

[0100] Step B3: When the inner voltage sampled by the inner voltage sampling module = the outer voltage, the charging of the output capacitor C1 by the power conversion device is completed, and the drive wave generation of the power conversion device can be turned off; due to the errors of the voltage sampling module and the control unit, the actual voltages of the two cannot be exactly the same. If the front-stage circuit does not stop generating waves, after the main switch module S1 is closed, the power conversion device will directly enter the charging or discharging state, and the devices in the circuit may be over-powered and damaged due to passing through large currents;

[0101] Step B4: Close the main switch module S1; when the main switch module S1 is closed, the voltage difference across its contacts is very small, and at this time, the impact on the main switch module S1 and its peripheral circuit is very small;

[0102] Step B5: Delay for time t2. After the main switch module S1 is fully closed, the set voltage sent by the host computer or monitoring can be assigned to the output voltage set value. If the set voltage is greater than the outer voltage, the power conversion device operates in the charging mode; if the set voltage is less than the outer voltage, the power conversion device operates in the discharging mode.

[0103] Step B6: The control unit gradually releases the output current of the power conversion device in fixed steps until the output current set value is reached, realizing the soft start function of the output current.

[0104] For C, that is, the start-up process without voltage on the outer side:

[0105] Step C1: Assign the set voltage sent by the host computer or monitoring to the output voltage set value, and the set current sent by the host computer or monitoring can also be assigned to the output current set value.

[0106] Step C2: Close S1.

[0107] Step C3: After S1 is fully closed, the controller gradually releases the output voltage and current in fixed steps, realizing the soft start function of the output voltage and output current.

[0108] For the implementation mode with a soft start module, set the soft start time as t1. It can be referred to Figure 10 , and Figure 9 The differences are in Step B4 and Step C2.

[0109] Step B4: Close the soft start switch module S2, delay for time t1. After S2 is fully closed, then close the main switch module S1. Due to sampling error, there is a certain voltage across the contacts of S2 at the moment when S2 is closed. To reduce the impact current caused by this error, the soft start resistor R3 and the soft start switch module S2 are still retained in this scheme.

[0110] For Step C2, to maintain the consistency of the software logic, the opening process of S2 and S1 can be the same as that for starting up with voltage, that is, first close the soft start switch module S2, and then close the main switch module S1.

[0111] Step B7 can also be set after Step B6:

[0112] Step B7: After the soft start of the output current is completed, disconnect the soft start switch module S2.

[0113] Similarly, the soft start switch module S2 can also be disconnected after Step C3.

[0114] Based on the above embodiments, an embodiment of the present application further provides a computer-readable storage medium, in which a computer program or instruction is stored. When the computer program or instruction is executed by a computing device, the above-mentioned DC-side starting control method of the power conversion device is implemented.

[0115] An embodiment of the present application further provides a control unit, including a memory and a processor. The memory is electrically connected to the processor, and an executable program is stored in the memory. When the processor executes the executable program, the above-mentioned DC-side starting control method of the power conversion device is implemented.

[0116] Generally speaking, the present application proposes a DC-side starting control circuit, method and control unit for a power conversion device. By detecting the external voltage and controlling the internal soft start to charge the output capacitor, and then closing the main switch module, it can adapt to charge and discharge at a higher voltage without being equipped with a current-limiting resistor. It can be used for electric vehicle charging and discharging, and can be a circuit in a charging gun.

[0117] The device and system embodiments described above are merely illustrative. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without creative work.

[0118] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A starting control circuit for the DC side of a power conversion device, characterized in that, It includes a power conversion device, a positive line, a negative line, an inner voltage sampling module, an outer voltage sampling module, an output current sampling module, an output capacitor, a main switch module and a control unit; The input end of the power conversion device is used to connect to an input power supply; The positive line is electrically connected to the positive output end of the power conversion device, the positive electrode of the output capacitor, the positive electrode of the inner voltage sampling module and the positive electrode of the outer voltage sampling module respectively, and the positive line is used to be electrically connected to the positive electrode of the battery; The negative line is electrically connected to the negative output end of the power conversion device, the negative electrode of the output capacitor, the negative electrode of the inner voltage sampling module and the negative electrode of the outer voltage sampling module respectively, and the negative line is used to be electrically connected to the negative electrode of the battery; The output current sampling module is located in the positive line or the negative line; The main switch module is located in the positive line or the negative line and is between the outer voltage sampling module and the inner voltage sampling module; The input end of the control unit is electrically connected to the sampling end of the output current sampling module, the sampling end of the inner voltage sampling module and the sampling end of the outer voltage sampling module respectively; The outer voltage sampling module is used to detect the outer voltage, the inner voltage sampling module is used to detect the output voltage of the power conversion device, and when the control unit detects that the outer voltage value is in a first interval, it controls the output voltage value of the power conversion device to softly rise to the outer voltage value. The lower limit of the first interval is a positive value close to 0V, and the upper limit is the highest voltage allowed by the power conversion device.

2. The DC side starting control circuit of the power conversion device according to claim 1, characterized in that, The starting control circuit on the DC side of the power conversion device further includes a soft-start resistor and a soft-start switch module. The soft-start resistor and the soft-start switch module are connected in series to form a soft-start module, and both ends of the soft-start module are connected in parallel with the main switch module.

3. A starting control method for the DC side of a power conversion device, characterized in that, Applied to the control unit in the starting control circuit on the DC side of the power conversion device as described in claim 1, the method includes: S1-1. When it is detected that the outer voltage value is in a first interval, control the output voltage value of the power conversion device to softly rise to the outer voltage value. The lower limit of the first interval is a positive value close to 0V, and the upper limit is the highest voltage allowed by the power conversion device; S1-2. After the output voltage value of the power conversion device reaches the outer voltage value through soft start, first turn off the drive of the power conversion device, and then control the main switch module to close; S1-3. Start a delay when the control signal for controlling the main switch module to close is sent, and when the delay reaches a set first time, then control the output current of the power conversion device to softly rise. The first time is used to ensure that the main switch module completes the closing action.

4. The DC-side starting control method of the power conversion device according to claim 3, wherein The method further includes: S2-1. When it is detected that the outer voltage value is in a second interval, assign the target output voltage value of the power conversion device to a first voltage value, and control the main switch module to close. The upper limit of the second interval is a positive value close to 0V, and the lower limit is a negative value close to 0V; When a control signal for closing the main switch module is issued, start a delay. When the delay reaches a set second time, control the output current of the power conversion device to softly start, and control the output voltage of the power conversion device to softly rise to the target output voltage value. The second time is used to ensure that the main switch module completes the closing operation.

5. The DC-side starting control method of the power conversion device according to claim 3, characterized in that, The method further includes: When it is detected that the outer voltage value is greater than a preset maximum voltage value or less than a preset reverse connection voltage value, report an output terminal fault.

6. The DC side starting control method of the power conversion device according to claim 3, characterized in that, The DC side starting control circuit of the power conversion device further includes a soft start resistor and a soft start switch module. The soft start resistor and the soft start switch module are connected in series to form a soft start module, and both ends of the soft start module are connected in parallel with the main switch module; Step S1-2 includes: when the output voltage value of the power conversion device reaches the outer voltage value after soft start, first turn off the drive of the power conversion device, then control the soft start switch module to close. When a control signal for closing the soft start switch module is issued, start a delay. After the delay reaches a set soft start time, then control the main switch module to close.

7. The DC side starting control method of the power conversion device according to claim 3, characterized in that, The battery is located in the battery terminal device, and the control unit is communicatively connected to the battery terminal device; the method further includes: S3. Compare a signal collected inside the battery terminal device with at least one of the detected inner voltage value, outer voltage value, and output current value to determine whether a fault has occurred.

8. The DC-side starting control method of the power conversion device according to claim 7, characterized in that In the battery terminal device, a relay is connected at at least one end of the battery; Step S3 includes: judging whether the relay has an adhesion fault according to the comparison result of the signal collected inside the battery terminal device and the inner voltage value or the outer voltage value.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program or instruction. When the computer program or instruction is executed by a computing device, the DC side starting control method of the power conversion device according to any one of claims 3-8 is implemented.

10. A control unit, characterized in that, It includes a memory and a processor. The memory is electrically connected to the processor. The memory stores an executable program. When the processor executes the executable program, the DC side starting control method of the power conversion device according to any one of claims 3-8 is implemented.

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