JP2021145429A - Power conversion device - Google Patents

Abstract

To quickly suppress an output current of a second power supply when the output voltage of a power supply system rises during constant current operation of the second power supply in the power supply system in which the second power supply is connected in parallel to a first power supply that outputs a constant voltage.SOLUTION: A power conversion device 101 includes a second power supply 106 connected in parallel to a first power supply 104. A drive unit of the second power supply 106 switches between first control for operating a power conversion unit in a constant current mode based on a current limit value and second control for operating the power conversion unit in a mode different from the constant current mode. The drive unit performs third control to cause the power conversion unit to output a current lower than the current limit value when the output voltage of the second power supply 106 reaches a predetermined rising state during the first control or when a release condition for canceling the constant current mode is satisfied.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a power converter.

In electric vehicles and the like, a technique is adopted in which the voltage of a high-voltage battery (for example, DC 300V) is converted into a low voltage (for example, DC 14V) by a DC-DC converter and supplied to a load. In this type of power conversion device, when the required current of the load of the power supply destination is large, the current capacity of one DC-DC converter may be insufficient. As a countermeasure, for example, it is conceivable to use a plurality of DC-DC converters connected in parallel. Patent Document 1 discloses an example thereof.

Japanese Unexamined Patent Publication No. 2015-144534

The inventor of the present application has assumed a power supply system in which a first power supply that outputs a constant voltage and a second power supply that outputs a constant current are connected in parallel as a power supply system in which a plurality of power supplies are connected in parallel. In this power supply system, there is a concern that the output voltage of the second power supply may exceed the target voltage of the power supply system when the output current of the first power supply drops or stops due to a sudden drop in the load current or the like. In order to suppress such a voltage rise, it is necessary to promptly change the current limit value for performing constant current control to a smaller value. However, in the method of giving a command to change the current limit value by communication, it takes time in the process of transmitting the command, receiving the command, calculating the current limit value, resetting the current limit value, etc., so that the second power supply Output current cannot be suppressed quickly.

The present disclosure discloses that in a power supply system in which a second power supply is connected in parallel to a first power supply that outputs a constant voltage, a second power supply is used when the output voltage of the power supply system rises during constant current operation of the second power supply. One of the purposes is to quickly suppress the output current of.

The power conversion device, which is one of the present disclosures, is
A power conversion device used in a power supply system having a first power supply that outputs a constant voltage based on a first target voltage and the first power supply performs power conversion between a first conductive path and a second conductive path. hand,
A second power source connected in parallel to the first power source between the first conductive path and the second conductive path is provided.
The second power source includes a power conversion unit that performs power conversion between the first conductive path and the second conductive path, and a drive unit that drives the power conversion unit.
The drive unit switches between a first control for operating the power conversion unit in a constant current mode based on a current limit value and a second control for operating the power conversion unit in a mode different from the constant current mode.
The drive unit is lower than the current limit value when the output voltage of the second power supply reaches a predetermined rising state during the first control or when the release condition for canceling the constant current mode is satisfied. A third control is performed to output the current to the power conversion unit.

The power conversion device, which is one of the present disclosures, is a power supply system in which a second power supply is connected in parallel to a first power supply that outputs a constant voltage, and the output voltage of the power supply system during constant current operation of the second power supply. When the voltage rises, the output current of the second power supply can be quickly suppressed.

FIG. 1 is a block diagram schematically illustrating an in-vehicle power supply system including the power conversion device of the first embodiment of the present disclosure. FIG. 2 is a block diagram schematically illustrating the electrical configuration of the power conversion device of the first embodiment. FIG. 3 is a circuit diagram illustrating a specific configuration of a first power conversion unit in the power conversion device of the first embodiment. FIG. 4 is a circuit diagram illustrating a specific configuration of a second power conversion unit in the power conversion device of the first embodiment. FIG. 5 is a functional block diagram showing functions executed by the power supply in-power control unit by blocks. FIG. 6 is a block diagram schematically illustrating the configuration of the control unit in the power conversion device of the first embodiment. FIG. 7 is a flowchart illustrating the flow of control performed by the in-power supply control unit (drive unit) of the second power supply in the power conversion device of the first embodiment. FIG. 8 is a graph in the case where the load current suddenly decreases during the first control (constant current control) in the power conversion device of FIG. FIG. 8 shows the output current value I1 of the first power supply, the output current value I2 of the second power supply, and the total current value Iz when the control unit in the power supply of the second power supply does not perform the third control (current suppression control). It is a graph which shows the relationship. FIG. 9 is a graph relating to the operation of the power conversion device of the first embodiment under the same conditions as in FIG. 8, and is a graph when a sudden decrease in load current occurs during the first control (constant current control). .. FIG. 9 shows the output current value I1 of the first power supply, the output current value I2 of the second power supply, and the total current value Iz when the control unit in the power supply of the second power supply can perform the third control (current suppression control). It is a graph which shows the relationship. FIG. 10 shows the output current value I1 of the first power supply, the output current value I2 of the second power supply, and the total current value Iz when the control unit in the power supply of the second power supply does not perform the third control (current suppression control). It is a graph which shows the relationship. FIG. 10 is a graph when the output current value I1 of the first power supply becomes 0 according to the sudden decrease in the load current. FIG. 11 is a graph relating to the operation of the power conversion device of the first embodiment under the same circumstances as in FIG. FIG. 11 shows the output current value I1 of the first power supply, the output current value I2 of the second power supply, and the total current value Iz when the control unit in the power supply of the second power supply can perform the third control (current suppression control). It is a graph which shows the relationship.

The embodiments of the present disclosure are listed and illustrated below. The features [1] to [12] exemplified below may be combined in any way within a consistent range.

[1] Power conversion used in a power supply system including a first power supply that outputs a constant voltage based on a first target voltage and the first power supply performs power conversion between a first conductive path and a second conductive path. The apparatus includes a second power source connected in parallel to the first power source between the first conductive path and the second conductive path, and the second power source is the first conductive path. It has a power conversion unit that performs power conversion between the second conductive path and a drive unit that drives the power conversion unit, and the drive unit performs the power conversion in a constant current mode based on a current limit value. The first control for operating the unit and the second control for operating the power conversion unit in a mode different from the constant current mode are switched, and the drive unit outputs the second power supply during the first control. A power conversion device that performs a third control to output a current lower than the current limit value to the power conversion unit when the voltage reaches a predetermined rising state or when the release condition for canceling the constant current mode is satisfied. ..

The power conversion device of the above [1] enables the second power supply to perform a constant current operation in a power supply system in which the second power supply is connected in parallel to the first power supply that outputs a constant voltage. Further, the power conversion device described above has a second power conversion device when the output voltage of the power supply system actually rises to a "predetermined rise state" during the first control (control to operate in the constant current mode) of the second power supply. The power supply itself can quickly switch to the third control (control that suppresses the current). Alternatively, the power conversion device described above is in a state in which the output voltage of the power supply system can be increased by satisfying the condition for releasing the constant current mode during the first control (control to operate in the constant current mode) of the second power supply. In some cases, the second power source itself can quickly switch to the third control (control that suppresses the current). That is, this power conversion device suppresses the output current of the second power supply even when there is a concern that the output voltage of the power supply system may rise during the first control of the second power supply (control to operate in the constant current mode). The third control can be quickly shifted to, and the rise in the output voltage of the power supply system can be quickly suppressed.

[2] The power conversion device according to [1], wherein the predetermined rising state is a state in which the output voltage of the second power supply reaches a threshold value during the first control.

The power conversion device of the above [2] more easily realizes a configuration capable of determining whether or not the output voltage of the power supply system has increased during the first control (control to operate in the constant current mode) of the second power supply. can do.

[3] The power conversion device according to [1], wherein the predetermined rising state is a state in which the rate of increase in the output voltage of the second power supply reaches a constant value during the first control.

The power conversion device of the above [3] more accurately determines whether or not the output voltage of the power supply system suddenly rises beyond a predetermined rise during the first control (control to operate in the constant current mode) of the second power supply. I can judge. The shorter the cycle for monitoring the output voltage and the cycle for comparing the output voltage with the threshold value, the higher the responsiveness of the power conversion device, which is advantageous.

[4] The second control is a control for operating the power conversion unit in a constant voltage mode based on a second target voltage higher than the first target voltage, and the drive unit operates when a switching condition is satisfied. The power according to [1], wherein the constant current mode is switched to the constant voltage mode, and the drive unit performs the third control when the constant current mode is switched to the constant voltage mode during the first control. Conversion device.

The power conversion device of the above [4] switches to the constant voltage mode during the first control (control to operate in the constant current mode) of the second power supply, and starts the constant voltage control to output a relatively high second target voltage. In that case, it is possible to quickly shift to the third control. The shorter the calculation cycle for determining which mode is adopted by the power conversion device, the higher the responsiveness and the more advantageous it becomes.

[5] The driving unit performs the first control when the output voltage of the second power supply drops to a predetermined value lower than that in the predetermined rising state during the third control [2] to [2]. 4] The power conversion device according to any one of.

The power conversion device of the above [5] quickly suppresses the output current of the second power supply according to a state in which the output voltage of the power supply system is concerned to rise, and then until the output voltage of the second power supply reaches a predetermined value. The third control (current suppression control) can be continued. Then, this power conversion device can return the second power supply to the first control (constant current control) after confirming that the output voltage of the second power supply is suppressed to a predetermined value.

[6] The second power supply switches from the constant voltage mode to the constant current mode when the second switching condition is satisfied, and the drive unit changes from the constant voltage mode to the constant current mode during the third control. The power conversion device according to [4], wherein the first control is performed when the current is switched to.

The power conversion device of the above [6] outputs a relatively high second target voltage when the constant voltage mode is switched to the constant current mode during the third control (current suppression control) of the second power supply. When the situation is resolved, the third control can be quickly released and the first control can be shifted. The shorter the calculation cycle for determining which mode is adopted by the power conversion device, the higher the responsiveness and the more advantageous it becomes.

[7] The second power supply has a receiving unit that receives a command value from an external device of the second power supply, and the driving unit receives the command received by the receiving unit when performing the first control. The power conversion device according to any one of [1] to [6], which sets the current limit value based on the value.

The power conversion device of the above [7] sets a current limit value based on a command value received by the receiving unit when performing the first control (constant current control). With such a configuration, if there is a concern that the output voltage will rise, if only the method of updating the current limit value based on the command value issued from the outside is adopted, the output voltage will rise. There is a concern that it may take some time before the current limit value is set according to the above. However, in the above power conversion device, the second power supply itself can switch to the third control (current suppression control) according to the situation where there is a concern that the output voltage will rise, so that the switching is caused by a communication delay or the like. Delays are less likely to occur.

[8] The command value is a value corresponding to the total current value supplied by the power supply system or the value of the first current supplied by the first power supply, and the drive unit performs the first control. The power conversion device according to [7], which sets the current limit value according to the total current value or the value of the first current based on the command value.

In the power conversion device of the above [8], the second power supply sets a total current value or a current limit value according to the value of the first current based on communication with the outside when performing the first control (constant current control). Can be set. That is, the power conversion device can adjust the output current of the second power supply by more accurately reflecting the total current value or the value of the first current during the first control (constant current control). .. However, when there is a concern that the output voltage of this power converter will rise, a new command value corresponding to this situation will be transmitted by communication, and the current setting value will be updated according to this command value. Until then, the previous "current limit value according to the total current value or the value of the first current" is maintained. In other words, if no measures are taken for this power converter, there is a concern that it will take time for the output current of the second power supply to be actually suppressed after the situation where there is a concern that the output voltage will rise. be. However, the above-mentioned power conversion device can quickly switch to the third control (current suppression control) by the second power supply itself judging the situation where there is a concern about an increase in the output voltage, which is caused by a communication delay or the like. Therefore, it is possible to suppress an excessive increase in the output voltage due to the delay in updating the current limit value.

[9] The drive unit sets the ratio between the value of the first current and the current limit value to a predetermined ratio based on the total current value or the value of the first current during the first control. The power conversion device according to [8], which sets a current limit value.

In the power conversion device of the above [9], the value of the output current from the first power supply and the value of the output current from the second power supply can be easily maintained at a predetermined ratio during the first control (constant current control). Then, when there is a concern about an increase in the output voltage during the first control (constant current control), the power conversion device suppresses the output current rather than keeping it at the predetermined ratio. Can be prioritized quickly.

[10] The first power supply, the control unit that controls the first power supply and the second power supply, and the first power supply or the control unit transmits the command value [7] to [9]. The power conversion device according to any one of the above.

In the power conversion device of the above [10], the second power supply can set the current limit value by communication with the control unit or the first power supply during the first control (constant current control). Then, when there is a concern about an increase in the output voltage during the first control (constant current control), the second power supply quickly controls the current by determining and driving the second power supply itself. You can switch.

[11] The first power supply includes the first power supply, and the first power supply drives a first power conversion unit that performs power conversion between the first conductive path and the second conductive path, and the first power conversion unit. The second drive unit includes a first drive unit, a detection unit that detects the value of the output current output from the first power conversion unit, and a transmission unit that transmits information that specifies the value of the output current. The power supply includes the power conversion unit which is the second power conversion unit and the drive unit which is the second drive unit, and the reception unit receives at least information specifying the value of the output current and drives the power supply. Described in [10], the unit sets the current limit value so that the ratio between the value of the first current and the current limit value becomes the predetermined ratio based on the specified information during the first control. Power converter.

In the power conversion device of the above [11], the value of the output current from the first power supply and the value of the output current from the second power supply are based on the detection values actually detected by the first power supply during the first control (constant current control). It becomes easier to keep the value of the output current more accurately at a predetermined ratio.

[12] The power conversion device according to any one of [1] to [11], wherein the rated current value of the second power supply is smaller than the rated current value of the first power supply.

The power conversion device of the above [12] can relatively suppress the rated current value of the second power supply, and can perform a characteristic operation by the second power supply whose rated current value is suppressed.

<First Embodiment>
1. 1. Overall Configuration The vehicle-mounted power supply system 100 according to the first embodiment shown in FIG. 1 can function as a vehicle-mounted DC voltage supply system mounted on a vehicle such as an electric vehicle. The power supply system 100 may supply a DC voltage to the load 110. The power supply system 100 includes a power conversion device 101 and a battery 102.

The load 110 may be any electric device mounted on the vehicle, and may be, for example, an accessory device (cell motor, alternator, radiator cooling fan, etc.) necessary for operating the engine or motor. The type of load 110 is not limited, and may include an electric power steering system, an electric parking brake, lighting, a wiper drive unit, a navigation device, and the like.

The battery 102 is, for example, a battery (for example, a secondary battery) that supplies a high voltage (for example, 300 V). The positive electrode terminal on the high potential side of the battery 102 is electrically connected to the first conductive path 11. The negative electrode terminal on the low potential side of the battery 102 is electrically connected to a ground (not shown).

The power conversion device 101 is a device that performs power conversion between the first conductive path 11 and the second conductive path 12. The power conversion device 101 mainly includes a first power supply 104, a second power supply 106, and a control unit 108. The first power source 104 and the second power source 106 are connected in parallel between the first conductive path 11 and the second conductive path 12. As shown in FIG. 2, the first power conversion unit 21 and the second power conversion unit 22 are connected in parallel between the first conductive path 11 and the second conductive path 12. The power conversion device 101 steps down the input voltage input from the battery 102 via the first conductive path 11 and applies an output voltage lower than the voltage of the first conductive path 11 to the second conductive path 12. Can be done.

In this specification, unless otherwise specified, the voltage means the potential difference from the ground. For example, the voltage of the first conductive path 11 means the potential difference between the first conductive path 11 and the ground, and the voltage of the second conductive path 12 means the potential difference between the second conductive path 12 and the ground.

Both the first power supply 104 and the second power supply 106 function as DC-DC converters. The first power supply 104 and the second power supply 106 convert the DC voltage VH input from the battery 102 into predetermined output voltages V1 and V2, respectively, and output the DC voltage VH from their respective output terminals.

The first power source 104 is a device provided between the first conductive path 11 and the second conductive path 12 and capable of performing power conversion so as to output a constant voltage to the second conductive path. As shown in FIG. 2, the first power supply 104 includes a first power conversion unit 21 that performs power conversion, an in-power supply control unit 31 that drives the first power conversion unit 21, an interface unit 61, and a first voltage. It has a value detection unit 41 and a first current value detection unit 51. The in-power supply control unit 31 corresponds to an example of a first drive unit that drives the first power conversion unit 21. In the following description, the interface unit 61 is also referred to as an IF unit 61.

The first power conversion unit 21 is a device that performs power conversion between the first conductive path 11 and the second conductive path 12, and specifically, from the first conductive path 11 via the first input path 71. The operation of converting the input electric power and outputting the electric power to the second conductive path 12 via the first output path 81 is performed. The first input path 71 is a conductive path branched from the first conductive path 11, one end of which is electrically connected to the first conductive path 11 and the other end of which is electrically connected to the first power conversion unit 21. .. One end of the first output path 81 is electrically connected to the first power conversion unit 21, and the other end is electrically connected to the second conductive path 12.

The first power conversion unit 21 is configured as, for example, a full-bridge type isolated DCDC converter as shown in FIG. In FIG. 3, the first voltage value detection unit 41, the first current value detection unit 51, and the like are omitted. The first power conversion unit 21 includes an input circuit unit 21X, a transformer unit 21Y, and an output circuit unit 21Z. The input circuit unit 21X includes a plurality of semiconductor switch elements 21A, 21B, 21C, 21D and a capacitor 21E, and is electrically connected to the primary coil 21F of the transformer unit 21Y. The input circuit unit 21X generates an AC voltage in the primary coil 21F according to the switching operation of the plurality of semiconductor switch elements 21A, 21B, 21C, 21D. The switching operation of the plurality of semiconductor switch elements 21A, 21B, 21C, and 21D is controlled by the in-power supply control unit 31, and specifically, CV (Constant Voltage) control described later is performed. The output circuit section 21Z includes diodes 21J and 21K, an inductor 21L, and a capacitor 21M, is electrically connected to the secondary coil 21G and 21H of the transformer section 21Y, and is an AC voltage applied to the secondary coil 21G and 21H. Is rectified and a DC voltage is output. The first power conversion unit 21 performs voltage conversion by switching operations of the semiconductor switch elements 21A, 21B, 21C, and 21D. The first power conversion unit 21 steps down the input voltage VH (potential difference between the first conductive path 11 and the conductive path 13A on the ground side) applied to the first conductive path 11 and outputs the voltage to the first output path 81. A voltage (potential difference between the first output path 81 and the ground-side conductive path 13B) is generated. The conductive paths 13A and 13B are reference conductive paths maintained at, for example, about 0 V.

As shown in FIG. 2, the first current value detection unit 51 is interposed in the middle of the first output path 81. The first current value detection unit 51 detects the value of the current flowing through the first output path 81 (first current value I1), and inputs a signal indicating the first current value I1 to the in-power supply control unit 31. When the first power conversion unit 21 performs a power conversion operation (specifically, a step-down operation), the first current value detection unit 51 outputs the output current output by the first power conversion unit 21 via the first output path 81. Is detected as the first current value I1. In this example, the first current value detection unit 51 corresponds to an example of the detection unit, and detects the value of the output current (first current value I1) output from the first power conversion unit 21.

The first voltage value detection unit 41 detects the voltage value (first voltage value V1) of the first output path 81, and inputs a signal indicating the first voltage value V1 to the in-power supply control unit 31. When the first power conversion unit 21 performs the power conversion operation, the first voltage value detection unit 41 detects the value of the output voltage applied by the first power conversion unit 21 to the first output path 81 as the first voltage value V1. Then, a signal indicating this output voltage is input to the power supply internal control unit 31.

The IF unit 61 receives the data transmitted from the control unit 108 and inputs the data to the power supply in-power control unit 31. Further, the IF unit 61 can cooperate with the in-power supply control unit 31 to transmit the first current value I1 and the first voltage value V1 acquired by the in-power supply control unit 31 to the control unit 108. The IF unit 61 corresponds to an example of a transmission unit, and has a function of transmitting information for specifying an output current value (first current value I1) output by the first power conversion unit 21. In this example, the information for specifying the output current value (first current value I1) corresponds to an example of the command value. The information for specifying the output current value (first current value I1) may be the output current value (first current value I1) itself, and a constant value is set for the output current value (first current value I1). It may be an added value, or it may be a value obtained by multiplying the output current value (first current value I1) by a constant coefficient.

The in-power supply control unit 31 is configured as a control device having an information processing function, and is configured by, for example, a microcomputer including an internal memory. The internal memory stores a program to be executed by the in-power supply control unit 31, necessary parameters, and the like. The in-power supply control unit 31 can control the first power conversion unit 21 based on the data received from the IF unit 61. For example, the in-power supply control unit 31 calculates a set value required for the operation of the first power conversion unit 21 and sets it in the first power conversion unit 21.

In this configuration, the control unit 108 operates so as to give a constant output voltage target value to the first power supply 104. In the following description, the output voltage target value given to the first power supply 104 by the control unit 108 is also referred to as a “first target voltage”. Further, in the following description, the mode in which a constant target voltage is output by the above CV control is also referred to as a constant voltage mode.

When the first target voltage is given by the control unit 108, the first power supply 104 can perform a voltage conversion operation (step-down operation) so that the voltage of the first output path 81 becomes the first target voltage. Specifically, the in-power supply control unit 31 drives the first power conversion unit 21 so as to output the first target voltage to the first output path 81. The first power conversion unit 21 operates in a constant voltage mode by being driven by the in-power supply control unit 31 (the above-mentioned CV control), steps down the DC voltage VH input from the battery 102, and sets the voltage of the first output path 81 to the above. The voltage conversion operation can be performed so as to be the first target voltage.

Specifically, the in-power supply control unit 31 periodically performs a feedback calculation to update the duty of the PWM signal given to the semiconductor switch elements 21A, 21B, 21C, 21D. The in-power supply control unit 31 calculates the deviation between the first target voltage and the first voltage value V1 (voltage of the first output path 81) detected by the first voltage value detection unit 41 in the feedback calculation of each cycle. do. Then, in the feedback calculation of each cycle, the in-power supply control unit 31 brings the voltage of the first output path 81 closer to the first target voltage by the PI calculation formula or the PID calculation formula based on the deviation and the predetermined gain. Determine the amount of operation (duty increase / decrease). Then, the in-power supply control unit 31 calculates a new duty by adding the operation amount (duty increase / decrease amount) determined in this way to the current control amount (duty before change). In this way, the in-power supply control unit 31 can update the duty of the PWM signal in each cycle by the feedback calculation in each cycle.

The second power source 106 is a device capable of performing power conversion between the first conductive path 11 and the second conductive path 12. As shown in FIG. 2, the second power supply 106 includes a second power conversion unit 22 that performs power conversion, an in-power supply control unit 32 that drives the second power conversion unit 22, an interface unit 62, and a second voltage. It has a value detecting unit 42 and a second current value detecting unit 52. The second power conversion unit 22 corresponds to an example of the power conversion unit. The in-power supply control unit 32 corresponds to an example of a drive unit and corresponds to an example of a second drive unit. In the following description, the interface unit 62 is also referred to as an IF unit 62.

The second power conversion unit 22 is connected in parallel to the first power conversion unit 21, converts the power input from the first conductive path 11 via the second input path 72, and forms the second output path 82. The operation of outputting electric power to the second conductive path 12 is performed. The second input path 72 is a conductive path branched from the first conductive path 11, one end of which is electrically connected to the first conductive path 11 and the other end of which is electrically connected to the second power conversion unit 22. .. One end of the second output path 82 is electrically connected to the second power conversion unit 22, and the other end is electrically connected to the second conductive path 12.

As shown in FIG. 4, the second power conversion unit 22 is configured as a full-bridge type isolated DCDC converter similar to the first power conversion unit 21 shown in FIG. In FIG. 4, the second voltage value detecting unit 42, the second current value detecting unit 52, and the like are not shown. The second power conversion unit 22 includes an input circuit unit 22X, a transformer unit 22Y, and an output circuit unit 22Z. The input circuit unit 22X includes a plurality of semiconductor switch elements 22A, 22B, 22C, 22D and a capacitor 22E, and is electrically connected to the primary coil 22F of the transformer unit 22Y. The input circuit unit 22X generates an AC voltage in the primary coil 22F according to the switching operation of the plurality of semiconductor switch elements 22A, 22B, 22C, 22D. The switching operation of the plurality of semiconductor switch elements 22A, 22B, 22C, and 22D is controlled by the in-power supply control unit 32, and specifically, CVCC (Constant Voltage Constant Curent) control is performed. The output circuit section 22Z includes diodes 22J and 22K, an inductor 22L, and a capacitor 22M, is electrically connected to the secondary coil 22G and 22H of the transformer section 22Y, and is an AC voltage applied to the secondary coil 22G and 22H. Is rectified and a DC voltage is output. The second power conversion unit 22 performs voltage conversion by switching operations of the semiconductor switch elements 22A, 22B, 22C, and 22D. The second power conversion unit 22 steps down the input voltage VH (potential difference between the first conductive path 11 and the conductive path 13C on the ground side) applied to the first conductive path 11 and outputs the voltage to the second output path 82. A voltage (potential difference between the second output path 82 and the ground-side conductive path 13D) is generated. The conductive paths 13C and 13D are reference conductive paths maintained at, for example, about 0 V.

As shown in FIG. 2, the second current value detection unit 52 is interposed in the middle of the second output path 82. The second current value detection unit 52 detects the value of the current flowing through the second output path 82 (second current value I2), and inputs a signal indicating the second current value I2 to the in-power supply control unit 32. When the second power conversion unit 22 performs a power conversion operation (specifically, a step-down operation), the second current value detection unit 52 outputs the output current output by the second power conversion unit 22 via the second output path 82. Is detected as the second current value I2.

The second voltage value detection unit 42 detects the voltage value (second voltage value V2) of the second output path 82, and inputs a signal indicating the second voltage value V2 to the in-power supply control unit 32. When the second power conversion unit 22 performs the power conversion operation, the second voltage value detection unit 42 detects the value of the output voltage applied by the second power conversion unit 22 to the second output path 82 as the second voltage value V2. Then, a signal indicating this output voltage is input to the power supply internal control unit 32.

The IF unit 62 receives the data transmitted from the control unit 108 and inputs the data to the power supply in-power control unit 32. Further, the IF unit 62 may cooperate with the in-power supply control unit 32 to transmit the second current value I2 and the second voltage value V2 acquired by the in-power supply control unit 32 to the control unit 108. The IF unit 62 corresponds to an example of a receiving unit, and functions to receive a command value from an external device of the second power supply 106. Specifically, the IF 62 has a function of receiving information transmitted by the IF 61 (for example, information for specifying an output current value (first current value I1) output by the first power conversion unit 21).

The in-power supply control unit 32 is configured as a control device having an information processing function, and is configured by, for example, a microcomputer including an internal memory. The internal memory stores a program to be executed by the in-power supply control unit 32, necessary parameters, and the like. The in-power supply control unit 32 can control the second power conversion unit 22 based on the data received from the IF unit 62. For example, the power supply in-power control unit 32 calculates a set value required for the operation of the second power conversion unit 22 and sets it in the second power conversion unit 22.

In this configuration, the control unit 108 or the first power supply 104 operates so as to give the second power supply 106 a value for determining an output voltage target value or an output voltage target value. In the following description, the output voltage target value of the second power supply 106 is also referred to as a “second target voltage”. The second target voltage is, for example, a value slightly higher than the first target voltage. The second target voltage may be directly applied to the second power supply 106 from the control unit 108 or the first power supply 104. Alternatively, the first target voltage may be applied to the second power supply 106 from the control unit 108 or the first power supply 104, and the second target voltage may set a voltage at which the second power supply 106 is a certain level higher than the first target voltage. ..

Further, the control unit 108 or the first power supply 104 operates so as to give a current limit value or a value for determining the current limit value to the second power supply 106. The current limit value may be directly given from the control unit 108 or the first power supply 104 to the second power supply 106, the load current value is given from the control unit 108 to the second power supply 106, and the second power supply 106 is given the load current value. The current value of a certain ratio of the above may be used as the current limit value. The load current value in this case is the current value supplied from the power supply system 100 to the load 110. Alternatively, the first power supply 104 may give the first current value I1 to the second power supply 106, and the second power supply 106 may set the current limit value based on the first current value I1.

In this configuration, when the control unit 32 (drive unit) in the power supply performs the first control (constant current control), the current limit value is set according to the command value based on the command value received by the IF unit 62 (reception unit). (For example, a value corresponding to the first current value I1) is set. In the typical example described below, the first current value I1 is given to the second power supply 106 from the first power supply 104, and the second power supply 106 has the first current value based on the first current value I1. This is an example of setting the current limit value so that the ratio between I1 and the current limit value becomes a predetermined ratio. Specifically, the information (information) that the IF unit 62 (reception unit) receives the ratio between the first current value I1 and the current limit value from the IF unit 61 during constant current control by the power supply control unit 32 (drive unit). The current limit value is set so as to have a predetermined ratio based on the information that identifies the first current value I1).

The second power supply 106 operates by CVCC control based on the second target voltage and the current limit value. The second power supply 106 can also operate in a constant voltage mode that outputs a designated constant voltage (second target voltage) by the above-mentioned CV control. The CV control performed by the second power supply 106 corresponds to an example of the second control. Further, the second power supply 106 can also operate so as to output a designated constant current value (the above-mentioned current limit value) by CC (Constant Curent) control. The CC control performed by the second power supply 106 corresponds to an example of the first control. In the following description, the mode that outputs the specified constant current value is also referred to as the constant current mode. That is, the second power supply 106 can operate by switching between the operation in the constant voltage mode and the constant current mode.

FIG. 5 is a functional block diagram conceptually showing the functions executed by the in-power supply control unit 32 by blocks. Each function of the target value setting unit 32A, the constant current mode calculation unit 32B, the constant voltage mode calculation unit 32C, the arbitration unit 32D, and the PWM signal generation unit 32E in FIG. 5 may be realized by software by a microcomputer or the like. , May be implemented by a hardware circuit. The target value setting unit 32A gives the current limit value Itb to the constant current mode calculation unit 32B and gives the second target voltage Vtb to the constant voltage mode calculation unit 32C based on the information from the interface unit 62.

The second power conversion unit 22 steps down the DC voltage VH input from the battery 102 when operating in the constant current mode, that is, when the first control (constant current control) is performed by the in-power supply control unit 32. 2 A voltage conversion operation is performed in which the current in the output path 82 is set as the current limit value. The in-power supply control unit 32 can periodically perform a feedback calculation for operating the second power conversion unit 22 in the constant current mode at a predetermined calculation cycle. Specifically, the constant current mode calculation unit 32B periodically performs a feedback calculation in the above calculation cycle to calculate an operation amount (a new duty for bringing the current value of the second output path 82 closer to the current limit value). .. In the feedback calculation of each cycle, the constant current mode calculation unit 32B has the current limit value Itb and the second current value I2 (current of the second output path 82) detected by the second current value detection unit 52 in the calculation cycle. Calculate the deviation from the value). Then, in the cycle of performing the calculation, the constant current mode calculation unit 32B sets the current value of the second output path 82 to the current limit value by the calculation formula predetermined for the deviation of the cycle and the predetermined gain. The amount of operation (new duty) for approaching Itb is determined. The above-mentioned calculation formula may be a PI (Proportional-Integral) calculation formula or a PID (Proportional-Integral-Differential) calculation formula. For example, when the constant current mode calculation unit 32B calculates the manipulated variable (new duty) by the PI calculation formula, the manipulated variable (new duty) is calculated by the PI calculation formula based on the above deviation and the predetermined proportional gain and integral gain. Duty) is calculated. This manipulated variable is the result of the feedback calculation of the cycle in which the calculation is performed, and is a new duty to be changed from the current duty in the case of the constant current mode.

When the second power conversion unit 22 operates in the constant voltage mode, that is, when the second control (constant voltage control) is performed by the in-power supply control unit 32, the second power conversion unit 22 steps down the DC voltage VH input from the battery 102 to make a second control. A voltage conversion operation is performed in which the voltage of the output path 82 is set as the second target voltage. The in-power supply control unit 32 periodically performs a feedback calculation for operating the second power conversion unit 22 in the constant voltage mode in the above calculation cycle. Specifically, the constant voltage mode calculation unit 32C periodically performs a feedback calculation in the above calculation cycle to calculate an operation amount (a new duty for bringing the voltage value of the second output path closer to the second target voltage). .. In the feedback calculation of each cycle, the constant voltage mode calculation unit 32C has the second target voltage Vtb and the second voltage value V2 (of the second output path 82) detected by the second voltage value detection unit 42 in the calculation cycle. Calculate the deviation from the voltage). Then, in the cycle of performing the calculation, the constant voltage mode calculation unit 32C sets the voltage of the second output path 82 as the second target by the PI calculation formula or the PID calculation formula based on the deviation of the cycle and the predetermined gain. The amount of operation for approaching the voltage Vtb is determined. For example, when the constant voltage mode calculation unit 32C calculates the manipulated variable (new duty) by the PI calculation formula, the manipulated variable (new duty) is calculated by the PI calculation formula based on the above deviation and the predetermined proportional gain and integral gain. Duty) is calculated. This manipulated variable is the result of the feedback calculation of the cycle in which the calculation is performed, and is a new duty to be changed from the current duty in the case of the constant voltage mode.

The arbitration unit 32D determines in advance whether to select between the operation amount (duty) calculated by the constant current mode calculation unit 32B and the operation amount (duty) calculated by the constant voltage mode calculation unit 32C. Determined by selection method. In the typical example described below, a method of selecting a smaller operation amount (calculation result in which the duty ratio becomes smaller) from both the operation amounts calculated by the constant current mode calculation unit 32B and the constant voltage mode calculation unit 32C is adopted. NS. In the present specification, when the switching condition is satisfied, the arbitration unit 32D selects the operation amount calculated by the constant voltage mode calculation unit 32C from the state in which the operation amount calculated by the constant current mode calculation unit 32B is selected. This is the case when the state is switched to. Further, when the second switching condition is satisfied, the arbitration unit 32D selects the operation amount calculated by the constant current mode calculation unit 32B from the state in which the operation amount calculated by the constant voltage mode calculation unit 32C is selected. This is the case when the state is switched. The arbitration method is not limited to this determination method, and other determination methods may be adopted. In the present disclosure, the arbitration unit 32D selects the operation amount calculated by the constant current mode calculation unit 32B during the period when the third control (current suppression control) is not performed (the period during which the normal control based on communication is performed). The control in the case is the first control (constant current control). Further, when the arbitration unit 32D selects the operation amount calculated by the constant voltage mode calculation unit 32C during the period when the third control (current suppression control) is not performed (the period when the normal control based on communication is performed). The control is the second control (constant voltage control). In this way, the in-power supply control unit 32 (drive unit) operates the second power conversion unit 22 (power conversion unit) in the constant current mode based on the current limit value, and in a mode different from the constant current mode. The second control for operating the second power conversion unit 22 is switched.

The arbitration unit 32D selects a smaller operation amount from the operation amount (duty) calculated by the constant current mode calculation unit 32B and the operation amount (duty) calculated by the constant voltage mode calculation unit 32C. Then, the PWM signal generation unit 32E outputs the PWM signal of the operation amount (duty) selected by the arbitration unit 32D as, for example, the PWM signal of the cycle next to the calculation cycle in which the operation amount is determined.

Since such an operation is performed, the in-power supply control unit 32 operates the second power conversion unit 22 in the constant current mode during the period when the operation amount calculated by the constant current mode calculation unit 32B is adopted by the arbitration unit 32D. The constant current control is continued. Further, in the power supply in-power supply control unit 32, the constant voltage control for operating the second power conversion unit 22 in the constant voltage mode continues during the period when the operation amount calculated by the constant voltage mode calculation unit 32C is adopted by the arbitration unit 32D. ..

As shown in FIG. 6, the control unit 108 includes a CPU (Central Processing Unit) 120, a memory 122, an interface unit (hereinafter, referred to as an IF unit) 124, and a bus 126. Data transmission between each unit in the control unit 108 is performed via the bus 126. The memory 122 has one or more storage media, and includes, for example, a rewritable semiconductor non-volatile memory. The memory 122 stores a program executed by the CPU 120, predetermined parameters, and the like. A part of the memory 122 is used as a work area when the CPU 120 executes a program. The control unit 108 is, for example, an ECU (Electronic Control Unit) of an electric vehicle or the like.

The CPU 120 has a function of controlling the operations of the first power source 104 and the second power source 106, controls the first power conversion unit 21 by giving an instruction to the first power source 104, and gives an instruction to the second power source 106. This controls the second power conversion unit 22. Specifically, the CPU 120 transmits the first target voltage to the first power supply 104 via the IF unit 124. The first power supply 104 can operate in the constant voltage mode based on the first target voltage, and operates so as to output a voltage equal to the first target voltage. Further, the CPU 120 may transmit the first target voltage or the second target voltage and the load current value or the current limit value to the second power supply 106 via the IF unit 124. The second power supply 106 operates to output a current equal to the current limit value when operating in the constant current mode, and operates to output a voltage equal to the second target voltage when operating in the constant voltage mode. ..

2. Power conversion control The following description relates to the power conversion control performed by the second power source 106.
The control of FIG. 7 is a control that the second power supply 106 (specifically, the control unit 32 in the power supply) repeatedly executes after the predetermined start condition is satisfied. The predetermined start condition is, for example, when the vehicle is in the starting state, when the power supply to the in-power supply control unit 32 is started, when other start conditions are satisfied, and the like. The second power supply 106 starts normal control based on communication as an initial operation immediately after the above start condition is satisfied. In the normal control based on communication, the constant current mode calculation unit 32B and the constant voltage mode calculation unit 32C calculate after setting the current limit value Itb based on the above-mentioned command value (for example, the first current value I1) obtained by communication. Is performed, and the arbitration unit 32D is a control that determines the operation amount by the above-mentioned arbitration. The normal control based on communication is either the first control (constant current control) or the second control (constant voltage control) described above. In normal control based on communication, the PWM signal generation unit 32E outputs a PWM signal of an operation amount (duty) determined by the arbitration unit 32D. When normal control based on communication is performed, the second power conversion unit 22 is operated in the constant current mode during the period in which the arbitration unit 32D continues to adopt the operation amount calculated by the constant current mode calculation unit 32B. 1 Control (constant current control) continues. As long as the output voltage of the first power supply 104 is the first target voltage and the output current of the second power supply 106 is the current limit value, the control unit 32 in the power supply has the above-mentioned first control as normal control based on communication. (Constant current control) is performed.

The in-power supply control unit 32 starts the control of FIG. 7 and performs the process of step S1 when the start condition is satisfied or the control of FIG. 7 is completed. In step S1, the power supply control unit 32 determines whether or not the control of the second power supply 106 is communication-based normal control, and if it is communication-based normal control, proceeds to step S2. When the in-power supply control unit 32 determines in step S1 that the control of the second power supply 106 is the third control (current suppression control), the process proceeds to step S5. At the time of the first step S1 after the above start condition is satisfied, the in-power supply control unit 32 performs normal control based on communication as the default control, and therefore determines Yes in step S1. Further, at the time of the next step S1 when the control of FIG. 7 is restarted after the processing of steps S3 and S6, the in-power supply control unit 32 performs normal control based on communication, so that in step S1. Judge Yes. Further, in the next step S1 when the control of FIG. 7 is started again after the processing of steps S4 and S7, the in-power supply control unit 32 performs the third control (current suppression control), so that step S1 Judged as Yes.

When the power supply control unit 32 determines in step S1 that the second power supply 106 is performing normal control based on communication, the output voltage value of the second power supply 106 is set in advance in the first threshold value Vth1 in step S2. Judge whether or not it is the above. The first threshold value Vth1 is a value higher than the constant voltage (first target voltage) of the first power supply 104. Further, the first threshold value Vth1 is a value lower than the target voltage (second target voltage) in the constant voltage mode of the second power supply 106. When the power supply control unit 32 determines in step S2 that the output voltage value of the second power supply 106 (that is, the output voltage value of the second power conversion unit 22) is not equal to or higher than the first threshold level Vth1, communication is performed in step S4. Continue normal control based on.

When the in-power supply control unit 32 determines in step S2 that the output voltage value of the second power supply 106 is equal to or higher than the first threshold value Vth1, the current suppression control (third control) is performed in step S3. This current suppression control corresponds to an example of the third control. This current suppression control is, for example, a control that gradually reduces the target current value of the second power supply 106 from the current current limit value (value determined based on the command value acquired by communication). The in-power supply control unit 32 sets the target current value by gradually reducing it from the current current limit value while the current suppression control continues, and targets the output current value I2 of the second power conversion unit 22. The second power conversion unit 22 is operated so as to have a current value. The speed at which the target current value is reduced is predetermined by the in-power supply control unit 32.

In this way, the in-power supply control unit 32 (drive unit) has a current lower than the current limit value when the output voltage of the second power supply 106 reaches a predetermined rising state during the first control (constant current control). 3rd control (current suppression control) can be performed to output the power to the second power conversion unit 22 (power conversion unit). Then, in the present embodiment, the predetermined rising state is a state in which the output voltage of the second power supply 106 reaches a threshold value (specifically, the first threshold value Vth1) during the first control (constant current control).

When the in-power supply control unit 32 determines in step S1 that the control of the second power supply 106 is not normal control based on communication (that is, when it is determined to be current suppression control), the output of the second power supply 106 is determined in step S5. It is determined whether or not the voltage value is equal to or higher than the second threshold value Vth2. The second threshold value Vth2 is a value lower than the first threshold value Vth1. Further, the second threshold value Vth2 is a value lower than the constant voltage (first target voltage) output by the first power supply 104.

When the power supply control unit 32 determines in step S5 that the output voltage value of the second power supply 106 is not equal to or higher than the second threshold value Vth2, the power supply control unit 32 continues the normal control based on communication in step S7. As long as the output voltage of the first power supply 104 is the first target voltage and the output current of the second power supply 106 is the current limit value, the in-power supply control unit 32 is the above-mentioned first control (constant) as normal control based on communication. Current control) is performed. When the in-power supply control unit 32 determines in step S5 that the output voltage value of the second power supply 106 is less than the second threshold value Vth2, the in-power supply control unit 32 performs the third control (current suppression control) in step S6.

As described above, the control unit 32 (drive unit) in the power supply has a predetermined value (third) that is lower than that when the output voltage of the second power supply 106 is in the above-mentioned "predetermined rising state" during the third control (current suppression control). When the voltage drops below the 2 threshold Vth2), the first control (constant current control) is performed.

Examples of the effects of the present disclosure are as follows.
The power conversion device 101 enables the second power supply 106 to perform a constant current operation in the power supply system 100 in which the second power supply 106 is connected in parallel to the first power supply 104 that outputs a constant voltage. However, in the configuration in which the second power supply 106 simply performs a constant current operation, there is a problem as shown in FIG. 8, and the power conversion device 101 can solve this problem as shown in FIG.

The example of FIG. 8 is an example in which the third control (current suppression control) is not performed in the configuration shown in FIGS. 1 to 6. In the example of FIG. 8, the load current suddenly drops in the period T4 from the time ta, and the total current value Iz (the sum of the current value I1 of the first power supply 104 and the current value I2 of the second power supply 106) suddenly decreases. ing. In the example of FIG. 8, even if the output current of the first power supply 104 suddenly decreases due to the sudden decrease of the load current, the current limit value of the second power supply 106 is updated to the time td by communication, as in the period T12. 2 The output current value I2 of the power supply 106 is about to be maintained at the current current limit value. In the example of FIG. 8, the current limit value is updated at the time td, and the output current value I2 of the second power supply 106 decreases in the subsequent period T13, but the period T12 up to that point is the second power supply 106. The output current cannot be suppressed. In the example of FIG. 8, in the latter half of the period T12, the second power supply 106 attempts to output a current larger than the current required by the load as a constant current. Then, the second power supply 106 cannot maintain the constant current mode and switches to the operation in the constant voltage mode, which causes the output voltage of the second power supply 106 to rise, which in turn causes the output voltage of the power supply system 100 to rise. .. However, as shown in FIG. 9, the power conversion device 101 of the present disclosure can rapidly reduce the output current by the third control (current suppression control), so that such an increase in the output voltage can be surely suppressed. Can be done.

In the example of FIG. 9, similarly to the example of FIG. 8, a sudden drop in the load current occurs in the period T4 from the time ta, and the total current value Iz (current value I1 of the first power supply 104 and current value of the second power supply 106) occurs. The sum with I2) is decreasing sharply. In the power conversion device 101, even if the load current suddenly decreases as in the period T4 during the first control of the second power supply 106 (during the constant current control of the period T21) and the output voltage of the power supply system 100 rises, the second power conversion device 101 is second. The power supply 106 itself can quickly detect a "predetermined rising state". Then, the second power supply 106 can switch from the first control (constant current control) to the third control (current suppression control) in response to the detection of the “predetermined rising state”. In the example of FIG. 9, the output voltage of the second power supply 106 is less than the first threshold value Vth1 before the time tb, and the output voltage of the second power supply 106 becomes the first at the time tb due to the sudden decrease in the load current in the period T4. It is 1 threshold Vth1 or more. When the output voltage of the second power supply 106 becomes equal to or higher than the first threshold level Vth1 in this way, the in-power supply control unit 32 controls the second power conversion unit 22 for the first control (constant current) as in the period T22. The output current value I2 is reduced by switching from the control) to the third control (current suppression control).

In this way, the power conversion device 101 may output an excessive current from the second power supply 106 during the first control (constant current control) of the second power supply 106, and the output voltage may increase accordingly. However, the output current of the second power supply 106 can be rapidly reduced to recover the output voltage.

When the output voltage of the second power supply 106 reaches the second threshold value Vth2 while the in-power supply control unit 32 (drive unit) is performing the third control (current suppression control) as in the period T22 of FIG. Switches from the third control (current suppression control) to the first control (constant current control). In the example of FIG. 9, the output voltage of the second power conversion unit 22 (power conversion unit) reaches the second threshold value Vth2 at the time tk of the third control (current suppression control). Then, the in-power supply control unit 32 (drive unit) switches the control for the second power conversion unit 22 from the third control (current suppression control) to the second control (constant current control) immediately after the time tk.

In this way, the power conversion device 101 quickly suppresses the output current of the second power supply 106 according to the state in which the output voltage of the power supply system 100 is concerned to rise, and then the output voltage of the second power supply 106 becomes a predetermined value. The third control can be continued until (second threshold Vth2) is reached. Then, the power conversion device 101 returns the second power supply 106 to the first control (constant current control) after confirming that the output voltage of the second power supply 106 has been suppressed to a predetermined value (second threshold value Vth2). be able to.

On the other hand, in the example of FIG. 8, even if the output current of the first power supply 104 decreases due to the sudden decrease of the load current in the period T4, the current limit value of the second power supply 106 is updated to the time td according to the communication result. Until then, the output current of the second power supply 106 is maintained. That is, in the example of FIG. 8, the output current of the second power supply 106 cannot be suppressed until the period T13 after the time td, and the output voltage of the second power supply 106 rises, which in turn causes the output voltage of the power supply system 100 to rise. It will occur. On the other hand, the power conversion device 101 of the present disclosure can solve this problem as shown in FIG. The alternate long and short dash line Ix in FIG. 9 is a change in the output current value of the first power supply 104 when it is operated as shown in FIG. 8, and the alternate long and short dash line Iy in FIG. 9 is a change in the output current value when it is operated as shown in FIG. It is a change in the output current value of the two power sources 106.

FIG. 10 is a graph when the current value I1 of the first power supply 104 becomes 0 due to a sudden decrease in the load current. FIG. 10 is a graph relating to the same device as in FIG. 8, and is an example in which the current suppression control is not performed in the device having the configuration shown in FIGS. 1 to 6. In the example of FIG. 10, the load current suddenly decreases from the time ta, and the total current value Iz (the sum of the current value I1 of the first power supply 104 and the current value I2 of the second power supply 106) decreases sharply. Then, in the example of FIG. 10, the current limit value is changed from the time td according to the communication performed after the time ta, and the current value I2 of the second power supply 106 is reduced. However, in the example of FIG. 10, the current value I1 of the first power supply 104 reaches 0 at time te as the load current suddenly decreases, and then is maintained at 0 from time te. In the example of FIG. 10, a transient voltage rise occurs during the period T14 in which the output current of the first power supply 104 suddenly decreases due to the sudden decrease in the load current. Further, in the subsequent period T15, the current value I1 of the first power supply 104 becomes 0, and the second power supply 106 is maintained in the constant voltage mode, so that the output voltage is constantly increased.

On the other hand, in the power conversion device 101 of the present disclosure, as shown in FIG. 11, a sudden decrease in the load current similar to that in FIG. 10 occurs during the first control of the second power supply 106 (during the constant current control in the period T21). Also, the third control (current suppression control) can be performed from the time tb when the "predetermined rising state" occurs. As a result, the power conversion device 101 can reduce the output current value I2 from the time tb, and can suppress the transient voltage rise which is a concern in the period T4. Moreover, since the power conversion device 101 can suppress or prevent the current value I1 of the first power supply 104 from reaching 0, it also suppresses a steady increase in the output voltage as in the period T15 of FIG. Can be done. The alternate long and short dash line Ix in FIG. 11 is a change in the output current value of the first power supply 104 when it is operated as shown in FIG. 10, and the alternate long and short dash line Iy in FIG. 11 is the change in the output current value when it is operated as shown in FIG. It is a change in the output current value of the two power sources 106.

The power conversion device 101 sets a current limit value based on a command value received by the receiving unit when performing the first control (constant current control). With such a configuration, if there is a concern that the output voltage will rise, if only the method of updating the current limit value based on the command value issued from the outside is adopted, the output voltage will rise. There is a concern that it may take some time before the current limit value is set according to the above. However, in the power conversion device 101, the second power supply 106 itself can switch to the third control (current suppression control) according to the situation where there is a concern that the output voltage will rise, so that the switching is caused by a communication delay or the like. Delays are less likely to occur.

In the power conversion device 101, the second power supply 106 corresponds to the value of the output current of the first power supply 104 (first current value I1) based on the communication with the outside when the first control (constant current control) is performed. The current limit value can be set. That is, the power conversion device 101 can adjust the output current of the second power supply 106 by more accurately reflecting the first current value I1 during the first control (constant current control). However, when the power conversion device 101 is in a situation where there is a concern that the output voltage may rise, a new command value corresponding to this situation is transmitted, and the current setting value is updated according to the command value. Will maintain the previous "current limit value according to the first current value I1". That is, if no measures are taken in this power conversion device 101, it takes time from the situation where there is a concern about an increase in the output voltage until the output current of the second power supply 106 is actually suppressed. There are concerns. However, since the power conversion device 101 can quickly switch to the third control (current suppression control) by determining the situation in which the output voltage is concerned to rise by the second power supply 106 itself, it is caused by a communication delay or the like. Therefore, it is possible to suppress an excessive increase in the output voltage due to the delay in updating the current limit value.

The in-power supply control unit 32 (drive unit) sets the ratio of the first current value I1 and the current limit value Itb to a predetermined ratio based on the first current value I1 during the first control (constant current control). Set the current limit value Itb to. This power conversion device makes it easy to keep the value I1 of the output current from the first power supply 104 and the value I2 of the output current from the second power supply at a predetermined ratio during the first control (constant current control). Then, when the output voltage of the power supply system 100 is in a state of concern during the first control (constant current control), the power conversion device 101 does not keep the output current at the predetermined ratio. Can be quickly prioritized to suppress.

The second power supply 106 can set the current limit value Itb by communicating with the first power supply 104 during the first control (constant current control). Then, when the output voltage of the power supply system 100 is concerned about an increase during the first control (constant current control), the second power supply 106 suppresses the current by determining and driving the second power supply 106 itself. You can quickly switch to control.

The power conversion device 101 is based on the detection value (first current value I1) actually detected by the first power supply 104 during the first control (constant current control), and is the value of the output current from the first power supply 104. It becomes easier to keep the value I1 and the value I2 of the output current from the second power source 106 more accurately at a predetermined ratio.

In the power conversion device 101, the rated current value of the second power supply 106 is smaller than the rated current value of the first power supply 104. The power conversion device 101 can relatively suppress the rated current value of the second power supply 106, and can perform a characteristic operation by the second power supply 106 in which the rated current value is suppressed.

<Other Embodiments>
The present disclosure is not limited to the embodiments described by the above description and drawings. For example, the features of the embodiments described above or below can be combined in any combination within a consistent range. Further, any of the features of the above-mentioned or later-described embodiments may be omitted unless it is clearly stated as essential. Further, the above-described embodiment may be modified as follows.

In the above embodiment, the “predetermined rising state” is a state in which the output voltage of the second power supply 106 reaches the first threshold value Vth1 during the first control, but is not limited to this example. For example, the "predetermined rising state" may be a state in which the rate of increase in the output voltage of the second power supply 106 reaches a certain value during the first control. In this example, the determination in step S2 of FIG. 7 performed by the in-power supply control unit 32 may be changed to the determination of "whether or not the rate of increase in the output voltage of the second power supply 106 is equal to or higher than a certain value". Then, the in-power supply control unit 32 performs the process of step S3 when it is determined in step S2 that the rate of increase in the output voltage of the second power source 106 is equal to or greater than a certain value, and when it is determined that the rate of increase is less than a certain value. May perform the process of step S4.

In the above embodiment, the “predetermined rising state” is a state in which the output voltage of the second power supply 106 reaches the first threshold value Vth1 during the first control, but is not limited to this example. For example, the "predetermined rising state" may be "switching from the constant current mode to the constant voltage mode during the first control (constant current control)". "Switching from constant current mode to constant voltage mode" means that the calculation result of the constant voltage mode calculation unit 32C is selected from the state in which the arbitration unit 32D selects the calculation result of the constant current mode calculation unit 32B. It has switched to the state. In this example, if the determination in step S2 of FIG. 7 performed by the in-power supply control unit 32 is changed to the determination of "whether or not the constant current mode is switched to the constant voltage mode during the first control (constant current control)". good. Then, when the in-power supply control unit 32 determines in step S2 that the constant current mode has been switched to the constant voltage mode, the process of step S3 may be performed, and if not, the process of step S4 may be performed. ..

In the above embodiment, the "predetermined rising state" is a state in which the output voltage of the second power supply 106 reaches the first threshold value Vth1 during the first control (constant current control), but is not limited to this example. For example, the "predetermined rising state" may be "switching from the constant current mode to the constant voltage mode during the first control (constant current control)". "Switching from constant current mode to constant voltage mode" means that the calculation result of the constant voltage mode calculation unit 32C is selected from the state in which the arbitration unit 32D selects the calculation result of the constant current mode calculation unit 32B. It has switched to the state. In this example, if the determination in step S2 of FIG. 7 performed by the in-power supply control unit 32 is changed to the determination of "whether or not the constant current mode is switched to the constant voltage mode during the first control (constant current control)". good. Then, when the in-power supply control unit 32 determines in step S2 that the constant current mode has been switched to the constant voltage mode, the process of step S3 may be performed, and if not, the process of step S4 may be performed. ..

In the above embodiment, the determination in step S5 of FIG. 7 may be changed to the determination of "whether or not the constant voltage mode is switched to the constant current mode". Here, "switching from the constant voltage mode to the constant current mode" means that the calculation result of the constant current mode calculation unit 32B is selected from the state in which the arbitration unit 32D selects the calculation result of the constant voltage mode calculation unit 32C. It is that it has switched to the state of being. In this case, if the in-power supply control unit 32 determines in step S5 that the constant voltage mode has been switched to the constant current mode, the process of step S7 is performed, and if not, the process of step S6 is performed. good.

In the above embodiment, the first power supply 104 transmits the current value I1 of the first power supply 104 to the second power supply 106 as a command value, and the second power supply 106 sets the current limit value based on this command value. Not limited to the example. For example, the first power supply 104 calculates the current limit value Itb so that the current value I1 and the current limit value Itb are in a predetermined ratio based on its own current value I1, and the second power supply 104 uses this current limit value Itb as a command value. It may be transmitted to the power source 106. Alternatively, the control unit 108 may transmit the current value I1 of the first power supply 104 acquired from the first power supply 104 to the second power supply 106 as a command value. Alternatively, the control unit 108 calculates the current limit value Itb so that the current value I1 and the current limit value Itb become a predetermined ratio based on the current value I1, and transmits this current limit value Itb as a command value to the second power source. You may. Alternatively, the control unit 108 seconds the sum (total current value Iz) of the current value I1 of the first power supply 104 acquired from the first power supply 104 and the current value I2 of the second power supply 106 acquired from the second power supply 106. It may be transmitted to the power source 106. Alternatively, the control unit 108 may transmit the value of a predetermined ratio of the total current value Iz to the second power supply 106 as the current limit value Itb.

In the above embodiment, the in-power supply control unit 32 (drive unit) sets the ratio of the first current value I1 and the current limit value Itb to a predetermined ratio based on the first current value I1 during the first control (constant current control). The current limit value Itb is set so as to be, but the present invention is not limited to this example. The in-power supply control unit 32 (drive unit) is based on the total current value Iz (I1 + I2) obtained from the control unit 108 for the ratio of the first current value I1 and the current limit value Itb during the first control (constant current control). The current limit value Itb may be set so as to be a predetermined ratio of the total current value Iz. In this case, the total current value Iz corresponds to an example of the command value. In this case, the control unit 108 continuously monitors the total current value Iz (the sum of the first current value I1 and the second current value I2), and updates the latest total current value Iz at short time intervals in the second power supply 106. You can send it to. Further, the control unit 32 (driving unit) in the power supply is not limited to these examples, and the first current value I1 is used as a command value and the first current value I1 and the current limit value Itb are used as variables. The current limit value Itb may be determined according to the first current value I1 by using a predetermined calculation formula. Alternatively, the in-power supply control unit 32 (driving unit) uses a predetermined arithmetic expression in which the total current value Iz is a command value and the total current value Iz and the current limit value Itb are variables, and the total current value Iz is used. The current limit value Itb may be determined accordingly.

In the above embodiment, the power conversion device 101 is a device including the control unit 108, but a device such as the control unit 108 that does not include control may be a power conversion device. For example, the portion of the power conversion device 101 excluding the control unit 108 may be the power conversion device.

In the above embodiment, the power conversion device 101 is a device including the first power supply 104, but a device not including the first power supply may be a power conversion device. For example, the portion of the power converter 101 excluding the first power supply 104 may be the power converter, or the portion of the power converter 101 excluding the first power supply 104 and the control unit 108 may be the power converter. good.

In the above embodiment, the isolated DCDC converter as shown in FIGS. 3 and 4 is exemplified as a specific configuration of the first power conversion unit 21 and the second power conversion unit 22, but the configurations other than those shown in FIGS. DCDC converter may be used.

In the above embodiment, the power supply system 100 is mounted on a vehicle such as an electric vehicle, but the present invention is not limited to this. The power supply system 100 may be mounted on a vehicle of a type other than these, for example, a PHEV (Plug-in Hybrid Electric Vehicle), a HEV (Hybrid Electric Vehicle), or may be mounted on a device other than the vehicle.

It should be noted that the embodiments disclosed this time are examples in all respects and are not restrictive. The scope of the present invention is not limited to the embodiments disclosed here, and includes all modifications within the scope indicated by the claims or within the scope equivalent to the claims. Is intended.

11: First conductive path 12: Second conductive path 13A: Conductive path 13B: Conductive path 13C: Conductive path 13D: Conductive path 21: First power conversion unit 21A: Semiconductor switch element 21B: Semiconductor switch element 21C: Semiconductor switch element 21D: Semiconductor switch element 21E: Condenser 21F: Primary side coil 21G: Secondary side coil 21H: Secondary side coil 21J: Diode 21K: Diode 21L: Incubator 21M: Condenser 21X: Input circuit section 21Y: Transformer section 21Z: Output circuit Part 22: Second power conversion unit 22A: Semiconductor switch element 22B: Semiconductor switch element 22C: Semiconductor switch element 22D: Semiconductor switch element 22E: Condenser 22F: Primary side coil 22G: Secondary side coil 22H: Secondary side coil 22J: Diode 22K: Diode 22L: inductor 22M: Condenser 22X: Input circuit unit 22Y: Transformer unit 22Z: Output circuit unit 31: Power supply internal control unit 32: Power supply internal control unit 32A: Target value setting unit 32B: Constant current mode calculation unit 32C : Constant voltage mode calculation unit 32D: Mediation unit 32E: PWM signal generation unit 41: First voltage value detection unit 42: Second voltage value detection unit 51: First current value detection unit 52: Second current value detection unit 61: Interface unit 62: Interface unit 71: First input path 72: Second input path 81: First output path 82: Second output path 100: Power supply system 101: Power conversion device 102: Battery 104: First power supply 106: First 2 Power supply 108: Control unit 110: Load 120: CPU
122: Memory 124: IF unit 126: Bus

Claims (10)

A power conversion device used in a power supply system having a first power supply that outputs a constant voltage based on a first target voltage and the first power supply performs power conversion between a first conductive path and a second conductive path. hand,
A second power source connected in parallel to the first power source between the first conductive path and the second conductive path is provided.
The second power source includes a power conversion unit that performs power conversion between the first conductive path and the second conductive path, and a drive unit that drives the power conversion unit.
The drive unit switches between a first control for operating the power conversion unit in a constant current mode based on a current limit value and a second control for operating the power conversion unit in a mode different from the constant current mode.
The drive unit is lower than the current limit value when the output voltage of the second power supply reaches a predetermined rising state during the first control or when the release condition for canceling the constant current mode is satisfied. A power conversion device that performs a third control for outputting an electric current to the power conversion unit. The power conversion device according to claim 1, wherein the predetermined rising state is a state in which the output voltage of the second power supply reaches a threshold value during the first control. The power conversion device according to claim 1, wherein the predetermined rising state is a state in which the rate of increase of the output voltage of the second power supply reaches a constant value during the first control. The second control is a control for operating the power conversion unit in a constant voltage mode based on a second target voltage higher than the first target voltage.
When the switching condition is satisfied, the drive unit switches from the constant current mode to the constant voltage mode.
The power conversion device according to claim 1, wherein the drive unit performs the third control when the constant current mode is switched to the constant voltage mode during the first control. The driving unit performs the first control when the output voltage of the second power supply drops to a predetermined value lower than that in the predetermined rising state during the third control. The power conversion device according to any one item. The second power supply switches from the constant voltage mode to the constant current mode when the second switching condition is satisfied.
The power conversion device according to claim 4, wherein the drive unit performs the first control when the constant voltage mode is switched to the constant current mode during the third control. The second power supply has a receiving unit that receives a command value from an external device of the second power supply.
The power conversion device according to any one of claims 1 to 6, wherein the drive unit sets the current limit value based on the command value received by the reception unit when performing the first control. .. The command value is a value corresponding to the total current value supplied by the power supply system or the value of the first current supplied by the first power supply.
The power conversion device according to claim 7, wherein the drive unit sets the current limit value according to the total current value or the value of the first current based on the command value when the first control is performed. The drive unit sets the ratio between the value of the first current and the current limit value to a predetermined ratio based on the total current value or the value of the first current during the first control. The power conversion device according to claim 8. With the first power supply
A control unit that controls the first power supply and the second power supply,
Including
The power conversion device according to any one of claims 7 to 9, wherein the first power supply or the control unit transmits the command value.

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