JP2001037219A - Power source unit and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of a power source, enable effective charge of a battery, and realize energy saving, in a power source unit having a battery and a switching power source. SOLUTION: The primary side of an insulating transformer 1 is driven by the oscillation of a MOS-FET 2. An AC generated on the secondary side is rectified and smoothed with a diode 14 and a capacitor 15, and its output voltage Vo is supplied to a load. When a residual charge detecting means 25 detects that the residual charge of the battery 20 is lower than a specified value, the battery 20 is charged. In this case, an oscillator circuit with a comparator 27 is operated by a signal from a mode switching control means 26, and oscillation with the MOS-FET 2 is intermittently performed. The battery 20 is charged by the state of intermittent oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply having a storage battery and a switching power supply, and more particularly to a power supply for charging a storage battery by an output of the switching power supply and a control method thereof.

[0002]

2. Description of the Related Art As a power supply device for supplying power to equipment and charging a battery of the equipment, for example, a power supply apparatus having a circuit configuration as shown in FIG. 4 is generally known. This is based on a self-excited flyback converter (RCC: ringing choke converter) as a basic circuit.

In the circuit shown in FIG. 4, an insulating transformer 1 of a converter is constituted by a primary winding Np on an input side, a secondary winding Ns on an output side, and a tertiary winding Nb for control. Three
The next winding Nb is a MOS-FET which is a switching element.
2 is a drive winding for the gate control transistor 3. The switching element may be a bipolar transistor instead of the MOS-FET2.

The input voltage Vi from the DC power supply E is a DC voltage which is rectified by a bridge diode (not shown) and smoothed by an electrolytic capacitor. The input voltage Vi is connected to one end of the primary winding Np of the transformer 1 and 3
Applied between the other end of the next winding Nb,
Side is the end of the primary winding Np, and the (-) side is the tertiary winding N
b are connected at the beginning of winding. NOS-
The drain of the FET 2 is connected to the beginning of the winding of the primary winding Np, and the source is connected to the beginning of the winding of the tertiary winding Nb.

[0005] The (+) side of the DC power supply E and the MOS-FE
A startup resistor 4 and a gate protection resistor 5 are provided between the gates of T2.
Is connected. A Zener diode 6 is connected between the gate of the MOS-FET 2 and the (−) side of the DC power supply E.
Are connected, and a bias is applied to the transistor 3 and the collector of the phototransistor of the photocoupler 7 for feedback. A series circuit of a capacitor 8 and a resistor 9 is connected between the gate of the MOS-FET 2 and the end of the tertiary winding Nb.

A resistor 10 for limiting the base current of the transistor 3 is connected between the photocoupler 7, the emitter of the phototransistor, and the base of the transistor 3, and the photocoupler 7 of the resistor 10 and the tertiary winding Nb are connected. A capacitor 11 for controlling the base current is connected between the start of the winding. A Zener diode 12 and a resistor 13 are connected in series between the base current limiting resistor 10 of the transistor 3 and the end of the tertiary winding Nb. At the beginning of the winding of the secondary winding Ns of the insulating transformer 1, the anode side of the rectifying diode 14 is connected. An electrolytic capacitor 15 is connected between the cathode side of the diode 14 and the end of the secondary winding Ns to perform smoothing.

The output voltage Vo of the converter is equal to the resistance 1
6 and the variable resistor 17, and the divided voltage is used as a shunt regulator 1 for feedback control.
8, the current flowing through the light emitting diode of the photocoupler 7 is controlled by being compared with a reference voltage. The resistor 19 is a resistor for limiting a current flowing through the light emitting diode of the photocoupler 7.

In the circuit shown in FIG. 4, a battery 20 serving as a storage battery has a battery charge switching transistor 21 functioning as a switch and a backflow preventing diode 2.
2, the output voltage Vo is supplied. The output voltage V1 of the battery 20 is divided and detected by two high-impedance resistors 23 and 24 for voltage detection, and a decrease in the battery voltage is detected by remaining capacity detection means 25 for detecting the remaining capacity of the battery 20. Is done. Then, the mode switching control unit 26 applies a bias to the base of the transistor 21 that switches whether or not to supply power to the battery 20 according to the detection signal from the remaining capacity detection unit 25.

In the circuit having the above structure, the MOS-FET
A bias is applied to the gate of the gate 2 by the starting resistor 4 to make the gate conductive. When the MOS-FET 2 is turned on, the input voltage Vi is applied to the primary winding Np of the transformer 1, and a voltage is generated in the tertiary winding Nb such that the winding end side is (+). At this time, although a voltage is induced also in the secondary winding Ns, the voltage is not transmitted to the secondary side since the voltage is set to (−) on the rectifying diode 14 side. Therefore, the current flowing through the primary winding Np is only the exciting current of the insulating transformer 1, and energy proportional to the square of the exciting current is stored in the insulating transformer 1. This exciting current increases in proportion to time.

The capacitor 11 connected to the base of the transistor 3 via the Zener diode 12 and the resistor 13 is charged by the voltage induced in the tertiary winding Nb of the transformer 1, and a current flows through the base of the transistor 3. Is supplied. When the current reaches a certain value, the transistor 3 is turned on. This transistor 3
Is turned on, no bias is applied to the gate of the MOS-FET 2, and the MOS-FET 2 is turned off. At this time, a voltage is generated in each winding of the insulating transformer 1 in a direction opposite to that at the time of startup, and a voltage is generated in the secondary winding Ns with the rectifying diode 14 being (+). The stored energy is rectified and smoothed and transmitted to the secondary side.

Further, a voltage is generated in the tertiary winding Nb with the Zener diode 12 as (-), and the base of the transistor 3 is reverse-biased. When the base current value becomes lower than a certain value, the transistor 3 is turned off. become. When all the energy stored in the insulating transformer 1 is transmitted to the secondary side, the MOS-FET 2 starts up again.

On the other hand, since a large amount of current from the photocoupler 7 flows when the output voltage Vo is high, a current is supplied to the capacitor 11 and the charging time is shortened. This indicates that the conduction time of the MOS-FET 2 is shortened. As a result, the energy stored in the insulating transformer 1 is reduced, so that the output voltage Vo is reduced and the constant voltage operation is performed. When the output voltage is low, the operation is reversed.

The MO is connected to both ends of the primary winding Np.
When the S-FET 2 shifts from the conducting state to the non-conducting state, a snubber circuit including a diode 39, a capacitor 40, and a resistor 41 for absorbing a surge voltage having a (+) polarity on the winding start side is added.

FIG. 5 is a diagram showing waveforms at various parts of the circuit in the above-described RCC system. Vg indicates the gate voltage of the MOS-FET2, Vds indicates the drain-source voltage of the MOS-FET2, Id1 indicates the drain current, and Id2 indicates the current flowing through the rectifying diode 14 on the secondary side.

First, the ON period of the MOS-FET 2 will be described. The bias is applied to the gate of the MOS-FET 2 by the starting resistor 4, and the MOS-FET 2 becomes conductive when the potential of Vg increases. At this time, Id1 increases linearly with time with a positive slope, and energy is stored in the insulating transformer 1. At this time, Vds is MOS
Since the FET 2 is in the conductive state, the potential is almost zero, and the diode 14 on the secondary side is reverse-biased,
Id2 does not flow.

When the capacitor 11 is charged and the transistor 3 is turned on, the gate voltage Vg of the MOS-FET 2 becomes zero and the MOS-FET 2 becomes non-conductive, so that Id1 becomes zero and Vds becomes zero. Input voltage V
i. At this time, the secondary side rectifying diode 14
Becomes conductive, and the energy stored in the insulating transformer 1 is transmitted to the secondary side. Also, at this time, Id2 decreases linearly with a negative slope.

Although the switching means for controlling the supply / interruption of the input voltage Vi is not specified in the circuit shown in FIG. 4, the power supply device has two modes. One is the input voltage V
i is applied to the power supply to obtain an output voltage Vo;
The other is a mode in which the input voltage Vi is cut off, and power is supplied from the battery 20 for storage and clock functions.
When the remaining capacity detecting means 25 determines that the capacity of the battery 20 is low, the switch means is turned on and the battery 20 is charged with the output voltage Vo.

FIG. 6 shows the relationship between the output voltage (W) and the power supply efficiency (%) in the oscillation mode in which the output voltage Vo is obtained by applying the input voltage Vi and supplied to the load. The power (P) required for charging the battery 20 is lower than the power required during normal use.

[0019]

However, in the above-described conventional power supply device, not only the RCC system shown in FIG. In the configuration where the efficiency is maximized, there is a problem that the efficiency of the power supply is reduced where the output power is small.In addition, the power required for charging the storage battery is higher than the power required for normal use. There was a problem that the battery had to be charged in a place where the power supply was inefficient, which was rather small.

The present invention has been made in view of the above problems, and provides a power supply device capable of efficiently charging a storage battery and saving energy, and a control method thereof. It is intended to be.

[0021]

A power supply device and a control method thereof according to the present invention are configured as follows.

(1) It has a storage battery and an output transformer whose primary winding is oscillated by a switching element to generate an AC in a secondary winding, and rectifies the AC generated in a secondary winding of the output transformer. Power supply to the load
Control means for intermittently oscillating the primary winding of the output transformer is provided, and the storage battery is charged in the intermittent oscillating drive state.

(2) In the configuration of (1), the drive value of the switching element is controlled by comparing the detected value of the voltage supplied to the load with a reference value.

(3) In the configuration of the above (1) or (2), there is provided a stop means for stopping the driving of the switching element, and the control means controls the stop period to drive the oscillation of the primary winding of the output transformer. And stop was repeated.

(4) In any one of the above constitutions (1) to (3), there is provided a detecting means for detecting a remaining capacity of the storage battery, so that the storage battery is charged when the remaining capacity falls below a predetermined value. did.

(5) In the configuration of (4), there is provided switching means for switching between a continuous oscillation mode using a switching element, an intermittent oscillation mode using the switching element, and an oscillation stop mode. During operation, when the remaining capacity of the storage battery falls below a predetermined value, the storage battery is charged in the intermittent oscillation mode, and when the storage capacity of the storage battery reaches the predetermined value, the oscillation stop mode is set.

(6) In any one of the above constitutions (3) to (5), the driving stop period of the switching element is controlled by a control signal from the main unit in which the storage contents are held by the storage battery.

(7) In the configuration of (6), the control signal is a signal converted into an analog signal by the D / A converter of the main unit.

(8) It has a storage battery and an output transformer whose primary winding is oscillated by a switching element to generate an alternating current in the secondary winding, and rectifies the alternating current generated in the secondary winding of the output transformer. In the control method of the power supply device supplying the load to the load, the storage battery is charged in an intermittent oscillation driving state in which the oscillation driving of the primary winding of the output transformer is intermittent.

(9) In the configuration of (8), the drive value of the switching element is controlled by comparing the detected value of the voltage supplied to the load with a reference value.

(10) In the configuration of (8) or (9), the drive stop period of the switching element is controlled to repeat the oscillation drive and stop of the primary winding of the output transformer.

(11) In any one of the constitutions (8) to (10), the remaining capacity of the storage battery is detected, and the storage battery is charged when the remaining capacity falls below a predetermined value.

(12) In the configuration of the above (11), a continuous oscillation mode using the switching element, an intermittent oscillation mode using the switching element, and an oscillation stop mode are switched by a control signal, and the storage battery is operating in the oscillation stop mode. Then, when the remaining capacity of the storage battery falls below a predetermined value, the storage battery is charged in the intermittent oscillation mode, and when the remaining capacity of the storage battery reaches the predetermined value, the oscillation stop mode is set.

(13) In any one of the above constitutions (10) to (12), the driving stop period of the switching element is controlled by a control signal from the main unit in which the storage content is held by the storage battery.

(14) In the configuration of the above (13), the drive stop period of the switching element is controlled by a control signal converted into an analog signal by the D / A converter of the main unit.

[0036]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a circuit diagram showing a configuration of a power supply device according to a first embodiment of the present invention. The same components as those in FIG. Description is omitted. In this embodiment, the above-described self-excited flyback converter (RCC) is used as a basic configuration. However, not only this RCC but also a current resonance type or forward type converter may be used.

The difference from the circuit shown in FIG. 4 of this embodiment is that an oscillation circuit by a comparator 27 is added to the secondary side of the isolation transformer (output transformer) 1. The output terminal of the comparator 27 is connected to the cathode side of the light emitting diode of the photocoupler 7, and a non-inverting input terminal (+) receives a constant voltage from a series circuit of the resistor 32 and the Zener diode 28. GN is connected to the inverting input terminal (-).
A capacitor 30 and a resistor 31 are connected in parallel with the resistor D, and a resistor 29 and a zener diode 36 are connected between the capacitor 30 and the output terminal of the voltage Vo. Further, the collector of a transistor 33 for switching the power mode operation is connected to the inverting input terminal via a resistor 34 and a zener diode 36. The base of the transistor 33 is connected to the mode switching control means 2 via a base current limiting resistor 35.
6 is connected.

Here, in the circuit of FIG. 1, the detected value of the output voltage Vo supplied to the load is compared with a reference value to determine the output voltage Vo.
Control means for controlling the S-FET 2 comprises a comparator 27 and a charging circuit for the resistor 29 and the capacitor 30. Stop means for stopping the oscillation driving of the primary winding Np of the transformer 1 by the MOS-FET 2 is a gate control transistor. The control means controls the stop period to control the primary winding Np of the transformer 1.
It is possible to repeat the oscillating drive and stop.

The power supply mode switched by the mode switching control means 26 includes an oscillation mode (1) in which the oscillation is driven by the MOS-FET 2 to supply power to the load.
(Continuous oscillation mode), oscillation mode (2) (intermittent oscillation mode) in which the above-described oscillation drive and stop are repeated, and battery mode (oscillation stop) in which oscillation drive is completely stopped and power is supplied to the load using only battery 20 Mode). When the remaining capacity of the battery 20 falls below a predetermined value (set value) by the remaining capacity detection means 25 during operation in the battery mode, the battery 20 is operated in the oscillation mode (2) and
0, and the remaining capacity of the battery 20 becomes a predetermined value (set value)
After reaching, set the battery mode again.

That is, in the oscillation mode (1), the input from the mode switching control means 26 to the base of the transistor 33 is at a high level, and the voltage at the inverting input terminal of the comparator 27 is , The output terminal of the comparator 27 becomes high impedance, and the converter performs a normal oscillation operation. At this time, the Zener diode 3
6 prevents charging of the capacitor 30 during normal oscillation.

When the input to the base of the transistor 33 becomes a low level, the transistor 33 is turned off, the capacitor 30 is charged from the output voltage Vo via the resistor 29, and the voltage of the capacitor 30 rises. I do. Then, when the voltage becomes higher than the constant voltage by the Zener diode 28, the output terminal of the comparator 27 becomes low level, a current flows through the light emitting diode of the photocoupler 7, and the capacitor 11 on the primary side of the transformer 1 is charged. The voltage increases, and the transistor 3 is turned on.

As a result, the MOS-FET 2 is turned off, and the oscillation stops. When the oscillation stops, the capacitor 30 discharges via the resistor 31, and its voltage also decreases according to the discharge. When this voltage becomes equal to or lower than the constant voltage of the Zener diode 28, the output terminal of the comparator 27 becomes high impedance and starts oscillating again. By repeating the above operation, the oscillation state can be intermittently controlled.

As described above, the oscillation mode (1) and the oscillation mode (2) are controlled by the control signal from the mode switching control means 26.
And the switching operation can be performed. The mode switching control means 26 is also connected to a switching transistor 21 for switching the charging operation of the battery 20. When the mode is changed to the oscillation mode (2), the transistor 21 is switched.
To a conductive state, and the battery 20 is charged.

FIG. 2 is a diagram showing waveforms at various points in the circuit of FIG. 1 when oscillation is intermittently performed. V2 indicates the voltage of the capacitor 30, and V- indicates the voltage of the non-inverting input terminal of the comparator 27. The waveforms other than the voltages V2 and V- are Vg, Vds, Id1, and Vg described in the circuit of FIG.
Each waveform of Id2 is shown.

When the base voltage of the transistor 33 goes low, the voltage of the capacitor 30
5 and discharge by the resistor 31 are repeated, and V
It oscillates according to waveform 2. Oscillation is stopped when the voltage V2 becomes higher than the voltage V3 at the non-inverting input terminal of the comparator 27, and oscillates when the voltage becomes higher. When the oscillation is intermittently performed as described above, the output voltage Vo is lower than that in the normal oscillation state.

In this embodiment, as described above, the battery 20
The power supply device has three modes, ie, an oscillation mode (1), an oscillation mode (2), and a battery mode. In order to supply necessary power during normal use, the oscillation mode (1) is used. Operates and supplies power to the load. Further, when the main body enters a power saving mode such as a memory holding mode such as a standby mode or a clock function holding mode, the input voltage Vi of the DC power supply E is cut off and power is supplied in a battery mode. When the voltage drop of the battery 20 is detected by the remaining capacity detection means 25 of the battery 20, the input voltage Vi of the DC power source E is input, the power source is operated in the oscillation mode (2), and the battery 20 is charged. I do. When the voltage of the battery 20 returns to normal, the input power is cut off again, and the battery 20 operates in the battery mode.

Therefore, as shown in FIG. 6, the efficiency of the power supply can be improved, and the battery 20 can be charged more efficiently. In addition, it is possible to suppress the input power on the primary side at the same output, and to save energy.

(Second Embodiment) FIG. 3 is a circuit diagram showing a configuration of a second embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same components. In the figure, 37 is a main body control means for controlling each part of the main body device provided with the present power supply device, and 38 is a D / A converter for converting a digital signal into an analog signal.
The analog control signal is a power mode switching transistor 3
3 is input to the base.

The difference between this embodiment and the first embodiment is that the first embodiment
In this embodiment, the constant voltage from the Zener diode 28 is applied to the non-inverting input terminal of the comparator 27.
The analog control signal is D / A converted by the / A converter 38, and then input to the non-inverting input terminal of the comparator 27. Thus, the output voltage in the oscillation mode (2) can be made variable according to the set value of the main body control unit 37.

That is, while the time constant of the resistor 29 and the capacitor 30 and the time constant of the capacitor 30 and the resistor 31 do not change, the threshold level of the voltage may be raised or lowered in order to change the voltage V3 of the Zener diode 28. Yes, the frequency is constant, but the comparator 27
A PWM (Pulse Width Modulator) that changes the time when the output terminal of the
(ion) control, and the output voltage Vo can be changed. Therefore, the output voltage Vo can be reduced by lowering the voltage of the non-inverting input terminal, and the output voltage Vo can be increased by increasing the voltage of the non-inverting input terminal.

As described above, in this embodiment, the main body control means 3
7, the output voltage Vo can be arbitrarily changed by the analog control signal. Therefore, it is possible to easily cope with a change in the target capacity or the like of the battery 20 to be charged.

[0053]

As described above, according to the present invention,
By intermittently performing the oscillation state, the efficiency of the power supply can be improved with respect to the power required to charge the storage battery, the storage battery can be charged more efficiently, and the primary side is turned on at the same output. Power can be reduced,
Energy saving can be achieved.

Since the output voltage can be arbitrarily changed by an analog control signal from the main unit, it is possible to easily cope with a change in the target capacity of the storage battery to be charged.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing waveforms at various points during intermittent oscillation of the first embodiment.

FIG. 3 is a circuit diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a general power supply device.

FIG. 5 is a diagram showing waveforms at various parts of an RCC power supply device;

FIG. 6 is an explanatory diagram showing a relationship between output power and power supply efficiency.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulation transformer (output transformer) 2 MOS-FET (switching element) 3 Gate control transistor 4 Starting resistance 7 Photocoupler 11 Capacitor 14 Diode 15 Electrolytic capacitor 18 Shunt regulator 20 Battery (storage battery) 21 Transistor 25 Remaining capacity detecting means 26 Mode Switching control means 27 Comparator 28 Zener diode 29 Resistor 30 Capacitor 31 Resistor 33 Transistor 37 Body control means 38 D / A converter

Claims (14)

[Claims] A storage battery and an output transformer whose primary winding is oscillated by a switching element to generate an alternating current in a secondary winding, and rectifies the alternating current generated in the secondary winding of the output transformer. A power supply device for supplying power to a load, wherein control means is provided for interrupting oscillation driving of the primary winding of the output transformer, and the storage battery is charged in the intermittent oscillation driving state. 2. The power supply device according to claim 1, wherein a driving value of the switching element is controlled by comparing a detected value of a supply voltage to a load with a reference value. 3. The switching device according to claim 1, further comprising: a stop unit for stopping driving of the switching element, wherein the control unit controls the stop period to repeat the oscillation drive and stop of the primary winding of the output transformer. 2. The power supply device according to 2. 4. The power supply device according to claim 1, further comprising detection means for detecting a remaining capacity of the storage battery, and charging the storage battery when the remaining capacity falls below a predetermined value. 5. A switching device for switching between a continuous oscillation mode using a switching element, an intermittent oscillation mode using the switching element, and an oscillation stop mode, wherein the remaining capacity of the storage battery is reduced while the storage battery is operating in the oscillation stop mode. 5. The power supply device according to claim 4, wherein the storage battery is charged in the intermittent oscillation mode when the voltage falls below a predetermined value, and the oscillation stop mode is set when the remaining capacity of the storage battery reaches the predetermined value. 6. The power supply device according to claim 3, wherein a driving stop period of the switching element is controlled by a control signal from a main unit in which storage contents are held by a storage battery. 7. The power supply device according to claim 6, wherein the control signal is a signal converted into an analog signal by a D / A converter of the main device. 8. A storage battery and an output transformer whose primary winding is oscillated by a switching element to generate an AC in a secondary winding, and rectifies the AC generated in a secondary winding of the output transformer. Controlling the power supply device to supply the load to the load, wherein the storage battery is charged in an intermittent oscillation drive state in which the oscillation drive of the primary winding of the output transformer is intermittent. . 9. The control method for a power supply device according to claim 8, wherein a driving value of the switching element is controlled by comparing a detected value of a supply voltage to the load with a reference value. 10. The control method according to claim 8, wherein the drive stop period of the switching element is controlled to repeat the oscillation drive and stop of the primary winding of the output transformer. 11. The control method according to claim 8, wherein the remaining capacity of the storage battery is detected, and the storage battery is charged when the remaining capacity falls below a predetermined value. . 12. A continuous oscillation mode using a switching element, an intermittent oscillation mode using the switching element, and an oscillation stop mode are switched by a control signal, and when the storage battery is operating in the oscillation stop mode, the remaining capacity of the storage battery becomes a predetermined value. 12. The control method for a power supply device according to claim 11, wherein the storage battery is charged in an intermittent oscillation mode when the battery power drops further, and the oscillation stop mode is set when the remaining capacity of the storage battery reaches a predetermined value. . 13. The driving stop period of a switching element is controlled by a control signal from a main unit in which storage contents are held by a storage battery.
13. The method for controlling a power supply device according to any one of 0 to 12. 14. The control method for a power supply device according to claim 13, wherein a drive stop period of the switching element is controlled by a control signal converted into an analog signal by a D / A converter of the main unit. .