JP5604947B2 - Power supply device and voltage adjustment method - Google Patents

Description

  The present invention relates to a power supply device including a plurality of battery cells and a voltage adjustment method.

  In recent years, most portable electronic devices such as mobile phones use a secondary battery such as a rechargeable lithium ion secondary battery as a power source. Secondary batteries are also used in hybrid vehicles (HV) that use both an engine and a motor as a power generation source, and in electric vehicles (EV: Electric Vehicle) that use only a motor as a power generation source. . Thus, in recent years, secondary batteries have been used for various purposes.

  The rated voltage of the battery cell constituting the secondary battery is about several volts. For this reason, the secondary battery that requires an output voltage higher than the rated voltage of the battery cell includes a battery module in which a plurality of battery cells are connected in series. In such a battery module, in order to prevent individual battery cells from being overcharged or overdischarged, the voltage of all battery cells constituting the battery module is adjusted to be constant.

  Patent Document 1 below is a method for charging a battery module in which a plurality of battery cells are connected in series, and reduces the voltage difference between the battery cells by discharging high-voltage battery cells in the middle of charging. A charging method for further charging is disclosed. In Patent Document 2 below, the first and second capacitors connected in series are connected in parallel to the first and second battery cells, respectively, and the charge of the first capacitor charged by the first battery cell is described. A method for reducing the voltage detection error of the first battery cell by moving the first capacitor to the second capacitor, and further charging one of the first and second battery cells by the second capacitor to which the charge has been moved is disclosed. Yes.

Japanese Patent No. 3229696 Japanese Patent Laid-Open No. 2004-47407

  By the way, the charging method disclosed in Patent Document 1 described above connects a battery cell having a high voltage to a resistor, and discharges the battery cell having a high voltage by consuming electric energy charged in the battery cell by the resistor. ing. For this reason, there is a problem that electric energy charged in the battery cell is consumed unnecessarily, resulting in a large energy loss and poor efficiency.

  Further, the method disclosed in Patent Document 2 described above moves the first capacitor charge charged by the first battery cell to the second capacitor and uses it to detect the voltage of the first battery cell. Since it is used for charging the second battery cell, the electrical energy charged in the first battery cell is not consumed wastefully. However, in order to realize the method disclosed in Patent Document 2, a large-capacitance capacitor is required, which increases the size.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply device and a voltage adjustment method that can improve efficiency with a simple configuration.

In order to solve the above-described problems, a power supply device according to the present invention includes a battery module (10) in which a plurality of battery cells (11) are connected in series. A primary circuit having a primary winding (21) and a switching element (22) provided correspondingly, and a secondary circuit (27) having a secondary winding (27) magnetically coupled to each of the primary windings. A converter (20, 60) including a secondary side circuit, and the output of the secondary side circuit of the converter as a power source, the primary side circuit of the converter so that the output voltage of the secondary side circuit is constant And a control unit (50) for controlling the switching element provided in the device.
Further, in the power supply device of the present invention, the converter has a winding ratio with respect to the secondary side winding set to a predetermined value, and is magnetically coupled to each of the primary side winding and the secondary side winding. A third-side circuit having a third-side winding (61) that controls the switching element provided in the first-side circuit of the converter so that the output voltage of the third-side circuit is constant. It is characterized by doing.
Moreover, the power supply device of this invention is equipped with the cell voltage detection part (40) which each detects the voltage of these battery cells, and the said control part respond | corresponds to the voltage detected by the said cell voltage detection part. The switching element is controlled so that the discharge amount of the battery cell having a high voltage is increased.
In the power supply device of the present invention, the control unit performs pulse width modulation control on the switching element based on a detection result of the cell voltage detection unit.
The voltage adjustment method of the present invention is a voltage adjustment method for a power supply device (1, 2) including a battery module (10) in which a plurality of battery cells (11) are connected in series, and corresponds to each of the battery cells. A primary side circuit having a primary side winding (21) and a switching element (22), and a secondary side winding (27) magnetically coupled to each of the primary side windings. An output voltage used as a power source is obtained from the secondary side circuit of the converter (20, 60) including the side circuit, and the primary side circuit of the converter is made constant so that the output voltage of the secondary side circuit is constant. The switching element provided in the control unit is controlled.
In the voltage adjustment method of the present invention, the converter has a winding ratio with respect to the secondary side winding set to a predetermined value, and is magnetically connected to each of the primary side winding and the secondary side winding. The switching element provided in the primary circuit of the converter is controlled so that the output voltage of the tertiary circuit is constant. .
Further, the voltage adjustment method of the present invention detects the voltages of the plurality of battery cells, and controls the switching element so that the discharge amount of the battery cells having a high voltage increases according to the detected voltage. It is characterized by.

  According to the present invention, a primary side circuit having a primary side winding and a switching element corresponding to each of the battery cells included in the battery module, and a secondary side winding magnetically coupled to each of the primary side windings) A converter including a secondary side circuit having a secondary side circuit, and a controller that uses the output of the secondary side circuit of the converter as a power source so that the output of the secondary side circuit of the converter is constant. Since the provided switching element is controlled and the electric power discharged from the battery cell is reused as the power source of the power source unit, there is an effect that the efficiency can be increased with a simple configuration.

It is a circuit diagram which shows the principal part structure of the power supply device by 1st Embodiment of this invention. It is a circuit diagram which shows the principal part structure of the power supply device by 2nd Embodiment of this invention.

  Hereinafter, a power supply device and a voltage adjustment method according to an embodiment of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a circuit diagram showing a main configuration of the power supply device according to the first embodiment of the present invention. As shown in FIG. 1, the power supply device 1 according to the present embodiment includes a battery module 10, a converter 20, a voltage detection unit 30, a cell voltage detection unit 40, and a control unit 50. From the battery module 10, power supply terminals T11, While supplying electric power to the outside via T12, the battery module 10 can be charged by electric power supplied from the outside via the power supply terminals T11 and T12.

  The battery module 10 includes a plurality of battery cells 11 connected in series. The positive electrode of the battery cell 11 located at one end is connected to the power supply terminal T11, and the negative electrode of the battery cell 11 located at the other end is connected to the power supply terminal T12. It is connected to the. The battery cell 11 is a rechargeable battery cell such as a nickel / cadmium battery, a nickel / hydrogen battery, or a lithium ion battery, and is in a number corresponding to the output voltage required for the power supply device 1 (for example, several tens of cells). Degree) connected in series.

  The converter 20 includes a transformer Tr, a primary circuit provided on the primary side of the transformer Tr, and a secondary circuit provided on the secondary side of the transformer Tr, and is a battery module under the control of the control unit 50. 10 is charged or discharged. The converter 20 is a so-called flyback converter, and the power necessary for the voltage detector 30, the cell voltage detector 40, and the controller 50 while equalizing the voltage of the battery cell 11 provided in the battery module 10. Is provided to generate

  The primary side circuit of the converter 20 includes a primary side winding 21, a transistor 22 (switching element), diodes 23 and 24, a capacitor 25, and a resistor 25, and is provided corresponding to each of the battery cells 11 included in the battery module 10. It is done. The primary side winding 21 is a winding provided on the primary side of the transformer Tr, and one end thereof is connected to the positive electrode of the corresponding battery cell 11 and the other end is connected to the collector electrode of the transistor 22.

  The transistor 22 has a gate electrode connected to the control unit 50 and an emitter electrode connected to the negative electrode of the corresponding battery cell 11, and is switched on or off under the control of the control unit 50. When the transistor 22 is switched between the on state and the off state, the current flowing through the primary side winding 21 changes and a voltage is induced in the secondary side circuit. The emitter electrode of the transistor 22 is connected to the anode electrode of the diode 23, and the collector electrode is connected to the cathode electrode of the diode 23.

  The diode 24 has an anode electrode connected to a connection point between the primary winding 21 and the collector electrode of the transistor 22, and a cathode electrode connected to one electrode of the capacitor 25 and one end of the resistor 26. The other electrode of the capacitor 25 and the other end of the resistor 26 are connected to one end of the primary side winding 21 (that is, the positive electrode of the battery cell 11).

  The secondary side circuit of the converter 20 includes a secondary side winding 27, a diode 28, and a capacitor 29. The primary side circuit described above is provided corresponding to each of the battery cells 11, whereas only one secondary side circuit is provided. The secondary winding 27 is a winding provided on the secondary side of the transformer Tr and is magnetically coupled to each of the primary windings 21 provided in the primary circuit. Therefore, when the current flowing in any of the primary windings 21 provided in the primary circuit changes, a voltage corresponding to the change is induced in the secondary winding 27. One end of the secondary winding 27 is connected to the anode electrode of the diode 28, and the other end is connected to the terminal T22.

  The diode 28 and the capacitor 29 form a rectifier circuit and rectify the voltage induced in the secondary winding 27. Therefore, the DC voltage rectified by this rectifier circuit appears between the terminals T21 and T22. Here, although not shown in FIG. 1, the terminals T21 and T22 are connected to the voltage detector 30, the cell voltage detector 40, and the controller 50, and the voltage appearing between the terminals T21 and T22. Is used as the power supply voltage for each of these parts.

  The voltage detection unit 30 includes a differential amplifier 31 and a photocoupler 32, operates with a voltage appearing between the terminals T21 and T22 of the converter 20, and detects a voltage appearing between the terminals T21 and T22 of the converter 20. . The differential amplifier 31 has a non-inverting input terminal connected to the terminal T21 and an inverting input terminal connected to the terminal T22, and outputs a signal indicating a difference between the potential of the terminal T21 and the potential of the terminal T22. The photocoupler 32 converts the signal output from the differential amplifier 31 into an optical signal and outputs the optical signal to the control unit 50. The photocoupler 32 is provided to insulate the differential amplifier 31 connected to the secondary side of the transformer Tr from the control unit 50 connected to the primary side of the transformer Tr.

  The cell voltage detection unit 40 includes a plurality of differential amplifiers 41 and a selection circuit 42, operates with a voltage appearing between terminals T 21 and T 22 of the converter 20, and a plurality of battery cells provided in the battery module 10. 11 voltages are detected. The differential amplifier 41 is provided corresponding to each of the battery cells 11 included in the battery module 10, and the non-inverting input terminal is connected to the positive electrode of the corresponding battery cell 11, and the inverting input terminal is connected to the negative electrode. Yes. The selection circuit 42 sequentially selects the output signals output from each of the differential amplifiers 41 in a preset order for each preset period, and outputs them to the control unit 50.

  The control unit 50 includes a control circuit 51 and a plurality of driver circuits 52, operates with a voltage appearing between the terminals T21 and T22 of the converter 20, and a voltage appearing between the terminals T21 and T22 of the converter 20 is constant. Thus, the transistor 22 provided in the primary circuit of the converter 20 is controlled. For example, when the power supply voltage required by the voltage detector 30, the cell voltage detector 40, and the controller 50 is 12 volts, the transistor 22 is set so that the voltage appearing between the terminals T21 and T22 is 12 volts. To control.

  Control circuit 51 outputs a control signal for controlling transistor 22 provided in the primary circuit of converter 20 based on the detection result of voltage detection unit 30. Specifically, the control circuit 51 outputs a control signal for performing switching control of the transistor 22 by PWM (Pulse Width Modulation) control. Here, the control signal 51 performs PWM control on the transistor 22 so that the discharge amount of the battery cell 11 with a relatively high voltage detected by the cell voltage detection unit 40 is increased.

  That is, the control circuit 51 increases the on-duty ratio for the transistor 22 provided corresponding to the battery cell 11 whose voltage detected by the cell voltage detection unit 40 is relatively high, and the detected voltage is reversed. The transistor 22 provided corresponding to the relatively low battery cell 11 is controlled to lower the on-duty ratio. Here, the on-duty ratio is a ratio between a control cycle of PWM control and a time during which the transistor 22 is in an on state within the control cycle of PWM control. The driver circuit 52 is provided corresponding to each of the transistors 22 provided on the primary side of the converter 20 and is driven to drive the corresponding transistor 22 based on a control signal output from the control circuit 51. Generate a signal.

  In the above configuration, when a control signal for PWM control is output from the control circuit 51 to each of the driver circuits 52, a drive signal corresponding to the control signal is generated in each of the driver circuits 52. This drive signal is output to the corresponding transistor 22 provided on the primary side of the converter 20, whereby each of the transistors 22 is switched. Then, the current flowing in the primary side winding 21 provided on the primary side of the converter 20 changes and a voltage is induced in the secondary side winding 27. The induced voltage is rectified by the diode 28 and the capacitor 29, and a DC voltage appears between the terminals T21 and T22. The DC voltage appearing at the terminals T21 and T22 is supplied to the voltage detection unit 30, the cell voltage detection unit 40, and the control unit 50 as a power supply voltage.

  Thereby, the detection result of the voltage detection unit 30 is input to the control circuit 51, and the control circuit 51 sets each of the transistors 22 provided on the primary side of the converter 20 so that the detection result of the voltage detection unit 30 becomes constant. A control signal for controlling the signal is output. At this time, the detection result of the cell voltage detector 40 is also input to the control circuit 51. The control signal 51 refers to the detection result of the cell voltage detection unit 40 and outputs a control signal for PWM control of the transistor 22 so that the discharge amount of the battery cell 11 having a relatively high detected voltage is increased.

  Specifically, a control signal with a high on-duty ratio is output for the transistor 22 provided corresponding to the battery cell 11 whose voltage detected by the cell voltage detector 40 is relatively high. On the other hand, for the transistor 22 provided corresponding to the battery cell 11 whose voltage detected by the cell voltage detector 40 is relatively low, a control signal with a low on-duty ratio is output. When such control is performed, the amount of discharge from the battery cell 11 having a high voltage increases, and on the contrary, the amount of discharge from the battery cell 11 having a low voltage decreases, and the voltage of the battery cell 11 can be made uniform. .

  Further, the electric power discharged from the battery cell 11 is converted into a voltage via the transformer Tr and output from the terminals T21 and T22 of the converter 20 to operate the voltage detection unit 30, the cell voltage detection unit 40, and the control unit 50. Used for. Thus, in this embodiment, since the electric power discharged from the battery cell 11 is reused without wasting it, efficiency can be improved. Moreover, since it is not necessary to supply power for operating the voltage detection unit 30, the cell voltage detection unit 40, and the control unit 50 from the outside, the efficiency can be increased with a simple configuration.

[Second Embodiment]
FIG. 2 is a circuit diagram showing a main configuration of a power supply device according to the second embodiment of the present invention. In FIG. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals. In FIG. 2, for the sake of simplification, the driver circuit 52 provided in the cell voltage detection unit 40 and the control unit 50 is not shown, and connection lines and driver circuits between the cell voltage detection unit 40 and the battery cells 11 are omitted. A connection line between the transistor 52 and the transistor 22 provided in the primary circuit of the converter 20 is not shown.

  As shown in FIG. 2, the power supply device 2 of the present embodiment has a configuration in which a converter 60 is provided instead of the converter 20 in FIG. 1 and a differential amplifier 70 is provided instead of the voltage detection unit 30. The converter 60 includes a tertiary circuit in addition to the primary circuit and the secondary circuit described above. The tertiary circuit is composed of a tertiary winding 61, a diode 62, and a capacitor 63, and outputs a DC voltage of, for example, 5 volts.

  As with the secondary side winding 27 provided in the secondary side circuit, only one tertiary side winding 61 provided in the tertiary side circuit is provided, and the primary side winding 21 provided in the primary side circuit It is magnetically coupled to the secondary winding 27 provided in each and the secondary circuit. Further, the winding ratio of the tertiary winding 61 with respect to the secondary winding 27 is set to a predetermined winding ratio. For example, when the voltage output from the secondary circuit is 12 volts, the winding ratio with respect to the secondary winding 27 is set so that the voltage output from the tertiary circuit is 5 volts. Yes.

  One end of the tertiary winding 61 is connected to the anode electrode of the diode 62, and the other end is connected to the inverting input terminal of the differential amplifier 70. The diode 62 and the capacitor 63 form a rectifier circuit similarly to the diode 28 and the capacitor 29 provided in the secondary circuit, and rectify the voltage induced in the tertiary winding 61. The cathode electrode of the diode 62 and one electrode of the capacitor 63 are connected to the non-inverting input terminal of the differential amplifier 70, and the other electrode of the capacitor 63 is connected to the inverting input terminal of the differential amplifier 70. Therefore, the DC voltage rectified by this rectifier circuit appears between the inverting input terminal and the non-inverting input terminal of the differential amplifier 70.

  The differential amplifier 70 outputs a signal indicating the potential difference between the electrodes of the capacitor 63 provided in the tertiary circuit to the control circuit 51. The tertiary winding 61 is provided on the primary winding 31 side and does not need to be insulated. Therefore, it is not necessary to provide the one corresponding to the photocoupler 32 in FIG. Here, since the tertiary winding 61 is set to a predetermined winding ratio with respect to the secondary winding 27 as described above, the potential difference between the electrodes of the capacitor 63 is the terminal T21 of the converter 60. The potential difference between T22 is a value corresponding to the winding ratio between the secondary winding 27 and the tertiary winding 61.

  Therefore, if the control circuit 51 refers to the signal output from the differential amplifier 70 and controls the transistor 22 provided in the primary circuit of the converter 20 so that the output voltage of the tertiary circuit is constant, The voltage appearing between the terminals T21 and T22 of the converter 20 can be made constant. For example, if the output power of the tertiary circuit is controlled to be 5 volts, the voltage appearing between the terminals T21 and T22 can be 12 volts.

  Although not shown in FIG. 2, the detection result of the cell voltage detector 40 is input to the control circuit 51. Also in this embodiment, the on-duty ratio is increased for the transistor 22 provided corresponding to the battery cell 11 whose voltage detected by the cell voltage detection unit 40 is relatively high, and the voltage detected conversely. The control circuit 51 controls the transistor 22 provided corresponding to the battery cell 11 having a relatively low value to reduce the on-duty ratio. For this reason, the voltage of the battery cell 11 can be equalized similarly to 1st Embodiment.

  Also in the present embodiment, the electric power discharged from the battery cell 11 is converted into a voltage via the transformer Tr and output from the terminals T21 and T22 of the converter 20, and the voltage detector 30, the cell voltage detector 40, and It is used for operating the control unit 50. Therefore, since the electric power discharged from the battery cell 11 is reused without being wasted, efficiency can be improved. Moreover, since it is not necessary to supply power for operating the voltage detection unit 30, the cell voltage detection unit 40, and the control unit 50 from the outside, the efficiency can be increased with a simple configuration.

  The power supply device and the voltage adjustment method according to the embodiment of the present invention have been described above. However, the present invention is not limited to the above-described embodiment, and can be freely changed within the scope of the present invention. For example, in the above embodiment, the case where the converters 20 and 60 are so-called flyback converters has been described as an example, but these may be forward converters or push-pull converters. That is, the converter may be a switching converter.

DESCRIPTION OF SYMBOLS 1, 2 Power supply device 10 Battery module 11 Battery cell 20 Converter 21 Primary side winding 22 Switching element 27 Secondary side winding 40 Cell voltage detection part 50 Control part 60 Converter 61 Tertiary side winding

Claims (5)

In a power supply device including a battery module in which a plurality of battery cells are connected in series,
A primary side circuit having a primary side winding and a switching element provided corresponding to each of the battery cells, and a secondary side circuit having a secondary side winding magnetically coupled to each of the primary side windings And a tertiary circuit having a tertiary winding that is magnetically coupled to each of the primary windings and the secondary winding with a winding ratio to the secondary winding set to a predetermined value; A converter comprising:
The output of the secondary side circuit of the converter is a power source, and the output voltage of the tertiary side circuit is a predetermined voltage corresponding to the winding ratio of the secondary side winding and the tertiary side winding , And a control unit that controls the switching element provided in a primary circuit of the converter. A cell voltage detector for detecting the voltage of each of the plurality of battery cells,
2. The power supply device according to claim 1 , wherein the control unit controls the switching element so that a discharge amount of a battery cell having a high voltage is increased in accordance with a voltage detected by the cell voltage detection unit. . The power supply apparatus according to claim 2 , wherein the control unit performs pulse width modulation control on the switching element based on a detection result of the cell voltage detection unit. A voltage adjustment method for a power supply device including a battery module in which a plurality of battery cells are connected in series,
A primary side circuit having a primary side winding and a switching element provided corresponding to each of the battery cells, and a secondary side circuit having a secondary side winding magnetically coupled to each of the primary side windings And a tertiary circuit having a tertiary winding that is magnetically coupled to each of the primary windings and the secondary winding with a winding ratio to the secondary winding set to a predetermined value; An output voltage used as a power source is obtained from the secondary side circuit of the converter including the output voltage of the tertiary side circuit in accordance with a winding ratio between the secondary side winding and the tertiary side winding. as a predetermined voltage, the voltage adjusting method characterized by controlling the switching element provided on the primary circuit of the converter. 5. The voltage according to claim 4 , wherein the voltage of the plurality of battery cells is detected, and the switching element is controlled so as to increase the discharge amount of the battery cell having a high voltage according to the detected voltage. Adjustment method.

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