JP6672949B2 - Charging device - Google Patents

Description

  The present invention relates to a charging device.

  The charging device that charges the secondary battery includes one or more power supply units that convert input AC power into predetermined DC power and output the converted DC power. For example, when three-phase AC power is input to the power supply unit, the power supply unit includes three DC converters for respectively converting the corresponding one-phase AC power of the three-phase AC power into predetermined DC power. Can be Further, in order to protect the DC converter (specifically, the circuits and elements constituting each of the three DC converters) from the overcurrent caused by the output short-circuit of the charging device during the charging operation, the output is provided in the DC converter. A short circuit protection circuit may be provided.

  Note that, as related techniques, techniques described in Patent Documents 1 to 4 are known.

JP-A-2004-266951 JP 2012-090472 A JP 2010-233369 A JP 2012-175823 A

  However, if the output short-circuit protection circuit is provided for each of the plurality of DC converters, the power supply unit (and, consequently, the charging device) needs to have the same number of output short-circuit protection circuits as the plurality of DC converters. become. In addition, there is a possibility that the protection operation varies among a plurality of output short-circuit protection circuits due to individual differences between circuit elements and the like.

  An object according to one aspect of the present invention is to provide a charging device that protects a plurality of DC converters included in a power supply unit from an overcurrent caused by an output short circuit of the charging device using a single output short-circuit protection circuit. It is.

  A charging device according to one aspect of the present invention includes a plurality of DC / DC converters connected in parallel, a total current sensor that outputs a voltage corresponding to a total output current of each of the plurality of DC / DC converters, A comparator for comparing the voltage value with a voltage threshold. Further, the charging device includes a power supply unit control unit that stops the plurality of DC / DC converters according to a comparison result between the voltage value and the voltage threshold.

  According to the charging device according to one embodiment, a plurality of DC converters included in the power supply unit can be protected from an overcurrent caused by an output short-circuit of the charging device using a single output short-circuit protection circuit.

FIG. 2 is a diagram illustrating an example of a schematic overall configuration of a charging device according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of a part of the charging device according to the first embodiment and a related power storage device. FIG. 9 is a diagram illustrating a configuration example of a part of a charging device according to a second embodiment and a related power storage device. It is a figure explaining an example of an output short circuit protection current value which a charging device according to a 2nd embodiment sets.

Hereinafter, embodiments will be described in detail with reference to the drawings.
<First embodiment>
FIG. 1 is a diagram illustrating an example of a schematic overall configuration of the charging device according to the first embodiment. In the configuration example illustrated in FIG. 1, the charging device 1 as an example of the charging device according to the first embodiment includes four power supply units 11 and a charging device control unit 12.

  Each power supply unit 11 converts AC power (for example, three-phase AC power) input from outside the charging device 1 into predetermined DC power and outputs the DC power. In addition, in the configuration example shown in FIG. 1, four power supply units 11 are included in the charging device 1, but the charging device according to the embodiment may include an arbitrary number of power supply units.

  The charging device control unit 12 is configured using, for example, a processor such as a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or a PLD (Programmable Logic Device). The charging device control unit 12 controls the operation of each unit included in the charging device 1.

  Each power supply unit 11 includes three DC converters 111, a power supply unit controller 112, an output short-circuit protection circuit 113, and an AC / DC (Alternating Current / Direct Current) converter 114.

  The three DC converters 111 respectively convert the corresponding one-phase AC power of the three-phase AC power input to the power supply unit 11 from the outside of the charging device 1 into predetermined DC power. Although the configuration example illustrated in FIG. 1 includes three DC converters 111, the charging device according to the embodiment includes two DC conversion units 111 according to a transmission format of AC power input to the charging device. Any number of DC converters described above may be included.

  Each DC converter 111 includes a PFC (Power Factor Correction) circuit 1111, an insulated DC / DC (Direct Current / Direct Current) converter 1112, and a non-insulated DC / DC converter 1113. In addition, in the configuration example illustrated in FIG. 1, the charging device 1 includes the non-insulated DC / DC converter 1113, but the charging device according to the embodiment does not necessarily include the non-insulated DC / DC converter. .

  The PFC circuit 1111 removes a harmonic component of the input AC current and converts the input AC power into DC power. The insulated DC / DC converter 1112 insulates the input side (primary side) from the output side (secondary side) and outputs a stable DC voltage / current from the DC voltage / current input from the PFC circuit 1111. . The non-insulated DC / DC converter 1113 converts a DC voltage input from the isolated DC / DC converter 1112 into a desired DC voltage / current corresponding to a load (for example, the secondary battery 21) connected to the charging device 1. Is output.

  The power supply unit control unit 112 is configured using, for example, a processor such as a CPU, an FPGA, a PLD, or the like. The power supply unit control unit 112 controls the operation of each unit included in the power supply unit 11. The power supply unit control unit 112 operates with the DC power supplied from the AC / DC converter 114. AC / DC converter 114 converts AC power input from outside charging device 1 to DC power, and outputs DC power to power supply unit control unit 112.

  The output short-circuit protection circuit 113 protects each of the plurality of DC converters 111 included in the power supply unit 11 from an overcurrent caused by the output short-circuit of the charging device 1. That is, the power supply unit 11 includes a single output short-circuit protection circuit 113. Therefore, according to the charging device according to the embodiment, compared with the case where a plurality of output short-circuit protection circuits are provided corresponding to a plurality of DC converters, a space for mounting the output short-circuit protection circuit on the power supply unit is provided. Can be reduced. Further, according to the charging device according to the embodiment, it is possible to prevent the inconvenience that the protection operation varies among the plurality of output short-circuit protection circuits.

  In each power supply unit of the charging device according to the first embodiment, a specific example of protecting a plurality of DC converters from overcurrent caused by an output short circuit of the charging device using a single output short-circuit protection circuit is shown in FIG. Will be described below with further reference to FIG.

  FIG. 2 is a diagram illustrating a configuration example of a part of the charging device according to the first embodiment and a related power storage device. For the sake of clarity, FIG. 2 shows only some of the components included in charging device 1 shown in FIG. For example, FIG. 2 illustrates a plurality of non-insulated DC / DC converters 1113, a power supply unit control unit 112, and an output short circuit protection circuit 113 included in an arbitrary power supply unit 11 among the plurality of power supply units 11 illustrated in FIG. It is shown. FIG. 2 shows a configuration example in which each unit of the non-insulated DC / DC converter 1113, which is an example of the DC / DC converter according to the embodiment, is protected from overcurrent caused by output short-circuit. However, for example, in a configuration in which the power supply unit 11 does not include the non-insulated DC / DC converter 1113, the output short-circuit protection circuit 113 is used to protect each part of the isolated DC / DC converter 1112 from overcurrent caused by output short-circuit. It is also possible to change to Alternatively, the output short-circuit protection circuit 113 can be changed to protect each part of the PFC circuit 1111 including the function as an AC / DC converter from an overcurrent caused by an output short-circuit.

The non-insulated DC / DC converter 1113 includes a first capacitor C ₁ , a DC / DC control circuit CON, a first switching element SW ₁ , a second switching element SW ₂ , an inductor L, and a second capacitor C ₂ . Including. The non-insulated DC / DC converter 1113 further includes a current sensor SNSR _I , a fuse F, and a diode D.

The first capacitor _{C 1} smoothes the DC voltage input from the insulated type DC / DC converter 1112. The DC / DC control circuit CON generates (and amplifies) and outputs a PWM (Pulse Width Modulation) signal having a predetermined duty ratio in accordance with the start signal input from the power supply unit control unit 112. The first switching element SW ₁ and the second switching element SW ₂ is to respectively turned on or off according to the PWM signal input from the DC / DC control circuit CON, time-share input DC voltage. The inductor L and the second capacitor C ₂ is a time divided DC voltage smoothed, and outputs the desired DC voltage / current. Diode D prevents the backflow of the output current through the inductor L and the second capacitor C _2.

Current sensor SNSR _I measures the value of the output current through the inductor L and the second capacitor _{C 2.} For example, as shown by a broken line (1) in FIG. 2, when a short circuit occurs inside the non-isolated DC / DC converter 1113, the DC / DC control circuit CON outputs the current measured by the current sensor SNSR _I. Overcurrent is detected from the value. Upon detecting the overcurrent, the DC / DC control circuit CON changes the duty ratio of the PWM signal or stops the output of the PWM signal. By such control of the DC / DC control circuit CON, each unit (circuit and element) in the non-insulated DC / DC converter 1113 is protected from an overcurrent caused by an internal short circuit of the non-insulated DC / DC converter 1113. Further, when such an internal short circuit occurs, each part of the non-insulated DC / DC converter 1113 may be protected from overcurrent by cutting the fuse F.

The output short-circuit protection circuit 113 includes a total current sensor 1131, a comparator 1132, and a threshold setting unit 1133.
The direct current output from the plurality of non-insulated DC / DC converters 1113 is input to the total current sensor 1131. The total current sensor 1131 outputs a voltage corresponding to the total output current of each of the plurality of non-insulated DC / DC converters 1113.

  The comparator 1132 compares the value of the output voltage from the total current sensor 1131 with a voltage threshold. The voltage threshold is a voltage value corresponding to the output short-circuit protection current value, and the output short-circuit protection current value is a circuit that configures a DC converter (for example, a DC / DC converter) from an overcurrent caused by an output short circuit of the charging device. And the upper limit current value for protecting the element. In the charging device according to the first embodiment, the voltage threshold is set in advance by the threshold setting unit 1133 as a fixed value supplied by the voltage source V.

  When the value of the output voltage from the total current sensor 1131 exceeds the voltage threshold, the comparator 1132 outputs an output short-circuit protection signal to the power supply unit control unit 112. The power supply unit control unit 112 stops the plurality of non-insulated DC / DC converters 1113 according to the input output short-circuit protection signal.

  For example, after the power storage device 2 is connected to the charging device 1 and charging of the secondary battery 21 included in the power storage device 2 is started, as shown by a broken line (2) in FIG. When a short circuit occurs in the output of the charging device 1, the charging device 1 operates as described below. The power storage device 2 may be mounted and connected to a vehicle such as an electric vehicle, a hybrid car, or an electric forklift. The secondary battery 21 is, for example, a lead battery, a lithium ion battery, or a lithium ion capacitor, and may include a plurality of battery cells unlike the configuration example of FIG.

  When the output short-circuit of the charging device 1 occurs, a short-circuit current, which is an overcurrent, flows through each of the plurality of non-insulated DC / DC converters 1113 via the total current sensor 1131. The total current sensor 1131 outputs to the comparator 1132 a voltage corresponding to the sum of the short-circuit currents output from each of the plurality of non-insulated DC / DC converters 1113.

  When the value of the output voltage from the total current sensor 1131 exceeds the voltage threshold, the comparator 1132 sends the output short-circuit protection signal to the power supply unit control unit 112, for example, by changing the output from the comparator 1132 from Low to Hi. Output.

  When the output short-circuit protection signal is input to the power supply unit control unit 112, the power supply unit control unit 112 turns off the start signal output to the DC / DC control circuit CON of each of the plurality of non-insulated DC / DC converters 1113 ( That is, the output of the start signal is stopped). Further, the power supply unit control unit 112 outputs a power-off signal to each of the plurality of non-insulated DC / DC converters 1113 DC / DC control circuits CON.

When the activation signal from the power supply unit control unit 112 is turned off, DC / DC control circuit CON stops generating the first switching element SW ₁ and the second PWM signal output to the switching element SW _2. As a result, no current flows through each part of the plurality of non-insulated DC / DC converters 1113. That is, the short-circuit current flowing to each part of the plurality of non-insulated DC / DC converters 1113 stops.

  When the short-circuit current stops, a voltage corresponding to a current value of 0 is output from the total current sensor 1131. As a result, in the comparator 1132, the value of the output voltage from the total current sensor 1131 becomes equal to or less than the voltage threshold, the comparator 1132 stops outputting the output short-circuit protection signal, and the output short-circuit protection signal is input to the power supply unit control unit 112. Will not be. Therefore, the power supply unit control unit 112 may turn on the start signal to the DC / DC control circuit CON of each of the plurality of non-insulated DC / DC converters 1113 again (that is, restart the output of the start signal). is there. However, as described above, the power of the DC / DC control circuit CON of each of the plurality of non-insulated DC / DC converters 1113 is turned off by the power supply off signal from the power supply unit control unit 112. Therefore, even if the power supply unit control unit 112 restarts the output of the activation signal, the stopped short-circuit current can be prevented from flowing again.

  The power supply unit control unit 112 outputs an output short-circuit diagnosis to the charging device control unit 12. When the output short-circuit diagnosis is input to the charging device control unit 12, the charging device control unit 12 stops the operations of the plurality of power supply units 11 and stops the output of the entire charging device 1. Thereafter, the charging device control unit 12 may notify the user of an error indicating that an output short circuit has occurred, for example, by an indicator lamp (not shown). Alternatively, the charging device control unit 12 may retry the plurality of power supply units 11 a plurality of times to confirm that the output short circuit is not erroneously detected.

As described above, according to the charging device according to the first embodiment, a plurality of DC converters included in the power supply unit are converted from an overcurrent caused by an output short circuit of the charging device using a single output short-circuit protection circuit. Can be protected.
<Second embodiment>
For example, the rated voltage of the secondary battery differs depending on the type of the secondary battery. Also, for example, the terminal voltage of the secondary battery changes during charging such as CC (Constant Current) charging. It is desirable that the charging device can charge these various secondary batteries having different voltages. Therefore, the voltage threshold value described above as a fixed value can be set to correspond to, for example, an output short-circuit protection current value when a low-voltage secondary battery is charged with a relatively large current. However, there is a limit to the power that can be output by each power supply unit that constitutes the charging device. Therefore, when an output short circuit occurs while the high-voltage secondary battery is being charged by a relatively small current, the value of the overcurrent caused by the output short circuit corresponds to the set voltage threshold. Before reaching the output short-circuit protection current value, the circuits and elements constituting the DC converter may be damaged.

  The charging device according to the second embodiment is further configured to change the voltage threshold according to the voltage of the secondary battery to be charged. With such a configuration, even if the charging device according to the second embodiment charges various secondary batteries having different voltages, a plurality of DC converters can be connected to a single unit due to an overcurrent caused by an output short circuit of the charging device. Quick protection with output short circuit protection circuit.

  FIG. 3 is a diagram illustrating a configuration example of a part of the charging device according to the second embodiment and a related power storage device. In FIG. 3, the same components as those of the charging device 1 shown in FIG. 1 are denoted by the same reference numerals as those of the charging device 1 'which is an example of the charging device according to the second embodiment. I have. The overall configuration of the charging device 1 'may be similar to that of the charging device 1 shown in FIG.

  The charging device 1 'includes an output short-circuit protection circuit 113' instead of the output short-circuit protection circuit 113. The output short-circuit protection circuit 113 'includes a threshold setting unit 1133' instead of the threshold setting unit 1133. In addition, the charging device 1 'may further include a voltage sensor 115 for measuring an output voltage of the charging device'.

In the configuration example illustrated in FIG. 3, the threshold setting unit 1133 ′ includes a voltage source V that supplies a predetermined voltage, a first resistor R ₁ , a third switching element SW ₃ , a second resistor R ₂ , and a third resistor. including a capacitor _{C 3.} Third switching element SW ₃ is turned or off according to the PWM signal from the power supply unit control section 112, the predetermined voltage of the voltage source V timeshare a first resistor R ₁ minute drop voltage. Third capacitor C _3, when the divided voltage is a second resistor R ₂ minutes drop the voltage by smoothing, and outputs a voltage smoothed to the comparator 1132 as a voltage threshold.

A specific example of setting the voltage threshold according to the voltage of the secondary battery to be charged in the charging device according to the second embodiment will be described below with further reference to FIG.
In the charging start process before the charging of the secondary battery 21 by the charging device 1 ′, the charging device control unit 12 transmits the voltage value of the secondary battery 21 from the battery control unit 22 of the power storage device 2 via communication. get. The battery control unit 22 is a device or a circuit that controls the operation of each unit of the power storage device 2 including the secondary battery 21. The voltage value acquired by the charging device control unit 12 is, for example, a rated voltage of the secondary battery 21.

  The charging device control unit 12 calculates an outputable current value of each power supply unit 11 from the acquired voltage value. For example, as shown in FIG. 4A, when the maximum output power of the power supply unit 11 is 3.5 kW, the voltage and current that can be output by the power supply unit 11 are surrounded by oblique lines in FIG. Limited to the specified range. The charging device control unit 12 calculates an outputable current value of the power supply unit 11 from the voltage value acquired from the battery control unit 22 so that the maximum outputable power is output from each power supply unit 11. For example, when the voltage value acquired from the battery control unit 22 is 52 [V], the charging device control unit 12 outputs an outputable current value of the power supply unit = 70 [A] (3.5 [W] / 52 [ V]). The charging device control unit 12 transmits the calculated outputable current value to the power supply unit control unit 112.

  The power supply unit control unit 112 acquires an output short-circuit protection current value corresponding to the outputable current value received from the charging device control unit 12. For example, the power supply unit control unit 112 may hold in advance a plurality of output short-circuit protection current values corresponding to a plurality of outputable current values as shown in FIG. Then, the power supply unit control unit 112 may obtain an output short-circuit protection current value corresponding to the output-capable current value received from the charging device control unit 12 from the plurality of held output short-circuit protection current values. The power supply unit control unit 112 acquires a voltage value corresponding to the acquired output short-circuit protection current value as a voltage threshold. For example, when the threshold setting unit 1133 'is configured as shown in FIG. 3, the power supply unit control unit 112 generates and generates a PWM signal whose duty ratio is set according to the voltage value corresponding to the acquired output short-circuit protection current value. get.

  The power supply unit control unit 112 outputs the obtained voltage threshold to the threshold setting unit 1133 '. For example, when the threshold setting unit 1133 'is configured as shown in FIG. 3, the power supply unit control unit 112 outputs the acquired PWM signal to the threshold setting unit 1133'.

  The threshold setting unit 1133 ′ sets the voltage threshold received from the power supply unit control unit 112 and outputs it to the comparator 1132. For example, when the threshold setting unit 1133 'is configured as shown in FIG. 3, the threshold setting unit 1133' generates and sets a voltage threshold from the PWM signal received from the power supply unit control unit 112, and compares the voltage threshold with a comparator. 1132. Thus, the threshold voltage for output short-circuit protection is set according to the voltage value of the secondary battery 21 charged by the output power of the plurality of non-insulated DC / DC converters 1113.

  Thus, according to the charging device according to the second embodiment, the voltage threshold is changed according to the voltages of various secondary batteries having different voltages. Therefore, according to the charging device according to the second embodiment, even if various secondary batteries having different voltages are charged, a plurality of DC converters are connected to a single DC conversion unit due to an overcurrent caused by an output short circuit of the charging device. It can be quickly protected by using the output short circuit protection circuit.

  Next, when the charging of the secondary battery 21 by the charging device 1 'is started, the charging device control unit 12 acquires the voltage value of the secondary battery 21 at predetermined time intervals during charging. The acquired voltage value is, for example, the terminal voltage of the secondary battery 21. The charging device control unit 12 may acquire the voltage value measured by the voltage sensor 115 as the voltage value of the secondary battery 21. Alternatively, the charging device control unit 12 may acquire the voltage value of the secondary battery 21 from the battery control unit 22 via communication. The charging device control unit 12 calculates an outputable current value of the power supply unit 11 from the acquired voltage value so that the maximum outputable power is output from each power supply unit 11, and controls the calculated outputable current value to the power supply unit. To the unit 112.

  The power supply unit control unit 112 reacquires the output short-circuit protection current value corresponding to the outputable current value received from the charging device control unit 12. Then, the power supply unit control unit 112 acquires a voltage value corresponding to the reacquired output short-circuit protection current value, and outputs the acquired voltage value to the threshold setting unit 1133 'as a voltage threshold. For example, when the threshold setting unit 1133 'is configured as shown in FIG. 3, the power supply unit control unit 112 generates and obtains the PWM signal according to the voltage value corresponding to the re-acquired output short-circuit protection current value, and obtains the PWM signal. The PWM signal is output to the threshold setting unit 1133 '.

  The threshold setting unit 1133 ′ sets the voltage threshold received from the power supply unit control unit 112 and outputs the voltage threshold to the comparator 1132. For example, when the threshold setting unit 1133 'is configured as shown in FIG. 3, the threshold setting unit 1133' generates and sets a voltage threshold from the PWM signal received from the power supply unit control unit 112, and sets the voltage threshold. Is output to the comparator 1132.

  Thus, according to the charging device according to the second embodiment, the voltage threshold is changed according to the voltage of the secondary battery that changes during charging. For this reason, according to the charging device according to the second embodiment, a plurality of DC converters are connected to a single DC conversion unit in accordance with a change in the voltage of the secondary battery during charging, due to an overcurrent caused by an output short circuit of the charging device. Can be quickly protected by using the output short-circuit protection circuit.

It should be noted that the present invention is not limited to the above embodiment, and various improvements and modifications can be made without departing from the spirit of the present invention.
For example, in the charging device according to the second embodiment, the charging device control unit 12 may hold a correspondence table between the voltage of the secondary battery and the output short-circuit protection current value as shown in FIG. Good. Then, the charging device control unit 12 obtains the output short-circuit protection current value or voltage threshold corresponding to the obtained voltage value of the secondary battery, and outputs the obtained output short-circuit protection current value or voltage threshold to the power supply unit control unit 112. May be. In addition, the power supply unit control unit 112 may hold a correspondence table between the voltage of the secondary battery and the output short-circuit protection current value as shown in FIG. Then, the power supply unit control unit 112 may obtain the voltage value of the secondary battery 21 from the charging device control unit 12, and may obtain the output short-circuit protection current value and the corresponding threshold voltage based on the obtained voltage value. .

REFERENCE SIGNS LIST 1 Charging device 11 Power supply unit 111 DC converter 1111 PFC circuit 1112 Insulated DC / DC converter 1113 Non-insulated DC / DC converter C ₁ First capacitor C ₂ Second capacitor CON DC / DC control circuit SW ₁ First Switching element SW ₂ Second switching element L Inductor SNSR _I Current sensor F Fuse D Diode 112 Power supply unit control section 113, 113 ′ Output short circuit protection circuit 1131 Total current sensor 1132 Comparator 1133, 1133 ′ Threshold setting section V Voltage source R ₁ First resistor R ₂ Second resistor SW ₃ Third switching element C ₃ Third capacitor 114 AC / DC converter 115 Voltage sensor 12 Charger control unit 2 Power storage device 21 Secondary battery 22 Battery control unit

Claims (3)

A plurality of DC / DC converters connected in parallel;
A total current sensor that outputs a voltage corresponding to a sum of output currents of the plurality of DC / DC converters;
A comparator that compares the value of the voltage with a voltage threshold,
A power supply unit control unit that stops the plurality of DC / DC converters according to a comparison result between the voltage value and the voltage threshold value ;
A threshold setting unit that sets the voltage threshold,
The power supply unit control unit calculates an output current value of each of the plurality of power supply units including the DC / DC converter calculated from a voltage value of the secondary battery charged by the output power of the plurality of DC / DC converters. A charging device that obtains the voltage threshold according to a corresponding output short-circuit protection current value, and outputs the obtained voltage threshold to the threshold setting unit . The charging device according to claim 1,
The comparator outputs an output short-circuit protection signal when the value of the voltage exceeds the voltage threshold,
The power supply unit control unit, when receiving the output short-circuit protection signal, stops outputting a start signal to a plurality of DC / DC control circuits that control output voltages of the plurality of DC / DC converters, A charging device that outputs a power-off signal to turn off the power of each of the plurality of DC / DC control circuits to the plurality of DC / DC control circuits. The charging device according to claim 1 ,
The power supply unit control unit acquires the voltage value at predetermined time intervals during charging of the secondary battery, reacquires the voltage threshold according to the acquired voltage value of the secondary battery, and reacquires the voltage threshold. Is output to the threshold setting unit,
The charging device, wherein the threshold setting unit sets the reacquired voltage threshold.

Images