JP2006014545A - Step-up device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the size of a step-up device, and to realize a large step-up ratio by reducing power loss in the circuit. <P>SOLUTION: For a plurality of capacitors 11a-11c, first and second switching elements 15a and 15b are connected in parallel during first period to perform charging with an input voltage Vin, and third and fourth switching elements 15c and 15d are connected in series during second period to perform step-up discharge for a load 21. A control circuit 18 adjusts the first period and the second period to realize a large step-up ratio. As compared with a case where a coil (reactor) is used in chopper control, the size is reduced, and power loss is also reduced in the circuit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a booster that boosts an input voltage.

  In recent years, electric motors are used not only for trains such as railways, but also for automobiles for traveling. As an electric motor in such an automobile, there is an example in which a driving voltage is driven via an inverter with a DC voltage of about 200 to 300V.

  On the other hand, the drive voltage of the electric motor mounted on the automobile has shifted to a high voltage with the aim of improving the acceleration force of the automobile, and a drive voltage exceeding 500V is required.

  For this reason, as the drive voltage, it is necessary to drive the load while adjusting both the high voltage exceeding 500 V as described above and the increase in the capacity of the rechargeable battery in order to reduce the discharge rate.

  In general, a booster (a booster circuit) is used to adjust the input voltage Vin and apply a drive voltage to a load in accordance with various situations. This boosting device outputs a voltage by controlling the chopper while increasing the electric energy of the input voltage Vin from a generator or the like with a coil (reactor), and boosts the voltage by the ratio of the ON time and OFF time of a pulse in a fixed period. Control the ratio.

  As described above, the booster using the chopper control controls the boost ratio by the ratio of the pulse ON time to the OFF time in a certain period. When this boost ratio is increased, the rise time of the waveform of the electronic circuit is increased. In addition, since there is a limit to the responsiveness of the fall time, not only is it difficult to ensure a sufficient boost ratio, but if the responsiveness of the waveform is not sufficient, a large power loss can occur.

  Moreover, in the voltage booster using chopper control, a coil (reactor) is used, so that the size is increased and the space saving of the automobile is reversed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a booster device that can be miniaturized, has a small power loss in a circuit, and can realize a large boost ratio.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a boosting device that boosts and outputs an input voltage, and switches a plurality of capacitors to a parallel connection and a series connection. A connection switching unit; a first period in which the plurality of capacitors are connected in parallel by the connection switching unit and charging is performed by the input voltage; and a plurality of capacitors are connected in series by the connection switching unit to perform discharge output. And a control means for alternately controlling the two periods.

  A second aspect of the present invention is the booster according to the first aspect, wherein the connection switching means switches the plurality of capacitors into a parallel connection state and a serial connection state under the control of the control circuit. Switch means for switching.

  A third aspect of the present invention is the booster according to the second aspect, wherein the booster is connected in series to the output portions of the plurality of capacitors that are connected in series by the connection switching means, while the connection An output capacitor connected in parallel with the plurality of capacitors brought into parallel connection by the switching means; and the output capacitor is charged by a discharge voltage of the plurality of capacitors in the second period. In the first period, discharge is output.

  In the boosting device according to the first and second aspects of the present invention, the input voltage is charged to each of the plurality of capacitors in parallel, and the plurality of capacitors are switched in series to perform the boost discharge. The rough boost ratio can be easily adjusted by the number of capacitors. Therefore, for example, a large boost ratio can be easily realized, for example, an output voltage of about N times the input voltage is output using N capacitors.

  Further, as compared with the booster using the chopper control, the size can be reduced because the coil (reactor) is not required.

  In addition, since a high output voltage is output using the charging of the capacitor, power loss is reduced as compared with a booster using chopper control.

  Then, by adjusting the first period and the second period by the control means, fine boost adjustment can be easily performed.

  In the boosting device according to the third aspect of the present invention, since the output capacitor is charged by the discharge voltages of the plurality of capacitors in the second period and discharged in the first period, the output voltage has a steep change. It is possible to prevent and perform stable voltage output.

<Configuration>
FIG. 1 is a block diagram schematically showing a supply path for a regenerative voltage of an automobile equipped with a booster (boost circuit) 1 according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing the booster 1. is there.

  As shown in FIG. 1, the booster 1 is used when boosting the input voltage Vin and outputting it to a load 21 when an input voltage Vin is applied from a generator 5 or the like. As described above, the input voltage Vin is boosted to obtain a voltage approximately N times (N is a natural number of 2 or more). In this embodiment, an example in which the input voltage Vin is boosted three times will be described.

  Specifically, as shown in FIG. 2, the booster 1 includes an output capacitor 7 connected to both ends of a load 21, three capacitors (first to third capacitors) 11a to 11c, and these capacitors. Three diodes 13a to 13c for connecting one end of each of 11a to 11c in parallel to the input voltage Vin which is an AC voltage, and the second capacitor 11b and the third of the three capacitors 11a to 11c The first and second switching elements (switching means) 15a and 15b for turning on and off the parallel grounding at the other ends of the capacitors 11c and the series connection of the first capacitor 11a and the second capacitor 11b are turned on and off. The third switching element (switching means) 15c, the second capacitor 11b, and the third capacitor 11c connected in series are turned on and off. The fourth switching element (switch means) 15d, the output diode 17 connected between one end of the third capacitor 11c and the load 21, and the capacitors 11a to 11c are connected in parallel by turning on and off the switching elements 15a to 15d. A control circuit (control means) 18 for controlling the charging time at the time of connection and the consumption time at the time of series connection is provided, and the boosted voltage output to the load 21 is adjusted by the control by the control circuit 18. ing.

  In FIG. 2, for the sake of convenience, the control circuit 18 is shown to output a gate signal only to the second switching element 15b. However, in actuality, not only the second switching element 15b but also each of the other switching elements 15b. A gate signal is also output to the switching elements 15a, 15c, and 15d.

  The output capacitor 7 is for supplying a stable drive voltage to the load 21 by charging and discharging the output capacitor 7.

  The anodes of the first to third diodes 13a to 13c are connected to one end of the generator 5 that performs AC output.

  One end of the first capacitor 11 a is connected to the cathode of the first diode 13 a, and the other end of the first capacitor 11 a is connected to the other end of the generator 5.

  One end of the second capacitor 11b is connected to the cathode of the second diode 13b, and the other end of the second capacitor 11b is connected to the collector of the first switching element 15a.

  One end of the third capacitor 11c is connected to the cathode of the third diode 13c, and the other end of the third capacitor 11c is connected to the collector of the second switching element 15b.

  The first to fourth switching elements 15a to 15d function as connection switching means for switching connection of the capacitors 11a to 11c between parallel connection and series connection.

  That is, the first switching element 15a is an npn-type transistor that is turned on / off in response to the gate input from the control circuit 18, the collector is connected to the other end of the second capacitor 11b, and the emitter is the generator 5 that performs AC output. Connected to the other end.

  The second switching element 15b is also an npn-type transistor that is turned on / off in response to the gate input from the control circuit 18, the collector is connected to the other end of the third capacitor 11c, and the emitter is the other end of the generator 5 that performs AC output. Connected to.

  The third switching element 15c is also an npn-type transistor that is turned on / off in response to a gate input from the control circuit 18, a collector is connected to a connection point between the first diode 13a and the first capacitor 11a, and an emitter is It is connected to a connection point between the second capacitor 11b and the first switching element 15a.

  The fourth switching element 15d is also an npn-type transistor that is turned on / off in response to a gate input from the control circuit 18, a collector is connected to a connection point between the second diode 13b and the second capacitor 11b, and an emitter is It is connected to a connection point between the third capacitor 11c and the second switching element 15b.

  The output diode 17 has an anode connected to the connection point between the third diode 13 c and the third capacitor 11 c, and a cathode connected to both the load 21 and the output capacitor 7.

  Due to the connection relationship between the capacitors 11a to 11c and the diodes 13a to 13c, for example, the first and second switching elements 15a and 15b for grounding are turned on and the third and fourth switching elements 15c and 15c for series connection are connected. When 15d is off, the three capacitors 11a to 11c are connected in parallel to each other with respect to the current flowing from one end of the generator 5 to the other end through the diodes 13a to 13c. In this parallel connection state, the capacitors 11a to 11c are charged with the input voltage Vin, and a relatively small drive voltage is supplied to the load 21 (in FIG. 3). (See T1 below).

  When the first and second switching elements 15a and 15b for grounding are off and the third and fourth switching elements 15c and 15d for series connection are on, the first to third capacitors 11a to 11c are used. Are connected in series, and the capacitors 11a to 11c connected in series function as a battery and supply a relatively high voltage to the load 21 (see T2 in FIG. 3: described later).

  For example, a microcomputer chip including a ROM and a RAM is used as the control circuit 18. The control circuit 18 includes a charging time in parallel connection (parallel charging period T1: first period) and a consumption time in series connection (series discharging period T2: By adjusting the second period), the voltage booster 1 outputs a stable voltage about three times the input voltage Vin.

<Operation>
The operation of the booster 1 having the above configuration will be described. 3 shows the first and second switching elements 15a and 15b for grounding, the third and fourth switching elements 15c and 15d for series connection, the output voltage applied to the load 21 from the capacitors 11a to 11c, and the load 21. FIG. 3A is a timing chart showing the output voltage with respect to the first and second switching elements 15a and 15b for grounding, and FIG. 3B is a third serial connection terminal. The fourth switching elements 15c and 15d are turned on and off, (C) in the figure is an output voltage applied from the capacitors 11a to 11c to the load 21, and (D) in the figure is an output applied to the load 21. Each voltage is shown.

  First, when the capacitors 11a to 11c are charged, the grounding first and second switching elements 15a and 15b are turned on and become conductive in period (A1) in FIG. Further, in the period T1, as shown in FIG. 3B, the third and fourth switching elements 15c and 15d for series connection are turned off.

  In this period T1, the three capacitors 11a to 11c are connected to one end of the generator 5 through the respective diodes 13a to 13c on the upstream side, and are connected to the generator through the first and second switching elements 15a and 15b for grounding on the downstream side. 5, the input voltage Vin given from one end of the generator 5 is commonly applied to the three capacitors 11a to 11c connected in parallel to each other, and the input voltage Vin is further increased. The output is provided in common to the load 21 and the output capacitor 7 connected in parallel to the load 21 through the output diode 17.

  In this period T1, the three capacitors 11a to 11c are simultaneously charged by the input voltage Vin, while power is supplied to the load 21 by discharging from the output capacitor 7 as shown in FIG. Since the voltage gradually converges to the input voltage Vin through the third diode 13c and the output diode 17, the output voltage output to the load 21 becomes relatively small.

  Next, when the capacitors 11a to 11c are discharged, the grounding first and second switching elements 15a and 15b are turned off and in a cut-off state, as in the period T2 in FIG. . At the same time, like the period T2 in FIG. 3B, the third and fourth switching elements 15c and 15d for series connection are turned on and become conductive.

  Then, the three capacitors 11a to 11c are connected in series, and the number of capacitors 11a to 11c (three) is boosted compared to the parallel connection in the period T1, and the load 21 is applied. The boosted power is supplied and the output capacitor 7 is charged.

  Here, the drive voltage output to the load 21 is discharged by connecting the three capacitors 11a to 11c in series as shown in FIG. 3D, and the output capacitor 7 is charged. On the other hand, the voltage becomes high in the series discharge period T2, while the three capacitors 11a to 11c are connected and charged in parallel, and the voltage starts to decrease in the parallel charge period T1 in which the output capacitor 7 is discharged. .

  However, when the parallel sufficient period T1 is shorter than the series discharge period T2, sufficient charging is not performed at the start of the series discharge period T2, so that the output voltage to the load 21 decreases as a whole. FIG. 4 is a diagram showing a change in the output voltage applied to the load 21 when the parallel charging period T1 and the series discharging period T2 are changed in the booster according to this embodiment, and FIG. When the parallel charge period T1 is longer than the series discharge period T2, FIG. 5B shows the case where the parallel charge period T1 is equal to the series discharge period T2, and FIG. Each short case is shown. As shown in FIGS. 4A to 4C, the case where the parallel charging period T1 is longer than the series discharge period T2 is applied to the load 21 as compared to the case where the parallel charging period T1 is shorter than the series discharge period T2. The output voltage increases overall.

  Therefore, the boosted voltage output to the load 21 can be adjusted by controlling the parallel charging period T1 and the series discharging period T2 under the control of the control circuit 18. Specifically, if the parallel charging period T1 is made longer than the series discharging period T2, the output voltage to the load 21 can be increased, and a voltage about three times the input voltage Vin is efficiently output. be able to.

  As described above, the plurality of capacitors 11a to 11c are switched between the serial connection for boosting discharge and the parallel connection for charging by the input voltage Vin by the switching elements 15a to 15d, and the parallel charging period T1. Since boosting is performed by controlling the series discharge period T2, a rough boosting ratio can be easily adjusted by the number of capacitors 11a to 11c connected in series. For example, the input voltage can be reduced to about N by using N capacitors. A large step-up ratio can be easily realized, such as outputting a double output voltage.

  Further, as compared with the booster using the chopper control, the size can be reduced because the coil (reactor) is not required.

  Furthermore, since the capacitors 11a to 11c generally have a small power loss, the power loss of the entire booster can be minimized.

  Further, by adjusting the first period (parallel charge period) T1 and the second period (series discharge period) T2 by the control circuit 18, fine boost adjustment can be easily performed.

  In the above embodiment, an example in which the voltage of about three times the input voltage Vin is output using the three capacitors 11a to 11c has been described. However, N (where N is an integer of 2 or 4 or more). The capacitor may be used to output a voltage approximately N times the input voltage Vin. In this way, a voltage of about N times can be easily obtained by N capacitors, so that the boost ratio can be set freely by simply setting the number of capacitors used, and the design is easy. Can provide.

1 is a block diagram showing a state where a booster according to an embodiment of the present invention is applied to an automobile. 1 is a circuit diagram showing a booster device according to an embodiment of the present invention. It is a timing chart which shows operation and output voltage of each part of a booster concerning one embodiment of the present invention. It is a figure which shows the change of the output voltage applied to the load at the time of changing a parallel charge period and a series discharge period in the voltage booster which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Booster device 7 Output capacitor 11a-11c Capacitor 13a-13c 1st-3rd diode 15a, 15b Grounding switching element 15c, 15d Switching element for series connection 17 Output diode 18 Control circuit 21 Load

Claims (3)

A booster that boosts and outputs an input voltage,
Multiple capacitors,
Connection switching means for switching the connection of the plurality of capacitors between parallel connection and series connection;
A first period in which the plurality of capacitors are connected in parallel by the connection switching means and charging is performed by the input voltage; and a second period in which the plurality of capacitors are connected in series by the connection switching means and discharged. A booster comprising control means for alternately controlling. The step-up device according to claim 1,
The booster device, wherein the connection switching means is switch means for switching the plurality of capacitors between a parallel connection state and a series connection state under the control of the control circuit. The booster device according to claim 2,
An output connected in series with the plurality of capacitors placed in series by the connection switching means while being connected in series to the output portions of the plurality of capacitors placed in series connection by the connection switching means Further equipped with a capacitor for
The boosting device, wherein the output capacitor is charged by a discharge voltage of the plurality of capacitors in the second period and discharges and outputs in the first period.

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