JPH02118708A - Dc power unit - Google Patents

Abstract

PURPOSE:To hold the voltages of double ends in a load constant by connecting in serial a diode for reverse flow prevention, a shunt for load and output current detection between double ends of the serial circuit of two bleeder resistances. CONSTITUTION:The title device is the DC power device executing feeding for th load such as an accumulator, and it is provided with the serial circuit 8 of two bleeder resistances connected between both output terminals of an output side rectifier circuit 5, the diode for reverse flow prevention connected in serial between double ends of the serial circuit 8, the load, the shunt 9 for load and output current detection and an invertor control part. Thus, the voltage-drop of the shunt 9 due to the fluctuation of the output current and the forward direction voltage drop of the diode 10 are cancelled and the fluctuation of the double voltages of the load due to the fluctuation of the output current is controlled in the close circuit of the serial circuit 8 of double voltage-dividing resistances 8a and 8b, the diode 10, the load and the shunt 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DC power supply device that supplies power to a load such as a storage battery.

[Conventional technology]

Generally, a DC power supply device serving as a charging device for charging a storage battery as a load is configured as shown in FIG. 2, for example.

In the figure, (1) is an AC power supply, and (2) is an AC power supply (
(1) an input side rectifier circuit that rectifies the output of (2); (3) an inverter section consisting of a transistor as a switching element connected to the output terminal of the input side rectifier circuit (2); (4)
is an output transformer in which both ends of the primary winding (4a) are connected to the output terminals of the inverter section (3), and (5) is a transformer (4a) connected to the output terminal of the inverter section (3).
), the output side rectifier circuit connected to the secondary winding (4b) of (
6).

(7) is recessed with smoothing glue and capacitor.

It is connected in series between the positive and negative output terminals of the output side rectifier circuit (5).

(8) Series circuit of two voltage dividing resistors (8a) and (8b) connected in parallel to the capacitor (7), (9) is a current-carrying path between the resistor (8b) and the capacitor (7) The output current detection shunt provided in the
) is connected to one end of the backflow prevention diode, aυ is a storage battery as a load, its positive terminal is connected to the cathode of diode 01, and its negative terminal is connected to the other end of resistor (8b) and is grounded. ing.

@ is an error amplifier that amplifies and outputs the error between the detected potential at the connection point (P) of both resistors (8a) and (8b) and the reference potential from the reference power supply Q3, and α is the drive section, and the error amplifier α
] so that the error caused by and the drive unit α constitute an inverter control unit (g).

[Problem to be solved by the invention]

In a conventional DC power supply, the connection point (P) is The detection potential of the diode 0Q is controlled to be constant, and the voltage across the series circuit (8) is always controlled to be constant. However, if the load fluctuation is large, a forward voltage drop due to the internal resistance of the diode 0Q and a voltage drop across the diode 00. Storage battery Q
Due to the voltage drop due to the resistance of the wiring between η, the storage battery aυ
There is a problem that the voltage across the terminal fluctuates greatly.

Therefore, in order to reduce the effects of load fluctuations.

It is considered that a diode 00 is provided in the current-carrying path between the capacitor (7) and the resistor (8a), and a storage battery αυ is connected in parallel to a series circuit of one resistor (8a) and (8b).

This suppresses fluctuations in the voltage across the storage battery αυ due to load fluctuations, but when a common storage battery Q1 is charged by a redundant parallel operation system using multiple DC power supplies, If the series circuit of the voltage dividing resistor is short-circuited, the output voltage of the device becomes Ov, and the output IE voltage of the entire system becomes Ov, causing the inconvenience that the entire system goes down, and the AC power supply (1) is turned off. Sometimes both resistances (8a).

The storage battery θυ ends up being discharged via (8b).

The present invention has been made with the above points in mind, and it is an object of the present invention to make it possible to suppress voltage fluctuations across a load.

[Means to solve the problem]

In order to achieve the above object, the DC power supply device of the present invention includes an input side rectifier circuit that rectifies the output of the AC power supply.

an inverter section including a switching element connected to an output terminal of the input side rectifier circuit; and an output transformer having a primary winding connected to the output terminal of the inverter section.

and an output side rectifier circuit following the secondary winding of the transformer.

A series circuit of two voltage dividing resistors connected between both output terminals of the output (1) rectifier circuit.

A backflow prevention diode, a load, and an output current detection shunt connected in series between both ends of the series circuit.

The inverter control section outputs a control signal to the control terminal of the switching element to control the output of the inverter section so that the detected potential at the connection point of both the resistors becomes equal to the reference potential. .

[For production]

With the above configuration, when the output current fluctuates due to load fluctuations, V is connected to the series circuit of both voltage dividing resistors, the diode, and the closed circuit of the load 1 shunt, and the shunt current due to fluctuations in the output current is applied. The voltage drop across the device and the forward voltage drop across the diode cancel each other out.

Variations in both ends of the load due to variations in the output current are suppressed, and variations in the voltage across the load due to load variations as in the prior art are prevented, and the voltage across the load is held constant.

〔Example〕

An embodiment will be described with reference to FIG.

In FIG. 1, the same symbols as in FIG. 2 indicate the same or equivalent parts, and the points that are different from FIG. 2 are as follows.

This is the point where the output current detection shunt (9) is provided in the energizing path between the negative terminal of the storage battery 0υ and the resistor (8b), and the negative terminal of the storage battery 0υ is grounded.

Note that the resistance value of both resistors (8a) and (8b) is R+
, R2 To L.

The forward voltage drop of diode 00 is Vf, and the shunt (9
), then R+/R2=Vf
The dynamic resistances (8a) and (8b) are selected so that /Vs.

In the configuration shown in FIG. 1, the inverter section (3
) dynamic resistance (8a) due to constant WEE control of the output.

(8b) Potential difference Vd (
= V2-Vs.

(2) Both end chambers 8E) of the resistor (8b) are always kept constant.

At this time, the voltage 8E on the anode side of the diode QQ
vO is determined by the potential at the connection point (P) based on the voltage division ratio of the two resistors (8a) and (8b).

Also, the voltage Vo on the cathode side of the diode αO
' is the value obtained by subtracting the forward voltage drop Vf of diode a0 from the voltage Vo on the anode side, that is, Vo = (Vo - Vf)
becomes.

By the way, due to load fluctuations), the output current I of the device.

When V rapidly decreases, the voltage drop Vs of the first shunt (9) decreases, so feedback control is performed so that the potential difference Vd becomes constant so as to compensate for the decrease in the voltage drop Vs.

At this time, as the voltage drop Vs decreases, the voltage V2 (=Vd +Vs) across the resistor (8b) decreases, and
The voltage across the resistor (8a) Ffl V' t decreases, and the voltage ■0 on the anode side of the diode Q(I decreases, for example, ΔVo, but due to the decrease in the output current ■0, the diode OQ
The forward voltage drop Vf also decreases, for example, by ΔVf, so the voltage rEVO' on the cathode side of the diode αO.

Vo'=(Vo-ΔVo)-(Vf-Δvf)=(
Vo - Vf ) - (ΔVo - ΔVf), and ΔVo - ΔVf becomes 0, and the diode α
Fluctuations in the voltage Vo' on the cathode side of 0 are suppressed.

On the other hand, when the output current Io of the device suddenly increases due to load fluctuation, the voltage drop Vs of the shunt i (9) increases,
As the voltage 2 across the resistor (8b) increases, the resistor (
8a) increases, the voltage on the anode side of the diode α0 increases, and the forward voltage drop Vf of the diode αO also increases due to the increase in output current, so the voltage vo' on the cathode side of the diode 00 increases. Fluctuations are suppressed.

Conditions for suppressing variations in the voltage vo' on the cathode side of the diode aO due to load variations in this manner will be described below.

Dynamic resistance (8a), (8b) t7) Series circuit (8) Oi
ItllEEwoVa.

Assume that the voltage of the reference power supply (to) is Vr, and the resistance of the shunt (9) and the internal resistance of the diode 00 are Rs and Rd, respectively.

The voltage across the resistor (8b) 2 is as follows: V2 = Vs + Vd = Vs + Vr = R, +R2Va =
R, +R2(Vs +Vf +Vo')...■, where Vs = IoRs, Vf = I
oRd, by substituting these into equation
Vo'), and if we organize this.

becomes.

By the way, in formula (■), in order for the relationship between voltage vO' on the cathode side of diode aO and voltage %Vr of reference power supply □□□ to not depend on current Io, if the value in 11 on the left side of formula (■) is zero, then Well, that is.

5 (Rs+Rd) -Rs = O...■ Only needs to hold, and by rearranging the 0 formula, the following relationship is obtained, and by substituting the ■formula into the ■formula, R1+R2 Va = -Vr holds, a 8EVa will depend on 1rEVr.

Therefore, the ratio RI/R2 of one resistor (8a) and (8b)
1 so that the ratio of the internal resistance Rd of the diode αO to the resistance Rs of the shunt (9) is equal to Rd/Rs.
Both resistors (8a).

By selecting (8b), even if there is a fluctuation in the output current Io, the i E Vo on the cathode side of the diode OQ
That is, the voltage across the storage battery q1) can be controlled to be constant by the voltage Vr of the reference power source 04.

In this way, according to the embodiment, even if there is a fluctuation in the output current due to load fluctuation, it is possible to prevent the voltage across the storage battery 0υ, which is the load, from changing, and to maintain the voltage across the storage battery αυ constant. The voltage across the load does not fluctuate due to load fluctuations, unlike in the conventional case.

In addition, when charging the storage battery 01) as a common load by the redundant parallel operation system using multiple DC power supplies shown in Fig. 1, the molecular resistance (8a) in one device
, (8b) is short-circuited, the backflow prevention effect of the diode a0 eliminates the problem of the entire system going down as in the conventional case.

Note that even if the backflow prevention diode Ql and the output current detection shunt (9) in FIG. , (8b) equal to the ratio of the resistance of the current shunt (9) to the internal resistance of the diode α0, it is possible to suppress fluctuations in the voltage across the load due to load fluctuations.

Further, in the above embodiment, the case where the load is a storage battery and the battery is charged has been described, but the present invention is not limited to this, and the present invention can be applied when a backflow prevention diode and an output current detection shunt are required. Can be applied.

〔Effect of the invention〕

Since the present invention is constructed as described in one or more of the above descriptions, it achieves the advantages described below.

Since a backflow prevention diode, load, and output current detection shunt are connected in series between the two terminals of a series circuit of two voltage dividing resistors, even if the output DC fluctuates by 1 due to load fluctuations, it will not change as before. It is possible to suppress fluctuations in the voltage across the load, and to maintain the voltage across the load constant.

Also, by making the ratio of the two voltage dividing resistors equal to the ratio of the internal resistance of the diode and the resistance of the shunt.

Fluctuations in the voltage across the load depending on the output current can be reliably prevented, and the constant voltage characteristics of the device can be improved over time.

[Brief explanation of drawings]

FIG. 1 is a wiring diagram of one embodiment of the DC power supply device of the present invention, and FIG. 2 is a wiring diagram of a conventional example. (1)...AC power supply, (2)...input side rectifier circuit,
(3)...Inverter section, (4)=Output transformer, (4a), (4b)...Primary. Secondary winding, (5)... Output side rectifier circuit, (8)...
series circuit. (8a), (8b)...Voltage dividing resistor, (91... Output current detection shunt, αQ... Backflow prevention diode, aυ
...Storage battery, QFJ...Inverter control unit.

Claims (2)

[Claims] (1) An inverter section comprising an input rectifier circuit that rectifies the output of an AC power supply, a switching element connected to an output terminal of the input rectifier circuit, and a primary winding connected to the output terminal of the inverter section. an output transformer connected to the secondary winding of the transformer, an output rectifier circuit connected to the secondary winding of the transformer, a series circuit of two voltage dividing resistors connected between both output terminals of the output rectifier circuit, and the series circuit A reverse current prevention diode, a load and output current detection shunt connected in series between both ends of the resistor, and a control signal applied to the control terminal of the switching element so that the detected potential at the connection point between the two resistors is equal to the reference potential. and an inverter control section that outputs and controls the output of the inverter section. (2) The DC power supply device according to claim (1), wherein the ratio of the two voltage dividing resistors is equal to the ratio of the internal resistance of the reverse current prevention diode and the resistance of the output current detection shunt. .