JPH09252575A - Power supply circuit - Google Patents

Abstract

(57) Abstract: A power supply circuit capable of reducing power consumption of a power supply is provided. A power supply circuit includes a main power supply circuit 2, a start switch 10 and an auxiliary power supply control circuit. When the starting switch 10 is off, the current flowing through the resistor 22 does not flow to the starting switch 10 but to the light emitting diode 45 of the photocoupler 44 and to the base of the transistor 12. As a result, the transistor 12 is turned on and the transistor 1
4 base current is pulled to the collector side of transistor 12. Therefore, the transistor 14 does not operate. When the start switch 10 is on, the current flowing through the resistor 22 does not flow to the light emitting diode 45 of the photocoupler 44, but flows through the start switch 10 to the ground. Therefore, the base current of the transistor 14 is not pulled by the transistor 12, and the transistor 14 operates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for supplying electric power of a power supply to a load.

[0002]

2. Description of the Related Art The use of a DC / DC converter as a power supply circuit for an electric vehicle such as an electric vehicle or an electric scooter has been studied.

A self-excited DC / DC converter automatically starts oscillating when it is electrically connected to a battery (power source) and always operates as long as it is connected to the battery.

The separately excited DC / DC converter is
It has a dedicated IC for controlling its oscillation. The separately-excited DC / DC converter is also the self-excited DC.
Similar to the / DC converter, when it is electrically connected to the battery, the dedicated IC starts oscillating and always drives as long as it is connected to the battery.

Therefore, it is difficult to use a DC / DC converter, particularly a self-excited DC / DC converter, as the power supply circuit.

[0006] For example, in an electric vehicle, when the key switch is off, electric power is not supplied to the motor. However, as described above, the DC / DC converter is irrespective of whether the key switch is on or off. Is driven (oscillation)
However, this consumes the battery power.

Further, in the conventional power supply circuit, there is a problem that over discharge is likely to occur. If the battery is over-discharged, the battery may deteriorate, and a predetermined voltage may not be obtained even if it is recharged, or the battery may become unusable.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply circuit which can reduce the power consumption of the power supply.

[0009]

This and other objects are achieved by the present invention which is defined below as (1) to (8).

(1) A power supply circuit having a DC / DC converter and a start switch for supplying electric power from a power supply to a load, wherein the voltage of the power supply is applied to the DC / DC converter. In the state, when the start switch is turned on, driving of the DC / DC converter is permitted, and when the start switch is turned off,
A power supply circuit characterized in that driving of the DC / DC converter is prohibited.

(2) A DC / DC converter that includes at least a first switching element and is driven by the operation of the first switching element, a second switching element that controls the operation of the first switching element, and a starter. A power supply circuit for supplying electric power of a power supply to a load, the switch being on when the voltage of the power supply is applied to the DC / DC converter. , The second switching element is turned off, whereby the operation of the first switching element is permitted, and when the start switch is turned off, the second switching element is turned on, whereby the second switching element is turned on. A power supply circuit characterized in that the operation of the first switching element is prohibited.

(3) The first switching element is
A transistor, and the second switching element is
The power supply circuit according to (2) above, which controls the supply of a base current of the first switching element.

(4) The power supply circuit according to any one of (1) to (3), wherein the DC / DC converter is a self-excited type.

(5) The power source voltage detecting means for detecting the voltage of the power source is provided, and the driving of the DC / DC converter is prohibited when the voltage of the power source is lower than a reference voltage. The power supply circuit according to any one of 1) to (4).

(6) A power supply voltage detecting means for detecting the voltage of the power supply and a holding means for holding the state in which the driving of the DC / DC converter is prohibited are provided, and the voltage of the power supply is higher than the reference voltage. When it becomes small, the DC / D
The power supply circuit according to any one of (1) to (4), wherein the driving of the C converter is prohibited, and the driving prohibition state is held by the holding means.

(7) The power supply circuit according to (6), wherein the holding means releases the holding of the drive prohibited state when the start switch is switched.

(8) An accessory power supply circuit for supplying power to the accessory, and an accessory power supply control circuit for controlling the accessory power supply circuit to interlock with the DC / DC converter. The power supply circuit according to any one of (1) to (7).

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The power supply circuit of the present invention will now be described in detail with reference to the preferred embodiments shown in the accompanying drawings.

FIG. 1 is a block diagram showing a configuration example in which the power supply circuit of the present invention is applied to a power supply circuit of an electric scooter.

As shown in FIG. 1, the power supply circuit 1 includes a main power supply circuit 2, a start switch (key switch) 10 provided in the main power supply circuit 2, an auxiliary power supply control circuit 3, and an auxiliary machine. Power supply circuit 5. The start switch 10 is
When the key of the electric scooter is rotated in a predetermined direction, it is turned on (contact is closed), and when it is rotated in the opposite direction, it is turned off (contact is opened).

At the input terminals (input terminals of the main power supply circuit 2) A and B of the power supply circuit 1, the voltage V ₁ is an ideal voltage (maximum voltage).
DC power supply (battery) 4 to be the main circuit switch 4
0. That is, the positive side of the DC power source 4 is connected to the input terminal A via the main circuit switch 40, and the negative side (ground side) of the DC power source 4 is connected to the input terminal B, whereby the DC power source is connected. The voltage of 4 is applied between the input terminals A and B. In this case, the "ideal voltage of the DC power supply 4" refers to the voltage of the DC power supply 4 when the DC power supply 4 is completely charged.

The voltage V ₁ of the DC power source 4 is not particularly limited, but in this embodiment, the voltage V ₁ is 48V.

An input side of the control / driver circuit 6 and an input side of the auxiliary power supply control circuit 3 are connected to the output terminals C and D, respectively. In this case, the output terminal C is on the positive side and the output terminal D is on the negative side (ground side).

The control / driver circuit 6 is composed of an inverter drive circuit, an inverter control circuit, a power supply output monitoring circuit for auxiliary machinery (all not shown), and the like.

The control / driver circuit 6 includes an inverter 15 for driving a motor (load) 7 and the motor 7
The output side of the magnetic pole detector 16 for detecting the magnetic pole position of the rotor is connected to the accelerator 60, respectively.

An auxiliary machine 8 is connected to the output side of the auxiliary machine power supply circuit 5.

As the auxiliary machine 8, for example, a headlight,
Brake lamps, blinkers, buzzers and the like are included.

Before describing the power supply circuit 1, the main operation of the electric scooter related to the power supply circuit 1 will be briefly described.

As shown in FIG. 1, when the main circuit switch 40 is off, the voltage of the DC power supply 4 is not applied to the main power supply circuit 2, the auxiliary machine power supply circuit 5 and the inverter 15, and the main circuit When the switch 40 is on, the voltage of the DC power supply 4 is applied to the main power supply circuit 2, the auxiliary power supply circuit 5, and the inverter 15.

When the main circuit switch 40 is turned on and the start switch 10 is turned on (DC power supply 4
The voltage of the DC power supply 4 is stepped down by the main power supply circuit 2, and the control / driver circuit 6 and the auxiliary equipment power supply control circuit 3 are supplied from the main power supply circuit 2 as will be described later. Applied to each.

The control / driver circuit 6 includes an inverter 15
Power is supplied from the DC power supply 4 to the motor 7 via the, and the drive of the motor 7 is controlled.

That is, the inverter control circuit (not shown) of the control / driver circuit 6 operates based on the signals from the accelerator 60 and the signal from the magnetic pole detector 16 corresponding to the magnetic pole position of the rotor. Control the drive. At this time, an inverter drive circuit (not shown) drives the gate of the inverter 15. And
By driving the inverter 15, the motor 7 is energized in a predetermined drive pattern (energization pattern) and rotates at a predetermined rotation speed.

In this case, the voltage output from the auxiliary power supply circuit 5 described later is applied to the auxiliary power supply output monitoring circuit (not shown) of the control / driver circuit 6 and detected by the auxiliary power supply output monitoring circuit. (Monitored). Then, the control / driver circuit 6 permits the driving of the motor 7 only when the voltage detected by the power supply output monitoring circuit for auxiliary machinery is equal to or higher than a predetermined value.

The auxiliary machine power supply circuit 5 is adapted to interlock with the main power supply circuit 2 by the auxiliary machine power supply control circuit 3. That is, when the main power supply circuit 2 drives (rises), the auxiliary power supply circuit 5 drives (rises), and when the main power supply circuit 2 stops, the auxiliary power supply circuit 5 stops.
This point will be described later in detail.

When the accessory power supply circuit 5 starts up, the voltage of the DC power supply 4 is stepped down by the accessory power supply circuit 5 and applied from the accessory power supply circuit 5 to the accessory 8. As a result, the auxiliary machine 8
Can be driven (lighting, blinking, sounding, etc.).

Next, the power supply circuit 1 will be described.

2 and 3 (FIG. 3 is a continuation of FIG. 2),
2 is a circuit diagram showing a configuration example of a main power supply circuit 2 shown in FIG. 1. FIG.

As shown in these figures, the main power supply circuit 2
Is a one-stone self-excited DC / DC converter (ringing choke converter (RCC)) 9, a Zener diode 31, a transistor 11, a transistor (second switching element) 12, a photocoupler 41,
44 and a noise removing capacitor 71. Hereinafter, the "one-stone self-exciting DC / DC converter" is simply referred to as "DC / DC converter".

As the Zener diode 31, a Zener voltage (breakdown voltage) having substantially the same value as a preset reference voltage (discharge end voltage) V ₀ is used.

That is, when the voltage of the DC power supply 4 (the voltage applied between the DC power supply 4 and the input terminals A and B) is equal to or higher than the reference voltage V ₀ , the Zener diode 31 supplies a Zener current (reverse current). And if the reference voltage is less than V ₀ ,
It is designed not to pass the Zener current.

The reference voltage V ₀ is preferably set so that the DC power source 4 will not be over-discharged.

That is, the reference voltage V ₀ is preferably about 60 to 85% of the ideal voltage V ₁ of the DC power supply 4.

If the reference voltage V ₀ is higher than the upper limit, the voltage of the DC power supply 4 becomes relatively lower than the reference voltage V ₀ and the main power supply circuit 2 is stopped relatively quickly depending on the type of the DC power supply 4 and the condition of use. In some cases, the electric power of the DC power supply 4 cannot be fully utilized.

If the reference voltage V ₀ is smaller than the lower limit, the DC power supply 4 may be over-discharged and the DC power supply 4 may be deteriorated depending on the type of the DC power supply 4 and the usage condition.

In this embodiment, the reference voltage V ₀ is 3
It is set to 0V.

Here, the Zener diode 31 constitutes a power supply voltage detecting means for detecting the voltage of the DC power supply 4.

The DC / DC converter 9 includes the primary coil 6
2, a transformer 61 having a drive coil 63, secondary coils 64 and 65.

In this transformer 61, the drive coil 63 and the secondary coil 64 are determined according to the number of turns of the primary coil 62.
Step-down transformer (step-down transformer) with fewer turns of 65 turns
Is used.

The winding start of each coil of the transformer 61 is T1 side in the primary coil 62, and T in the drive coil 63.
In the 7 side, the secondary coils 64 and 65, respectively, T3
And T4 side.

The DC / DC converter 9 has a transistor 13, a transistor (first switching element) 14, resistors 23, 24 and 25, and a capacitor 7 on the primary side.
2 and 73.

The oscillation frequency of the DC / DC converter 9 is determined by the resistors 23, 24 and 25, the capacitors 72 and 73, the input voltage, the size (size) of the load, and the like.

The transistors 13 and 14 of the DC / DC converter 9 and the transistors 11 and 12 are used.
As each of them, for example, a bipolar transistor, a field effect transistor (FET) or the like can be used.

The DC / DC converter 9 has a rectifying diode 33, a photocoupler 47, a shunt regulator (variable shunt regulator) 81, and a rectifier diode 33 on the secondary side.
Resistors 27 and 28 and a capacitor 74 for removing noise
And a smoothing circuit 90 including a choke coil (inductor) 91 and electrolytic capacitors 92 and 93.

In this case, the minimum value of the voltage applied to the shunt regulator 81, that is, the breakdown voltage between the cathode and the anode of the shunt regulator 81, due to the current flowing from the cathode of the shunt regulator 81 to the anode by the resistors 27 and 28. Determined.

In this embodiment, the resistors 27 and 28 are set so that the breakdown voltage between the cathode and the anode of the shunt regulator 81 is 15V.

FIG. 4 shows the auxiliary equipment power supply control circuit 3 shown in FIG.
FIG. 3 is a block diagram illustrating a configuration example of FIG.

As shown in the figure, the auxiliary equipment power supply control circuit 3
Is a step-down means 30 for stepping down the voltage, and this step-down means 30
It is composed of a resistor 29 and a photomoss switch 51 connected to the output side of the. The MOSFET 53 of the photo-MOS switch 51 functions as a switch of the auxiliary machine power supply circuit 5.

By the way, with the photo-MOS switch 51,
The main power supply circuit 2 side and the auxiliary power supply circuit 5 side are electrically disconnected.

The auxiliary power supply circuit 5 has a separately excited DC / DC converter (not shown). This DC / DC converter is a MOSFET of the photomos switch 51.
When 53 is turned on, it is driven, and when it is turned off, it is stopped.

Next, the operation of the power supply circuit 1 will be described. The description when the main circuit switch 40 is off is omitted, and only the case where the main circuit switch 40 is on will be described.

Operation by Turning ON / OFF the Start Switch 10 As shown in FIG. 2, when the start switch 10 of the power supply circuit 1 is OFF, the current flowing through the resistor 22 can flow to the start switch 10. Instead, it flows to the light emitting diode 45 of the photocoupler 44. This current flows from the anode of the light-emitting diode 45 to the cathode of the transistor 1
Pour into the base of 2.

As a result, the transistor 12 turns on (holds the on state), a current flows from the collector of the transistor 12 to the emitter, and the base current of the transistor 14 is pulled to the collector side of the transistor 12. That is, the current flowing through the resistor 23 does not flow to the base of the transistor 14 but flows from the collector of the transistor 12 to the emitter of the transistor 12 and then to the ground (minus side of the power supply 4).

Therefore, the transistor 14 does not operate (switch) (is prohibited). That is, D
Driving (oscillation) of the C / DC converter 9 is prohibited.

Even when the start switch 10 is turned off while the DC / DC converter 9 is being driven, as described above, the current flowing through the resistor 23 flows from the collector of the transistor 12 to the emitter and the ground. Flow to. Then, the voltage generated in the drive coil 63, that is, the current flowing from the drive coil 63 into the base of the transistor 14 also becomes
It is pulled to the ground at the base end of the transistor 14.

Therefore, the DC / DC converter 9 immediately stops driving.

When the start switch 10 of the power supply circuit 1 is turned on, the current flowing through the resistor 22 is the photo coupler 4
4 does not flow to the light emitting diode 45, and the start switch 10
To flow to the ground.

Therefore, since no current flows through the base of the transistor 12, the transistor 12 holds the off state. Therefore, the current flowing through the resistor 23 is not pulled to the transistor 12 side, and
It flows into the base of 4.

Therefore, the transistor 14 is activated (permitted to activate). That is, driving of the DC / DC converter 9 is permitted.

The operation of driving the DC / DC converter 9 will be described below.

As shown in FIG. 2, first, the current flowing through the resistor 23 flows into the base of the transistor 14 and the transistor 14 becomes conductive. As a result, a voltage is applied to the primary coil 62 of the transformer 61.

As described above, the winding start of each coil of the transformer 61 is T1 side in the primary coil 62, T7 side in the drive coil 63, T3 side in the secondary coils 64 and 65, respectively. And T4 side.

Since the drive coil 63 is wound in the same direction as the primary coil 62, a voltage having the same polarity as that of the primary coil 62 is generated in the drive coil 63. This voltage is a positive feedback voltage that makes the transistor 14 more conductive.

Due to the positive feedback voltage generated in the drive coil 63, a differential wave-shaped current attenuated by the time constant of the capacitor 73 and the resistor 25 flows into the base of the transistor 14 and the transistor 14 is rapidly turned on ( Saturates). At this time, the voltage of the primary coil 62 becomes the input voltage (V _IN ) -the collector-emitter voltage (V _CE ) of the transistor 14.

In this case, since the polarities of the voltages of the secondary coils 64 and 65 are opposite to the rectifier diode 33 (see FIG. 3), no current flows through the secondary coils 64 and 65. Therefore, the current flowing through the primary coil 62 is
There is only one exciting current (I _C ).

The exciting current (I
_C ), that is, the collector current of the transistor 14 is
Increases almost in proportion to time.

When the collector current of the transistor 14 increases and it becomes impossible to maintain the saturation of the transistor 14, the transistor 14 goes out of saturation, and the collector-emitter voltage (V _CE ) of the transistor 14 increases, which causes the saturation. The voltage of the primary coil 62 drops.

When the voltage of the primary coil 62 decreases, the voltage of the drive coil 63 also decreases, which further increases the collector-emitter voltage (V _CE ) of the transistor 14. Since this operation is also positively fed back, the transistor 14 is turned off rapidly.

When the transistor 14 is turned off, the polarities of the voltages of the secondary coils 64 and 65 are in the forward direction with respect to the rectifying diode 33 (see FIG. 3).
3 becomes conductive, and T5 and T6 of the secondary coils 64 and 65 to T
A current (secondary current) flows in the direction of 3 and T4. The energy flowing in the rectifier diode 33 causes the energy stored in the transformer 61 to be supplied to the output side.

The current flowing through the rectifier diode 33 decreases at a predetermined speed, and when all the energy stored in the transformer 61 is supplied to the output side, the current becomes
It becomes 0, and the rectifying diode 33 is turned off.

At this moment, the voltage of each coil of the transformer 61 becomes 0, and again, as described above, the resistance 2
The current flowing through the transistor 3 makes the transistor 14 conductive.

Thereafter, the same operation as described above is repeated, and D
The oscillation of the C / DC converter 9 is maintained.

As described above, when the DC / DC converter 9 is driven, the voltage (electric power) applied between the input terminals A and B is changed from the primary side to the secondary side by the action of the transformer 61. It is stepped down and transmitted.

Then, as shown in FIG. 3, the secondary coil 6
As described above, the AC voltage generated in the Nos. 4 and 65 is applied to the rectifying diode 33, and by the rectifying diode 33,
It is rectified and further smoothed by the smoothing circuit 90.

As shown in FIG. 1, this DC voltage is output from the output terminals C and D and applied to the control / driver circuit 6 and the auxiliary power supply control circuit 3, respectively. As a result, the control / driver circuit 6 can be driven, and when the control / driver circuit 6 drives the inverter 15,
Electric power is supplied from the DC power supply 4 to the motor 7.

Here, as shown in FIG. 3, the voltage on the secondary side of the DC / DC converter 9 has a predetermined value (15 in this embodiment).
V) or less, no current flows through the shunt regulator 81.

When the voltage on the secondary side of the DC / DC converter 9 exceeds a predetermined value, the shunt regulator 81
An electric current flows from the cathode to the anode. That is, the shunt regulator 81 causes a breakdown,
The current of the light emitting diode 48 of the photocoupler 47 is drawn. As a result, a current flows through the resistor 26 from the anode of the light emitting diode 48 to the cathode, and the photocoupler 47
The phototransistor 49 is turned on.

As a result, the current is applied to the drive coil 63.
Flow from the rectifier diode 32 to the rectifier diode 3
2 rectifies, flows from the collector of the phototransistor 49 to the emitter, and flows into the base of the transistor 13.

As a result, as shown in FIG. 2, the transistor 13 becomes conductive, current flows from the collector to the emitter of the transistor 13, and the base current of the transistor 14 decreases.

In this case, as the voltage on the secondary side of the DC / DC converter 9 is higher, the collector current of the transistor 13 is larger and the base current of the transistor 14 is smaller.

As a result, the DC / DC converter 9 2
The voltage on the secondary side, that is, the voltage output from the main power supply circuit 2 decreases to a predetermined value, and a constant output voltage is obtained.

The transistor 13 during such constant voltage control is in the active region, and the transistor 1
A variable resistance is provided between the collector and the emitter of No. 3.

When the voltage on the secondary side of the DC / DC converter 9 is extremely high, the base current of the transistor 14 becomes almost 0, and thus the transistor 14 has a base current.
Temporarily turns off (for a moment) and stops its operation. Then, when the voltage on the secondary side of the DC / DC converter 9 returns to a predetermined value, no current flows in the shunt regulator 81, so the transistor 14 starts operating again.

Protection and Latching Operation of DC Power Source 4 As shown in FIG. 2, when the voltage between the input terminals A and B is equal to or higher than the reference voltage V ₀ (30 V in this embodiment), the Zener diode 31 passes through the resistor 20. Zener current flows from the cathode to the anode. This current is applied to the transistor 11
Flows into the base of the transistor 11 and turns on the transistor 11.

Therefore, the current flowing through the resistor 21 does not flow to the light emitting diode 42 of the photocoupler 41, but flows from the collector of the transistor 11 to the emitter thereof, and then to the ground.

Therefore, as long as the start switch 10 is on, no current flows through the base of the transistor 12, so that the transistor 12 is kept off. Therefore, the current flowing through the resistor 23 flows into the base of the transistor 14 without being pulled toward the transistor 12 side.

Therefore, the transistor 14 is activated.
That is, driving of the DC / DC converter 9 is permitted.

When the voltage between the input terminals A and B is smaller than the reference voltage V ₀ , the Zener current does not flow in the Zener diode 31. That is, since no current flows into the base of the transistor 11, the transistor 11 is turned off.

Therefore, the current flowing through the resistor 21 flows to the light emitting diode 42 of the photocoupler 41. This current is
It flows from the anode of the light emitting diode 42 to the cathode, and flows into the base of the transistor 12.

As a result, the transistor 12 is turned on,
A current flows from the collector to the emitter of the transistor 12, and the base current of the transistor 14 changes to the transistor 12.
Pulled to the collector side of. That is, the current flowing through the resistor 23 does not flow to the base of the transistor 14, but flows from the collector of the transistor 12 to the emitter of the transistor 12, and then to the ground.

Therefore, the transistor 14 does not operate. That is, driving of the DC / DC converter 9 is prohibited.

On the other hand, when a current flows from the anode of the light emitting diode 42 to the cathode thereof, the phototransistor 43 of the photocoupler 41 is turned on, and the phototransistor 43 pulls the base current of the transistor 11 to the ground.

That is, as long as the current flows from the anode to the cathode of the light emitting diode 42 of the photocoupler 41, the voltage between the input terminals A and B becomes the reference voltage V ₀ or more, and the Zener current flows in the Zener diode 31. However, this current does not flow into the base of the transistor 11 and is pulled to the ground by the phototransistor 43 of the photocoupler 41.

Therefore, the transistor 11 is held in the off state, and as a result, the transistor 14 is also held in the off state as described above. That is, DC / DC
The drive prohibited state of converter 9 is held.

Therefore, the photo coupler 41 and the transistor 11 constitute a holding means for holding the state in which the driving of the DC / DC converter 9 is prohibited.

Here, the fact that the voltage between the input terminals A and B is smaller than the reference voltage V ₀ means that the remaining amount of power of the DC power supply 4 is small, but in such a case, as described above. Since the driving of the DC / DC converter 9 is prohibited, the power of the DC power supply 4 is prevented from being consumed any more, and thus the DC power supply 4 is protected.

When the voltage between the input terminals A and B is smaller than the reference voltage V ₀ , the start switch 10 is turned on and D
Since the C / DC converter 9 does not drive,
It can be recognized that the DC power supply 4 should be charged.

Reset Operation As shown in FIG. 2, when the starter switch 10 switches from on to off when the transistor 11 is held in the off state, the current flowing through the resistor 22 is as described above. The light flows from the anode of the light emitting diode 45 of the photocoupler 44 to the cathode thereof, which turns on the phototransistor 46 of the photocoupler 44.

Therefore, the current flowing through the light emitting diode 42 of the photocoupler 41 is bypassed by the phototransistor 46. That is, the current flowing through the resistor 21 does not flow to the light emitting diode 42 of the photocoupler 41,
It flows to the phototransistor 46 of the photocoupler 44.

Therefore, the phototransistor 43 of the photocoupler 41 is turned off (the photocoupler 41 is reset), and the phototransistor 43 prevents the base current of the transistor 11 from being pulled.

However, when the voltage between the input terminals A and B is smaller than the reference voltage V _0, even if the start switch 10 is turned on after the reset, the operation described above is only repeated and DC / The DC converter 9 is not driven.

However, when the DC power supply 4 is charged and the voltage between the input terminals A and B becomes equal to or higher than the reference voltage V ₀ , a Zener current flows through the Zener diode 31, and this current flows into the base of the transistor 11, This turns on the transistor 11.

When the starting switch 10 is turned on in such a state, no current flows through the light emitting diode 45 of the photocoupler 44, and the phototransistor 46 is turned off.
The current flowing through the resistor 21 does not flow to the light emitting diode 42 of the photocoupler 41, but flows from the collector of the transistor 11 to the emitter thereof, and then to the ground.

Therefore, as described above, the transistor 12 is turned off, which causes the transistor 14 to
Operate. That is, driving of the DC / DC converter 9 is permitted.

Operation of Auxiliary Machinery Power Supply Control Circuit 3 As shown in FIG. 1, the main power supply circuit 2, that is, DC / D
When the C converter 9 is driven, a DC voltage is applied to the auxiliary power supply control circuit 3 from the output terminals C and D of the main power supply circuit 2.

Then, the main power supply circuit 2, that is, DC /
When the DC converter 9 is stopped, no DC voltage is applied to the accessory power supply control circuit 3.

As shown in FIG. 4, the auxiliary power supply control circuit 3
When a voltage is applied to the step-down means 30 of FIG. 1, this voltage is stepped down by the step-down means 30 and applied to the light emitting diode 52 of the photomos switch 51.

As a result, a current flows from the anode of the light emitting diode 52 to the cathode through the resistor 29, and the MOSFET 53 of the photomos switch 51 is turned on. That is, as shown in FIG. 1, the contacts of the power supply circuit 5 for auxiliary machinery are closed (the output terminals E and F are conducted).

Here, a voltage is applied between the source and drain of the MOSFET 53 from the DC power supply 4 via the auxiliary power supply circuit 5 and the output terminals E and F.

Therefore, when the MOSFET 53 is turned on,
A current flows between the source and the drain of the MOSFET 53, that is, the auxiliary power supply circuit 5, and this current becomes a signal for driving the auxiliary power supply circuit 5, and the auxiliary power supply circuit 5 is driven. Therefore, the voltage is applied from the power supply circuit 5 for the auxiliary machine to the auxiliary machine 8 to supply the electric power.

On the other hand, as shown in FIG. 4, when the voltage is not applied to the step-down means 30 of the auxiliary machine power supply control circuit 3, the MOSFET 53 of the photomos switch 51 is off, so the source of this MOSFET 53 is turned off. -No current flows between the drains.

Therefore, the accessory power supply circuit 5 is not driven, and no voltage is applied from the accessory power supply circuit 5 to the accessory 8.

Therefore, the power consumption of the DC power source 4 due to the driving of the auxiliary machine 8 and the auxiliary machine power supply circuit 5 is prevented.

As described above, the power supply circuit 1 of this embodiment
According to the above, the drive of the self-excited DC / DC converter 9 can be controlled by switching the start switch 10.

Therefore, even when the main circuit switch 40 is on, by turning off the start switch 10, the main power supply circuit 2, that is, the DC / DC converter 9 is turned on.
The power consumption of the DC power supply 4 can be reduced.

The power supply circuit 1 has a small number of parts, has a simple circuit structure, and is advantageous in downsizing. Further, cost can be reduced.

Further, according to the power supply circuit 1, when the voltage of the DC power supply 4 becomes lower than the reference voltage V ₀ , the main power supply circuit 2,
That is, since the DC / DC converter 9 is stopped, it is possible to prevent the DC power supply 4 from being over-discharged.

In this case, it is not necessary to separately provide a power source or the like for detecting the voltage of the DC power source 4. Therefore, the number of parts is small and the circuit configuration is simple.

Further, the power supply circuit 1 has a latch function for holding the drive prohibition state (stop state) of the DC / DC converter 9 when the voltage of the DC power supply 4 becomes lower than the reference voltage V ₀ , and the start switch 10. Since it has a reset function to release it when it is turned off, it is highly safe. Further, it is possible to reliably prevent the DC power supply 4 from being over-discharged, and thus to prevent the DC power supply 4 from being deteriorated.

For example, when the latch function is not provided,
When the voltage of the DC power supply becomes lower than the reference voltage V ₀ , DC /
Even if the DC converter temporarily stops, the DC / DC converter starts driving immediately after the voltage of the DC power supply returns to the reference voltage V ₀ , and the power of the DC power supply is consumed again. In this case, the voltage of the DC power supply drops rapidly, unlike when it is completely charged, so driving and stopping of the DC / DC converter are repeated in the vicinity of the reference voltage V _0. Although the power supply may be deteriorated, in the power supply circuit 1 of the present embodiment, the DC / DC converter 9 is kept in the drive-inhibited state by the latch function as described above. Deterioration due to over-discharging of the power supply 4 is reliably prevented.

As compared with the case where the above-mentioned latch operation or reset operation is performed by using a relay or the like, the structure is simple and it is advantageous for downsizing, and it is strong against vibration and shock.
High reliability.

Further, the power supply circuit 1 has a power supply control circuit 3 for an auxiliary machine, and by this power supply control circuit 3 for an auxiliary machine, the power supply circuit 5 for an auxiliary machine is a main power supply circuit 2, that is, DC / D
Since it is linked to the C converter 9, the operation can be simplified and the drive of the accessory power supply circuit 5 can be controlled appropriately and reliably.

For example, even when the main circuit switch 40 is on, by turning off the start switch 10,
The auxiliary power supply circuit 5 can be stopped in conjunction with the main power supply circuit 2, whereby power consumption in the auxiliary power supply circuit 5 can be prevented and a switch for driving the auxiliary 8 It is possible to prevent power consumption in the auxiliary machine 8 due to forgetting to turn off the power. Further, it is possible to prevent the DC power supply 4 from being over-discharged due to the power consumption of the auxiliary machine 8 and the auxiliary machine power supply circuit 5.

As compared with the case where the auxiliary power supply circuit 5 is interlocked with the main power supply circuit 2 by using a relay or the like, the structure is simple and advantageous for downsizing, and it is strong against vibration and shock and reliable. It is highly likely.

The power supply circuit of the present invention is not limited to the power supply circuit of the electric scooter described above, but other than this, for example, an electric vehicle,
It is applied to the power circuit of other devices such as electric vehicles such as forklifts, electric bicycles, notebook computers, etc. that have a built-in power supply (battery).

The power supply circuit of the present invention has been described above based on the illustrated configuration example, but the present invention is not limited to this.

For example, in the above-mentioned embodiment, the one-stone self-exciting DC / DC converter is used as the DC / DC converter, but the DC / DC converter used in the present invention is not limited to this. In the present invention, for example, various self-excited DC / DC converters and various other-excited DC / DC converters may be used.

Further, in the present embodiment, the step-down transformer is used as the transformer of the DC / DC converter, but the present invention is not limited to this, and, for example, a step-up transformer or an insulation transformer. Etc. may be used.

[0138]

As described above, according to the power supply circuit of the present invention, by switching the start switch, DC / DC
Since the drive of the converter can be controlled, the power consumption of the power supply can be reduced.

The power supply circuit of the present invention, in particular, when the start switch is on, the second switching element is turned off, whereby the operation of the first switching element is permitted, and the start switch is turned off. In the case where the second switching element is turned on while the second switching element is on, and the operation of the first switching element is prohibited by this, the circuit configuration is simple and advantageous for downsizing.

Further, in the power supply circuit of the present invention provided with the self-excited DC / DC converter, there is no need to provide a dedicated IC or a complicated circuit for controlling the oscillation, unlike the separately excited DC / DC converter. Since the drive of the DC / DC converter can be controlled, the circuit configuration is simple and the cost can be reduced.

Further, when the power supply voltage detecting means for detecting the voltage of the power supply is provided and the driving of the DC / DC converter is prohibited when the voltage of the power supply is lower than the reference voltage, in particular, DC / DC converter When the holding means for holding the state in which the driving of the DC converter is prohibited is provided, it is possible to prevent the power supply from being over-discharged, and thus to prevent the power supply from being deteriorated.

Further, when the auxiliary power supply circuit has an auxiliary power supply control circuit for controlling the DC / DC converter to interlock, the auxiliary power supply circuit can be driven (start / stop) properly and reliably. ) Can be controlled.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example when a power supply circuit of the present invention is applied to a power supply circuit of an electric scooter.

FIG. 2 is a circuit diagram showing a configuration example of a main power supply circuit shown in FIG.

3 is a circuit diagram (continuation of FIG. 2) showing a configuration example of a main power supply circuit shown in FIG.

FIG. 4 is a block diagram showing a configuration example of an auxiliary power supply control circuit shown in FIG.

[Explanation of symbols]

 1 Power Supply Circuit 2 Main Power Supply Circuit 3 Power Supply Control Circuit for Auxiliary Machine 30 Step-Down Means 4 DC Power Supply 40 Main Circuit Switch 5 Power Supply Circuit for Auxiliary Machine 6 Control and Driver Circuit 60 Accelerator 7 Motor 8 Auxiliary Machine 9 DC / DC Converter 10 Start Switch 11-14 Transistor 15 Inverter 16 Magnetic pole detector 20-29 Resistor 31 Zener diode 32, 33 Rectifying diode 41, 44, 47 Photocoupler 42, 45, 48 Light emitting diode 43, 46, 49 Phototransistor 51 Photomos switch 52 Light emitting diode 53 MOSFET 61 Transformer 62 Primary coil 63 Drive coil 64, 65 Secondary coil 71-74 Capacitor 81 Shunt regulator 90 Smoothing circuit 91 Choke coil 92, 93 Electrolytic capacitor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H03K 17/22 H03K 17/22 B 17/30 17/30 Z

Claims (8)

[Claims] 1. A power supply circuit having a DC / DC converter and a start switch for supplying electric power from a power supply to a load, wherein the voltage of the power supply is applied to the DC / DC converter. If the start switch is turned on, the drive of the DC / DC converter is permitted, and if the start switch is turned off, the DC / DC converter is turned on.
A power supply circuit characterized by being configured so that driving of a converter is prohibited. 2. A D comprising at least a first switching element and driven by the operation of the first switching element.
A power supply circuit having a C / DC converter, a second switching element for controlling the operation of the first switching element, and a start switch, the power supply circuit for supplying the power of the power supply to a load, the voltage of the power supply. Is applied to the DC / DC converter, and the start switch is on, the second switching element is turned off, whereby the operation of the first switching element is permitted, and A power supply circuit, characterized in that, when the start switch is off, the second switching element is turned on, thereby inhibiting the operation of the first switching element. 3. The power supply circuit according to claim 2, wherein the first switching element is a transistor, and the second switching element controls supply of a base current of the first switching element. . 4. The power supply circuit according to claim 1, wherein the DC / DC converter is a self-excited type. 5. A power supply voltage detecting means for detecting a voltage of the power supply, wherein when the voltage of the power supply is lower than a reference voltage, the D
The power supply circuit according to claim 1, wherein the driving of the C / DC converter is prohibited. 6. A power supply voltage detecting means for detecting a voltage of the power supply, and a holding means for holding a state in which driving of the DC / DC converter is prohibited, wherein the voltage of the power supply is smaller than a reference voltage. The power supply circuit according to any one of claims 1 to 4, wherein the drive of the DC / DC converter is prohibited when this occurs, and the drive prohibition state is held by the holding means. 7. The power supply circuit according to claim 6, wherein the holding means releases the holding of the drive prohibited state when the start switch is switched. 8. An accessory power supply circuit for supplying electric power to the accessory, and an accessory power supply control circuit for controlling the accessory power supply circuit to interlock with the DC / DC converter. The power supply circuit according to any one of 1 to 7.