JP2009247101A - Charger device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact charger device wherein importance is placed on environment resistance and a secondary battery can be charged with a high power factor. <P>SOLUTION: A control unit 17 controls a time ratio (a duty ratio in a SW control signal S1) in switching driving of a switching element SW1 based on an AC input voltage Vacin, AC input current Iacin, and a maximum output voltage Vmax. Thereby, a lithium-ion battery 20 can be charged with an output voltage Vout containing a pulsating flow of appropriate magnitude, and a smoothing capacitor 15C can be used which has smaller capacitance than that in the conventional cases where charging is carried out with a constant voltage and a constant current. The harmonic current contained in the alternating input current Iacin is also reduced, thereby the power factor is enhanced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charging device that includes a switching element and charges a secondary battery.

  Conventionally, various switching power supply devices including switching elements have been proposed (for example, Patent Document 1). Among these, in a switching power supply device (charging device) for charging a secondary battery, for example, after rectifying an AC voltage (commercial voltage) input from a commercial power source, the rectified voltage is switched by a switching element. The voltage obtained by this switching is smoothed by a smoothing capacitor or the like, and the secondary battery is charged with a constant voltage and a constant current based on the DC voltage obtained thereby. At this time, in order to obtain power from the commercial power source, it is necessary to reduce the harmonic current on the input side to some extent according to the standard.

JP 2004-304961 A

  Therefore, various power factor improvement type charging devices have been proposed. In these charging devices, it is essential to convert the AC power into DC using a large-capacity smoothing capacitor or the like. If a smoothing capacitor or the like having a sufficient capacity is not used, the output voltage from the charging device includes a pulsating current, and it becomes difficult to charge a constant voltage and a constant current using the DC voltage as described above. Because it will end up. For this reason, in a conventional power factor correction type charging device, a large-capacity smoothing capacitor such as an electrolytic capacitor is used in order to reduce a change in output voltage. An electrolytic capacitor is an optimal device for a smoothing capacitor from the viewpoint of capacity, cost, and volume.

  However, it has been found that this electrolytic capacitor has a problem in environmental resistance. In a charging application for an in-vehicle secondary battery which has been attracting attention in recent years, it is necessary to mount the above-described power factor improvement type charging device in a car. At this time, the charging device is required to withstand an in-vehicle environment. In response to such demands, a charging device using an electrolytic capacitor cannot satisfy characteristic stability and life characteristics. Therefore, a charging device using a film capacitor having a large capacity and a high withstand voltage is currently used, but there is a problem that the charging device itself is increased in size.

  Here, in the switching power supply device of Patent Document 1, the average value of the output current and the output voltage value are used as the input signal of the correction feedback loop, thereby controlling the time ratio (duty ratio) when driving the switching element. It is supposed to be. Therefore, it is conceivable to apply such a time ratio control operation also to the switching element in the charging device. However, in Patent Document 1, since the duty ratio is controlled by using the average value of the output current, it is necessary to use a large-capacity smoothing capacitor as described above in order to obtain a high power factor. Therefore, it is considered difficult to reduce the size of the device.

  As described above, in the conventional technology, it is difficult to charge the secondary battery with a high power factor without increasing the size of the apparatus configuration that places importance on environmental resistance, and there is room for improvement.

  The present invention has been made in view of such problems, and an object thereof is to provide a small-sized charging apparatus capable of charging a secondary battery with a high power factor while placing importance on environmental resistance. is there.

  The charging device of the present invention is for charging a secondary battery, and rectifies an AC input voltage to generate a rectified voltage, and generates a pulse voltage by switching the rectified voltage. A switching element for smoothing, a smoothing capacitor for generating an output voltage to be supplied to the secondary battery by smoothing the pulse voltage, and a control unit. The control unit performs switching driving on the switching element by pulse width modulation, and at the maximum value within a predetermined period of the AC input voltage, the AC input current flowing into the rectifier circuit, and the output voltage. Based on a certain maximum output voltage, the duty ratio at the time of the switching drive is controlled. The “AC input voltage” includes a voltage used as a power supply voltage for electrical equipment, and is preferably used for a so-called commercial power supply.

  In the charging device of the present invention, the AC input voltage is rectified in the rectifier circuit to generate a rectified voltage, and the rectified voltage is switched by the switching element to generate a pulse voltage. The pulse voltage is generated by the smoothing capacitor. By smoothing, an output voltage is generated, and this output voltage is supplied to the secondary battery, whereby the secondary battery is charged. Further, by controlling the time ratio at the time of switching driving by pulse width modulation for the switching element based on the AC input voltage, the AC input current, and the maximum output voltage, the secondary battery can be appropriately increased in size. It becomes possible to perform charging with the output voltage including the pulsating current. Thereby, the harmonic current contained in the AC input current can be reduced.

  In the charging device of the present invention, the control unit can detect the maximum output voltage from the output voltage for each predetermined period and can control the duty ratio using the detected maximum output voltage. . In this case, the control unit can detect the maximum output voltage at intervals of at least half a cycle of the cycle of the AC input voltage.

  In the charging device of the present invention, the control unit sets a target input current that is a target value within a predetermined period of the AC input current based on the maximum output voltage, and uses the set target input current to set the time ratio. Control is preferably performed. When configured in this way, the target value of the AC input current within the predetermined period is set according to the maximum output voltage that is the maximum value of the output voltage within the predetermined period, whereby the maximum output voltage is increased. The input current value can be adjusted in accordance with the voltage, and the secondary battery can be charged with the output voltage including a pulsating flow of an appropriate magnitude. Thereby, the harmonic current contained in the AC input current can be suppressed.

In this case, the control unit can set the target input current based on a comparison result between the maximum output voltage and a predetermined first threshold voltage. Specifically, for example, when the maximum output voltage (Vmax) is larger than the first threshold voltage (Vt1), the control unit uses the following equation (1) to calculate the target input current (I0). When the maximum output voltage (Vmax) is equal to or lower than the first threshold voltage (Vt1), the current target input current (I0 (n)) is calculated using the following equation (2). It is possible to reset the target input current to a new target input current (I0 (n + 1)). When configured in this manner, the target input current is set to the target maximum current value according to the magnitude of the maximum output voltage, thereby including a pulsating flow of an appropriate magnitude for the secondary battery. Charging with the output voltage can be made. Thereby, the harmonic current contained in the AC input current can be suppressed.
I0 = Imax (predetermined target maximum current value) (1)
I0 (n + 1) = I0 (n) × (Vt1 / Vmax) (2)

  Further, it is preferable that the control unit sets the target input current based on a comparison result between the maximum output voltage and a second threshold voltage that is lower than the first threshold voltage. When configured in this way, for example, the first threshold voltage is set to the maximum output voltage value at which the secondary battery can be normally charged, and the second threshold voltage is reduced to the harmonic current included in the AC input current. By setting the maximum output voltage value for the above, deterioration of the secondary battery due to excessive charging can be avoided while reducing the harmonic current on the input side.

  In addition, the control unit can set the target input current for every half period of the cycle of the AC input voltage. In this case, it is preferable that the control unit sets the target input current at a timing near the zero cross point in the AC input voltage. When comprised in this way, the harmonic current contained in alternating current input current is reduced more effectively. In this case, a zero cross point detection unit for detecting a zero cross point in the AC input voltage is provided, and the control unit obtains an AC input voltage in synchronization with the zero cross point detected by the zero cross point detection unit. More preferably, the target input current is set using the obtained AC input voltage. When configured in this way, even if the AC input current is distorted from a sine waveform due to noise or the like, the harmonic current on the input side is reliably reduced regardless of the waveform of the AC input voltage. Is done.

  In the charging device of the present invention, an AC input voltage detection unit that detects the AC input voltage is provided, and the control unit controls the time ratio using the AC input voltage detected by the AC input voltage detection unit. It is possible to do so. Moreover, while providing the alternating current input detection part which detects the said alternating current input current, the said control part may control a time ratio using the alternating current input current detected by this alternating current input current detection part. Is possible. In addition, an output voltage detection unit that detects the output voltage can be provided, and the control unit can control the duty ratio by using the output voltage detected by the output voltage detection unit.

  In the charging device of the present invention, the switching element may be provided in a booster circuit for boosting a rectified voltage to generate the pulse voltage.

  In the charging device of the present invention, it is preferable that the smoothing capacitor is configured using a film capacitor. When configured in this manner, the smoothing capacitor and the entire device can be easily miniaturized and the environment can be further improved, and the reliability of the device is improved as compared with the case where a conventional electrolytic capacitor is used.

  In the charging apparatus of the present invention, it is preferable that the secondary battery is configured using a lithium ion battery. In such a configuration, charging by an output voltage including a pulsating current is allowed, and therefore, it is more suitable by such a charging method.

  According to the charging device of the present invention, the time ratio at the time of switching driving by pulse width modulation to the switching element is controlled based on the AC input voltage, the AC input current, and the maximum output voltage. The secondary battery can be charged with an output voltage including a large pulsating current, and a smoothing capacitor with a smaller capacity can be used compared to the conventional case of charging with a constant voltage and constant current. It becomes. In addition, by such control, harmonic currents included in the AC input current can be reduced, and the power factor can be improved. Therefore, it is possible to realize a small charging device that charges the secondary battery with a high power factor while placing importance on environmental resistance.

  Hereinafter, the best mode for carrying out the present invention (hereinafter simply referred to as an embodiment) will be described in detail with reference to the drawings.

  FIG. 1 shows a circuit configuration of a charging device (charging device 1) according to an embodiment of the present invention. The charging device 1 is applied to, for example, an automobile and charges a lithium ion battery 20 that is a secondary battery based on an AC input voltage Vacin (so-called commercial voltage) supplied from a commercial power supply 10. The input voltage detection circuit 11, the rectifier circuit 12, the capacitor C1, the input current detection circuit 13, the booster circuit 14 including the switching element SW1, the smoothing circuit 15 including the smoothing capacitor 15C, and the output voltage detection circuit 16 and a control unit 17 for switching and driving the switching element SW1.

  The input voltage detection circuit 11 is disposed on the connection lines H1 and L1 between the input terminals T1 and T2 and a rectifier circuit 12 described later, and is supplied from the commercial power supply 10 via the input terminals T1 and T2. The AC input voltage Vacin is detected, and a detection signal S (Vacin) corresponding to the detected AC input voltage Vacin is output to the control unit 17. As a specific circuit configuration of the input voltage detection circuit 11, for example, the AC input voltage Vacin is detected by a voltage dividing resistor (not shown) disposed between the connection lines H1 and L1, and the input voltage detection circuit 11 is in accordance with this. Examples are those that generate voltage.

  The rectifier circuit 12 is a bridge type rectifier circuit having four rectifier diodes 12D1 to 12D4. Specifically, the anode of the diode 12D1 and the cathode of the diode 12D2 are connected to the input terminal T1 via the connection line H1, and the anode of the diode 12D3 and the cathode of the diode 12D4 are connected to the input terminal T2 via the connection line L1. It is connected. The cathode of the diode 12D1 and the cathode of the diode 12D3 are connected to the connection line H2, and the anode of the diode 12D2 and the anode of the diode 12D4 are connected to the connection line L2. With such a configuration, in the rectifier circuit 12, the input AC input voltage Vacin is rectified, and the rectified voltage V1 is generated between the connection lines H2 and L2.

  The capacitor C1 is disposed between the connection lines H2 and L2 between the rectifier circuit 12, the input current detection circuit 13 and the booster circuit 14 described later, and functions as a smoothing capacitor. Specifically, it is for smoothing and reducing noise or the like during a switching operation by the switching element SW1 described later.

  The input current detection circuit 13 is arranged on the connection line L2 between one end of the capacitor C1 and a booster circuit 14 to be described later, and receives the AC input current Iacin flowing into the rectifier circuit 12 as shown in FIG. In addition to detection, a detection signal S (Iacin) corresponding to the detected AC input current Iacin is output to the control unit 17. A specific circuit configuration of the input current detection circuit 13 includes, for example, a circuit including a current transformer.

  The booster circuit 14 includes a switching element SW1, an inductor 14L, and a diode 14D. Specifically, the inductor 14L is inserted and arranged on the connection line H2, one end is connected to the other end of the capacitor C1, and the other end is connected to one end (drain) of the switching element SW. The switching element SW1 is a switching element for switching the rectified voltage V1 to generate the pulse voltage V2. For example, a field effect transistor (MOS-FET), a bipolar transistor, It is comprised by IGBT (Insulated Gate Bipolar Transistor) etc. Here, the switching element SW1 is composed of an N-channel MOS-FET, the gate is connected to the signal line of the SW control signal S1 supplied from the control unit 17, the source is connected to the connection line L2, and the drain is connected. It is connected to the connection line H2. The anode of the diode 14D is connected to the other end of the inductor 14L and the drain of the switching element SW1, and the cathode of the diode 14D is connected to one end of a smoothing capacitor 15C described later. With this configuration, the booster circuit 14 generates a pulse voltage V2 boosted based on the rectified voltage V1, as will be described in detail later.

  The smoothing circuit 15 includes a smoothing capacitor 15C configured using, for example, a film capacitor. Specifically, one end of the smoothing capacitor 15C is connected to the cathode of the diode 14D, and the other end of the smoothing capacitor 15C is connected to the connection line L2. With such a configuration, the smoothing circuit 15 generates the output voltage Vout to be supplied to the lithium ion battery 20 by smoothing the pulse voltage V2.

  The output voltage detection circuit 16 is disposed on the connection lines H2 and L2 between the smoothing circuit 15 and the output terminals T3 and T4, and is supplied to the lithium ion battery 20 via the output terminals T3 and T4. The voltage Vout is detected, and a detection signal S (Vout) corresponding to the detected output voltage Vout is output to the control unit 17. As a specific circuit configuration of the output voltage detection circuit 16, as in the input voltage detection circuit 11, for example, the output voltage Vout is generated by a voltage dividing resistor (not shown) disposed between the connection lines H2 and L2. And generating a voltage corresponding to this.

  The controller 17 receives the AC input voltage Vacin (specifically, the detection signal S (Vacin)) supplied from the input voltage detection circuit 11 and the AC input current Iacin (specifically, the input current detection circuit 13). Generates the SW control signal S1 and switches based on the detection signal S (Iacin)) and the output voltage Vout (specifically, the detection signal S (Vout)) supplied from the output voltage detection circuit 16. By supplying to the gate of the element SW1, switching driving is performed on the switching element SW1 by pulse width modulation (PWM). Specifically, the control unit 17 includes the AC input voltage Vacin, the AC input current Iacin, and a maximum output voltage (maximum output voltage Vmax described later) that is a maximum value within a predetermined period of the output voltage Vout. Based on the above, the time ratio (duty ratio) at the time of switching driving of the switching element SW1 is controlled. As a result, unlike the conventional charging device, charging that includes a pulsating flow in the output voltage Vout is performed on the lithium ion battery 20, unlike charging with constant voltage and constant current.

  Here, with reference to FIG. 2, the detailed structure of the control part 17 is demonstrated. FIG. 2 shows a detailed block configuration of the control unit 17.

  The control unit 17 includes a calculation unit 171, a maximum value detection unit 172, a target current determination unit 173, and a duty ratio correction unit 174.

  The calculation unit 171 includes an AC input voltage Vacin (specifically, a detection signal S (Vacin)) supplied from the input voltage detection circuit 11 and a target input current (a target described later) supplied from a target current determination unit described later. The input current I0) is subjected to predetermined calculation processing, and has an absolute value calculation unit 171A and a multiplication unit 171B. The absolute value calculation unit 171A calculates the absolute value of the AC input voltage Vacin from the detection signal S (Vacin). The multiplier 171B multiplies the absolute value of the AC input voltage Vacin supplied from the absolute value calculator 171A by the target input current I0, and the multiplication result (Vacin × I0) is a time ratio described later. This is output to the correction unit 174.

  The maximum value detector 172 detects the maximum output voltage Vmax for each predetermined period from the output voltage Vout (specifically, the detection signal S (Vout)) supplied from the output voltage detection circuit 16. Specifically, such detection of the maximum output voltage Vmax is performed every period (at least 0.5 × T period) of at least a half period of the period T in the AC input voltage Vacin.

  The target current determination unit 173 sets a target input current I0 that is a target value within a predetermined period of the AC input current Iacin based on the maximum output voltage Vmax supplied from the maximum value detection unit 172. Specifically, the target input current I0 is set based on the comparison result between the maximum output voltage Vmax and a predetermined threshold voltage Vt1 set in advance. Further, such setting of the target input current I0 is performed every period (at least 0.5 × T period) of the period T in the AC input voltage Vacin (at least half period of the period T). It is updated every period). Details of the operation of the target current determination unit 173 will be described later.

  The duty ratio correction unit 174 includes an AC input current Iacin (specifically, a detection signal S (Iacin)) supplied from the input current detection circuit 13 and a calculation result (multiplication result (Vacin × Vacin × X)) supplied from the calculation unit 171. I0)) is used to generate and output the SW control signal S1 of the switching element SW1 by feedback correcting the time ratio of the switching element SW1, and the subtraction unit 174A, the PI compensation calculation unit 174B, have. The subtraction unit 174A obtains a difference between the multiplication result (Vacin × I0) and the detection signal S (Iacin) (subtracts the value of the detection signal S (Iacin) from the multiplication result (Vacin × I0)). An error value e (= (Vacin × I0) −Iacin) as a subtraction result is output. The PI compensation calculation unit 174B generates a SW control signal S1 that has been subjected to the time ratio correction by performing a predetermined PI compensation calculation on the input error value e. Details of the operation of the PI compensation calculation unit 174B will be described later.

  Note that the function of the control unit 17 of the present embodiment is configured by software, and all processing by the control unit 17 is performed by a digital signal processing device. Such a digital signal processing device is preferably composed of, for example, a logic circuit group or a microcomputer, and is preferably composed of a DSP (Digital Signal Processor).

  Next, the operation of the charging device 1 will be described in detail with reference to FIGS. 3 to 5 in addition to FIGS.

  First, with reference to FIGS. 1-4, the basic operation | movement (charging operation to the lithium ion battery 20) of the charging device 1 is demonstrated. Here, FIG. 3 is a timing waveform diagram showing the overall operation of the charging apparatus 1, (A) shows the AC input voltage Vacin, (B) shows the rectified voltage V1, and (C) shows the output voltage Vout. , Respectively. For the AC input voltage Vacin, the rectified voltage V1 and the output voltage Vout, the direction of the arrow shown in FIG. 1 represents the positive direction.

  In this charging device 1, for example, as shown in FIG. 3A, when an AC input voltage Vacin (commercial voltage) composed of a sine wave with a period T is supplied between the input terminals T1 and T2, the rectifier circuit 12 By rectification, for example, as shown in FIG. 3B, a rectified voltage V1 composed of a positive half wave is generated.

Next, the booster circuit 14 generates a boosted pulse voltage V2 by performing a boosting operation as shown in FIGS. 4A and 4B, for example, based on the rectified voltage V1. Specifically, the pulse voltage V2 is generated by switching the rectified voltage V1 by the switching element SW1. More specifically, first, when the switching element SW1 is turned on in response to the SW control signal S1 (on period Ton), for example, as shown in FIG. A current I1 flows to SW1, and thereby magnetic energy is stored in the inductor 14L. When the switching element SW1 is turned off in accordance with the SW control signal S1 (off period Toff), for example, as shown in FIG. 4B, the current I2 in the order of the inductor 14L, the diode 14D, and the capacitor 15C. As a result, the magnetic energy stored in the inductor 14L is stored in the capacitor 15C, and a boosting operation is performed. It should be noted that the relationship between the rectified voltage V1 and the pulse voltage V2 during such a boosting operation is expressed as shown in the following equation (10).
V2 = {(Ton + Toff) / Toff} × V1 (10)

  Next, in the smoothing circuit 15, the input pulse voltage V <b> 2 is smoothed, and an output voltage Vout to be supplied to the lithium ion battery 20 is generated. In the present embodiment, the output voltage Vout includes a pulsating flow having a cycle of 0.5 × T as shown in FIG. 3C, for example. Thereby, the lithium ion battery 20 is charged by the output voltage Vout including such a pulsating current and the output current Iout shown in FIG.

  Next, referring to FIG. 5 in addition to FIGS. 1 to 4, the control operation of the switching element SW by the control unit 17, which is one of the characteristic parts of the present invention, will be described in detail. FIG. 5 is a flowchart showing an example of the control operation by the control unit 17 (specifically, the determination process of the target input current I0 by the target current determination unit 173).

  First, during the charging operation, the AC input voltage Vacin is detected by the input voltage detection circuit 11, the AC input current Iacin is detected by the input current detection circuit 13, and the output voltage Vout is detected by the output voltage detection circuit 16. The Then, the detection signal S (Vacin) from the input voltage detection circuit 11, the detection signal S (Iacin) from the input current detection circuit 13, and the detection signal S (Vout) from the output voltage detection circuit 16 are supplied to the control unit 17, respectively. Is done.

  Then, the control unit 17 performs a control operation as described below based on the detection signal S (Vacin), the detection signal S (Iacin), and the detection signal S (Vout), thereby performing the time ratio correction SW. A control signal S1 is generated.

  First, as shown in FIG. 2, the absolute value calculation unit 171A in the calculation unit 171 calculates the absolute value of the AC input voltage Vacin from the detection signal S (Vacin).

  On the other hand, in the maximum value detection unit 172, for example, the detection signal S (Vout) is like the maximum output voltages Vmax (n−1), Vmax (n), Vmax (n + 1),... Shown in FIG. Thus, for each period of a half period of the period T in the AC input voltage Vacin (0.5 × T period), the maximum output voltage Vmax that is the maximum value of the output voltage Vout within that period is detected.

  Next, in the target current determination unit 173, based on the input maximum output voltage Vmax, for example, as shown in FIG. 5, within a predetermined period in the AC input current Iacin (here, the period T in the AC input voltage Vacin). A target input current I0, which is a target value within a half cycle period (0.5 × T period), is set (updated as needed) every 0.5 × T period. In the present embodiment, for example, as shown in FIG. 3C, such setting of the target input current I0 is performed at a timing near the zero cross point in the AC input voltage Vacin.

More specifically, the target current determining unit 173 first compares the maximum output voltage Vmax and the threshold voltage Vt1 (step S11 in FIG. 5). Here, when the maximum output voltage Vmax is equal to or lower than the threshold voltage Vt1 (step S11: N), the target input current I0 is set using the following equation (11) (step S12). On the other hand, when the maximum output voltage Vmax is larger than the threshold voltage Vt1 (step S11: N), a new target input current is calculated from the current target input current (I0 (n)) using the following equation (12). The target input current I0 is reset to (I0 (n + 1)) (step S13). After that, it is determined whether or not the entire process for determining the target input current I0 is to be ended (step S14). If not to be ended (step S14: N), the process returns to step S11 and ends. In this case (step S14: Y), the entire process for determining the target input current I0 is completed.
I0 = Imax (predetermined target maximum current value) (11)
I0 (n + 1) = I0 (n) × (Vt1 / Vmax) (12)

  The time ratio in the SW control signal S1 described above is such that the AC input current Iacin varies in proportion to the absolute value of the AC input voltage Vacin, and the absolute value of the AC input voltage Vacin is maximized. The AC input current Iacin corresponds to the target input current I0. Imax is a value corresponding to the maximum rated input current value of the secondary battery to be charged, and Vt1 is a value corresponding to the maximum rated input voltage value of the secondary battery to be charged.

  Next, the multiplication unit 171B in the calculation unit 171 multiplies the absolute value of the AC input voltage Vacin supplied from the absolute value calculation unit 171A and the target input current I0 supplied from the target current determination unit 173, respectively. The multiplication result (Vacin × I0) is output to the duty ratio correction unit 174.

  Next, in the duty ratio correction unit 174, based on the detection signal S (Iacin) supplied from the input current detection circuit 13 and the multiplication result (Vacin × I0) supplied from the calculation unit 171, the switching element SW1 The SW control signal S1 is generated by feedback correction of the time ratio. Specifically, first, the subtraction unit 174A obtains the difference between the multiplication result (Vacin × I0) and the detection signal S (Iacin) (the value of the detection signal S (Iacin) is obtained from the multiplication result (Vacin × I0)). By subtracting, an error value e (= (Vacin × I0) −Iacin) as a subtraction result is output. Then, the PI compensation unit 174B performs a predetermined PI compensation operation on the input error value e by using the following equations (13) and (14) in synchronization with the switching frequency, thereby correcting the time ratio. The SW control signal S1 subjected to is generated.

  The switching element SW1 in the booster circuit 14 performs a switching operation in accordance with the SW control signal S1 thus corrected for the time ratio, thereby performing the above-described generation operation and boosting operation of the pulse voltage V2. The Rukoto.

  Thus, in charging device 1 of the present embodiment, AC input voltage Vacin is rectified in rectifier circuit 12 to generate rectified voltage V1, and this rectified voltage V1 is switched by switching element SW1 to generate a pulse. The voltage V2 is generated, and the pulse voltage V2 is smoothed by the smoothing capacitor C1 to generate the output voltage Vout. The output voltage Vout is supplied to the lithium ion battery 20, whereby the lithium ion battery 20 is Charging is done. Thereby, the lithium ion battery 20 is charged with the output voltage Vout including the pulsating flow.

  At this time, the control unit 17 controls the time ratio (duty ratio in the SW control signal S1) at the time of switching driving for the switching element SW1 based on the AC input voltage Vacin, the AC input current Iacin, and the maximum output voltage Vmax. Thus, charging with the output voltage Vout including a pulsating flow of an appropriate magnitude is possible, and the AC input current Iacin can obtain the same phase and waveform as the AC input voltage Vacin. The harmonic current contained in Iacin is reduced.

  As described above, in the present embodiment, the time ratio (duty ratio in the SW control signal S1) at the time of switching driving for the switching element SW1 is controlled based on the AC input voltage Vacin, the AC input current Iacin, and the maximum output voltage Vmax. As a result, it is possible to charge the lithium ion battery 20 with the output voltage Vout including a pulsating flow of an appropriate magnitude. A small smoothing capacitor 15C can be used. In addition, by such control, the harmonic current included in the AC input current Iacin can be reduced, and the power factor can be improved. Therefore, it is possible to realize a small charging device that charges the secondary battery with a high power factor while placing importance on environmental resistance.

  In addition, a target input current I0 that is a target value within a predetermined period of the AC input current Iacin is set based on the maximum output voltage Vmax, and the duty ratio is controlled using the set target input current I0. Therefore, since the target value of the AC input current Iacin within the predetermined period can be set according to the maximum output voltage Vmax, which is the maximum value of the output voltage Vout within the predetermined period, the magnitude of the maximum output voltage Vmax. The input current value can be adjusted accordingly, and the lithium ion battery 20 can be charged with the output voltage Vout including a pulsating flow of an appropriate magnitude. Thereby, the harmonic current contained in the AC input current Iacin can be suppressed.

  When the maximum output voltage Vma is equal to or lower than the threshold voltage Vt1, the target input current I0 is set using the above equation (11), and when the maximum output voltage Vma) is larger than the threshold voltage Vt1, Since the target input current is reset from the current target input current I0 (n) to the new target input current I0 (n + 1) using the above equation (12), the maximum output voltage Vmax is increased. Accordingly, the target input current I0 can be set to the target maximum current value Imax, so that the lithium ion battery 20 can be charged with the output voltage Vout including a pulsating flow of an appropriate magnitude. Become. Thereby, the harmonic current contained in the AC input current Iacin can be suppressed.

  In addition, since the target input current I0 is set at a timing near the zero cross point in the AC input voltage Iacin, the harmonic current included in the AC input current Iacin can be more effectively reduced. .

  In addition, since the smoothing capacitor 15C is configured using a film capacitor, the smoothing capacitor 15C and the charging device 1 as a whole can be easily miniaturized and have a higher resistance compared to the case where a conventional electrolytic capacitor is used. Since the environment can be improved, the reliability of the apparatus can be improved.

  Furthermore, since the secondary battery to be charged is configured using a lithium ion battery, charging by the output voltage Vout including the pulsating current can be allowed, and it is adapted by such a charging method. It becomes possible to set it as the structure which carried out.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to this embodiment, and various modifications can be made.

  For example, as in the charging device 1 </ b> A illustrated in FIG. 6, a zero cross point detection circuit 18 that detects a zero cross point in the AC input voltage Vacin may be provided instead of the input voltage detection circuit 11. Specifically, the zero cross point detection circuit 18 includes a transformer 181, four diodes 18 D 1 to 18 D 4, a resistor 18 R, a constant voltage source 182, and a comparator 183. Here, one winding 181A of the transformer 181 is connected between the connection lines H1 and L1, and the other winding 181B includes the cathode of the diode 18D1 and the anode of the diode 18D3, the cathode of the diode 18D2, and the diode 18D4. Connected between the anodes. The anodes of the diodes 18D1 and 18D2 are grounded to each other, and the cathodes of the diodes 18E3 and 18D4 are connected to one end of the resistor 18R and the negative input terminal of the comparator 183. The other end of the resistor 18R is grounded, and the positive input terminal of the comparator 183 is connected to a constant voltage source 182 that is a power source of the constant voltage Vc. Also, a zero cross point detection signal S (zp) is output from the output terminal of the comparator 183 and supplied to the control unit 17A. With this configuration, in the charging device 1A, the control unit 17A can calculate the AC input voltage Vacin in synchronization with the zero cross point (specifically, the detection signal S (zp)) detected by the zero cross point detection circuit 18. The target input current I0 is set using the obtained AC input voltage Vacin. As a result, even when the AC input current Iacin is distorted from a sine waveform due to noise or the like, the harmonic current can be reliably reduced regardless of the waveform of the AC input voltage Vacin. Become.

  In the above embodiment, the target input current I0 is set by comparing the maximum output voltage Vmax and the threshold voltage Vt1, but for example, as shown in FIG. The target input current I0 may be set based on a comparison result between Vmax and a threshold voltage Vt2 that is lower than the threshold voltage Vt1. When configured in this way, for example, the threshold voltage Vt1 is set to the maximum output voltage value at which the lithium ion battery 20 can be normally charged, and the threshold voltage Vt2 is reduced to a harmonic current included in the AC input current Iacin. Therefore, it is possible to avoid deterioration of the lithium ion battery 20 due to excessive charging while reducing the harmonic current.

  In the above embodiment, the PI compensation unit 174B generates the SW control signal S1 with the time ratio corrected by performing the PI compensation calculation using the above equations (13) and (14). As described above, for example, the SW control signal S1 subjected to the time ratio correction may be generated by performing the P compensation calculation or the PID compensation calculation using the following expression (15) or (16). .

  In the above-described embodiment, the target input current I0 is set at a timing near the zero cross point in the AC input voltage Iacin. However, such a target input current I0 is set to other values. You may make it carry out at timing.

  Further, the configurations of the rectifier circuit, the booster circuit, the smoothing circuit, and the control unit described in the above embodiment are not limited to these, and may be other configurations.

  For example, in the above-described embodiment, the case where the rectifier circuit and the booster circuit are separately provided and the switching element is provided in the booster circuit has been described. For example, as in the charging device 1B illustrated in FIG. As an alternative, the synchronous rectifier circuit 19 may be used as a part of the booster circuit, and the switching elements SW11 to SW14 in the synchronous rectifier circuit 19 may also serve as switching elements of the booster circuit. Specifically, the synchronous rectifier circuit 19 includes two inductors 14L1 and 14L2, four switching elements SW11 to SW14, and a diode 14D. The inductor 14L1 is inserted and disposed on the connection line H1, and the inductor L2 is inserted and disposed on the connection line L1. The gate of the switching element SW11 is connected to the signal line of the SW control signal S11 supplied from the control unit 17B, the source is connected to the connection line H1, and the drain is connected to the connection line H2. The gate of the switching element SW12 is connected to the signal line of the SW control signal S12 supplied from the control unit 17B, the source is connected to the connection line L2, and the drain is connected to the connection line H1. The gate of the switching element SW13 is connected to the signal line of the SW control signal S13 supplied from the control unit 17B, the source is connected to the connection line L1, and the drain is connected to the connection line H2. The gate of the switching element SW14 is connected to the signal line of the SW control signal S14 supplied from the control unit 17B, the source is connected to the connection line L2, and the drain is connected to the connection line L1. The anode of the diode 14D is connected to the drains of the switching elements SW11 and SW13, and the cathode of the diode 14D is connected to one end of the smoothing capacitor 15C. With this configuration, in the synchronous rectifier circuit 19, when the AC input voltage Vacin is positive, the switching elements SW11 and SW14 are turned on, the switching element SW13 is turned off, and the switching element SW12 is turned on / off (the time ratio is Controlled state). On the other hand, when the AC input voltage Vacin is negative, the switching elements SW12 and SW13 are turned on, the switching element SW11 is turned off, and the switching element SW14 is turned on / off (time ratio is controlled).

  In the above embodiment, the function of the control unit 17 is configured by software. However, the function of the control unit 17 may be configured by hardware. However, when configured by hardware, the circuit scale increases, and it is difficult to correct variations in each element. Therefore, it is preferable to configure by software as in the above embodiment.

  Furthermore, in the above-described embodiment, the case where the secondary battery to be charged is configured using a lithium ion battery has been described. However, the charging device of the present invention is compatible with secondary batteries other than lithium ion batteries. It is possible to apply.

It is a circuit diagram showing the structure of the charging device which concerns on one embodiment of this invention. It is a block diagram showing the detailed structure of the control part shown in FIG. It is a timing waveform diagram for demonstrating operation | movement of the whole charging device. FIG. 2 is a circuit diagram for explaining the operation of the booster circuit shown in FIG. 1. It is a flowchart showing an example of the control action by a control part. It is a circuit diagram showing the structure of the charging device which concerns on the modification of this invention. It is a schematic diagram for demonstrating the threshold voltage which concerns on the other modification of this invention. It is a circuit diagram showing the structure of the charging device which concerns on the other modification of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,1A, 1B ... Charging apparatus, 10 ... Commercial power supply, 11 ... Input voltage detection circuit, 12 ... Rectifier circuit, 13 ... Input current detection circuit, 14 ... Boost circuit, 15 ... Smoothing circuit, 16 ... Output voltage detection circuit, 17, 17A, 17B ... control unit, 171 ... calculation unit, 171A ... absolute value calculation unit, 171B ... multiplication unit, 172 ... maximum value detection unit, 173 ... target current determination unit, 174 ... time ratio correction unit, 174A ... subtraction Unit, 174B ... PI compensation calculation unit, 18 ... zero cross point detection circuit, 181 ... transformer, 181A, 181B ... winding, 182 ... constant voltage power supply, 183 ... comparator, 19 ... synchronous rectifier circuit, 20 ... lithium ion battery, T1, T2 ... input terminal, T3, T4 ... output terminal, H1, L1, H2, L2 ... connection line, Vacin ... AC input voltage, V1 ... rectified voltage, V2 ... pulse voltage, V3 ... voltage Vc: constant voltage, Vout: output voltage, Vmax: maximum output voltage, Vt1, Vt2: threshold voltage, Iacin: AC input current, I0: target input current, Imax: target maximum current value, Iout: output current, I1, I2 ... current, S (Vacin), S (Iacin), S (Vout), S (zp) ... detection signal, S1, S11 to S14 ... SW control signal, 12D1 to 12D4 ... diode, C1 ... capacitor, SW1, SW11 SW14 ... transistor (switching element), 14L, 14L1, 14L2 ... inductor, 14D ... diode, 15C ... smoothing capacitor, 18D1-18D4 ... diode, 18R ... resistor, T ... period of AC input current, t0-t4 ... timing .

Claims (16)

A charging device for charging a secondary battery,
A rectifier circuit that rectifies an AC input voltage to generate a rectified voltage;
A switching element for switching the rectified voltage to generate a pulse voltage;
A smoothing capacitor that generates an output voltage to be supplied to the secondary battery by smoothing the pulse voltage;
The switching element is subjected to switching driving by pulse width modulation, and the AC input voltage, the AC input current flowing into the rectifier circuit, and the maximum output voltage that is the maximum value within a predetermined period of the output voltage. And a control unit that controls a time ratio during the switching drive. The said control part detects the said maximum output voltage from the said output voltage for every said predetermined period, and controls the said time ratio using this detected maximum output voltage. Charging device. The said control part performs the detection of the said maximum output voltage for every period for at least half period of the period in the said alternating current input voltage. The charging device of Claim 2 characterized by the above-mentioned. The control unit sets a target input current that is a target value within a predetermined period of the AC input current based on the maximum output voltage, and controls the time ratio using the set target input current. The charging device according to any one of claims 1 to 3, wherein The charging device according to claim 4, wherein the control unit sets the target input current based on a comparison result between the maximum output voltage and a predetermined first threshold voltage. When the maximum output voltage (Vmax) is less than or equal to the first threshold voltage (Vt1), the controller sets the target input current (I0) using the following equation (1), and When the maximum output voltage (Vmax) is larger than the first threshold voltage (Vt1), a new target input current (I0 (n)) is calculated from the current target input current (I0 (n)) using the following equation (2). The charging device according to claim 5, wherein the target input current is reset to I0 (n + 1)).
I0 = Imax (predetermined target maximum current value) (1)
I0 (n + 1) = I0 (n) × (Vt1 / Vmax) (2) The control unit sets the target input current based on a comparison result between the maximum output voltage and a second threshold voltage that is lower than the first threshold voltage. The charging device described in 1. The said control part performs the setting of the said target input electric current for every period for the half period of the period in the said alternating current input voltage. The charging device of Claim 4 characterized by the above-mentioned. The said control part performs the setting of the said target input current at the timing of the zero crossing point vicinity in the said alternating current input voltage. The charging device of Claim 8 characterized by the above-mentioned. A zero cross point detector for detecting a zero cross point in the AC input voltage;
The charging device according to claim 9, wherein the control unit sets the target input current using a zero cross point detected by the zero cross point detection unit. An AC input voltage detection unit for detecting the AC input voltage;
11. The charging according to claim 1, wherein the control unit controls the duty ratio using an AC input voltage detected by the AC input voltage detection unit. apparatus. An AC input current detection unit for detecting the AC input current;
The charging according to any one of claims 1 to 11, wherein the control unit performs the duty ratio control using an AC input current detected by the AC input current detection unit. apparatus. An output voltage detector for detecting the output voltage;
The charging device according to any one of claims 1 to 12, wherein the control unit controls the duty ratio by using an output voltage detected by the output voltage detection unit. The charging device according to any one of claims 1 to 13, wherein the switching element is provided in a boosting circuit for boosting the rectified voltage to generate the pulse voltage. . The charging device according to any one of claims 1 to 14, wherein the smoothing capacitor is configured using a film capacitor. The said secondary battery is comprised using the lithium ion battery. The charging device of any one of Claims 1 thru | or 15 characterized by the above-mentioned.

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