JP4174530B2 - Electronic device apparatus having a charging circuit - Google Patents

Description

  The present invention relates to charge control of an electronic device provided with a capacitor and its charger.

  When charging a capacitor such as an electric double layer capacitor with a constant current, the power supplied to the capacitor is given by the product of voltage and current. Accordingly, the supplied power is small at the beginning of charging, and the supplied power tends to increase in proportion to the charged voltage at the end of charging. When performing such charging, the power supply for charging will increase drastically when the charging voltage of the battery increases, and the cost and size of the charging circuit will increase to ensure the power supply capacity of the charging circuit. There is a problem.

  In addition, in the case of electronic equipment used in offices and homes, general outlets have a limit on the maximum supply current, and the power consumption distribution must be designed in consideration of the peak power of the charging circuit as a whole.

  In view of this, a charging control method for a capacitor is proposed in which the power supply mode for the battery is changed in accordance with the charging stage and the charging efficiency is increased by constant power (see, for example, Patent Document 1).

  FIG. 9 is a block diagram of a schematic configuration of the charging circuit, and FIG. 10 is a graph showing the relationship between current and voltage during charging.

  In FIG. 9, Vin is an input power source to the charging circuit, and C1, TR1, R1, D1, L1, and C2 constitute a power control circuit for controlling charging with a constant current, a constant voltage, and a constant power by the control unit. C3 and C4 are capacitors to be charged, R2 and R3 are resistances for detecting terminal voltages at both ends of the capacitor, R4 is a resistor for detecting current flowing through the capacitors, and power detection for obtaining power information from detected voltage information and current information, respectively. It has a circuit. LOAD indicates a load connected to the capacitor.

  In the initial charging state, the control unit 101 starts constant current charging at a current value i shown in FIG. When charging proceeds at a constant current, the charging voltage rises, and when the charging voltage reaches a predetermined value, switching to constant power control that is the power target value Po is performed. Thereafter, charging is performed by constant power control. When the charging voltage further rises and the voltage value reaches v, the charging is switched to constant voltage control, the charging current value decreases, and the charging is completed when the current becomes zero.

Such charge control is conventionally known as a method for charging a secondary battery such as a lithium ion battery, and is effective in reducing peak power during charging.
JP 2005-253288 A

  However, the above-described method has the following problems.

  In general offices and homes, there is an upper limit on the supply current for outlets for commercial power supply, and internal power distribution is such that the maximum current value is not exceeded when the maximum power consumption of the device is used in the design of electronic equipment. Need to do.

  Furthermore, devices that are used at different times depending on the operating state in electronic devices that have become more complex in recent years, and the power consumption of each device is different, so it is possible to create an operation sequence such that peak power does not overlap. It is normal that it is done.

  However, although the conventional charge control method can reduce the peak of power consumption compared to the case of no control, the target power cannot be controlled from the outside.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic device device that can always keep the power consumption of the entire device within a predetermined value by controlling the charging power of the battery.

  In order to solve the above-described problems, an electronic device device according to the present invention includes a power source that inputs an alternating current and outputs a direct-current voltage in an electronic device device that has a charging circuit that charges a capacitor. Input current information acquisition means for acquiring information on the input current supplied to the battery, voltage detection means for detecting the voltage across the terminals of the battery, current detection means for detecting the current flowing through the battery, and the battery When charging is started by constant current control, when it is determined that the power supplied to the battery has reached a target value based on the output of the voltage detection means and the output of the current detection means, switching to charging by constant power control is performed, Control means for switching to charging by constant voltage control when it is determined that the voltage between the terminals of the battery has reached a predetermined voltage based on the output of the voltage detection means; And the control means sets the target value in the constant power charging based on the input current information acquired by the input current information acquisition means, the efficiency of the power source, and the efficiency of charging the battery. Features.

  According to the present invention, by controlling the charging power maximum value to the storage device that occupies the input power according to the operating state of the electronic device device, the input power of the device always does not exceed the specified value and is optimal for the storage device. Can be recharged.

  Hereinafter, each embodiment of the present invention will be described with reference to FIGS.

(First embodiment)
First, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram showing a charge control circuit for a battery according to the first embodiment of the present invention. FIG. 2 is a block diagram showing a hardware configuration of an electronic device apparatus in which the charge control circuit of FIG. 1 is built. FIG. 3 is a graph showing the relationship between the voltage applied between the capacitor terminals during charging of the capacitor and the current flowing through the capacitor. FIG. 4 is a flowchart showing a method for controlling charging of the battery.

  In FIG. 1, Vin is an input power source to the charging circuit. The capacitor C1, the switching element TR1, the resistor R1, the diode D1, the coil L1, and the capacitor C2 constitute a power control circuit for controlling charging with constant current, constant voltage, and constant power by the CPU 10. 14 is a capacitor having capacitors C3 and C4, R2 and R3 are terminal voltage detection resistors at both ends of the capacitor, and R4 is a current detection resistor flowing through the capacitor. The voltage detection circuit 11 detects the terminal voltage across the capacitor from the voltage divided by the resistors R2 and R3. The current detection circuit 12 detects the current flowing through the battery 14 from the voltage across the resistor R4. Reference numeral 13 denotes a load connected to the battery 14.

  In FIG. 2, the alternating current input from the commercial power supply 21 is branched halfway and connected to the load 1. The load 1 is assumed to be capable of operating with direct commercial alternating current, such as an AC motor or heater. The other branch destination is the power supply device 22. The power supply device 22 uses a switching type insulated power supply for miniaturization. The output of the power supply device 22 is a DC voltage such as 24 V, 12 V, 5 V, and 3.3 V, for example, and is selectively used depending on the connected load device.

  In this embodiment, the power output is further divided into two systems, one of which is supplied to the load 2. The load 2 is a semiconductor device such as a memory. The other is supplied to the charger 23. The charger 23 supplies power to the load 3. The load 3 is a device such as a DC motor that requires a rapid peak current to flow at a specific timing. When supplying power to the load 3, a capacitor is connected between the load 3 and the power supply for the purpose of leveling the peak current viewed from the power supply side. This capacitor corresponds to the capacitor 14 (capacitors C3 and C4) in FIG. 1, and the load 3 corresponds to the load 13 in FIG.

  The larger the capacity of the battery, the more the peak power can be absorbed and leveled. Therefore, as the capacitors C3 and C4 of the capacitor 14, an electric double layer capacitor or the like that has been recently reduced in size, increased in capacity, and reduced in price is used.

  In this embodiment, a CPU (Central Processing Unit) is mounted in the charger 23, and various information can be calculated and processed. This CPU corresponds to the CPU 10 of FIG.

  The input part of the commercial power supply 21 is provided with current detection means 24 using a current-voltage conversion element such as a current transformer, for example, and the detection result is sent to the CPU 10 as input current information.

  In addition to the above-described device input current detection result, the CPU 10 receives the terminal voltage detection result of the capacitor 14 by the voltage detection circuit 11 and the detection result of the current flowing through the capacitor 14 by the current detection circuit 12 as information.

  The CPU 10 obtains input power information by calculation with voltage information of the commercial power source 21 set in advance from the device input current detection result, and calculates a power margin that can be used for charging the battery 14 from the result.

  Further, the CPU 10 calculates the power consumed by the charger 23 from the voltage information between the terminals of the battery 14 detected by the voltage detection circuit 11 and the current information flowing through the battery detected by the current detection circuit 12.

  Next, the control at the time of charge is demonstrated using the graph of FIG. 3, and the flowchart of FIG.

  First, the CPU 10 in the charger monitors the voltage of the battery 14 by the voltage detection circuit 11 and determines whether or not charging is necessary (step 1). When it is determined that the voltage of the battery 14 is lower than the reference value and charging is required, the input current value of the device is read (step 2), and the input power margin (power usable for charging) of the entire device is calculated. (Step 3), the charging target power value for the battery 14 is set (Step 4).

  After setting the target power, the CPU 10 starts charging the battery 14 with a constant current i (step 5). At this time, based on the current information detected by the current detection circuit 12, the CPU 10 controls the switching operation of the switching element TR1 so that the detected current value becomes the target value i.

  When charging by constant current control proceeds, the voltage between terminals of the battery 14 increases. An increase in voltage at a constant current means an increase in power consumption. And the voltage information between the terminals of the battery 14 that is detected by the voltage detection circuit 11 in parallel is acquired (step 6), and the power consumption is calculated based on the voltage information between the terminals and the constant current value i ( Step 7). The constant current charge control is continued until the charge power target value determined by the charge available power described above is reached.

  It is determined whether or not the calculated charging power has reached the power target value (step 8). When it is determined that the charging power has been reached, this time, from the voltage information obtained by the voltage detection circuit 11 and the current information obtained by the current detection circuit 12. The switching operation of the switching element TR1 is controlled so that the calculated power consumption is constant (step 9). That is, the charging is switched from charging by constant current control to charging by constant power control.

  At this time, the target value of the constant power control can be varied, and the target value is calculated by the CPU 10 from the power consumption of the entire apparatus. For example, in the case of using an outlet having a general upper limit of 15 A with an input of 100 V, it is calculated how much the current value detected by the input current detecting means 24 of the apparatus has a margin with respect to 15 A. In this embodiment, the maximum power that can be used for charging is determined including the efficiency of the power supply device and the efficiency of the charger. In this embodiment, the input voltage value is set to a predetermined fixed value. However, for example, the operator may input voltage information of an outlet used from the operation unit. Also, a means for detecting the input voltage supplied to the apparatus is provided, and the CPU 10 acquires the input voltage information from the input voltage detection means, and determines the power margin that can be used for charging from the acquired input current information and the input voltage information. You may ask.

As an example, assuming that the input current value is 14 A, the efficiency of the power supply is 80%, and the efficiency of the charger is 85%, the maximum power that can be used for charging is obtained as follows.
100 × (15-14) × 0.8 × 0.85 = 68 watts Further, if the input current value is 13.5 A, the maximum power that can be used for charging is
100 × (15-13.5) × 0.8 × 0.85 = 102 watts.

  In the example of FIG. 3, two types of cases where the power target value is P1 and P2 are shown. When the target power is controlled as P1, the power consumption of the entire apparatus excluding the charger is less and the power margin is higher than when the target power is controlled as P2. .

In the above formula, if P1 is replaced with 102 watts and P2 is replaced with 68 watts, the power margin of the device is
In the case of P1: 100 × (15-13.5) = 150 watts In the case of P2: 100 × (15-14) = 100 watts.

  As a matter of course, the charging time is shortened when P1 is charged as the target power value, but it can be said that the power consumption of the entire apparatus does not change. The target power value may be changed in real time according to the usage state of the apparatus.

  Returning to FIG. 4, it is determined whether or not the voltage value detected by the voltage detection circuit 11 during the constant power charging control has reached the target value v (step 10). If it is determined that it has reached, the switching operation of the switching element TR1 is controlled so as to perform constant voltage charging at a voltage value v from constant power charging (step 11). Thereafter, as charging progresses, the charging current gradually decreases, and when the current finally becomes zero, the battery is fully charged and charging is terminated (step 12).

  Thus, by monitoring the charge state of the battery and switching between constant current charge, constant power charge, and constant voltage charge, it is possible to charge efficiently without power over. In addition, by making the maximum charge power target value variable according to the operating state of the device, it is safe and efficient without operating the breaker in an environment where the power limit value is not so large, such as in offices and homes. It can be charged well.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 5 is a block diagram of a charging circuit for a battery according to the second embodiment of the present invention. FIG. 6 is a block diagram showing a hardware configuration of an electronic device apparatus incorporating the charging circuit of FIG. FIG. 7 is a graph showing the relationship between the voltage applied between the capacitor terminals during charging of the capacitor and the current flowing through the capacitor. FIG. 8 is a flowchart showing a method for controlling charging of the battery.

  In general, the rated value of the commercial power supply voltage cannot always be supplied depending on the state of the power transmission equipment or the surrounding power consumption state, and the supply voltage value always fluctuates. Further, assuming that the commercial power supply voltage fluctuates, the maximum power consumption cannot be estimated only from the detection result of the input current value. Thus, in the second embodiment, commercial power input voltage detection means is provided, and the power margin of the apparatus is obtained by calculation with the detection result of the current detection means.

  The calculation of the power margin is performed by the CPU 31 that controls the apparatus. The charger 33 may not have a CPU. By not having a dedicated CPU in the charger 33, the cost of the charger can be reduced.

  6 differs from the configuration shown in FIG. 2 in that the CPU 31 of the electronic device controls the charger and that the charger 33 does not have a CPU, and the other configurations are the same. 5 differs from the configuration shown in FIG. 1 in that instead of the CPU 10, the voltage detection circuit 11, and the current detection circuit 12, a control unit 30, error amplifiers OP1 to OP3, voltage sources Vr1, Vr, 2, and resistors R5 and R6 are provided. Other components are the same as those in FIG.

  The CPU 31 first reads the input voltage and input current of the commercial power supply to the apparatus (step 21), and calculates the margin of input power based on the input voltage and input current (step 2).

  Next, referring to a table storing data indicating the relationship between the preset power margin and the charging power setting value, the charging power setting value is determined based on the calculated result (step 3). In addition, this table may show the relationship between the input voltage of commercial power supply, input current, and charging power setting value.

  Next, the determined charging current set value is compared with the current charging power target value, and it is determined whether or not the charging power target value needs to be changed from the current value (step 4). If it is necessary to change, the charging power set value is changed (step 5). If there is no need to change, the operation of reading the input current and input voltage is repeated.

  Thereby, the input power margin value of the apparatus can be read in real time, and the maximum power value that can be used during charging can be controlled.

  Next, the configuration and operation of the charger will be described with reference to FIG.

  In the second embodiment, complicated power calculation is simplified by taking the form of pseudo constant power control. The configuration and operation of the circuit will be described.

  In FIG. 5, R4 is a resistor for detecting the current flowing in the capacitors C3 and C4 of the battery 14 and converting it to a voltage level. The error amplifier OP3 amplifies the voltage across R4 generated by the current flowing through the resistor R4, that is, the difference between the current flowing through the battery 14 and the value determined by the variable voltage source Vr2. The control unit 30 controls the switching operation of the switching element TR1 so that the output of the error amplifier OP1 becomes 0, that is, the current flowing through the battery 14 coincides with the value determined by the variable voltage source Vr2.

  R2 and R3 are resistors for detecting the voltage Vo between the terminals at both ends of the capacitor 14. The error amplifier OP2 amplifies the difference between the voltage divided by the resistors R2 and R3 and the reference voltage Vr1. Based on the output from the error amplifier OP2, the control unit 30 switches the output voltage Vo so that the voltage divided by R2 and R3 is the same as the reference voltage Vr1, that is, the voltage Vo between the terminals of the capacitor is constant. Controls the switching operation of TR1.

R5 and R6 are resistors for detecting the terminal voltage Vo at both ends of the battery 14. The reference voltage Vr2 (output value of the variable voltage source) can be varied from the outside. That is, the value of Vr2 is determined based on the target power determined by the CPU 31. Further, when viewed from the terminal voltage detection resistors R5 and R6, the amount of voltage drop generated in the current detection resistor R4 varies depending on the current flowing through the battery 14, and as a result, the following relational expression is established.
Vr2 = Vo * R6 / (R5 + R6) + Io * R4
Solving this equation for Vo gives:
Vo = − ((R5 + R6) × R4 / R6) × Io + ((R5 + R6) / R6) × Vr2
Furthermore, when the fixed value determined by the resistance value in the circuit is replaced with constants a and b, it can be expressed as follows.
Vo = −a × Io + b × Vr2 (1)
According to the equation (1), the capacitor terminal voltage Vo can be expressed as a linear equation related to Io flowing through the capacitor 14, the slope -a is determined by the circuit resistance value, and the intercept can be varied by the reference voltage Vr2 set from the outside. It shows you can.

Next, the charging power Po calculated from the capacitor terminal voltage Vo and the current Io flowing through the capacitor is
Po = Vo × Io, and solving this equation for Vo,
Vo = Po / Io (2)
It becomes.

FIG. 7 shows a graph showing changes in voltage and current when the battery 14 is charged.
Equation (2) shows that Vo is simply inversely proportional to Io with coefficient Po. Therefore, for example, if the circuit constant is determined so that the coefficient a in the equation (1) is 1, and the reference voltage Vr2 for determining the intercept is set to a value that approaches Po, the target power value is indicated by a solid line in FIG. It is possible to approximate the power during constant power control in a simple manner.

  FIG. 7 shows charging characteristics when the reference voltage set from the outside with respect to the power target value P1 is Vr21 and when the reference voltage set from the outside with respect to the power target value P2 is Vr22. Yes. The reference voltage Vr2 is determined by the power margin calculated by the device CPU 31 and is input to the charger 33 as a power target value.

  Next, a flow when actual charging is performed will be described with reference to FIG.

  First, charging is started at a constant current i. As charging progresses, the charging voltage of the battery 14 increases, and the power consumed by the charger 33 also increases. After that, when the voltage between the terminals of the battery 14 reaches a value determined by the value of Vr2 determined according to the power consumption of the device, the constant current charging is followed by the pseudo constant power straight line (primary expression of the current of the battery). The battery is switched to charging. The relationship between the constant power target value Po to be actually performed and the pseudo constant power target value Vr2 is determined by preparing a table storing data representing the relationship in advance. When the voltage between the terminals of the battery 14 reaches v, the pseudo constant power charging is switched to the constant voltage charging. Thereafter, the charging current decreases, and charging is completed when it becomes zero.

  In this embodiment, the CPU used for device main body control calculates the power consumption of the entire device, determines the power value that may be consumed on the charger side, and controls the maximum power value of the charger, the charger side Then, without having an expensive CPU dedicated, and without using a complicated circuit for power consumption calculation, it is possible to obtain a charging characteristic that approximates a constant power curve, so that the cost and size of the device are not increased. The configuration.

It is a circuit diagram which shows the structure of the charger which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the hardware constitutions of the electronic device apparatus which incorporated the charger of FIG. It is a graph which shows the relationship between the voltage which applies between capacitor terminals at the time of charge to a capacitor, and the current which flows into a capacitor. It is a flowchart which shows the charge control method to an electrical storage device. It is a circuit diagram which shows the structure of the charger which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the hardware constitutions of the electronic device apparatus which incorporated the charger of FIG. It is a graph which shows the relationship between the voltage which applies between capacitor terminals at the time of charge to a capacitor, and the current which flows into a capacitor. It is a flowchart which shows the charge control method to the electrical storage device which concerns on the 2nd Embodiment of this invention. It is a circuit diagram which shows the structure of the conventional charger. FIG. 10 is a diagram illustrating a relationship between current and voltage during charging in the charger of FIG. 9.

Explanation of symbols

10 CPU
DESCRIPTION OF SYMBOLS 11 Voltage detection circuit 12 Current detection circuit 14 Power storage device 21 Commercial power supply 22 Power supply circuit 23 Charger 24 Current detection means

Claims (2)

In an electronic device having a charging circuit for charging a capacitor,
A power source that inputs alternating current and outputs direct current voltage;
Input current information acquisition means for acquiring information of an input current supplied to the electronic device by the alternating current;
Voltage detecting means for detecting a voltage between terminals of the capacitor;
Current detecting means for detecting a current flowing through the battery;
Wherein to initiate the charge by the constant current control with respect to the capacitor, the voltage output and the current when the power supplied to the capacitor on the basis of the output of the detection means determines that it has reached the goal value constant power detection means Control means for switching to charging by control, and switching to charging by constant voltage control when it is determined that the voltage between the terminals of the battery has reached a predetermined voltage based on the output of the voltage detection means ;
And the control means sets the target value in the constant power charging based on the input current information acquired by the input current information acquisition means, the efficiency of the power source, and the efficiency of charging the battery. An electronic device having a charging circuit. Input voltage information acquisition means for acquiring information on an input voltage supplied to the electronic device device by the alternating current, and the control means is acquired by the input current information acquired by the input current acquisition means and the input voltage acquisition means. The electronic device apparatus having a charging circuit according to claim 1, wherein the target value in the constant power charging is set based on the input voltage information.

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