JP3758576B2 - Cordless equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used, for example, in an electric tool, an electric razor, a notebook computer, a mobile phone, a vacuum cleaner, etc., and after precharging electric energy, the charger and the main body are disconnected, and the electric energy is applied to the load. It relates to cordless equipment that can be supplied.
[0002]
[Prior art]
Conventionally, as shown in FIG. 8, this type of cordless device includes a charger 2 connected to an AC power source 1 of 100 V and 60 Hz, and a main body 3 detachably attached to the charger 2, and the charger 2 is an AC power source 1. Is connected to the transformer 4 for converting the input voltage to a low voltage of 24V, for example, to the secondary side of the transformer 4 and to the full-wave rectifier 5 for converting from AC to DC, to the output of the rectifier 5, It has the contacts 6 and 7 which make an electrical contact at the time of attachment / detachment.
[0003]
The main body 3 has a power storage element 8 using a nickel cadmium battery, a switch 9, and a load 10 using a motor. When the switch 9 is turned on, the main body 3 is disconnected from the charger 2. Even when the contact points 6 and 7 are separated from each other, it is possible to supply electric power to the load 10 from the power storage element 8 via the switch 9, and the cordless state can also be used. It was a thing.
[0004]
[Problems to be solved by the invention]
However, in the cordless device having the conventional configuration, the transformer 4 which is a constituent element of the charger 2 works at a low frequency of 50 Hz or 60 Hz, so that the shape and weight tend to increase. When it is necessary to carry the charger 2 in a bag or the like simultaneously with the main body 3, there is a first problem that the burden on the user is heavy.
[0005]
Although the transformer 4 can be provided inside the main body 3, in that case, the shape and weight of the main body 3 become large, and when used in a cordless state, the usability becomes very poor. This further increased the burden on the user.
[0006]
In addition, since the nickel cadmium battery constituting the electricity storage element 8 has a low single cell voltage of 1.2 V, when the design is such that a high voltage is supplied to the load, the number of cells in series increases and the cost increases. There is a second problem that the reliability is likely to be lowered due to variations in characteristics between cells as well as higher.
[0007]
Furthermore, there is a third problem that there are cases where charging is not possible due to poor contact when the contact is soiled because it has a contact.
[0008]
The present invention solves the above-described conventional problems, and an object thereof is to provide a cordless device capable of supplying a voltage higher than the voltage of a power storage element to a load and performing a charging operation without a contact while being small and light. And
[0009]
[Means for Solving the Problems]
In order to solve the conventional problems, a cordless device according to the present invention includes a choke coil, a step-up chopper circuit having a first switching element, a main body having a storage element and a load, a DC power supply, an excitation coil, and a second coil. The excitation coil is configured to be magnetically coupled to the choke coil during charging.
[0010]
As a result, the shape and weight of the charger can be reduced to improve usability, a high voltage can be supplied to the load even when the voltage of the power storage element is low, and a charging operation without a contact can be performed by using magnetic coupling. It provides cordless equipment.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The invention described in claim 1 includes a boost chopper circuit having a choke coil, a first switching element, a main body having a storage element and a load, a DC power source, an exciting coil, and a charger having a second switching element. The excitation coil is magnetically coupled to the choke coil during charging, so that the charger is small, light and easy to use, can supply a high voltage to the load by the operation of the boost chopper, and uses power transmission by magnetic coupling. Accordingly, a cordless device that can perform a charging operation without a contact is provided.
[0012]
The invention according to claim 2 is particularly configured to charge the choke coil by including a charging diode connected to the choke coil according to claim 1 and supplying a charging current to the storage element during charging. The present invention realizes a cordless device with little loss that can function effectively at times and can effectively supply the charging current of the storage element.
[0013]
According to a third aspect of the present invention, there is provided a cordless device capable of performing a charging operation with a small number of parts by configuring the charging diode according to the second aspect to be in a conductive state during an off period of the second switching element. It is to provide.
[0014]
In the invention described in claim 4, in particular, since the first switching element described in claim 1 is a MOSFET, high-frequency switching is performed with high efficiency, and energy that is effective even when the voltage of the storage element is low. It provides cordless equipment that can be used.
[0015]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0016]
Example 1
FIG. 1 is a circuit diagram of a cordless device according to a first embodiment of the present invention. In FIG. 1, a main body 101 and a charger 102 that can be attached to and detached from the main body 101 are connected. The charger 102 is connected to an AC power source 103 of 100 V 50 Hz or 60 Hz.
[0017]
The main body 101 is composed of a commutator motor, a load 104 that operates satisfactorily with a DC voltage of 24V, a nickel hydride battery in series of three cells, a storage element 105 having a rated voltage of 3.6V, a boost chopper circuit 106, a capacitor 107 , 108, a charging diode 109, and a switch 110.
[0018]
The step-up chopper circuit 106 includes a choke coil 120 in which an enamel wire is wound around a ferrite core, a first switching element 121 using a MOSFET, a diode 122, and a drive circuit 123 that controls on / off of the switching element 121.
[0019]
One charger 102 includes a full-wave rectifier 130 using four diodes, a choke coil 131, and a capacitor 132, and has a DC power supply 133 that outputs a DC voltage of about 130V. The second switching element 140 using an IGBT, a drive circuit 141 for controlling on / off of the switching element 140, and an enameled wire wound around a U-shaped ferrite core are used for the output of the choke coil 120 and the magnetic An exciting coil 142 to be coupled, and a capacitor 143 and a resistor 144 connected in series are connected in parallel to the exciting coil 142.
[0020]
The charging diode 109 is provided in the main body 101 and is in a conductive state during the off period of the second switching element 140 during charging, and supplies a charging current to the power storage element 105.
[0021]
2A and 2B show operation waveform diagrams during charging of the cordless device of the present embodiment, where FIG. 2A shows the gate voltage waveform Vge of the second switching element 140, and FIG. 2B shows the current of the second switching element 140. I1, (c) shows the current I2 of the choke coil 120, and (d) shows the waveform of the collector-emitter voltage Vce of the second switching element 140. At this time, the switch 110 is in an OFF state.
[0022]
The drive circuit 141 turns on and off the second switching element 140 at a frequency of 50 kHz during the charging operation during charging and sets the on-time to 8 μs, so that the charging current of the power storage element 105 is approximately 1 A.
[0023]
The period from t1 to t2 is an on period. During this period, Vce becomes almost zero, and the output voltage of the DC power supply 133 is almost applied to the exciting coil 142.
[0024]
Here, since the black circle mark is a voltage in the positive direction, the voltage generated in the magnetically coupled choke coil 120 is also a polarity in which the black circle mark is positive, so that the charging diode 109 is in a reverse blocking state, The choke coil 120 current does not flow. Therefore, due to the inductance of the exciting coil 142, the current increases with time and reaches 800 mA at t2.
[0025]
When the second switching element 140 enters the off period at t2, a voltage is generated in the direction in which the black circle is negative due to the magnetic energy stored during the on period, and the choke coil 120 A charging current flows to the storage element 105 through the charging diode 109.
[0026]
After that, the on period is entered again at t3, and this operation is repeated, whereby the charging current is continuously supplied to the power storage element 105 and charging is performed.
[0027]
Such an operation is performed at a switching frequency of 50 kHz, and the value is much higher than the commercial frequency, so that the choke coil 120 and the exciting coil 142 that are very small and light compared to the conventional transformer are used. Therefore, the shape and weight of the charger 102 can be reduced.
[0028]
In addition, the second switching element 140 can be configured with a small and lightweight element such as a TO-220 package, and the charging diode 109 can also be a small fast recovery type.
[0029]
3A and 3B show operation waveforms when used in a cordless state, where FIG. 3A shows the gate voltage Vgs of the first switching element 121, FIG. 3B shows the waveform of the current I3 of the first switching element 121, (C) shows the waveform of the current I2 of the choke coil 120, and (d) shows the waveform of the drain-source voltage Vds of the first switching element 121. In use, the charger 102 is removed, and the switch 110 is turned on by the user's operation. In use, the driving circuit 123 turns on the first switching element 121 at a frequency of 50 kHz and sets the on-time to 11 μs, so that the output voltage V3 to the load 104 is approximately 7V.
[0030]
It is also possible to adjust the DC voltage supplied to the load 104 by changing the ratio of the on-time of the first switching element 121, thereby making the power of the load 104 that is a commutator motor variable, for example, It is also possible to adjust the rotational speed and torque.
[0031]
A period from t1 to t2 is an on period, and during this period, current is supplied from the positive terminal of the power storage element 105 to the choke coil 120, the first switching element 121, the switch 110, and the negative terminal of the power storage element 105.
[0032]
The period from t2 to t3 is an off period. During this period, current is supplied from the choke coil 120 to the diode 122 and the load 104 by the magnetic energy stored in the choke coil 120 during the on period, and the negative terminal of the load 104 Current is supplied through a switch 110 to a negative terminal of the power storage element 105 via the switch 110. Therefore, the boost chopper circuit 106, which is a one-stone type in use, performs a boost operation.
[0033]
Here, since the switching frequency of the first switching element 121 is set to a considerably high value of 50 kHz, it is assumed that the small and light choke coil 120 sufficiently satisfies the function of the boost chopper circuit 122 in use. It can be used.
[0034]
In particular, in the present embodiment, since the first switching element 121 is a MOSFET, the power storage element 105 is a series of three nickel metal hydride batteries, and the rated voltage is a relatively low voltage of 3.6 V. Since the drain-source voltage during the on period can use an element with low on-resistance, it is possible to supply power to the load 104 with low loss, and there is little energy loss.
[0035]
In addition, switching operation at a high frequency is possible, and the choke coil 120 having a small inductance can be used. Therefore, there is an effect that the main body can be reduced in size.
[0036]
When the cordless coil is used, the inductance value of the choke coil 120 tends to decrease when the exciting coil 142 is not present due to an increase in the magnetic resistance of the magnetic circuit. However, the configuration of the present embodiment in which the MOSFET capable of high-frequency switching operation is used as the first switching element 121 works effectively.
[0037]
During charging, the switch 110 is turned off to basically prevent voltage application between the drain and source of the first switching element 121. During use, the diode 122 is connected to the voltage V3 output to the load 104. Therefore, if the voltage required for the load 104 is about several tens of volts, the first switching element 121 is low. The voltage rating is sufficient, and for example, it can be configured with a small and lightweight device such as a TO-220 package.
[0038]
Also, a small diode 122 can be used, and a Schottky barrier diode or the like can be used if the load 104 has a low voltage.
[0039]
In FIG. 3, the current I2 flowing through the choke coil 120 is positive in the left direction, and thus is shown as a negative value during use.
[0040]
As described above, in this embodiment, the choke coil 120 is rationally used both during charging and during operation, so that the choke coil 120 operates and has high efficiency and can suppress wasteful heat generation.
[0041]
Further, the voltage of the DC power supply 124 at the time of charging is 130V, and it can be realized with a simple configuration in which the 100V AC power supply 103 is directly rectified and used.
[0042]
In addition, the voltage supplied to the load 104 at the time of use is about 7V, and can be set to a value higher than the voltage 3.6V of the storage element. Therefore, for example, the commutator motor that is the load 104 has a required power. Even when it is large, it is possible to achieve a high voltage / small current specification in which the current flowing through the brush is suppressed, and it is possible to achieve excellent efficiency and reliability.
[0043]
In this embodiment, at the time of charging, the charging diode is in a conductive state during the off period of the second switching element 140, and operates as a flyback converter in the so-called general switching power supply. Therefore, the number of winding parts can be minimized, and the charging operation can be performed with a simple configuration as compared with a circuit configuration such as a forward converter.
[0044]
In addition, the charging diode 109 is in a reverse blocking state during the on-time of the second switching element 140 at the time of charging, and suppresses the outflow of current from the power storage element 105, so that the charging operation can be performed efficiently. It becomes.
[0045]
In addition, since energy transmission from the main body 101 to the charger 102 during charging is performed by magnetic coupling without using a contact, contact failure due to contamination of the contact or a problem of reliability does not occur, which is extremely excellent. Cordless equipment will be realized.
[0046]
【The invention's effect】
As described above, according to the first to fourth aspects of the present invention, there is provided a cordless device that is small and lightweight, can supply a voltage higher than the voltage of the storage element to the load, and can perform a charging operation without a contact. Can be provided.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a cordless device according to a first embodiment of the present invention. FIG. 2 is an operation waveform diagram when the cordless device is charged. FIG. 3 is an operation waveform diagram when the cordless device is used. Circuit diagram of a conventional cordless device [Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 Main body 102 Charger 104 Load 105 Power storage element 106 Boost chopper circuit 109 Charging diode 120 Choke coil 121 First switching element 133 DC power supply 142 Excitation coil 140 Second switching element

Claims (4)

A booster chopper circuit having a choke coil, a first switching element, a main body having a storage element and a load, a DC power source, an excitation coil, and a charger having a second switching element; A cordless device that is magnetically coupled to a choke coil. The cordless device according to claim 1, further comprising a charging diode connected to the choke coil and configured to supply a charging current to the storage element during charging. The cordless device according to claim 2, wherein the charging diode is in a conductive state during an off period of the second switching element. The cordless device according to claim 1, wherein the first switching element is a MOSFET.

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