KR100312353B1 - Digital control type UPS and Digital control method in UPS - Google Patents

Abstract

The present invention relates to a digital control UPS (Uninterruptible Power Supply) and a digital control method of a UPS. The A / D converter 19 converts the input / output analog signals of the UPS into digital signals, and the signal processing unit 21 for rectifying and converting the input power digitally when the input power is bypassed. Provides a driving signal, senses the state before the device is turned off, protects the device, converts the real-time response signal from the device into a digital signal and outputs it, and transfers all running data to the PC through the communication connection. A microprocessor 20 for preventing a malfunction in advance and a communication connection unit 22 for serial communication with the microprocessor 20 at a long distance; And a display 23 for displaying a failure factor of the UPS according to the control of the microprocessor 20 as a digital signal.

Description

Digital control type UPS and Digital control method in UPS}

The present invention relates to an uninterruptible power supply (hereinafter, referred to as 'UPS'), and in particular, all control methods except the display part can be digitally controlled by making one chip (One-Chip), Protects data caused by momentary machine malfunctions caused by all obstacles (noise, surge, sag, etc.) The present invention relates to a UPS of a digital control method and a digital control method of the UPS, which reduce weight and minimize a loss rate of various semiconductor devices by adjusting a response speed of adverse effects caused by the obstacles.

Recently, various semiconductor devices have been further refined by the development of high-tech industries, and thus, a lot of instability factors have occurred. Examples include voltage and frequency fluctuations, instantaneous voltage enhancement, surges, and momentary power outages.

This power instability caused huge losses both in time and economics, such as load malfunctions and the loss and destruction of important data.

In order to prevent the problems caused by the instability of the power supply, a UPS, which is a high-reliability power supply unit that supplies high-quality power, is required.

The control method of the UPS is analog control method and digital control method. In the current UPS market, all control methods except the display part adopt analog control method.

As shown in FIG. 1, a general UPS employing such an analog system includes an input transformer 1 for transforming an input AC power source, a rectifier 2 for converting a transformed AC into a DC, and the rectifier 2. ), An inverter (3) for receiving the DC power output from the battery (7) connected in parallel and the DC power converted by the rectifier and converting the AC power into an AC power, an output transformer (4) for transforming the converted AC power, and finally It consists of a secondary inverter switch (5) for supplying a stable power, and a bypass switch (6) connected between the inverter switch and the input terminal of the input transformer (1).

However, the conventional analog control system UPS, which is constructed and used as described above, has a problem that the size of the UPS becomes large because it is composed of various elements. That is, since the input and output transformers 1 and 4 perform 60 Hz filtering, they are designed on the basis of the capacity, and thus, the volume becomes large, resulting in a problem that the size of the UPS becomes large. That is, there are many difficulties in capacity expansion.

In addition, the momentary malfunction of the machine may cause damage to each important device, the response speed is slowed due to external obstacles, there is a problem that the operation of the UPS unstable.

In addition, although an analog UPS has a system self-diagnosis function, it does not identify a cause of failure and has a problem of being very sensitive to noise.

In addition, the analog UPS may cause malfunction of the controller due to changes in component characteristics due to long-term use of components, and effects such as ambient temperature and humidity, and have a drift that has a fatal effect on lifespan and reliability.

In order to solve the above problems, the present invention reduces the size of the UPS, protects important components from instantaneous mechanical malfunction caused by the analog UPS, and speeds up the response speed of the device even when an external obstacle occurs. Alternatively, the purpose is to minimize the loss rate of the semiconductor and the like by controlling late digitally. Furthermore, the present invention provides device protection that cannot be solved by analog methods due to load diversification (eg, protects devices from unrecognized surges when using analog methods) and UPS status monitoring and power supply through PC communication. It is possible to have a control system that can monitor and control the power failure and abnormal state of the system through PC monitor at any time.

In order to achieve this object, the UPS of the digital control method of the present invention is a digitized signal for real-time control and sequentially checks the process of FIG. 2 and then proceeds the following process so that obstacles (instantaneous overvoltage, low voltage, It shows the state of surge and sag outage, and it checks the defective state of the device (thyristor, IGBT, etc ..).

1 is a configuration diagram of a typical UPS,

2 is a block diagram of a UPS according to the present invention,

3 is a conceptual diagram illustrating a control method for operating a UPS from an external signal;

4 is a dead time diagram generated when an IGBT semiconductor is turned on or off.

FIG. 5 is a timing diagram showing a switching point occurring when switching inverter power and KEPCO power;

6 is an operational waveform diagram of an inverter configuration and its components;

7 and 8 are the results of observing the waveform of FIG. 6 with a scope (Scope),

9 is a conversion and schematic diagram of analog and digital signals;

10 is a flow chart of the invention according to FIG.

<Explanation of symbols for main parts of drawing>

12,15: first and second rectifiers 13,16: first and second inverters

14: high frequency transformer 17: static switch

18: battery

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, FIG. 2 is a schematic diagram of a UPS of a digital control method according to the present invention for clearly showing a part contrasted with FIG. 1, which is an exemplary diagram when a PWM (pulse width modulation) signal control method is adopted. The overall configuration of the UPS is as shown in FIG. 3 to be described later.

The UPS shown in FIG. 2 includes a first rectifier (for example, using a silicon controlled rectifier (SCR)) 12 that receives an AC power and converts it into direct current, and a battery 18 that is a charging unit connected in parallel with the first rectifier. A first inverter 13 which receives the output DC power source and the rectified DC power source and converts the AC power source into AC power; A second rectifier (using SCR) 15 for converting the power into direct current, a second inverter 16 for reconverting the direct-current power back to an AC power at 60 Hz to prevent noise caused by the generated high frequency; The second inverter 16 is composed of a static switch 17 which is a semiconductor such as a thyristor or the like which is switched in accordance with the re-converted AC power and returns its output to the first rectifier 12. Above, the first and second inverters 13 and 16 use IGBTs.

In the UPS of the present invention, when the high frequency transformer 14 is used between the first inverter 13 and the second rectifier 15 without using the input / output transformers 1 and 4, the weight of the conventional UPS is single phase. In comparison with the conventional UPS of FIG. 1, it is about 1/3 lighter, and in the case of three phases, it can be reduced in weight and size to about 2/3. That is, the present invention can achieve a miniaturization and light weight of a UPS by using a high frequency PWM switch method (50KHz). At this time, in miniaturizing the UPS, the present invention reduces the volume of the UPS by making the frequency high frequency among voltage, current, and frequency, which are transformer capacity calculation criteria. The high frequency transformer 14 sets the selection criteria of the transformer to 25.6 KHz instead of 60 Hz, and uses a ferrite core having a high magnetic flux density to solve the heat generation problem of the transformer.

3 is a block diagram illustrating a digital control UPS according to the present invention connected to the components of FIG. 2.

3, the UPS input and output analog signals such as battery current, DC voltage, temperature (0-40 degrees at operation, ideal temperature 15-25 degrees), synchronization, input / output current, input / output voltage, etc. are converted into digital signals. A / D converter 19 for converting, first and second rectifiers 12 and 15, first and second inverters 13 and 16 and SCR static switch 17 shown in FIG. A signal processor 21 for rectifying and converting the input power digitally, including the input power, and providing a driving signal to each device of the signal processor 21, and real-time response to these devices before they are turned off. Detects and protects the semiconductor device, converts this signal into a digital signal, outputs it, automatically performs the efficiency test of the battery 18 at regular intervals, and transfers all running data to the PC through the communication connection. To prevent malfunction 3 is a microprocessor 20 of the RISC (reduced instruction type computer) type, and RS- for serial communication with the microprocessor 20 during operation experiments with all parameter settings using an external PC or a network at a long distance. A 232C communication connection section 22 and a display 23 for displaying a state (for example,) of the input / output digital signal of the microprocessor 20 are configured.

In the above, the microprocessor 20 performs self-tests and diagnostics on reliability and performance, and provides complete diagnostic information by performing a complete self-test on the position and the battery each time the operation is started.

Referring to the operation of FIG. 3 based on the configuration, the analogized signals as described above in the UPS are sent to the microprocessor 20 through the A / D converter 19 and converted into digital signals. The response signal is designed to respond in real time. Therefore, response time can be made very fast. For example, in the present invention, signal processing is possible faster than the response speed of the semiconductor from several ms to several ns, so that the protection of the UPS device is perfect. In addition, as shown in FIG. 3, all signals are operated through the microprocessor 20, so that PC communication is very easy.

However, since the actual control part of the UPS is an analog method, it has a great influence on the addition and cost of parts that need to design a separate A / D converter and a separate microchip for PC communication. That is, as shown in FIG. 3, since the microprocessor 20 transmits all data as a digital signal that can be read by a PC, when the microprocessor 20 communicates with the serial port 22, which is a communication connection unit, the microprocessor 20 is in parallel with the actual values. Since communication allows communication without the configuration of a separate circuit, there is no need to add components for PC communication.

FIG. 4 is a waveform diagram showing switching times (Turn-ON and OFF) of the elements of the first inverter (IGBT) 13 in FIG. 2. This is because the above-mentioned analog UPS has a problem that affects the addition and cost of parts that need to be designed by using a separate A / D converter and a separate microchip for PC communication. It is possible by changing. If you check the device catalog for the turn-off time of the IGBT gate (semiconductor device), the IGBT must be turned off within the maximum 0.8 최대 -1.0㎲ to protect the IGBT. In other words, the device must be turned off quickly. Therefore, microprocessor control has a faster response speed of 100 ns, so if the IGBT and the semiconductor are affected by any external condition, the first inverter (IGBT) 13 and the SCR static switch 17 are turned off faster than this. By switching to bypass, the device can be reliably protected from external factors.

FIG. 5 illustrates a transfer time between the inverter and the KEPCO. FIG. 5 is a description of the SCR static switch 17 of FIG. 2 and illustrates the transition from the inverter to the KEPCO.

In general, when switching from bypass to inverter and from inverter to bypass, when switching is performed within about 4 ms, when KEPCO is momentarily disconnected, it was not detected mechanically or visually. However, due to the development of device civilization, the need for faster transfer time is needed due to the appearance of devices that require more precision. To solve this problem, the transfer time can be advanced up to 20 ms, making it almost impossible to identify and recognize (the transfer time is a time that does not disappear completely).

6 is a configuration diagram and an operation timing diagram of the inverter 16 shown in FIG. 2.

It is common for the PWM frequency generated by the high frequency transformer 14 to be turned on at the same time when the second inverter 16 is driven. In this case, DC (+) and DC (-) imbalances may occur during PWM formation. The unbalanced voltage bias of these devices can be considered a fatal factor to destroy semiconductor devices including IGBTs.

As shown in FIG. 6, the internal structure of the inverter 16 includes a high driver 16a composed of transistors Q1 and Q3, and a row driver 16b composed of transistors Q2 and Q4.

In order to minimize the problem of unbalanced voltage bias of the inverter having such a configuration, FIG. 7 is possible because the following progress command is made by the data promised in the microprocessor 20 at a digitally accurate time.

That is, as shown in FIG. 7, the row driver 16b is first determined by comparing the value previously set by the program to a '0' point. In this case, a half cycle of the frequency formed at 50 KHz, that is, a high frequency of 25 KHz, is kept alive before the inverter turns on. As already set to the '0' point, the imbalance of the inverter does not occur as shown in the waveform shown in FIG.

In FIG. 8, the inverter is driven by turning on only the gate sides of the IGBTs Q1 and Q3 in the high driver 16a in the imbalanced state to form a gate PWM.

In the above-described method of generating the PWM sine wave signal of the inverter shown in FIG. 6, the upper driver (or upper inverter) 16a when the transistors Q2 and Q4 of the lower driver (or lower inverter) 16b are always on. The half-cycle on / off method by transistors Q1 and Q3 is used. More specifically, as shown in Fig. 6, in order for the inverter driving states to operate Q1 and Q3, the conventional method selects and uses a method in which Q1 and Q3 switch simultaneously. This method is cumbersome in that a separate '0' point, that is, a circuit for maintaining an equal state of DC (+) and DC (-), needs to be added. In addition, the driving of the analog signal may result in the loss of the IGBT element of the first inverter 13 shown in FIG. 2 according to the failure and error of the used component (ie, DC (+), DC (-)). Due to the imbalance of).

To solve this problem, as shown in FIG. 6, the pulse of the lower driver 16b is driven in a single pulse so that Q4 can always maintain a '0' point in the open state while the PWM is switched, and the phase reversal is performed. By doing so, the operating states of Q2 and Q4 can be solved in the same manner as the operations of Q1 and Q3. That is, the imbalanced state of DC (+) and DC (-) was solved. Thus, the actual IGBT switching frequency switches to 50KHz (previous about 20KHz) but only 25KHz. This can only be done by precise real-time commands in digital control.

As described above, for the digital control method of the UPS of the present invention, the analog signals output from the elements as shown in FIG. 2 must be converted into digital signals. That is, the system for converting this analog signal into a digital signal is shown in FIG. FIG. 9 is described with a flowchart as shown in FIG. 10.

Referring to FIG. 10, the input voltage is detected 30 and compared with a preset reference value X. As a result of the comparison, if the detected input voltage is not greater than the reference value, the input voltage is detected again 32, and if the input voltage is large, the input voltage signal is converted into a digital signal (33). Then, the microprocessor 20 designates 34 in real time, activates the first and second rectifiers 12 and 15 (35) to detect the DC power, and the detected DC power is a preset reference value ( If not greater than 36, the second rectifier 15 is stopped (37) and the state is shown on the display (38) while proceeding to the conversion step 33. After the real time designation 34 of the microprocessor, the lower inverter 16b of the first inverter 13 is started 39, and if the designated real time is larger than the IGBT arbitrary drive value Y provided in the lower inverter, (40) The second inverter 16 is started (41), and if not started, the second rectifier 15 is stopped (37). After the real time comparison, if the IGBT real time A of the first inverter and the second inverter is less than the transfer time B of the static switch 17 and 43 the PWM sine wave is detected 42, the static switch 17 is turned off. Start (47) and output the PWM sine wave through the second inverter (48). On the other hand, if the IGBT real time A is not less than the static switch switching time B, the static switch and the inverter are stopped and restarted (44, 45, 46). The function of controlling this series of processes was checked in the whole process of one-chipized processors, and then divided in time to proceed to the next step. In addition, if an error occurs in a load, that is, an external cause, the static switch first stops and stops the inverter. If there is no error, the process is repeated again.

As described above, in FIG. 2 of the present invention, when switching using only one SCR (thyristor) as a practical static switch, the switching is possible without a collision with KEPCO. ON), OFF (OFF) time by digitally match the inverter operation time, so that the UPS completes the normal self-diagnosis, and the static switch is turned off when the normal operation of the inverter is correctly performed to cut off the KEPCO power The method is possible because it is a digital real time control method.

That is, in order for the UPS to execute the process of FIG. 2, real-time control must be enabled. The control of such process can be programmed to be commanded by the microprocessor, and the first rectifier 12 and the first rectifier 12 shown in FIG. The inverter 13, the high frequency transformer 14, the second rectifier 15, the second inverter (IGBT 60Hz switch) 16 and the SCR static switch 17 to check whether there is any abnormality during the operation and to make normal operation When the time taken is 20ms, the turn-off time of the SCR static switch 17 is adjusted to enable the switchover from the KEPCO power supply to the inverter power supply at exactly 20ms after driving the inverter.

Using the digital control method of the UPS according to the present invention as described above, to protect the data due to the instantaneous malfunction of the machine caused by all external obstacles, to reduce the size of the UPS, and to reduce the adverse effects of the obstacles By adjusting the response speed or slowing down, it is possible to minimize the loss rate of various semiconductor devices.

In addition, the present invention has no drift phenomenon and is strong against noise compared to the conventional analog system, and it is possible to immediately know the cause of failure through the display without additional hardware, PC communication, and capacity expansion are very easy. This has the effect of simplifying the overall structure.

Claims (6)

An A / D converter 19 for converting input / output analog signals of a UPS (Uninterruptible Power Supply) into digital signals; A signal processor 21 for receiving and rectifying and digitally driving an element driving signal when the input power is bypassed; It provides a drive signal to the device, senses the state before the device is turned off, protects the device, converts and outputs a real-time response signal from the device into a digital signal, and transmits all running data through the communication connection unit. Microprocessor 20 for delivering to the PC to prevent malfunction in advance; A communication connection unit 22 for serial communication with the microprocessor 20 during operation experiments with all parameter settings using an external PC or a network at a long distance; And An uninterruptible power supply of a digital control method comprising a display (23) for displaying the obstacles of the UPS according to the control of the microprocessor 20 as a digital signal. The method of claim 1, The signal processor 21, A first rectifier 12 which receives an AC power and converts it into a DC; A first inverter (13) for receiving the DC power output from the battery (18) connected in parallel with the first rectifier and the rectified DC power and converting the AC power into AC power; A high frequency transformer 14 that receives the converted AC power and generates a high frequency PWM sine wave of about 50 KHz; A second rectifier 15 for converting the AC power into DC; A second inverter 16 for reconverting the DC power back to AC power at 60 Hz to prevent noise caused by the generated high frequency; And And a static switch (17) which is switched according to the AC power reconverted by the second inverter (16) and returns its output to the first rectifier (12). The method of claim 2, The first and second inverters, An upper inverter 16a composed of two transistors Q1 and Q3; A lower inverter 16b composed of two transistors Q2 and Q4; And Each of the transformers (L) between the inverters are combined, the uninterruptible power supply of the digital control method characterized in that the on-off operation by a half cycle by the upper inverter in the always-on state of the lower inverter. The microprocessor 20 receives input / output analog signals indicating the state of the uninterruptible power supply (UPS) as digital signals converted through the A / D converter 19 and according to a supervisory control signal through a communication connection from a remote communication means. Power source input via the 1st rectifier 12, the 1st inverter 13, the high frequency transformer 14 which produces the high frequency PWM sine wave signal, the 2nd rectifier 15, the 2nd inverter 16, and the static switch 17 In the uninterruptible power supply (UPS) that controls the bypass to the KEPCO power supply and displays the control result on the display. A first step (30, 31) of detecting the input power and comparing it with a preset reference value (X); A second step (32, 33) of detecting the input power again if the detected input power is not greater than the reference value, and converting the input power signal into a digital signal as a result of the comparison; The microprocessor designates real time, activates the first and second rectifiers to detect the DC power and if the detected DC power is not greater than the preset reference value X, stops the second rectifier and proceeds to the conversion step 33. A third step 34 to 38 showing the state on the display as it proceeds; After the real time designation of the microprocessor, the lower inverter of the first inverter is started, and if the designated real time is greater than the IGBT arbitrary drive value Y provided in the lower inverter, the second inverter is started. Fourth steps 34, 39-41, 37 for stopping; After the real-time comparison, if the real time (A) of the first inverter and the second inverter is less than the transfer time (B) of the static switch and the PWM sine wave is detected, the static switch is started and the PWM sine wave is output through the second inverter. Fifth step (43, 42, 47, 48); And And a sixth step (44, 45, 46) of stopping and restarting the static switch and the inverter if the real time (A) is not less than the transfer time (B). The method of claim 4, wherein The microprocessor drives the pulse of the lower inverter side composed of the two transistors in a single pulse manner to control any one transistor to maintain a '0' point at all times while the PWM is switched. Digital control method of an uninterruptible power supply. The method of claim 4, wherein The microprocessor is a digital control method of an uninterruptible power supply, characterized in that for generating a PWM sine wave signal of the inverter during the operation of the UPS in a half cycle on / off method by the upper inverter in the always-on state of the lower inverter.