JP2011091898A - Battery charger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery charger wherein an active filter is configured without adding a direct-current reactor, a size and weight are reduced, and a battery and a commercial power supply are insulated from each other when the battery is charged. <P>SOLUTION: The battery charger is so configured that the following is implemented. When first and second relay switches RS1, RS2 are both on and third to fifth relay switches RS3 to RS5 are all off, power is supplied from a battery B to a motor M through an inverter 110. When the first and second relay switches RS1, RS2 are both off and the third to fifth relay switches RS3 to RS5 are all on, an active filter is comprised of feedback diodes equivalent to three phases of the inverter, a switching element, and a first capacitor C1. The battery B is charged with a current rectified at a rectification circuit 210 by the operation of a switching power supply portion 220. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a battery charger, and more particularly to an in-vehicle battery charger.

  A conventional vehicle battery charger that can be charged from a commercial power source such as a household power source will be described with reference to FIG. As shown in FIG. 4, the system configuration of the brushless motor M using the battery B is such that the battery B is charged to the AC outlet 10 connected to the AC power source via the charger 20, and the inverter 30 is driven by the battery B. It is comprised so that electric power may be supplied to the brushless motor M via.

  As shown in FIG. 5, the charger 20 includes a rectifier 21, an active filter 22, a switching circuit 23, an insulating transformer 28, and the like. The rectifier 21 is composed of a diode bridge, and is connected to the terminals 10 a and 10 b of the AC outlet 10.

  The active filter 22 includes a high-frequency choke coil 24 connected to the rectifier 21, a diode 25, a capacitor 26, and an FET 27. The active filter 22 shapes the waveform of the input current that has been full-wave rectified by the rectifier 21 to improve the power factor and reduce high-frequency components.

  In the active filter 22, when the FET 27 is on, the direct current output from the rectifier 21 flows through a series circuit including the choke coil 24 and the FET 27 to excite the choke coil 24. When the FET 27 is turned off, the accumulated excitation energy is converted back into a current, the back electromotive force generated in the choke coil 24 and the output voltage of the rectifier 21 are added, and the capacitor 26 is charged via the diode 25. That is, the DC current output from the rectifier 21 is smoothed by the capacitor 26.

  The switching circuit 23 connected in series with the primary winding of the isolation transformer 28 supplies the DC power smoothed by the capacitor 26 to the primary winding of the isolation transformer 28 when switched. Secondary AC power induced in the secondary winding of the insulating transformer 28 is smoothed by the capacitor 31 via the diode 29 and charges the battery B.

  As shown in FIG. 6, the inverter 30 that supplies the electric power of the battery charged by the charger 20 to the motor as described above converts the direct current power of the battery B into alternating current power, and thereby the stator winding MU of the brushless motor M. , MV, MW, and an inverter unit 32 for supplying power, and a capacitor 33 for stabilizing the power supply to the inverter unit 32. The stator windings MU, MV, MW are connected in a star shape. In the inverter unit 32, a three-phase six-arm bridge circuit is configured by six sets of FETs connected in parallel and a diode for circulation.

By the way, in order to reduce the size of the large-capacity battery B, there is a problem that the charger and the inverter that generate a large amount of heat are relatively large.
Therefore, instead of the system configuration as described above, Patent Document 1 proposes a charger in which a part of an inverter part is shared by a charger circuit.

  In Patent Document 1, a DC step-up chopper circuit is configured by connecting a part of switching elements and diodes constituting an inverter, and a rectifying circuit including a rectifying unit and a DC reactor including a rectifying element. A step-up chopper circuit charges a battery connected to the inverter circuit from an AC power source connected to the rectifier circuit. With this configuration, it is possible to reduce the size and weight.

JP-A-10-117441

  However, in the charger of Patent Document 1, since a DC reactor is newly added, there is a problem that the number of parts increases and the cost increases. In addition, when charging from a commercial power source, Patent Document 1 has a problem that an insulation measure is not taken between the battery and the commercial power source.

  An object of the present invention is to use an element that constitutes an inverter that is a component that generates a large amount of heat and a coil of a motor, so that an active filter can be constructed without adding a DC reactor and can be reduced in size and weight. And it is providing the battery charger which can insulate between a battery and commercial power sources at the time of battery charge.

  In order to solve the above problems, the invention described in claim 1 is directed to an inverter connected to the positive and negative electrodes of a battery via first and second switch means, and to the positive and negative electrodes of the battery. 1. a first capacitor connected via a second switch means; a rectifier circuit having an output terminal connected via a third switch means to a neutral point where the fixed windings of the motor are connected; An isolation transformer, a switching circuit provided on the primary side of the isolation transformer, which operates to supply and cut off current to the primary side, and is connected in parallel to the secondary side of the isolation transformer, and the switching circuit is switched When operated, a switching power supply unit comprising a converter including a second capacitor that is charged by a current flowing in the secondary winding of the isolation transformer, and on and off, And a fourth switch means for connecting or disconnecting between the flow circuit and the primary side of the converter, and a fifth switch means for connecting or disconnecting between the secondary side of the converter and the battery by turning on and off. When both the second switch means are on and the third to fifth switch means are both off, power is supplied from the battery to the motor via the inverter, and both the first and second switch means are off. When the third to fifth switch means are both on, a switching element provided according to a plurality of phases of the motor winding and the motor in the inverter and a plurality of switching elements connected in parallel to the switching element, respectively. Among the feedback diodes, at least one phase of the feedback diode, the switching element, and the first capacitor, an active filter Configured, by the operation of the switching power supply unit, it is an gist battery charger, characterized in that at rectified current to allow charging the battery by the rectifier circuit.

  According to a second aspect of the present invention, in the first aspect, the first to fifth switch means include a relay switch.

  According to the present invention, an active filter can be configured without adding a DC reactor, and the size can be reduced by using an element that constitutes an inverter, which is a component that generates a large amount of heat, and a motor coil (fixed winding). In addition, the weight can be reduced, and at the time of charging the battery, the battery and the commercial power source can be insulated by an insulating transformer.

The circuit diagram of the battery charger of one embodiment. The equivalent circuit at the time of battery charge of the battery charger of one Embodiment. The equivalent circuit at the time of battery charge of the battery charger of one Embodiment. The block diagram of the conventional battery charging system. The electric circuit diagram of the conventional battery charger. The drive circuit figure at the time of the conventional motor drive. The circuit diagram of the switching power supply part of other embodiment. The circuit diagram of the switching power supply part of other embodiment.

Hereinafter, an embodiment of a battery charger embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, the battery charger is a combination of a motor drive system circuit 100 and a battery charge system circuit 200.

(Motor drive system circuit 100)
The motor drive system circuit 100 will be described.
The motor drive system circuit 100 includes a first capacitor C1 and an inverter 110 that supplies power to the motor M. Specifically, the positive electrode and the negative electrode of the battery B are connected to the parallel circuit of the first capacitor C1 and the inverter 110 via the first relay switch RS1 and the second relay switch RS2. The first capacitor C1 is a smoothing capacitor made of an electrolytic capacitor, and stabilizes the power supply to the inverter 110. The first relay switch RS1 corresponds to first switch means, and the second relay switch RS2 corresponds to second switch means.

  The inverter 110 includes, for example, six switching elements 120a to 120f made of bipolar transistors, IGBTs, power MOSFETs, and the like, and feedback diodes 130a to 130f connected in parallel to the switching elements 120a to 120f, respectively. The inverter 110 converts the DC voltage of the first capacitor C1 into a three-phase AC and applies it to the motor M provided on the output side. In this embodiment, the motor M is a three-phase DC brushless motor. However, the motor M is not limited and may be driven by the inverter 110. Here, the upper switching elements 120a to 120c shown in FIG. 1 are called switching elements 120a to 120c on the high side 110A, and the feedback diodes 130a to 130c are called feedback diodes 130a to 130c on the high side 110A. In this way, the inverter 110 is a known three-phase six-arm bridge circuit.

  The lower switching elements 120d to 120f shown in FIG. 1 are referred to as low-side 110B switching elements 120d to 120f, and the feedback diodes 130d to 130f are referred to as low-side 110B feedback diodes 130d to 130f.

  As a control means, the control unit 150 includes a microcomputer or the like. The control unit 150 performs pulse width modulation (PWM) on the pulse signal in accordance with an input of a control signal (not shown) to drive the switching elements 120a to 120f on the high side 110A and the low side 110B of the inverter 110 on and off.

The fixed windings U, V, and W of each phase (three phases in this embodiment) of the motor M are connected in a star shape.
(Battery charging system circuit 200)
Next, the battery charging system circuit 200 will be described.

The battery charging system circuit 200 is a circuit including a part of the circuit constituting the inverter 110, the switching power supply unit 220, and the second capacitor C2.
Specifically, the rectifier circuit 210 can be connected to, for example, a commercial frequency AC power supply AC through AC outlets 212a and 212b. The rectifier circuit 210 converts alternating current into direct current. The positive output terminal of the rectifier circuit 210 is a connection point where the fixed windings U, V, W of the motor M are connected in a star shape via a third relay switch RS3 as a third switch means, that is, a neutral point T It is connected to the. The negative output terminal of the rectifier circuit 210 is connected to the negative electrode of the battery B via the second relay switch RS2.

  The switching power supply unit 220 of this embodiment includes an insulating transformer TR, a switching element 222, a diode D1, and a second capacitor C2. The insulating transformer TR is formed by winding a primary side winding TRa and a secondary side winding TRb around a ferrite core (magnetic core) (not shown).

  Specifically, both connection points of the fourth relay switch RS4, the primary winding TRa of the isolation transformer TR and the series circuit of the switching element 222 are connected via the first relay switch RS1 and the second relay switch RS2. The battery B is connected to the positive electrode and the negative electrode of the battery B, respectively. In this way, the series circuit is connected in parallel to the first capacitor C1 by being connected to the battery B. The fourth relay switch RS4 corresponds to fourth switch means. The switching element 222 is on / off controlled by the control unit 150.

  A secondary circuit winding TRb of the insulation transformer TR forms a series circuit from the fifth relay switch RS5 and the diode D1, and both terminals of the series circuit are connected to the battery B with a positive electrode and a negative electrode. The diode D1 is reverse-biased with respect to the battery B.

  In the present embodiment, the switching power supply unit 220 includes a flyback converter including the diode D1, the insulating transformer TR, and the switching element 222. The second capacitor C2 is connected in parallel to the series circuit of the diode D1 and the secondary winding TRb. The second capacitor C2 is an electrolytic capacitor. The switching element 222 constitutes a switching circuit.

  In the flyback converter, the isolation transformer TR functions as an inductor having two sets of windings. One winding stores energy in the transformer core, and the other winding transmits core energy to the second capacitor C2. In the present embodiment, when the first relay switch RS1 and the second relay switch RS2 are in the off state and the third relay switch RS3, the fourth relay switch RS4, and the fifth relay switch RS5 are in the on state, the switching element When 222 is turned on, the current rectified by the rectifier circuit 210 increases in the primary winding TRa of the isolation transformer TR while the switching element 222 is on. Here, since the secondary side voltage of the isolation transformer TR is reverse-biased by the diode D1, no secondary side current flows. When the first relay switch RS1 and the second relay switch RS2 are in the off state and the third relay switch RS3, the fourth relay switch RS4, and the fifth relay switch RS5 are in the on state, the switching element 222 is turned off. Since the magnetic field tries to maintain the current, the polarity of the transformer voltage is reversed, so that the current flows to the secondary side and the second capacitor C2 is charged and smoothed via the diode D1, so that the battery B can be charged. It has become.

The first relay switch RS1 to the fifth relay switch RS5 are ON / OFF controlled by the control unit 150.
(Operation of the embodiment)
Now, the operation of the battery charger configured as described above will be described with reference to FIGS.

(charging)
First, the case where the battery B is charged will be described. During charging, the control unit 150 controls the first relay switch RS1 and the second relay switch RS2 to insulate the primary side and the secondary side of the isolation transformer TR. Further, the control unit 150 turns on the third relay switch RS3, the fourth relay switch RS4, and the fifth relay switch RS5. When the third relay switch RS3 and the fourth relay switch RS4 are turned on, the input of the AC power supply AC and the primary side of the insulation transformer TR are connected, and when the fifth relay switch RS5 is turned on, the secondary side of the insulation transformer TR and the battery are connected. B is connected.

  The state in which each relay switch is turned on or off in this way is shown in the equivalent circuit of FIG. In this state, the control unit 150 turns off the switching elements 120a to 120c on the high side 110A and switches the switching elements 120d to 120f on the low side 110B while shifting the electrical phase angle by 120 °. In this state, when the control unit 150 performs the on / off operation of the switching element 222 of the switching power supply unit 220, the direct current rectified by the rectifier circuit 210 connected to the AC power supply AC is supplied to the fixed windings U, V, W and the low side 110B. The current can be passed through the switching circuit (switching element 222) through an active filter including the switching elements 120d to 120f, the high-side 110A feedback diodes 130a to 130c, and the first capacitor C1. The switching element 222 is turned on and off by the control unit 150, so that the secondary current of the insulation transformer TR is smoothed by charging the second capacitor C2 via the diode D1, and the battery B is charged.

  Since the active filter is formed at the time of charging as described above, the direct current that has been full-wave rectified by the rectifying circuit 210 can efficiently charge the battery B with the power factor improved.

(Discharge)
Next, the case where the motor M is driven by the battery B will be described.
When driving the motor M, that is, when discharging the battery B, the control unit 150 controls the first relay switch RS1 and the second relay switch RS2 to connect the battery B and the inverter 110.

  Further, the control unit 150 turns off the third relay switch RS3, the fourth relay switch RS4, and the fifth relay switch RS5. The positive output terminal of the rectifier circuit 210 and the motor M are insulated by turning off the third relay switch RS3. By turning off the fourth relay switch RS4, it is possible to prevent a voltage from being applied to the primary side of the isolation transformer TR. By turning off the fifth relay switch RS5, it is possible to prevent a voltage from being applied to the secondary side of the insulating transformer TR. The state in which each relay switch is turned on or off in this way is shown in the equivalent circuit of FIG.

  In this state, the control unit 150 performs pulse width modulation (PWM) on the pulse signal in accordance with an input of a control signal (not shown), and drives the switching elements 120a to 120f on the high side 110A and the low side 110B of the inverter 110 on and off.

By turning on and off the switching elements 120a to 120f, the direct current supplied from the battery B is converted into alternating current, and the motor M is rotationally driven.
The present embodiment has the following features.

  (1) The battery charger according to the present embodiment includes an inverter 110 that converts a DC voltage of the battery B into an alternating current by an on / off operation of the plurality of switching elements 120a to 120f and supplies the alternating current to the motor M. The battery B is connected to the positive electrode and the negative electrode via a first relay switch RS1 (first switch means) and a second relay switch RS2 (second switch means). In addition, the battery charger includes the first capacitor C1 connected to the positive and negative electrodes of the battery B via the first relay switch RS1 and the second relay switch RS2, and the fixed windings U, V, and W of the motor M. Is provided with a rectifier circuit 210 having an output terminal connected to a neutral point T to which is connected via a third switch means.

  The battery charger is provided on the primary side of the insulating transformer TR, the switching element 222a (switching circuit) that operates to supply and cut off the current on the primary side, and the insulating transformer TR. A switching power supply unit 220 including a flyback converter including a second capacitor C2 connected in parallel to the secondary side and charged by a current flowing through the secondary winding TRb when the switching element 222 performs a switching operation is provided. Yes.

  The battery charger includes a fourth relay switch RS4 (fourth switch means) that connects or disconnects the primary side of the rectifier circuit 210 and the switching power supply unit 220 (converter) by turning on and off, and a switching power supply unit 220 by turning on and off. 5th relay switch RS5 (5th switch means) which connects or interrupts between the secondary side of (converter) and battery B is provided.

  The battery charger is connected to the inverter from the battery B when the first relay switch RS1 and the second relay switch RS2 are both on and the third relay switch RS3, the fourth relay switch RS4 and the fifth relay switch RS5 are both off. Electric power is supplied to the motor M via 110. Further, the battery charger is configured such that when the first relay switch RS1 and the second relay switch RS2 are both off and the third relay switch RS3, the fourth relay switch RS4 and the fifth relay switch RS5 are both on, the winding of the motor M is performed. An active filter is configured by the feedback diode provided in accordance with a plurality of phases of the motor M in the line and the inverter 110, the feedback diode for three phases among the switching elements, the switching element, and the first capacitor C1. . The battery B is charged with the current rectified by the rectifier circuit 210 by the operation of the switching power supply unit 220.

  As a result, according to the present embodiment, an active filter is configured without adding a DC reactor by using an element that constitutes the inverter 110 that is a component that generates a large amount of heat and a coil (fixed winding) of the motor M. In addition, a separate component for configuring the active filter is not necessary, and the size and weight can be reduced. Further, at the time of charging the battery, the battery B and the commercial power source can be insulated by the insulating transformer TR.

  (2) In the battery charger of the present embodiment, the first to fifth switch means are configured by the first relay switch RS1 to the fifth relay switch RS5. As a result, it is not necessary to send a control signal or the like for turning on / off the switch between the inverter and the battery through which a large current flows and between the inverter and the rectifier circuit, and the size can be reduced.

In addition, this invention is not limited to the said embodiment, You may make it as follows.
The switching power supply unit 220 is not limited to a flyback converter, and may be a forward converter, a push-pull converter, a half bridge converter, or a full bridge converter as the switching power supply unit.

  For example, FIG. 7 shows a switching power supply 220 as a forward converter. In addition, the same code | symbol is attached | subjected about the same or equivalent structure as the said embodiment. The forward converter shown in FIG. 7 is known and will not be described in detail. However, when the switching element 222 is turned on, the current flowing in the primary winding TRa increases as the current flowing in the primary winding TRa increases. The flowing current flows to the choke coil L and the second capacitor C2 via the diode D1. Further, when the switching element 222 is turned off, the inductor current circulates through the second capacitor C2 and the diode D2. In the forward converter, a third winding TRc is provided on the primary side of the isolation transformer TR, and a diode D3 is connected in series to the winding TRc. The winding TRc returns the magnetization energy in the insulating core to the rectifier circuit 210.

  FIG. 8 shows an embodiment in which the switching power supply unit 220 is a push-pull converter. In addition, the same code | symbol is attached | subjected about the structure same as the said embodiment (The embodiment shown in FIGS. 1-3, FIG. 6) or an equivalent structure. Here, since the operation of the bush-pull converter is conventionally known, a specific circuit element connection configuration will be described.

  As shown in FIG. 8, the primary side winding TRa of the insulating transformer TR is divided into windings TRa1 and TRa2 across the center tap. A fourth relay switch RS4 is connected to the center tap. One winding TRa1 of the primary winding TRa is connected to a connection point between the negative output terminal of the rectifier circuit 210 and the second relay switch RS2 via a switching element 222a made of a bipolar transistor, a power MOSFET or the like.

  The other winding TRa2 of the primary winding TRa is connected to the connection point between the negative output terminal of the rectifier circuit 210 and the second relay switch RS2 via a switching element 222b made of a bipolar transistor, a power MOS-FET, or the like. Has been. The switching elements 222a and 222b as switching circuits are controlled by the control unit 150 so as to be alternately turned on for a predetermined on time. By alternately turning on the switching elements 222a and 222b, voltages having different polarities are alternately applied to the core of the insulating transformer TR. The switching elements 222a and 222b are provided with diodes D4 and D5 for recirculation, and return the magnetization energy to the input voltage when the switching elements 222a and 222b are off.

  As shown in FIG. 8, the secondary winding TRb of the insulating transformer TR is divided into windings TRb1 and TRb2 with a center tap interposed therebetween. The center tap of the secondary winding TRb of the insulation transformer TR is connected to the negative electrode of the battery B.

  Winding TRb1 is connected to choke coil L (reactor) via diode D1, and winding TRb2 is connected to a connection point between diode D1 and choke coil L via diode D2.

  In addition, the half-bridge converter and the full-bridge converter have the same connection configuration of various circuit elements on the secondary winding TRb side of the isolation transformer TR, as in the embodiment of the push-pull converter. The switching circuit on the primary winding TRa side of the isolation transformer TR is configured by a half-bridge or a full-bridge switching element composed of a bipolar transistor, a MOS-FET, etc. Of course, it can be adopted as the configuration of the power supply unit 220.

  In the embodiment, the fourth relay switch RS4, the primary winding TRa, and the switching element 222 are in the order of the series circuit. However, the order of the circuit elements constituting the series circuit is not limited to the description order. They may be arranged in any order.

  In the embodiment, when the battery B is charged, all the switching elements 120d to 120f are switched with the electrical phase angle shifted by 120 ° by the control unit 150, but all the switching elements of the low side 110B are switched. Instead of switching, any one may be switched, or any two switching elements may be combined to switch the electrical phase angle by 180 °. Even in this case, the battery B can be charged. Further, an active filter is constituted by the fixed windings U to W of the motor, the high-side feedback diodes 130a to 130c, and the first capacitor C1, which are connected to the switching elements that are switched.

  -Although the said motor was made into three phases, it is not limited to three phases, You may comprise with a brushless motor of multiple phases. In this case, the switching element of the inverter is provided corresponding to each phase. Also in this case, the controller 150 may turn off all the high-side switching elements and switch all the low-side switching elements with an electrical phase angle. Alternatively, instead of switching all the switching elements of the low side 110B, at least one of them may be switched. Even in this case, the battery B can be charged.

The feedback diode may be a parasitic diode when the switching element uses a power MOSFET, for example.
The switch means is not limited to a relay switch, and may be a switching element composed of a power transistor or the like.

B ... battery, C1 ... first capacitor, C2 ... second capacitor,
RS1 ... 1st relay switch (1st switch means),
RS2 ... second relay switch (second switch means),
RS3 ... third relay switch (third switch means),
RS4 ... 4th relay switch (4th switch means),
RS5 ... 5th relay switch (5th switch means),
TR: insulation transformer, TRa: primary winding, TRb: secondary winding,
T ... neutral point,
100: Motor drive system circuit,
110 ... Inverter, 110A ... High side, 110B ... Low side,
150 ... control part (control means),
200 ... battery charging system circuit, 220 ... switching power supply unit,
222: Switch element (switching circuit).

Claims (2)

An inverter connected to the positive and negative electrodes of the battery via first and second switch means;
A first capacitor connected to the positive and negative electrodes of the battery via first and second switch means;
A rectifier circuit in which an output terminal is connected via a third switch means to a neutral point where the fixed windings of the motor are connected;
Insulating transformer, a switching circuit provided on the primary side of the insulating transformer and operated to supply and cut off current on the primary side, and connected in parallel to the secondary side of the insulating transformer, and the switching circuit performs a switching operation. A switching power supply comprising a converter including a second capacitor that is charged by a current flowing through the secondary winding of the isolation transformer,
A fourth switch means for connecting or blocking between the rectifier circuit and the primary side of the converter by turning on and off;
A fifth switch means for connecting or disconnecting between the secondary side of the converter and the battery by turning on and off;
When the first and second switch means are both on and the third to fifth switch means are both off, power is supplied from the battery to the motor via the inverter.
When both the first and second switch means are off, and when the third to fifth switch means are both on, the windings of the motor and switching elements provided according to a plurality of phases of the motor in the inverter, Among the plurality of feedback diodes connected in parallel to the switching element, at least one phase of feedback diode, the switching element, and the first capacitor constitute an active filter, and the switching power supply unit operates, A battery charger characterized in that the battery can be charged with a current rectified by the rectifier circuit.   2. The battery charger according to claim 1, wherein the first to fifth switch means are relay switches.

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