JPS62173987A - Constant-voltage constant-frequency power source unit - Google Patents

Abstract

PURPOSE:To check the fluctuation of the output voltage by working out the output voltage error correction data adding the corrected amount for the output voltage error caused by DC input voltage fluctuation subsequent to output voltage fluctuation, and by performing the constant-voltage control. CONSTITUTION:The output voltage fluctuation of half a cycle in sudden load variation is detected by an instantaneous fluctuation detection circuit 18 in an inverter control section 5. An instantaneous fluctuation corrected amount calculation circuit 19 calculates the corrected amount for the output voltage error caused by the DC input voltage fluctuation subsequent to this fluctuation. This corrected amount and the output of an output voltage detection circuit 14 are added by an addition circuit 20 and the output voltage error correction data are worked out, with which the constant-potential control of the next half a cycle is performed.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is capable of extremely quickly (suppressing fluctuations within half a cycle) the fluctuations in output voltage caused by sudden changes in load, etc., to normal values. This invention relates to a constant voltage constant frequency power supply device that can be reset.

[Conventional technology]

2. Description of the Related Art Conventionally, a constant voltage constant frequency (CVCF) power supply device that uses an inverter and has an uninterruptible configuration has been used as a stabilized power supply device for, for example, electronic computers and broadcasting equipment. Especially in power supplies for electronic computers, extremely short power outages (
Output voltage fluctuations due to instantaneous power outages) or sudden changes in load can also be a problem, so products that have countermeasures against them (for example, the
No. 567) is used.

FIG. 5 is a block diagram showing an example of the configuration of a conventional constant voltage constant frequency power supply device. In the figure, 1 is an input terminal for AC input, 2 is a rectifier that rectifies the AC input, 3 is a DC filter for smoothing, 4 is an inverter, 5 is an inverter control unit, 6
is an inverter drive circuit, 7 is an AC filter, 8 is an output terminal, 9 is an output switch, 10 is a terminal for connecting a load, 1
1 is the load. -12 is a storage battery, and 13 is a DC switch, which is added to provide an uninterruptible function.If there is an abnormality in the AC input, the DC switch 13 is turned on, and the inverter 4 continues to operate using the storage battery 12 as a power source. .

The inverter control unit 5 combines an output voltage detection circuit 14 that monitors the output voltage, a DC input instantaneous fluctuation detection circuit 15 that detects instantaneous DC input fluctuations of the inverter 4, and the detection signal output of the rain detection circuit. It includes an adder circuit 16 that generates an output voltage error correction signal, and a control signal generation circuit 17 that receives the output voltage error correction signal output from the adder circuit 16 and generates an inverter control signal. The output voltage detection circuit 14 inputs the detected value of the output voltage of the constant voltage constant frequency power supply device and the output voltage setting value of the inverter (reference voltage: reference data at rated output) and calculates the difference (setting value - detected value). It is equipped with an error amplifier and an amplifier that take the value (value) and output an output voltage detection signal.

The output of the control signal generation circuit 17 is amplified by the drive circuit 6 and becomes an inverter drive signal.

The inverter 4 is configured using semiconductor switching elements (transistors), and is controlled by the inverter control section 5.

There are various methods for controlling the output voltage of an inverter, but among them, the PWM (pulse width modulation) method is quite popular because it has fast transient response such as sudden changes in load and has excellent stability. It's coming. When this PWM method is adopted, the inverter outputs a plurality of pulse trains whose pulse widths are changed so as to bring the output voltage closer to a set value (normal value) according to fluctuations in the output voltage.

[Problem to be solved]

As mentioned above, constant voltage constant frequency power supplies are configured to maintain a stable output voltage in response to load fluctuations.However, if a sudden change in load occurs, the output voltage may sudden fluctuations occur.

If this sudden change in output voltage occurs, problems such as causing malfunction will occur if an electronic computer is connected to the load. Therefore, especially in power supplies for electronic computers, it is necessary to perform constant voltage control so that fluctuations in the output voltage are suppressed only during a half cycle, and the output voltage settles within a predetermined accuracy (normal value) in the next half cycle. However, in the conventional power supply device, the inverter control section is constructed of an analog circuit, which causes a problem in that it takes a long response time and it is not possible to suppress the fluctuations in the output voltage within half a cycle.

The direct reason why it is difficult to suppress the fluctuation in the output voltage only during a half cycle is that when a sudden change in load occurs, the DC input voltage of the inverter 4 also fluctuates accordingly. A DC input instantaneous fluctuation detection circuit 15 is provided to detect this fluctuation and perform constant voltage control of the inverter, but the DC input circuit (especially the smoothing circuit, etc.) has a considerable time constant. Therefore, since a time delay detection operation is performed, there remains a problem that the output voltage control operation of the inverter also has a time delay, resulting in incomplete instantaneous correction. Moreover, the DC input instantaneous fluctuation detection circuit 15 is configured to include a differentiating circuit and the like in order to detect DC input fluctuations, and the adjustment of gain and response is complicated.

The present invention has been made in order to solve the above problems, and provides a constant voltage constant frequency power supply device that can suppress output voltage fluctuations that occur due to sudden changes in load to only a half cycle. The purpose is to

[Means for solving problems]

In order to achieve the above object, the inverter control section of the constant voltage constant frequency power supply device of the present invention generates an output voltage based on the output voltage detected by the output voltage detection means instead of the DC input instantaneous fluctuation detection circuit. An instantaneous fluctuation correction amount calculating means (calculating means) is provided for calculating an instantaneous fluctuation correction amount by extracting an output voltage fluctuation amount due to a fluctuation in the DC input voltage of the inverter accompanying a sudden change in load from the error data. The instantaneous fluctuation correction amount data created by the performance means is added to the above output voltage error data, and the data created by adding (
The inverter control signal is generated based on the output voltage error correction data). Note that since the instantaneous fluctuation correction amount calculation means is constructed from a digital circuit, the response speed is also increased.

[Effect]

Figure 2 shows the inverter output fluctuations and DC input voltage fluctuations that occur when a load is applied (rapid fluctuations in load).

When a load is applied for a certain period of time as shown in FIG. 2(a), the output voltage of the inverter changes instantaneously as shown in FIG. 2(b). The output voltage fluctuation amount (output voltage error of the power supply device) Ve of the inverter during the first half cycle that changes in response to load application is detected by the output voltage detection means, and output voltage error data Vα is calculated. If the DC input voltage fluctuates as shown by the broken line in (C), if the DC input instantaneous fluctuation detection circuit (15 in Figure 5) described in the conventional example is provided, the inverter control section will immediately detect the output voltage. It should be possible to correct it to a normal value, but in reality, as shown by the solid line in (C), the DC input voltage gradually decreases due to the time constant of the circuit, so the output of the inverter is It was not possible to return to the normal value (solid line) in the next half cycle.The difference Ve' from this normal value is the inverter output voltage error due to fluctuations in the DC input voltage, and in the present invention, the error amount is The corresponding instantaneous fluctuation correction amount data Vβ is calculated and added to the output voltage error data ■α, and an inverter control signal is generated based on the added data (output voltage error correction data) to control the output voltage. Therefore, it is possible to return to the normal value in the next half cycle, as shown by the solid line in Figure 2 (b).In other words, the output voltage fluctuations due to sudden changes in load are suppressed only during the half cycle. can do.

〔Example〕

Next, the present invention will be explained by examples.

Figure 1 is a block diagram showing an embodiment of the constant voltage constant frequency power supply device of the present invention.
Items with the same symbol as , indicate the same or equivalent parts,
Descriptions will be omitted as appropriate.

The inverter control unit 5 of the power supply device of the present invention includes an output voltage detection circuit 14 having an error amplifier and an amplifier, an output voltage taken in by the output voltage detection circuit 14, and a reference voltage (output voltage accuracy in steady state). an instantaneous voltage fluctuation detection circuit 18 having a comparator for comparing the reference value) and an instantaneous voltage fluctuation detection circuit 18 that receives the output of the rain detection circuit and calculates the instantaneous fluctuation correction amount of the output voltage (output voltage correction amount due to DC input fluctuation). a fluctuation correction amount calculation circuit 19; an addition circuit 20 that adds the output voltage error data ■α outputted by the output voltage detection circuit 14 and the instantaneous fluctuation correction amount data ■β outputted by the instantaneous fluctuation correction amount calculation circuit 19; Addition output of the adder circuit 20 ■α+■β
The control signal generation circuit 17 generates an inverter control signal (PWM signal for switching control) based on (output voltage error correction data).

The control operation performed by the inverter control section of the present invention is the third one.
The flowchart is as shown in the figure.

That is, the instantaneous voltage fluctuation detection circuit 18 determines whether the fluctuation in the output voltage of the power supply device taken in by the output voltage detection circuit 14 is large and whether the fluctuation value is within the reference value for output voltage accuracy.
When the voltage accuracy during steady state (for example, ±2%) is exceeded, it is recognized that an instantaneous voltage fluctuation has occurred. If this instantaneous voltage fluctuation exceeds a predetermined allowable range, it is assumed that some kind of abnormality has occurred in the power supply device, and the operation of the inverter is stopped. If it is within the allowable range, output voltage error data ■α is calculated from the output voltage error Ve of the power supply device detected by the output voltage detection circuit 14, and instantaneous fluctuation correction is performed to correct the inverter output voltage error Ve' due to DC input fluctuation. Calculate the quantity data ■β, and add the calculated data for both ■α+
■Output the inverter control signal with the output voltage error corrected based on β. Note that when the output voltage fluctuation of the power supply device is small, an inverter control signal is generated only by the output voltage error data ■α, and normal (normal) inverter control is performed.

FIG. 4 shows an embodiment in which the central part of the inverter control section is constructed using a computer (microcomputer). 21 is an arithmetic processing unit (CPU
). 22 is an output voltage detection section, which includes a transformer, a gold wave rectifier circuit, and an A/D converter. 23 is a storage unit for various data and programs, and includes a ROM and a RAM. Reference numeral 24 denotes a reference signal generating section for constant frequency control (which serves as a reference for the output frequency of the inverter), and includes an oscillator, a counter, and a comparator.

The arithmetic processing unit (CPU) 21 inputs the output voltage detection value data detected by the output voltage detection unit 22, compares it with reference data set and stored in advance in the storage unit 23, performs various judgments, and detects the output voltage error. Calculation of data Vα and instantaneous fluctuation correction - amount data ■β, and output voltage error correction data (Vα + ■
At the same time as calculating β), an inverter control signal (PWM signal) is generated based on the output voltage error correction data in response to the reference signal (coincidence signal that determines the PWM signal on/off timing) from the reference signal generator 24. I am doing it. Note that when it is determined that there is an abnormality in the detection data of the output voltage detection section 22, generation of the inverter control signal is stopped.

〔effect〕

As explained above, in the constant voltage constant frequency power supply device of the present invention, when a half-cycle output voltage fluctuation at the time of sudden load change is detected in the inverter control unit, the output voltage due to the DC input voltage fluctuation accompanying the fluctuation is detected. Since output voltage error correction data is created by adding the amount of correction for the error and constant voltage control is performed for the next half cycle, fluctuations in the output voltage can be suppressed only during the half cycle. Therefore, it is particularly effective when used as a power source for electronic computers, etc., where instantaneous power outages and output voltage fluctuations are a problem.

[Brief explanation of drawings]

1 and 4 are block diagrams showing embodiments of the apparatus of the present invention. Figure 2 is an explanatory diagram of the state when the load suddenly changes.
(C) shows the DC input voltage. FIG. 3 is a flowchart showing the control operation of the inverter control section of the device of the present invention, and FIG. 5 is a block diagram showing the configuration of the conventional device. 4... Inverter, 5... Inverter control unit, 6... Drive circuit, 14... Output voltage detection circuit, 17... Control signal generation circuit, 18... Instantaneous voltage fluctuation detection circuit, 19 . . . Instantaneous fluctuation correction amount calculation circuit, 20 . . . Addition circuit, 21 . . . Arithmetic processing unit (CPU).

Claims (1)

[Claims] 1. In a constant voltage constant frequency power supply device comprising an inverter, a control section and a drive circuit for the inverter, the inverter control section detects the output voltage of the device and outputs voltage error data. an instantaneous voltage fluctuation detection means for detecting the occurrence of instantaneous voltage fluctuation and determining whether the magnitude thereof is normal or abnormal by comparing the detected value of the output voltage with the output voltage reference value; calculation means for receiving the output of the detection means and calculating instantaneous fluctuation correction amount data for correcting fluctuations caused by DC input fluctuations in the output voltage; and output voltage error data created by the output voltage detection means and the calculation means. and a control signal generating means that generates an inverter control signal based on the output voltage error correction data resulting from the addition. Constant voltage constant frequency power supply.