JPH0120770B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a voltage/current control circuit, in particular, for example,
The present invention relates to a voltage/current control circuit that performs control to obtain predetermined voltage/current characteristics required for charging a battery from a single-phase AC power source.

When charging a battery, for example, after charging starts, a constant charging current is passed until the specified voltage is reached, and then the charging current is lowered to suppress the rise in battery voltage, giving so-called constant voltage/constant current characteristics. be done.

Conventionally, the first type of material that satisfies this type of characteristic is
A voltage/current control circuit as shown in the figure has been proposed. That is, in FIG. 1, 1 is a single-phase AC power transformer, which has a secondary voltage tap from which DC voltages of 6V, 12V, and 24V systems can be obtained. 2 is a bridge rectifier circuit for DC voltage 24V, which is composed of diodes 3-1, 3-2 and thyristors 4-1, 4-2; _g1 , _g2 are thyristors 4-1, 4-2;
The gate is 4-2. 5 is a center tap rectifier circuit with a DC voltage of 12V, and a thyristor 6-
1 and 6-2, and g ₃ and g ₄ are the gates of thyristors 6-1 and 6-2. 7 is direct current
This is a thyristor that performs rectification in the 6V system. The symbol shown in the figure is the polarity of the DC output terminal, and the battery is connected according to this polarity. At this time, in the DC 6V system, control to obtain the constant voltage/constant current characteristics described above is not performed. Reference numerals 8-1 and 8-2 are changeover switches for changing the DC voltage, and the changeover switches 8-1 and 8-2 are linked to change over the 6V, 12V, and 24V systems. Reference numeral 9 denotes a synchronization detection and gate control circuit, which performs synchronization detection using a transformer 10 connected to a single-phase power supply, and also
The next side is introduced into the gate control circuit 11 to gate the thyristors 4-1, 4-2, 6-1, 6-2.
g ₁ , g ₂ , g ₃ , and g ₄ are triggered to fire their respective thyristors to obtain desired battery charging characteristics. A single-phase transformer 12 is connected to a power source and serves as a power source for the gate control circuit 11. Therefore, the 24V and 12V secondary voltages from the single-phase AC power transformer 1 are introduced into the bridge rectifier circuit 2 and the center-tap rectifier circuit 5, and each voltage is adjusted by the gate signal synchronized with the single-phase AC power supply voltage. Thyristor 4-1, 4-2, 6-1, 6-
Gates g ₁ , g ₂ , g ₃ , and g ₄ of 2 are triggered and each thyristor is fired and phase controlled to achieve the desired output characteristics and the 24V or
A 12V battery will be charged.

In addition, 13 is a power switch, 14 is a breaker,
15 to 17 are resistors, 18 and 19 are diodes, 20 is a light emitting diode, 21 and 22 are fuses, and 23 is a plug.

The conventional voltage/current control circuit described above has a circuit configuration in which a transformer 10 is used to obtain synchronized gate signals for the bridge rectifier circuit 2 and the center tap rectifier circuit 5. Since the center tap rectifier circuit 5 and the center tap rectifier circuit 5 have independent circuit configurations, they have the drawbacks of being large in size and weight, requiring a large number of parts, and being expensive.

The present invention was made with the aim of solving the above-mentioned conventional drawbacks, and uses a small, lightweight, and inexpensive photo coupler as a synchronization detection means, and also uses a thyristor in common in the above-mentioned 24V and 12V systems. The aim is to reduce the number of components by using a rectifier circuit configuration and provide a new voltage/current control circuit. An embodiment will be described below with reference to the drawings.

FIG. 2 is a diagram showing an embodiment of the DC generation circuit excluding the synchronization detection circuit and the gate control circuit.
Corresponds to the one in the figure. 24 is a single-phase AC power transformer, which handles DC voltages of 6V, 12V, and 24V (12V and
The secondary voltage tap (which is commonly used with the 24V system and has an intermediate tap for the 12V system) and the secondary voltage tap (a, a' )have. 25 is a rectifier circuit with a diode 26-
1, 26-2 and thyristors 27-1, 27-2, g ₅ and g ₆ are the thyristors 2 and 2.
These are gates 7-1 and 27-2. The thyristors 27-1 and 27-2 of the rectifier circuit 5 are DC voltage
Commonly used in 12V and 24V systems, 12V with changeover switch 8-2 connected to the 12V contact
The system consists of a center tap rectifier circuit, and the 24V switch 8-2 is connected to the 24V contact.
A bridge rectifier circuit is constructed together with diodes 26-1 and 26-2. Reference numeral 28 is an ammeter, which is an instrument for measuring the load current of a battery or the like connected to a terminal, and a part of the load current flows through a shunt resistor 29 connected in parallel to the ammeter 28. Then, the potential difference generated between both ends OQ of the shunt resistor 29 is detected and used as the basis for current control which will be explained later.

FIG. 3 shows the configuration of an embodiment of the synchronous detection and gate control circuit of the voltage/current control circuit according to the present invention, in which reference numeral 30 is the gate control circuit;
3 is a reverse connection detection circuit, and 32 is a synchronization detection circuit.

The gate control circuit 30 has terminals O, P, and Q.
, and a and a', and these terminals are the terminals shown in FIG. are connected to each other. 33 is a rectifier, which includes a gate control circuit 30, a reverse connection detection circuit 31, and a synchronization detection circuit 3.
Control DC power is supplied to each of 2. 34 is a voltage regulator, 35 is a common ground, 36 is a voltage comparator, 37 is a current detector, 38 is a current comparator, 39
indicate reverse connection detectors, respectively. Note that any voltage regulator 34 may be used as the voltage regulator 34, but for example, it may have a function of maintaining the output voltage of the rectifier 33 at a constant voltage, and divide the constant voltage into the voltages (+), (0), (-) shown in the figure. ).
In addition, 40-1 and 40-2 are switches for switching to 6V, 12V, and 24V systems, and switches 40-1 and 40
-2 indicates those that are switched in conjunction with each other, and 41 to 44 indicate variable resistors, respectively. On the other hand, the synchronization detection circuit 32 has input terminals U and V, which are connected to the 12V and 24V system secondary terminals U and V of the single-phase AC power transformer 24 shown in FIG. Furthermore, the terminals g ₅ and g ₆ in the synchronization detection circuit 32 are gate terminals, and these terminals are connected to each thyristor 2 constituting the rectifier circuit 25 in FIG.
It is connected to each gate g ₅ and g ₆ of 7-1 and 27-2, and controls the phase of the thyristor. 4
5 and 46 are light emitting diodes, which are connected between input terminals U and V to respectively detect each positive half-wave period of the single-phase AC power source. Reference numerals 47 and 48 denote light-receiving transistors, and the light-emitting diodes 45 and 46 and the light-receiving transistors 47 and 48 form sets, respectively, in the relationship shown by dotted lines, and are combined to form a photo coupler. 49 and 50 are voltage comparators, which are operational amplifiers that output when the input voltage on the non-inverting input side (the input voltage from the photo coupler side) becomes higher than the reference voltage on the inverting input side (described later). to occur. 51 and 52 are thyristors, and upon receiving the output signals from the voltage comparators 49 and 50, the thyristors 51 and 52 fire, thereby generating gate signals at the gate terminals g ₅ and g ₆ , The phase of the thyristors 27-1 and 27-2 constituting the rectifier circuit 25 shown in FIG. 2 is controlled. That is, to explain the outline of the operation based on the above configuration, for example, the changeover switches 40-1, 40-2
Assuming that the voltage is on the 24V contact side, the output voltage and current of the rectifier circuit 25 constituting the bridge rectifier circuit in FIG. (to be described later), the voltage comparator 36 and the current comparator 3
The output from 8 is led to a maximum value detection circuit section consisting of diodes 72, 73, and 74, and the reference voltage of voltage comparators 49 and 50 in the synchronization detection circuit 32 is changed depending on the output of the larger one. , while changing the timing of firing the thyristors 51, 52 connected thereto, and
By the output from 52, the rectifier circuit 2 shown in FIG.
5 and adjust its output. In addition, 53 to 71 and 57', 5
9' is a resistor, 72 to 79 are diodes, 80,
81 and 82 each represent a capacitor.

The synchronization detection circuit 32 will be explained based on the above configuration. This circuit consists of a single-phase AC power transformer 24.
It is configured to detect signals synchronized with the 12V and 24V secondary side outputs. As is clear from FIG. 3, a light emitting diode 45 is located between the UV terminals, and the light emitting diode 45 emits light during a positive half wave of the single phase AC power supply voltage. Therefore, in the relationship shown by the dotted line, the light-receiving transistor 47 constituting the photo coupler turns on and generates a voltage across the resistor 63, which connects the resistor 64 and the capacitor to the non-inverting input terminal of the voltage comparator 49 via the resistor 64. A sawtooth wave voltage is applied by an integrating circuit comprised of 81 and 81.
On the other hand, a reference voltage set from the gate control circuit 31 side via a maximum value detection circuit consisting of diodes 72, 73, and 74 is applied to the inverting input terminal, which is the reference terminal of the voltage comparator 40. When the voltage applied to the non-inverting input terminal becomes larger than the reference voltage, the voltage comparator 49 generates an output, which becomes the gate signal for the thyristor 51 and fires the thyristor 51, causing the voltage from the input terminal U to be output. A gate signal is outputted to the terminal _g5 via the resistor 62, and the phase of the thyristor 27-1 constituting the rectifier circuit 25 shown in FIG. 2 is controlled by this output. The above explanation was about the operation during the positive half-wave of the single-phase AC voltage, but similarly, during the negative half-wave of the single-phase AC voltage between the UV terminals, the light emitting diode 46
The output of the voltage comparator 50 is connected to the thyristor 5 by a photo coupler consisting of a transistor 48 for photodetection.
Thyristor 2 ignites and outputs a gate signal to terminal _g6 , forming the rectifier circuit 25 shown in FIG.
7-2 phase control is performed. Therefore, phase control is performed in accordance with the reference voltage for each positive and negative half wave of the single-phase AC power supply voltage, so that the battery connected to the output terminal of the rectifier circuit 25 shown in FIG. 2 has desired charging characteristics. can get.

Next, consider the state in which voltage control is performed. Since the output terminal OP of the rectifier circuit 25 shown in FIG. 2 is connected between the OP terminals of the gate control circuit 30, the current flows as follows: O terminal → resistor 54 → resistor 53 →
A voltage with the polarity shown is generated across the resistor 54 through the P terminal. In addition, the variable resistor 42 has a voltage of the polarity shown (we are currently considering the 24V system, so the changeover switches 40-1 and 40-2 are turned to the 24V side, so we will explain the variable resistor 42. ) is connected to the resistor 54 via the resistor 56 and the resistor 55.
is in series with Assuming that the resistor 55 and the resistor 56 have the same resistance value, when the voltage between the terminals OP is at the desired setting value, the variable resistor 4
If the voltage on resistor 55 is selected to have the same value as the voltage on resistor 54, then under the condition that the voltage across the terminals OP is at the desired set value,
The potential at the connection point between and the resistor 56 becomes zero potential. On the other hand, the reference voltage of the voltage comparator 36 is the common ground 35
(zero potential), and the voltage comparator 36
monitors whether the potential at the connection point between the resistor 55 and the resistor 56 becomes larger or smaller than zero potential. Therefore, when the voltage across the terminals OP drops, the input terminal voltage of the voltage comparator 36 becomes greater than zero potential, and conversely, when the voltage between the terminals OP increases, the input terminal voltage of the voltage comparator 36 becomes less than zero potential. .
Therefore, when the voltage between the OPs drops, the input voltage becomes larger than the reference voltage as described above, and the voltage comparator 36 generates an output. If the voltage is the maximum in the maximum value detection circuit section, the voltage comparator 36
The output from the synchronization detection circuit 32 increases the reference voltage of the voltage comparators 49 and 50 in the synchronization detection circuit 32 via the diode 73. These things apply to each voltage comparator 4.
As a result, the ignition timing of the thyristors 51 and 52 is delayed with respect to the single-phase AC half wave applied to the thyristors 51 and 50, and as a result, the thyristors forming the rectifier circuit 25 shown in FIG. 27-
The ignition timing of 1, 27-2 is delayed and the rectifier circuit 25
lowers the output voltage.

Also, consider the state in which current control is performed. A shunt resistor 29 having a minute resistance is inserted on the output terminal side of the rectifier circuit 25 shown in FIG.
is applied to the input terminal of the current detector 37 via the OQ terminal of the current detector 37. On the other hand, the zero voltage of the common ground 35 is applied to the non-inverting input terminal serving as a reference of the current detector 37, and the output of the current detector 37 is proportional to the voltage drop. That is, it is proportional to the difference between the voltage at terminal Q and the zero voltage at common ground 35. Note that the capacitor 80 is for filtering high frequency components. Therefore, the output current from the rectifier circuit 25 shown in FIG. teeth
24V side), the reference voltage of the voltage comparators 49 and 50 in the synchronization detection circuit 32 is increased via the diode 72 (of course, the reference voltage of the current comparator 38 when the output is the maximum in the maximum value detection circuit section). That is, the phase of the thyristors 27-1 and 27-2 is controlled so as to delay the firing timing of the thyristors 51 and 52, thereby reducing the output current of the rectifier circuit 25 shown in FIG.

Further, the reverse connection detection circuit 31 will be explained. When the battery is in a normal connected state, the O terminal is polar and the P terminal is polar. Therefore, in a normal connection state, the negative potential from the P terminal is applied to the input terminal of the reverse connection detector 39 from the connection point between the resistor 53 and the resistor 54. No output is produced. However, if the battery is connected inversely to the polarity shown here, the P terminal, which had a negative polarity during normal operation, becomes positive and is applied to the gate control circuit 30. The potential at the connection point becomes positive and is introduced into the reverse connection detector 39. Therefore, the reverse connection detector 39 generates an output voltage of a sufficiently high value, which is introduced into the voltage comparators 49 and 50 in the synchronization detection circuit 32 via the diode 74 in the maximum value detection circuit section, and then outputs a reference voltage. raise. Therefore, the voltage comparators 49, 50
does not emit an output over all the positive and negative cycles of the single-phase AC power supply, and the rectifier circuit 25 shown in FIG. 2 is turned off.

The output from the voltage comparator 36 that performs the voltage control, the output from the current comparator 38 that performs the current control, and the output from the reverse connection detector 39 are the maximum values of the diodes 72, 73, and 74. In the detection circuit section, one of the largest values is extracted, and control is performed based on this. That is, when performing constant current and constant voltage control on the battery as described at the beginning of this specification, the current control is not performed until the terminal voltage of the battery (i.e., the voltage between terminals OP) reaches a predetermined value. The maximum value detection circuit section extracts the output from the diode 72, which works more effectively than the voltage control described above. When the terminal voltage of the battery reaches a predetermined value, thereafter, the maximum value detection circuit section extracts the output from the diode 73 based on voltage control. However, when the reverse connection detector 39 outputs an output, this output voltage is sufficiently large compared to the output from the diode 73 based on the voltage control and the output from the diode 72 based on the current control, and the output voltage from the diode 74 is The output of is extracted.

The above explanation is for the changeover switches 40-1, 40.
-2 to the 24V side, but it goes without saying that the above explanation also applies to the 12V system.

As explained above, according to the present invention, in a voltage/current control circuit that obtains a given charging characteristic by performing phase control of a rectifier circuit, the secondary side of a single-phase AC power transformer A rectifier circuit is configured that uses a common thyristor to switch the voltage and perform phase control, uses a photo coupler as a synchronization detection means, and also detects reverse connection for the voltage control section and current control section. It is an object of the present invention to provide a voltage/current control circuit for a single-phase AC power supply that is small, lightweight, has a reduced number of parts, is inexpensive, and prevents reverse connection, based on the circuit configuration as a means for controlling the phase through the circuit. It becomes possible.

[Brief explanation of drawings]

Fig. 1 is a voltage/current control circuit diagram of a single-phase AC power supply shown as a conventional example, Fig. 2 is an example of a DC generation circuit excluding a synchronization detection circuit and a gate control circuit, and Fig. 3 is a diagram according to the present invention. 1 shows an example configuration of a voltage/current control circuit. In the figure, 1 is a single-phase AC power transformer, 2 is a bridge rectifier circuit, 5 is a center tap rectifier circuit, 9 is a synchronization detection and gate control circuit, 11 is a gate control circuit, 24 is a single-phase AC power transformer, and 25 is a Rectifier circuit, 26-1, 26-2 are diodes, 27-
1, 27-2 is a thyristor, 28 is an ammeter, 29
is a shunt resistor, 30 is a gate control circuit, 31 is a reverse connection detection circuit, 32 is a synchronization detection circuit, 34 is a voltage regulator, 35 is a common ground, 36 is a voltage comparator, 37 is a current detector, 38 is a current comparison vessel, 39
is a reverse connection detector, 40-1, 40-2 are changeover switches, 45, 46 are light emitting diodes, 47, 4
Reference numeral 8 represents a light receiving transistor, 49 and 50 voltage comparators, 51 and 52 thyristors, 53 to 71 resistors, and 72 to 79 diodes.

Claims (1)

[Claims] 1. A single-phase AC power transformer having taps for obtaining multiple types of DC voltages, a changeover switch for switching the DC voltages, a rectifier circuit having a thyristor for rectifying each of the secondary voltages, and the output side of the rectifier circuit. a gate control circuit that controls the output characteristics of the rectifier circuit to have predetermined voltage and current characteristics according to a signal from the power supply; and a synchronous detection circuit that detects a synchronous signal from the power supply. In the control circuit, the changeover switch switches the connection of the secondary voltage tap of the single-phase AC power transformer to supply it to the rectifier circuit, and the gate control circuit includes at least a voltage control section, a current control section, and a maximum value detection section for detecting the maximum value output from each of the above sections,
The synchronization detection circuit includes a photo coupler for detecting a synchronization signal synchronized with the phase of the power supply voltage;
a voltage comparator circuit to which a synchronization signal from the photo coupler is applied; the synchronization signal from the photo coupler and the output signal from the maximum value detection section in the gate control circuit A voltage/current control circuit characterized in that the voltage/current control circuit is configured to control the firing angle of the thyristor of the rectifying circuit by comparing the firing angle of the rectifying circuit with the thyristor.