JPS644416B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting a rectifying power supply that generates an overvoltage during parallel operation.

When operating multiple rectifier power supplies in parallel, if each power supply has a different output voltage, the power supply with a higher output voltage will share more of the load than the power supply with a lower output voltage, resulting in overload. . Therefore, for example, by providing automatic load equalization circuits LU _A and LU _B as shown in Figure 1 (the figure shows the case of two power supplies), the FC _B output voltage of the power supply with less load sharing can be adjusted to Efforts are being made to equalize load sharing by increasing the power supply FC _A to a higher level.

This circuit converts _the load currents I A _{and I B} of each power supply device FC _A and FC _B detected by the DC current transformer as shown by the solid line in the figure. Resistors R _B1 , R _B2 of circuit LU B → diode _{D A} of equalizing circuit LU _A ] and [rectifier of equalizing circuit LU _B
REC _B → resistors R _A1 , R _A2 of the equalizing circuit LU _A → diode D _B of the equalizing circuit LU _B ], the input resistances R A2 , _{R B2} of the differential amplifiers DA _A , DA _B are mutually adjusted.
flow to. When the load currents are the same and therefore the output voltages are the same, the input conditions of the differential amplifiers DA _A and DA _B are the same so that they do not send out differential outputs.
Also, for example, if the load current I _A of power supply FC _A is
When FC _B becomes larger than I _B and the voltage of input resistor R _B2 of differential amplifier DA _B of power supply device FC _B becomes larger than that of R _A2 , causing a difference from the reference voltage V _rB , the The voltage adjustment circuit of the power supply device FC _B is controlled by the differential output to perform an operation to match the output voltage of the power supply device FC _A.

However, in this case, for example, even if the output voltage of a power supply unit running in parallel increases to a voltage value higher than an allowable level due to an accident, resulting in an overvoltage, the automatic load equalization circuit will prevent other voltage A rising action of the lower power supply is performed. This not only applies overvoltage to the load circuit and causes overcurrent to flow, but also
Until the automatic load equalization circuit operates and the output voltages of each power supply device become the same, the load sharing amount of the power supply device that has become overvoltage becomes large, which tends to lead to failures due to overcurrent. Therefore, it is necessary to provide protection by promptly stopping or cutting off the rectifier power supply that generates the overvoltage. However, since the output voltage of each power supply device is apparently the same due to parallel operation, it is impossible to detect an overvoltage power supply device only by detecting a voltage increase in the circuit.

To solve this problem, conventionally, each power supply device FC _A , FC _B , ... FC _N is connected in parallel to the load L via OR diodes D _A , D _B , ... _DN as shown in Fig. 2. At the same time, an overvoltage detector is installed on each power supply side of each diode to form a parallel operation circuit.
HV _A , HV _B ,...HV _N are provided and OR diodes are connected.
The reverse characteristics of D _A , D _B ...D _N prevent current from flowing into each overvoltage detector HV _A , HV _B , ... HV _N from other power supply devices, and each power supply device can operate independently. Detection of overvoltage is performed.

However, since the OR diodes D _A , D _B , ...D _N are each connected in series with the power supply circuit, the current capacity of the diodes must match that of the power supply device. For this reason, as the output capacity of the power supply device increases, it becomes larger and more expensive, resulting in a large and more expensive power supply device, and at the same time, there is a major drawback in that efficiency decreases due to increased loss.

The present invention aims to provide a method for detecting an overvoltage generating rectifier power supply device that eliminates the above-mentioned drawbacks, and will now be described in detail with reference to the drawings.

FIG. 3 is a basic circuit diagram of the present invention, and its features are as follows. That is, an overvoltage detection circuit OV is connected to the load terminals J and COM, and when it detects that the circuit voltage has increased to a predetermined value or more during parallel operation, it sends out a control signal _pz . As a result, each automatic load equalization circuit LU _A , LU _B ,...
Switch elements (for _{example , electronic} switches) for _{disconnecting} LU _N are turned _OFF . Then, the output equalization effect is stopped, and each power supply device FC _A , FC _B , . . . FC _N is made to share a load commensurate with their respective output voltages.

On the other hand, each power supply device FC _A , FC _B , ... FC _N has DC shunts SH _A , SH _B , ... connected in series to each circuit.
Load current detection circuits OC _A , OC _B ... with SH _N
OC _N is provided to detect each load current I _A , I _B ,...I _N ,
A stop or cutoff signal p _f is sent from a circuit that detects a load current larger than a predetermined value, and if the power supply device that detected a large load current is, for example, FC _A , it is stopped or cut off from the circuit. It is characterized by the following.

In this way, there is no need to provide an OR diode of a size corresponding to the current capacity for each rectified power supply as in the past, and the overvoltage detection circuit and load current detection circuit can be formed compactly using integrated circuits. This makes it possible to reliably select and detect rectifier power supplies that have generated overvoltage. Therefore, there is no need to make the power supply device large and expensive, and there is no reduction in efficiency as in the conventional case.

Next, the present invention will be explained in detail with reference to an embodiment circuit diagram shown in FIG. 4 and an operation explanatory diagram shown in FIG. In order to make the explanation easier to understand, Fig. 4 shows a power supply device that generates overvoltage.
FC _A is specified, and only one load current detection circuit OC _A is shown.

A Operation during steady operation The overvoltage detection circuit OV has load terminals J,
A parallel operation voltage V _L is applied from COM, and this voltage is divided by resistors R ₁ , R ₂ , variable resistor VR _1, etc. and applied to comparator IC ₁ . Then, it is compared with the reference voltage V _S created by the constant voltage element DZ ₁ and the resistor R _3. If the load voltage V _L is less than a predetermined value determined by V _S , the transistor Q ₁ is OFF and transistor Q ₂ is ON (at this time, transistor Q ₄ of load current detection circuit OC _A is OFF). For this reason the transistor
The control signal _pz of the automatic load equalization circuit by _Q1 is not sent out, and the control capacitor C of the overvoltage detection circuit OV is short-circuited by the transistor _Q2 , and its terminal voltage is kept at almost zero. .

On the other hand, in the load current detection circuit OC _A , the output voltage proportional to the load current I detected by the DC shunt SH is applied to the amplifier IC ₂ , and its output has a voltage between the operating voltage of the circuit +V _cc and -V _cc . Then, an output voltage V _d that maintains the potential relationship as shown in state 1 in FIG. 5 is sent out. (V _SH is DC shunt SH
is the output level of amplifier IC ₂ corresponding to the terminal voltage of . ) and V _d is the terminal voltage of the control capacitor C applied here in the comparator IC ₃ .
It is compared with V _c , but as mentioned above, since V _c is approximately zero, the output of comparator IC ₃ is approximately zero. Therefore, timed electronic switch IC ₄ does not operate.
Since transistors Q ₄ and Q ₅ are also in the OFF state,
The drive signal of the transistor Q ₂ of the overvoltage detection circuit OV is not sent out, and the stop or cutoff signal p _f of the rectifying power supply device FC _A is also not sent out.

B Operation when overvoltage occurs At time t ₁ in Figure 5, load terminals J and COM
When an overvoltage exceeding a predetermined value occurs in the comparator IC ₁
sends out an output, turning transistor Q ₁ ON and transistor Q ₂ OFF. For this reason, Q ₁ sends a control signal p _z to turn off the series disconnection switch element Z _A of the automatic load equalizing circuit LU _A , stopping the load equalizing action of each, and changing the output voltage to each rectifier power supply. to bear a load commensurate with the

On the other hand, at this time, the short circuit of the control capacitor C is released by turning off the transistor _Q2 , so
As shown in state 2 of FIG. 5, charging starts from time t ₁ and the voltage V _c gradually begins to rise, but at this time, the output voltage V _d of the amplifier IC ₂ undergoes a DC shunt due to the increase in the load current I. Since the terminal voltage of SH increases, it decreases to V _d ′. (In Figure 5, V _SH is the voltage level of the DC shunt SH converted to the output side of amplifier IC ₂ when the load current is steady, V _SH ′ is the voltage level when the load current increases, and V _SH ″ is the voltage level when the load current is ) The voltage V _c of the capacitor C and the output voltage V _d ' of the amplifier IC ₂ are compared by the comparator IC ₃ , whose output is When the voltage V _c is zero, it is zero as described above, and as it rises, it gradually increases, and at time t ₂ in state 2 in FIG. 5, when the level becomes higher than the output level of the amplifier IC ₂ ,
Operate timed electronic switch IC ₄ for a certain period of time,
Transistors Q ₄ , Q ₅ through transistor Q ₃
Turn on. As a result, the transistor Q ₅ sends out a stop or cutoff signal p _f for the rectifier power supply FC _A , and the transistor Q ₄ turns on the transistor Q ₂ of the overvoltage detection circuit OV to short-circuit the capacitor C and detect V _c as zero. Finish the action.

As is clear from the above explanation, according to the present invention, parallelization can be reliably achieved using a small and inexpensive control circuit, without making the rectifier power supply large and expensive as in the past, or using OR diodes that reduce efficiency. This has the excellent advantage of being able to selectively detect rectifier power supplies in which overvoltage has occurred during operation, and has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an automatic load equalization circuit, FIG. 2 is a circuit diagram for explaining a conventional overvoltage generation rectifier detection method, and FIG. 3 is a basic circuit diagram of the present invention.
FIG. 4 is a circuit diagram of an embodiment of the present invention, and FIG. 5 is an explanatory diagram of its operation. FC _A , FC _B , ...FC _N ... Rectifier power supply, LU _A ,
LU _B ,...LU _N ... Automatic load equalization circuit, I _A , I _B ,...
I _N ...Load current, J, COM...Load terminal, OV...
…Overvoltage detection circuit, SH _A , SH _B , … SH _N … DC shunt, OC _A , OC _B , … OC _N … Load current detection circuit, Z _A , Z _B , … Z _N … Series disconnection switch element,
R ₁ , R ₂ , R ₃ ...Resistance, VR ... Variable resistance, IC ₁ ...
...Comparator, ZD ₁ ... Constant voltage element, Q ₁ , Q ₂ ... Transistor, C ... Control capacitor, OC ...
Load current detection circuit, IC ₂ ... Amplifier, IC ₃ ... Comparator, IC ₄ ... Timed electronic switch, Q ₃ , Q ₄ , Q ₅ ...
transistor.

Claims (1)

[Claims] 1. In the parallel operation circuit of a rectifying power supply device equipped with an automatic load equalization function, a circuit is installed to detect a voltage increase exceeding a predetermined value in the parallel operation circuit, and when an overvoltage occurs, the above automatic load equalization function is stopped and each In addition to having the rectifier power supply share the load in accordance with the output voltage, a load current detection circuit provided in each rectifier power supply detects an increase in load current exceeding a predetermined value to detect an overvoltage-generating rectifier power supply. A method for detecting overvoltage generation rectifier power supply equipment during parallel operation.