JP2001309557A - Series-connection type constant current feed apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a voltage control operation for uniforming voltages shared by respective converters more stable and to stabilize the control operation even if a fault converter is produced. SOLUTION: This series-connection type constant current feed apparatus comprises a plurality of constant current converter units 1 whose outputs are connected in series to each other to supply constant currents to a load; a current control unit 3 which controls the currents of the respective converter units to be constant; a shared voltage calculation circuit 5 which is informed of the number of converters in operation by the outputs VPF of the respective converters and calculates uniform shared voltages 103; a voltage control circuit 14 which compares the detection voltage 101 of the outputs VPF with the shared voltage 103, outputs a control voltage 104 only when the differential voltage exceeds a reference value to control the output VPF to be approximately equal to the shared voltage, and, further, outputs an alarm signal 105 when the differential voltage exceeds a fault decision value to forcibly stop the operation of the constant current converter unit 1, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a series-connected constant-current power supply device, and more particularly to a plurality of constant-current converter boards which are connected in series to supply power to a load and shared by a current detector inserted in series with the load. The present invention relates to a series connected constant current power supply device to be controlled.

[0002]

2. Description of the Related Art In the case of a conventional constant current power supply apparatus in which a plurality of constant current converter boards are controlled by a constant current by common control, it is necessary to equalize the shared voltage of each constant current converter board. That is, if the shared voltages are unequal, the loads on the respective constant current converter boards will be unequal, causing problems such as the occurrence of failures and accelerated deterioration of the constant current converter boards where the loads are concentrated. For this reason, the shared voltage is equalized. As a method for this, a method has been adopted in which the control voltage of each constant current converter is manually adjusted when the apparatus is started up.

[0003] However, in the above-described voltage sharing method in the conventional constant current power supply device, in the case of a constant load, it is possible to equalize the shared voltage by adjusting the load. Each time the number of units increases or decreases, it is necessary to individually readjust the units. In particular, when the number of converter panels is large, it is extremely inconvenient for maintenance.

[0004] For this reason, a method of automatically adjusting the shared voltage is considered, and for example, there is a method described in Japanese Patent Application Laid-Open No. Hei 4-29926.

FIG. 4 is a block diagram showing this conventional example. As shown in FIG. 1, the voltage detector 46 is connected in parallel to a load 48 of a constant current power supply device that controls a plurality of constant current converter boards (PF1 to PFn) with a constant current by a common control. The output c of the voltage detector 6 is supplied to a voltage detection circuit (41) provided in each of the constant current converter boards (PF1 to PFn).
4n), the operation state a1 to an, for example, “1” during operation and “0” during stop are counted by the counter circuit 44,
The operating number information b is generated. The division circuit 45 inputs the output signal d divided based on the number-of-operations information b and the voltage signal c of the voltage detection circuit 46 of each converter board to the second error amplifiers (51 to 5n) in each converter board. Then, its output is connected in parallel to the output of the first error amplifiers (61 to 6n), and the shared voltages (V _{PF1 to} V _{PF1 to} V
_PFn ) are such that the load voltage V ₀ is 1 / N. N is the number of constant current converters in operation.

As described above, in a constant current supply device for performing constant current control of a plurality of constant current converter boards by common control, a voltage detector is connected in parallel to a load, and a voltage detection circuit provided in each constant current converter is connected. Is counted by a counting circuit, and the output signal obtained by dividing the output of the voltage detector by the information on the number of operating units and the voltage signal of the voltage detection circuit of each converter board are converted into a second error amplifier in each converter board. By amplifying the error and connecting the output in parallel with the output of the first error amplifier, the shared voltage of each of the constant current converter boards is automatically and evenly changed with respect to a load change or a change in the number of converter boards. It is possible to keep.

[0007]

As described above, in the conventional example, the shared voltage can be automatically equalized. However, the outputs of two error amplifiers are connected in parallel, and the combined output of the constant current converter is used. Since the output power is controlled,
There are the following problems. That is, in the case of a sudden load change, the outputs of the two error amplifiers for controlling the current and the voltage compete with each other to make the control operation unstable, and it takes time for the control operation to converge. In addition, since two control systems are constantly operating, the system is easily affected by external noise and the like.

Further, when counting the number of converter boards, the converter boards are classified into "1" during operation and "0" during stop, and the number of converter boards during operation is counted. At some point, the operation is counted as being in operation, so that an error occurs in the shared voltage, which may hinder the control operation. These are all problems that reduce the reliability of the apparatus.

[0009]

According to the present invention, there is provided a series-connected constant-current power supply apparatus comprising: a plurality of converters for connecting an output in series to supply power to a load; A current control unit that controls the output power of each converter in common by the first control voltage to make the load current constant, and counts the number of converters that are operating normally from the output voltage of each converter to determine the load voltage. A shared voltage calculation unit that divides by the number of converters to calculate a shared voltage for each of the converters, compares the output voltage of the converter with the shared voltage, detects a difference voltage therebetween, and detects the difference voltage exceeding a predetermined reference value. At the same time, the second control voltage generated from the difference voltage at this time is added to the first control voltage to perform correction control so that the output voltage becomes substantially equal to the shared voltage. And a plurality of voltage control unit provided in the converter is configured.

[0010] The voltage control section may have a function of issuing an alarm signal when the difference voltage exceeds a predetermined failure determination value and forcibly stopping the operation of the corresponding converter.

In addition, the voltage control section receives the shared voltage and the output voltage, calculates a difference voltage between the input voltage and the output voltage, and a predetermined reference for inputting and holding the difference voltage therein. A control start point determination circuit that outputs a control start signal when the difference voltage exceeds the reference value by comparing the control voltage with the value, and simultaneously converts the control voltage into the second control voltage by inputting the difference voltage. A control voltage generation and holding circuit that outputs the second control voltage at this time when input, and holds the second control voltage that is output when the control start signal stops until the next input of the control start signal And a voltage addition circuit that adds the output second control voltage to the first control voltage 1 and a failure determination value that receives the difference voltage and holds the difference voltage internally, and the difference voltage determines the failure determination value. Alert when the value is exceeded It may be configured with an alarm decision circuit for outputting a signal.

In addition, a pulse generation circuit for generating a control start pulse at a predetermined cycle is provided instead of the control start point determination circuit, and the control voltage generation and holding circuit inputs the difference voltage and outputs the difference voltage to the second control voltage. The second control voltage is output when the control start pulse is input at the same time as the signal conversion, and the second control voltage output when the control start pulse is turned off is input to the next control start pulse. May be held up to the maximum.

Further, the reference value of the control start determination circuit or the cycle of the pulse generation circuit and the failure determination value of the alarm determination circuit may be made variable.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing an internal circuit of a voltage control unit in FIG. 1, and FIG. 3 is an internal view of another embodiment of the voltage control unit in FIG. It is a circuit diagram showing a circuit.

First, the configuration will be described with reference to FIG. FIG. 1 shows an example in which two constant current converter units are connected in series for easy understanding, but it is of course possible to connect three or more constant current converter units.

Outputs are connected in series to supply power to a load 7 2
Provided in the two constant current converter sections 1a and 1b, respectively.
The constant current converter circuit 11 detects the load current.
Current detection circuit 2 and a control generated from the detection output.
The output voltage of each constant current converter circuit 11 is
Force the load current to the load 7 to a constant current by controlling the power in common
The current controller 3 and the output voltage of each constant current converter circuit 11
Pressure V_PFVoltage detection circuit that detects the
The circuit 12 and the converter operating normally from the detected voltage 101
Converter number counting circuit 6 for counting the number of converters
And the load voltage V ₀ And outputs a detection voltage 106.
Pressure detection circuit 4 and this detection voltage 106
Is divided by the equal shared voltage of each constant current converter circuit 11.
A shared voltage calculation circuit 5 for calculating 103;
1 and the shared voltage 103, and the difference voltage is detected.
When the difference voltage exceeds the specified reference value,
The control voltage 104 generated from the control voltage to the control voltage 102
And the output voltage V_PFIs almost equal to the sharing voltage 103
At the same time as the correction control, the difference voltage
Generates and responds to an alarm signal 105 when the specified value is exceeded
The operation of the constant current converter circuit 11 is forcibly stopped.
You. Voltage control circuit provided in each constant current converter unit 1
14 and a voltage addition circuit 13.

A diode 15 provided at the output of each constant current converter 1 is a connecting diode, and when one of the constant current converter circuits 11 fails and its output becomes zero, the diode 15 is short-circuited. This is for continuing power supply from a normal converter.

Next, an internal circuit of the voltage control circuit 14 will be described with reference to FIG. Sharing voltage 103 and detection voltage 1
01 (corresponding to the output voltage _VPF ), and a difference voltage calculation circuit 141 for calculating a difference voltage between them. The difference voltage is inputted and compared with a predetermined reference value held therein, and the difference voltage exceeds the reference value. Control start point determination circuit 1 that outputs a control start signal when
43, when the difference voltage is inputted and the signal is converted to the control voltage 104 and the control start signal is inputted at the same time, the control voltage 104 at this time is outputted and the control voltage 104 outputted when the control start signal is stopped is changed to the next. A control voltage generation / holding circuit 142 for holding the control start signal until it is input; and an alarm determination circuit 1 for comparing the difference voltage with a failure determination value held therein and outputting an alarm signal 105 when the difference voltage exceeds the failure determination value.
44.

Next, the overall operation will be described. The control system of this device is divided into a current control system and a voltage control system. The current control system operates with an analog signal, while the voltage control system operates with a digital signal. That is, the voltage detection circuit 415 of the voltage control system converts the detection voltage into a digital signal using the D / A converter, and outputs the digital signal as the detection voltages 106 and 101. Therefore, the converter number counting circuit 6 and the shared voltage calculation circuit 5 digitally process the detected voltages 106 and 101 and output the shared voltage 103 of the digital signal. The voltage control circuit 14 also receives the shared voltage 103 and the detection voltage 101 and performs digital processing. The output control voltage 104 is converted into an analog signal and output. The alarm signal 105 is a digital signal of 1,0.

The transient response speed of the current control system differs from that of the voltage control system, and the response speed of the voltage control system is set to be much lower than that of the current control system. That is, the environment,
The current control system, which keeps the load current fluctuation that changes every moment depending on the usage conditions, performs control that is continuous in time and has a fast response. It doesn't need to be controlled continuously in real time because it doesn't usually fluctuate except when
Therefore, the voltage control system performs control with a slow response only when the time fluctuates. Thereby, the control operation is stabilized.

Normally, the constant current converter circuit 11 is commonly controlled by the current control circuit 3 to make the current supplied to the load 7 constant. The output voltages V _PF1 , V _PF2 of the constant current converters 1a, 1b are respectively detected by the voltage detection circuit 12, and the detection voltages 101a,
It is output as 101b. The converter number counting circuit 6 receives the detection voltage 101, recognizes that there are two converters in operation, and sends the number data to the shared voltage calculation circuit 5. The voltage detection circuit 4 detects the output voltage V ₀ on the load side and divides the detection voltage 106 into a shared voltage calculation circuit 5
Sent to The shared voltage calculation circuit 5 detects the detected voltage 106
And it outputs the divided voltage 103 indicating a voltage value of V _0/2 by dividing the voltage value by the number indicated by.

The voltage control circuit 14 receives the detection voltage 101 and the shared voltage 103, and first receives an internal difference voltage calculation circuit 14
This voltage difference is calculated by 1 and a difference voltage indicating the value is output. If the difference voltage is 0, the control voltage 104 output from the control voltage generation and holding circuit 142 is 0V. That is,
In the voltage adding circuit 13, since the added voltage is 0V, the constant current control is performed only by the control voltage 102.

If it is assumed that the output voltage V _PF1 decreases for some reason from the state where the output voltages are equal and the output voltage V _PF2 increases accordingly by the constant current control, the following voltage control is started. In the constant current converter 1a, when a difference voltage is generated on the negative side and the value exceeds a reference value (for example, ± 10% fluctuation value) held by the control start point determination circuit 143, the control start determination circuit 143 outputs a control start signal. Is output. At this time, the positive-side differential voltage is also generated on the constant current converter 1b side at the same time, but the output timing of the control start signal output by the control start point determination circuit 143 is assumed to be earlier on the constant current converter 1a side.

The control voltage generation and holding circuit 142 receives the control start signal, converts the difference voltage at this time into a control voltage 104 of an analog signal, and outputs it. The control voltage 104 is added to the control voltage 102 by the adder circuit 13 to increase the output power of the constant current converter circuit 11 so that the output voltage V
Control to increase _PF . When the output voltage V _PF1 becomes substantially equal to the shared voltage 103, the control start signal is stopped and the control is completed. On the other hand, the load current increases due to this voltage control, but the constant current control is performed by the current control unit 3, so that the output voltage _VPF2 on the constant current converter unit 1b side is controlled to decrease. Then, both output voltages V _PF1 and V _PF2 return to the original equal state. However, the constant current converter 1
On the side a, the difference voltage remaining after the control remains and the control voltage 10
4 is held until the next control start signal is generated.

The voltage drop amount of the output voltage V _PF1 is equal to the reference value of 1
When the value becomes 0% or more, and becomes equal to or more than a failure determination value (for example, a 30% variation value) held in the alarm determination circuit 144, the alarm determination circuit 144 determines that a failure has occurred and the alarm signal 1
05 is output. Thereby, the constant current converter circuit 11
Is forcibly stopped. Therefore, the shared voltage 103 becomes V ₀ and the switching to the one-sided power supply from the constant current converter section 16 is promptly performed. Since the reference value and the failure determination value are rewritable, they can be set to optimal values.

Next, another embodiment will be described with reference to FIG. The difference from the example described with reference to FIG. 2 is that the control start point determination circuit 143 is replaced with a control start pulse generation circuit 145. That is, the former is different in that the voltage control is performed only when the difference voltage exceeds a predetermined reference value, whereas the voltage control is intermittently performed in a predetermined synchronization in the present embodiment. The control start pulse generation circuit generates a control start pulse having a time width necessary for the control operation in a cycle of one day to one month, and the control voltage generation and holding circuit 142 generates and holds the control voltage 104 by the pulse. It is. This example has a feature that the circuit can be simplified as compared with the former.

[0027]

As described above, the series connection type constant current supply device of the present invention performs the voltage control for equalizing the sharing voltage of each constant current converter when the variation amount of the sharing voltage exceeds the reference value. Since the control operation is performed only or intermittently, the chance of competing with the constant current control is reduced, and the effect of external noise can be reduced, so that the control operation is stabilized.

Further, when the output voltage of the constant current converter is at an intermediate voltage due to a failure, the operation is forcibly stopped, so that the number of converters in operation is accurate and the control operation is maintained normally. This has the effect of increasing reliability.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an internal circuit of the voltage control circuit in FIG.

FIG. 3 is a circuit diagram showing an internal circuit of another embodiment of the voltage control circuit in FIG. 1;

FIG. 4 is a block diagram showing a conventional example.

[Explanation of symbols]

 1a, 1b Constant current converter section 2 Current detection circuit 3 Current control circuit 4 Voltage detection circuit 5 Allocated voltage calculation circuit 6 Number of converters circuit 7 Load 11 Constant current converter circuit 12 Voltage detection circuit 13 Voltage addition circuit 14 Voltage control circuit 141 Difference Voltage calculation circuit 142 Control voltage generation and holding circuit 143 Control start point judgment circuit 144 Alarm judgment circuit 145 Control start pulse generation circuit

Claims (7)

[Claims] An output power of each converter is controlled in common by a plurality of converters connected in series to supply power to a load by detecting the load current and a first control voltage generated from the detected output. A current control unit that converts the load current into a constant current, and counts the number of converters that are operating normally from the output voltage of each of the converters, divides the load voltage by the number of converters, and calculates an equal shared voltage for each of the converters. A voltage calculator, comparing the output voltage of the converter with the shared voltage, detecting the difference voltage, and when the difference voltage exceeds a predetermined reference value, a second control voltage generated from the difference voltage at this time. And a plurality of voltage control units provided in each of the converters for correcting and controlling the output voltage to be substantially equal to the shared voltage by adding the control voltage to the first control voltage. Characteristic series connected constant current power supply device. 2. A plurality of converters which connect outputs in series to supply power to a load, and control the output power of each of the converters in common by detecting a load current and a first control voltage generated from the detected output. A current control unit that converts the load current into a constant current, and counts the number of converters that are operating normally from the output voltage of each converter, divides the load voltage by the number of converters, and calculates a shared voltage equivalent to each of the converters. A shared voltage calculator, comparing the output voltage of the converter with the shared voltage, detecting a difference voltage between them, and intermittently intermittently generating a second control voltage generated from the difference voltage at a predetermined cycle in the first control mode; A plurality of voltage control units provided in each of the converters for performing correction control so that the output voltage is substantially equal to the shared voltage by adding to a voltage. Continuous type constant current power supply device. 3. The voltage control unit according to claim 1, wherein when the difference voltage exceeds a predetermined failure determination value, an alarm signal is issued and the operation of the corresponding converter is forcibly stopped. 2. The series-connected constant current power supply device according to 2. 4. The voltage control unit receives the shared voltage and the output voltage, calculates a difference voltage between the input voltage and the difference voltage, and outputs a difference voltage between the shared voltage and the output voltage. A control start point determination circuit that outputs a control start signal when the difference voltage exceeds the reference value by comparing the control voltage with the value, and simultaneously converts the control voltage into the second control voltage by inputting the difference voltage. A control voltage generation and holding circuit that outputs the second control voltage at this time when input, and holds the second control voltage that is output when the control start signal stops until the next input of the control start signal And a voltage addition circuit that adds the output second control voltage to the first control voltage 1 and a failure determination value that receives the difference voltage and holds the difference voltage internally, and the difference voltage determines the failure determination value. Alarm signal when the value is exceeded 4. The series-connected constant-current power supply device according to claim 1, further comprising an alarm determination circuit that outputs a signal. 5. A voltage difference calculating circuit for inputting the shared voltage and the output voltage, calculating a difference voltage between the input voltage and the output voltage, and a pulse generating circuit for generating a control start pulse at a predetermined cycle. The second control voltage is output when the difference voltage is input and the signal is converted to the second control voltage at the same time as the control start pulse is input, and is output when the control start pulse is turned off. A control voltage generation and holding circuit that holds the second control voltage until the input of the next control start pulse, a voltage addition circuit that adds the output second control voltage to the first control voltage, 4. An alarm judgment circuit which receives the difference voltage and compares it with a failure judgment value held therein and outputs an alarm signal when the difference voltage exceeds the failure judgment value. Series-connected constant-current feeder. 6. The series-connected constant current power supply device according to claim 4, wherein the reference value and the failure determination value can be changed. 7. The series-connected constant-current power supply device according to claim 5, wherein a cycle of the control start pulse and the failure determination value can be changed.