JP5793673B2 - Charger - Google Patents

Description

  The present invention relates to a charger for charging a secondary battery.

  In recent years, there has been a demand for reducing power consumption of home appliances, and there is a charger that reduces standby power (see, for example, Patent Document 1). When no secondary battery is installed, this charger stops the operation of the circuit that supplies the charging current (charging power supply circuit), and the power supply circuit (charging) that secures the power supply for the microcomputer that performs charging control Only the device driving power supply circuit) is operated. When a secondary battery is mounted, charging is performed by operating a circuit for supplying a charging current (charging power supply circuit). As a result, it is possible to reduce the standby power in which the secondary battery is not attached.

JP-A-2005-333708

  However, the above charger needs to include two power supply circuits (transformers) including a charging power supply circuit and a charging device driving power supply circuit, which is accompanied by an increase in material cost.

  The present invention has been made in view of the above-described reasons, and an object of the present invention is to provide a charger capable of reducing standby power when a secondary battery is not mounted with a single power supply circuit. .

  The charger according to the present invention includes a connection portion to which a secondary battery is connected and a switching element. When the switching element is switched, the first and second control voltages from the external power source and the connection portion are provided. A power supply unit that generates an output voltage to be applied to the secondary battery connected to the battery, a charge control unit that uses the first control voltage as an operating power source and generates a parameter according to the state of the secondary battery, and Using a second control voltage as an operating power supply, a switching control unit that performs switching control of the switching element based on the parameter, an impedance element provided between connection terminals of the connection unit, and a current flowing through the impedance element And a secondary battery connected to the connecting portion if the current flowing through the impedance element is equal to or greater than a predetermined value. A connection detection unit for determining, wherein the switching control unit is capable of switching the switching control between a first state and a second state, and the first in the case where the switching control is in the first state. , The second control voltage and the output voltage are lower than when the switching control is in the second state, and when the connection detection unit determines that the secondary battery is not connected, The switching control unit sets the switching control to a first state, and the first control voltage in the first state is lower than an operable voltage range of the charge control unit, and the second control in the first state The control voltage is within the range of the operable voltage of the switching control unit, and the secondary battery charged with a voltage higher than the output voltage in the first state is connected to the secondary battery. And the connection detection unit determines that the secondary battery is connected, the switching control unit switches the switching control to the second state, and the first state in the second state The control voltage is within the range of the operable voltage of the charge control unit, and the second control voltage in the second state is within the range of the operable voltage of the switching control unit.

  In this charger, the connection detection unit preferably includes a capacitor connected in series to the impedance element.

  As described above, according to the present invention, there is an effect that it is possible to reduce standby power when a secondary battery is not mounted with a single power supply circuit.

It is a circuit block diagram of the charger of embodiment of this invention. (A)-(c) It is a timing chart at the time of a secondary battery connection same as the above. It is a circuit block diagram of a charger. (A) (b) It is a timing chart at the time of a secondary battery connection same as the above.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
The circuit block diagram of the charger of this embodiment is shown in FIG. The charger according to the present embodiment uses the commercial power source E1 (external power source) as an input power source to charge energy for charging the secondary battery E2 (for example, a lithium ion (Li-Ion) battery) or energy for driving the charger. obtain. Below, the structure of the charger of this embodiment is demonstrated.

  The power supply connection unit 1 is generally configured by an outlet plug, is connected to the commercial power supply E1, and the AC voltage output from the commercial power supply E1 is supplied to the rectifier circuit unit 2 via the power supply connection unit 1.

  The power supply connection unit 1 is generally configured by an outlet plug, is connected to a commercial power supply E1, and supplies an AC voltage to the rectification circuit unit 2.

  The rectifier circuit unit 2 includes a diode bridge including diodes D1 to D4 and a smoothing capacitor C1, and supplies the AC voltage supplied from the commercial power supply E1 to the power supply circuit unit 3 by full-wave rectification and smoothing.

  The power supply circuit unit 3 includes a transformer T1, and the transformer T1 includes a primary winding n1 and first to third secondary windings n21 to n23, and the primary winding n1 and the first to third third windings. The secondary windings n21 to n23 are insulated from each other.

  The primary winding n1 has one end connected to the positive electrode of the smoothing capacitor C1 and the other end connected to the negative electrode of the smoothing capacitor C1 via the switching means 5. The switching means 5 comprises a switching element Q1 made of a MOSFET, the drain terminal is connected to the other end of the primary winding n1, the source terminal is connected to the negative electrode of the smoothing capacitor C1, and the gate terminal is the switching control circuit unit. 4 is connected. The switching means 5 (switching element Q1) is controlled by the switching control circuit unit 4 (switching control unit) to control the current flowing through the primary winding n1. The power supply circuit section 3 and the switching means 5 constitute a power supply section of the present invention.

  A diode D5 and a smoothing capacitor C2 are connected in series between both ends of the first secondary winding n21, and an output voltage V1 applied to the secondary battery E2 is generated between both ends of the smoothing capacitor C2. One end of the first secondary winding n21 is connected to the anode of the diode D5, the cathode of the diode D5 is connected to the positive electrode of the smoothing capacitor C2, and the other end of the smoothing capacitor C2 is the other one of the first secondary winding n21. Connected to the end.

  A diode D6 and a smoothing capacitor C3 are connected in series between both ends of the second secondary winding n22, and a second control voltage V3 serving as an operation power supply for the switching control circuit unit 4 is applied between both ends of the smoothing capacitor C3. To generate. One end of the second secondary winding n22 is connected to the anode of the diode D6, the cathode of the diode D6 is connected to the positive electrode of the smoothing capacitor C3, and the negative electrode of the smoothing capacitor C3 is the other end of the second secondary winding n22. It is connected to the.

  The third secondary winding n23 has a diode D7 and a smoothing capacitor C4 connected in series between both ends, and a first control voltage V2 serving as an operating power supply for a charge control circuit unit 7 (charge control unit) described later. Is generated between both ends of the smoothing capacitor C4. One end of the third secondary winding n23 is connected to the anode of the diode D7, the cathode of the diode D7 is connected to the positive electrode of the smoothing capacitor C4, and the negative electrode of the smoothing capacitor C4 is the other end of the third secondary winding n23. It is connected to the.

  That is, the power supply circuit unit 3 and the switching means 5 constitute a flyback converter, and the primary side energy is transmitted to the secondary side by magnetic energy. When the switching element Q1 is turned on, a current flows through the primary winding n1, and a magnetic flux is generated by this current. The magnetic flux is transmitted to the first to third secondary windings n21 to n23 through the iron core of the transformer T1. In the present embodiment, backflow prevention diodes D5 to D7 are provided on the secondary side (first to third secondary windings n21 to n23), and the secondary side while the switching element Q1 is on. There is no current flowing through. The magnetic energy accumulated during this time is output as a current to the secondary side when the switching element Q1 is turned off. The energy transmitted to the secondary side can be adjusted by adjusting the ON period of the switching element Q1, that is, the first and second control voltages V2, V3 and the output voltage V1 can be varied. The adjustment of the ON period of the switching element Q1 generally uses PWM control, and the target value (parameter) of the ON period is determined by the charge control circuit unit 7 described later, and depends on the state of the secondary battery E2. Change. In the present embodiment, the flyback converter is used as an example, but a forward converter, a push-pull converter, or the like may be used.

  With the above configuration, the switching element Q1 is switched to generate the first and second control voltages V2, V3 and the output voltage V1.

  Further, the charger includes a battery connection unit 10 (connection unit) to which the secondary battery E2 is connected. The battery connection part 10 is a mechanical connection part used for connecting the secondary battery E2, and is connected to the positive terminal of the secondary battery E2 and the negative terminal connected to the negative electrode of the secondary battery E2. It consists of. The positive electrode terminal is connected to the positive electrode of the smoothing capacitor C2, the negative electrode terminal is connected to the negative electrode of the smoothing capacitor C2 via the resistor R1, and when the secondary battery E2 is connected to the battery connection unit 10, the battery connection unit 10 is connected. The output voltage V2 is applied to the secondary battery E2. In FIG. 1, only the positive electrode terminal and the negative electrode terminal are shown, but generally, a temperature detection terminal for detecting the temperature of the secondary battery E2 and an information terminal for obtaining information on the secondary battery E2. Etc. are also provided.

  In addition, the charger of the present embodiment includes a charge control circuit unit 7, a current detection unit 8, and a voltage detection unit 9, and the charge control circuit unit 7 detects the current detection unit 8 and the voltage detection unit 9. From the result, the state of the secondary battery E2 is determined, and the target value of the ON period of the switching element Q1 is determined.

  The current detection unit 8 is configured by a resistor R1 and is interposed between the negative electrode of the smoothing capacitor C2 and the negative electrode terminal of the battery connection unit 10. When the secondary battery E2 is connected to the battery connection unit 10, when a charging current I1 supplied from the smoothing capacitor C2 to the secondary battery E1 is generated, a voltage corresponding to the charging current I1 is generated between both ends of the resistor R1. Occur. The charging control circuit unit 7 detects the charging current I1 by detecting the voltage across the resistor R1.

  The voltage detection unit 9 is configured by connecting a series circuit including a plurality of resistors (not shown) between connection terminals (positive terminal and negative terminal) of the battery connection unit 10. When the secondary battery E2 is connected to the battery connection unit 10, the voltage detection unit 9 generates a partial pressure value of the secondary battery voltage V4 charged in the secondary battery E2. The charge control circuit unit 7 detects the secondary battery voltage V4 by detecting the divided voltage value of the secondary battery voltage V4.

  The charging control circuit unit 7 determines the state of the secondary battery E2 from the charging current I1 and the secondary battery voltage V4, and determines a target value for the ON period of the switching element Q1. Then, the switching control circuit unit 4 performs switching control of the switching element Q1 so that the ON period of the switching element Q1 matches the target value determined by the charge control circuit unit 7. For example, when the charging current I1 is larger than the target current value, the output voltage V1 is reduced and the energy supplied to the secondary battery E2 is reduced by switching control so that the ON period of the switching element Q1 is shortened. When the charging current I1 is smaller than the target current value, the output voltage V1 is increased to increase the energy supplied to the secondary battery E2 by performing switching control so that the ON period of the switching element Q1 becomes longer.

  Further, since the secondary battery E2 (especially a lithium ion battery) is dangerous when overcharged, the charge control circuit unit 7 gradually sets the target value of the charging current I1 when the secondary battery voltage V4 reaches a predetermined value. CV charge control is performed to lower.

  Although not shown in FIG. 1, a temperature detection function and an abnormality detection function for the secondary battery E2 are generally provided, and the charge control circuit unit 7 is used when the temperature exceeds a predetermined temperature or an abnormality occurs. In the event of occurrence of a failure, processing such as stopping switching control of the switching element Q1 is performed.

  Further, since the power supply voltage of the charge control circuit unit 7 of the present embodiment is a constant voltage (for example, 5V), the first control voltage V2 is converted to 5V using the constant voltage circuit unit 6 and the charge control circuit unit 7 is used. The charge control circuit unit 7 is driven by being applied to. The constant voltage circuit unit 6 includes a three-terminal regulator 61. The three-terminal regulator 61 has an input terminal connected to the positive electrode of the smoothing capacitor C4, and generates 5 V if the first control voltage V2 is within the operable voltage range of the three-terminal regulator 61. The output terminal of the three-terminal regulator 61 is connected to the positive electrode of the smoothing capacitor C5 and the power supply terminal of the charge control circuit unit 7. The generated 5V is smoothed and applied to the charge control circuit unit 7. The charge control circuit unit 7 is driven when 5 V is output from the three-terminal regulator 61. That is, when the first control voltage V2 is within the range of the operable voltage of the three-terminal regulator 61, the charge control circuit unit 7 is driven, and when outside the range, the charge control circuit unit 7 is stopped. Therefore, the operable voltage range of the three-terminal regulator 61 corresponds to the operable voltage range of the charge control unit of the present invention.

  Further, the target value of the ON period of the switching element Q1 determined by the charge control circuit unit 7 is transmitted to the switching control circuit unit 4 using the information transmission unit 12. The information transmission unit 12 includes a photocoupler PC1 and a resistor R2, and the primary side and the secondary side are insulated by using the photocoupler PC1. A series circuit including a resistor R2 and a diode D8 of the photocoupler PC1 is connected between the control terminal P71 of the charge control circuit unit 7 and the control power supply Vcc. In the present embodiment, the three-terminal regulator 61 also serves as the control power supply Vcc.

  Then, the charging control circuit unit 7 varies the output level of the control terminal P71 according to the target value of the ON period of the switching element Q1. As a result, the current flowing from the control power supply Vcc to the diode D8 of the photocoupler PC1 also varies. For example, when the target value for the on period is increased, the current flowing through the diode D8 is decreased by increasing the output level of the control terminal P71, and the base current of the transistor Tr1 of the photocoupler PC1 is also decreased. When the target value for the on period is decreased, the current flowing through the diode D8 is increased by decreasing the output level of the control terminal P71, and the base current of the transistor Tr1 is also increased.

  The switching control circuit unit 4 is configured by a power supply control IC or the like, and the first current output terminal P41 is connected to the collector of the transistor Tr1 of the photocoupler PC1. Then, the switching control circuit unit 4 acquires the target value of the on period from the charging control circuit unit 7 by detecting the current I2 output from the first current output terminal P41. Then, switching control of the switching element Q1 is performed based on the acquired target value of the ON period.

  That is, when the charging control circuit unit 7 increases the output level of the control terminal P71 in order to increase the target value of the ON period of the switching element Q1, the base current of the transistor Tr1 decreases, and the switching control circuit unit 4 The current I2 output from the first current output terminal P41 decreases. Further, when the charging control circuit unit 7 decreases the output level of the control terminal P71 in order to decrease the target value of the ON period of the switching element Q1, the first current output terminal P41 of the switching control circuit unit 4 outputs. The current I2 increases. And the switching control circuit part 4 performs switching control of the switching element Q1 so that it may become an ON period which the magnitude | size of the electric current I2 shows. That is, the charger of the present embodiment performs feedback control of the charging energy supplied to the secondary battery E2 using the charging control circuit unit 7.

  Further, the switching control circuit unit 4 uses the second control voltage V3 generated at both ends of the capacitor C3 as an operating power supply, and the second control voltage V3 is within the range of the operable voltage of the switching control circuit unit 4. In this case, the switching control circuit unit 4 is driven to perform switching control of the switching element Q1.

  In addition, the charger of this embodiment is provided with the switch part (not shown) which switches the switching element Q1 for a predetermined period at the time of starting when the power supply connection part 1 is connected to the commercial power supply E1. When the switch unit switches the switching element Q1 for a predetermined period, the second control voltage V3 falls within the operable voltage range of the switching control circuit unit 4, and the switching control circuit unit 4 is started. Then, after the switching control circuit unit 4 is started, the switch unit is stopped, and the switching control circuit unit 4 performs switching control of the switching element Q1.

  In addition, the charger of the present embodiment includes a battery attachment detection unit 11 that detects that the secondary battery E2 is attached, and a battery attachment signal transmission unit 13.

  The battery attachment detection unit 11 (connection detection unit) includes a resistor R3 (impedance element) and a diode D9 of a photocoupler PC2 (current detection element), and a series circuit including the resistor R3 and the diode D9 is connected to the battery. The portion 10 is connected between the positive terminal and the negative terminal.

  The battery mounting signal transmission unit 13 includes a transistor Tr2 of the photocoupler PC2, and the collector of the transistor Tr2 is connected to the second current output terminal P42 of the switching control circuit unit 4. Then, the switching control circuit unit 4 determines whether or not the secondary battery E2 is attached based on the current I3 output from the second current output terminal P42.

  When the secondary battery E2 is connected to the battery connection unit 10, the current I4 corresponding to the secondary battery voltage V4 charged in advance in the secondary battery E2 is changed from the positive terminal of the battery connection unit 10 to the resistor R3, the diode D9, It flows through the path of the negative electrode terminal of the battery connection unit 10. This current I4 increases the base current of the transistor Tr2, and increases the current I3 output from the second current output terminal P42. When the current I4 increases and the current I3 becomes equal to or greater than a predetermined value, the switching control circuit unit 4 determines that the secondary battery E2 is attached.

  The switching control circuit unit 4 switches the switching control between the first state and the second state in accordance with whether or not the secondary battery E2 is attached, so that the first and second control voltages V2 and V3 and the output voltage are switched. V1 is varied. Hereinafter, the first and second control voltages V2 and V3 and the output voltage V1 when the switching control is in the first state are referred to as first and second control voltages V2a and V3a and the output voltage V1a. The first and second control voltages V2 and V3 and the output voltage V1 when the switching control is in the second state are referred to as first and second control voltages V2b and V3b and the output voltage V1b. The first and second control voltages V2a and V3a and the output voltage V1a when the switching control is in the first state are the first and second control voltages V2b when the switching control is in the second state. , V3b and the output voltage V1b.

  The switching control circuit unit 4 sets the switching control to the first state when the secondary battery E2 is not attached. At this time, the first control voltage V2a is lower than the operable voltage range of the three-terminal regulator 61, the charging control circuit unit 7 is stopped, and the second control voltage V3a is operable by the switching control circuit unit 4. The switching control circuit unit 4 is driven within the voltage range. Since the output voltage V1a in the first state is low and the current I4 at this time is small, the current II3 output from the second current output terminal P42 is less than a predetermined value. Therefore, erroneous detection of the secondary battery E2 can be prevented.

  Moreover, the switching control circuit part 4 switches switching control from a 1st state to a 2nd state, when the secondary battery E2 is mounted | worn. At this time, the first control voltage V2b is driven by the charge control circuit unit 7 within the range of the operable voltage of the three-terminal regulator 61, and the second control voltage V3b is an operational voltage of the switching control circuit unit 4. The switching control circuit unit 4 is driven within the range.

  Next, operation | movement of the charger of this embodiment is demonstrated using Fig.2 (a)-(c).

  At time t0, when the power supply connection unit 1 is connected to the commercial power supply E1 and starts up, the switching unit starts the switching control circuit unit 4 by switching the switching element Q1 for a predetermined period.

  When the switching control circuit unit 4 is started, the current I3 output from the second current output terminal P42 is confirmed. When the current I3 is less than the predetermined value, the switching control circuit unit 4 determines that the secondary battery E2 is not attached and sets the switching control to the first state. Therefore, although the switching control circuit unit 4 is driven by the second control voltage V3a, the charge control circuit unit 7 is in the stopped state because the first control voltage V2a is lower than the operable range of the three-terminal regulator 61. Will remain.

  Then, at time t1, the secondary battery E2 charged with the secondary battery voltage V4 higher than the output voltage V1a is connected to the battery connection unit 10. The secondary battery E2 increases the current I4 flowing through the diode D9, whereby the current I3 becomes equal to or greater than a predetermined value, and the switching control circuit unit 4 determines that the secondary battery E2 is connected. Then, the switching control circuit unit 4 switches the switching control from the first state to the second state. As a result, the first control voltage V2b falls within the operable voltage range of the three-terminal regulator 61, and the charge control circuit unit 7 starts to be driven. Further, the output voltage V1 also increases, and charging of the secondary battery E2 is started.

  Thereafter, the charging control circuit unit 7 determines the target value of the on period from the state of the secondary battery E2, and the switching control circuit unit 4 performs feedback control so that the on period of the switching element Q1 matches the target value. .

  As described above, in the present embodiment, the first and second control voltages V2 and V3 and the output voltage V1 are reduced and the charging control circuit unit 7 is stopped during standby when the secondary battery E2 is not connected. Therefore, power consumption can be reduced.

  Further, in the present embodiment, the first control voltage V2 that is the operating power source of the charging control circuit unit 7, the second control voltage V3 that is the operating power source of the switching control circuit unit 4, and the output applied to the secondary battery E2. The voltage V1 is generated by a single power supply circuit (transformer T1). Therefore, unlike the prior art, it is not necessary to provide a plurality of power supply circuits (transformers), so that material costs can be reduced.

  As shown in FIG. 3, in the battery attachment detection unit 11, a capacitor C <b> 6 may be connected between the diode D <b> 9 of the photocoupler PC <b> 2 and the negative electrode terminal of the battery connection unit 10. When the capacitor C6 is not provided, when the power supply connection unit 1 is not connected to the commercial power supply E1 and the secondary battery E2 is attached, a minute current I4 flows from the secondary battery E2 to the resistor R3 and continues to be discharged. This will result in deep discharge. Therefore, by providing the capacitor C6 in the battery attachment detection unit 11, it is possible to prevent the current from continuing to flow from the secondary battery E2 to the resistor R3 and to prevent deep discharge of the secondary battery E2.

  As shown in FIGS. 4A to 4B, when the secondary battery E2 is mounted at time t2, the current I4 flows only for a predetermined time until the capacitor C6 is charged by the current I4, and then decreases. To do. Therefore, even when the commercial power supply E1 is not connected to the power supply connection portion 1, deep discharge of the secondary battery E2 can be prevented.

DESCRIPTION OF SYMBOLS 1 Power supply connection part 2 Rectification circuit part 3 Power supply circuit part 4 Switching control circuit part 5 Switching means 6 Constant voltage circuit part 7 Charge control circuit part 8 Current detection part 9 Voltage detection part 10 Battery connection part 11 Battery mounting detection part 12 Signal transmission Part 13 Battery mounting signal transmission part Q1 Switching element E2 Secondary battery

Claims (2)

A connection part to which a secondary battery is connected;
A power supply unit having a switching element and generating the first and second control voltages and the output voltage applied to the secondary battery connected to the connection unit from an external power supply by switching the switching element When,
A charge control unit that uses the first control voltage as an operating power supply and generates a parameter according to a state of the secondary battery;
A switching control unit configured to use the second control voltage as an operation power supply and perform switching control of the switching element based on the parameter;
An impedance element provided between the connection terminals of the connection portion; and a current detection element that detects a current flowing through the impedance element; and if the current flowing through the impedance element is a predetermined value or more, the connection portion A connection detector that determines that a secondary battery is connected;
The switching control unit can switch the switching control between a first state and a second state, and the first and second control voltages and the output when the switching control is the first state. The voltage is lower than when the switching control is in the second state,
When the connection detection unit determines that the secondary battery is not connected, the switching control unit sets the switching control to the first state, and the first control voltage in the first state is the charge Lower than the range of operable voltage of the control unit, the second control voltage in the first state is within the range of operable voltage of the switching control unit;
When the secondary battery charged with a voltage higher than the output voltage in the first state is connected to the connection unit, and the connection detection unit determines that the secondary battery is connected, the switching The control unit switches the switching control to the second state, and the first control voltage in the second state is within an operable voltage range of the charge control unit, and the first control voltage in the second state is The charger is characterized in that the control voltage of 2 is within an operable voltage range of the switching control unit.   The charger according to claim 1, wherein the connection detection unit includes a capacitor connected in series to the impedance element.

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