KR19990000604A - Single-phase small uninterruptible power supply - Google Patents

Abstract

The present invention relates to a single-phase small uninterruptible power supply (UPS) that directly transfers power to a load in a steady state in which a commercial power is supplied, trims the battery and improves an input power factor, and maintains an output voltage of a commercial frequency during a power failure, Diodes D1, D2, D3 and D4 connected in parallel in the reverse direction to the switches F1, F2, F3 and F4 and the switches F1, F2, F3 and F4, An inverter circuit 110 composed of capacitors C1, C2, C3, C4 connected in parallel to each other; A battery 4 for charging and supplying electric power; A triac 5 for receiving a control signal during a power failure; A capacitor C connected in parallel to the battery 4; A smoothing circuit 120 composed of an inductor L2 and a capacitor C _P ; A DC side voltage current detection circuit (10) for detecting a DC side voltage and current; A dc side control circuit (20) for outputting an adjustment signal for adjusting charging of the battery (4); A power filter 70 for filtering the power supply voltage signal; A phase synchronization circuit (PLL) 80 for outputting a signal synchronized with the frequency of the filtered signal; A power supply current control circuit (30) for outputting a reference voltage signal; A load voltage control circuit (40) for generating an output current reference signal according to a difference from a specific load voltage; An open / close control circuit (50) for supplying a signal for opening / closing the switches (F1, F2, F3, F4); A driving circuit 51 for driving the gates of the switches F1, F2, F3 and F4; An electrostatic detector (90) for detecting a blackout; And a control unit 100 for replacing the reference signal during the detection of the power failure. In addition, the power factor can be improved and the power factor can be reduced and the power factor can be reduced, This is a very useful and economical invention.

Description

Single-phase small uninterruptible power supply

The present invention relates to a single-phase small uninterruptible power supply, and more particularly, to a single-phase small uninterruptible power supply, more particularly, to a single-phase small uninterruptible power supply apparatus which improves an input power factor by supplying a reactive power of a load, Phase small uninterruptible power supply unit that supplies a charging power of a battery to a load to maintain an output voltage of a commercial frequency when a power failure occurs.

A conventional uninterruptible power supply includes a rectifying circuit 1 for obtaining a direct current from a commercial power supply as shown in FIG. 1; An inverter circuit (2) for converting the obtained direct current power into an alternating current power and supplying it to the load (3); And a battery 4 charged from the obtained direct current power source.

In the conventional uninterruptible power supply apparatus configured as described above, in the steady state in which power is supplied from the commercial power source, the power is converted into direct current by the rectifying circuit 1 and then converted into alternating current by the inverter circuit 2 The inverter circuit 2 is directly supplied to the load 3 and the electric power converted into the direct current by the rectifying circuit 1 charges the battery 4, 4) into an alternating current and supplies the alternating current to the load (3).

However, in the conventional uninterruptible power supply apparatus that operates as described above, the rectifier circuit 1 may be configured as a simple rectifier circuit to convert the commercial power source to DC, but in this case, the input side power factor is deteriorated, There arises a problem that it is required to provide Further, when the rectifying circuit 1 is constituted by an active element, the charging function and the power factor improvement can be achieved at the same time, but the apparatus becomes bulky.

Therefore, in order to solve the above-described problems, the present invention provides a small-sized configuration by not using a separate rectifier, and in a normal state in which the commercial power is supplied, Phase small uninterruptible power supply unit that charges a battery while improving an input power factor and supplies power to the battery when a power failure occurs.

Fig. 1 shows a general configuration of a conventional uninterruptible power supply,

Fig. 2 shows a configuration of a single-phase small uninterruptible power supply according to the present invention,

3 (a) shows a waveform for supplying the required current to the inverter circuit of the single-phase small uninterruptible power supply according to the present invention,

(B) shows a waveform in which the inverter circuit achieves zero voltage switching,

4 is a payload diagram of the input current voltage and the load current voltage in the steady state,

Fig. 5 is a circuit diagram of each configuration of the uninterruptible power supply apparatus of Fig. 2,

(A) is a circuit diagram of a power filter for a synchronizing signal,

(B) is a circuit diagram of a reference signal generating circuit centering on a phase synchronizing circuit,

(C) is a circuit diagram of the switching logic circuit,

(D) is a circuit diagram of the dc side control circuit,

(E) is a circuit diagram of the power supply current control circuit,

(Bar) is a circuit diagram of a control circuit for obtaining a sinusoidal load voltage,

(G) is a circuit diagram of the inverter current command conversion circuit,

FIG. 6 is a waveform diagram of the uninterruptible power supply apparatus of FIG. 2 during a power interruption and recovery process,

FIG. 7 is a waveform diagram for each mode at the time of load,

(A) is the operation waveform in the backup mode,

(B) is the operation waveform of the bypass mode,

FIG. 8 shows waveforms of voltage and current during the switching operation of the inverter circuit of FIG. 2. FIG.

Description of the Related Art [0002]

1: rectification circuit 2, 110: inverter circuit

3: Load 4: Battery

5: Triac 10: DC side voltage current detection circuit

20: DC side control circuit 30: Power supply current control circuit

40: load voltage control circuit 50: open / close control circuit

51: drive circuit 70: power filter

80: phase-locked loop 90: electrostatic detector

100: control unit 120: smoothing circuit

301: multiplier 401: switch

501: comparator 801: voltage-controlled oscillator

901: Upper circuit of the electrostatic detector 902: Window comparator

903: comparator

C, C _P , C1, C2, C3, C4: Capacitors D1, D2, D3, D4:

F1, F2, F3, F4: Switch

According to an aspect of the present invention, there is provided a single-phase small uninterruptible power supply apparatus comprising: an inverter circuit for forming an intermittent power path between a connection point of a commercial power supply and a load and a battery; A smoothing circuit connected between the inverter circuit and the load; Detecting means for detecting presence / absence of power failure of the commercial power supply; A current control element for disconnecting the commercial power supply path when the detection means senses a power failure; A reference signal generating means for generating a different reference signal according to whether or not the sensing means senses a power failure; And control means for comparing an output current control signal of a self-generated constant frequency with the reference signal and for interrupting the power path of the inverter circuit accordingly.

In the single-phase small-sized electroless-ago power supply apparatus according to the present invention, the sensing means senses whether or not the commercial power source is out of power, and when the sensing means senses a power failure, . The reference signal generating means generates a different reference signal according to the detection of the power failure of the sensing means. The reference signal generated when the commercial power is supplied is a signal corresponding to the ineffective current and the harmonic component generated in the load current, The signal generated at the time of power failure is a sinusoidal signal of a commercial frequency. Wherein the control means compares the generated reference signal with a signal for controlling the output current of the inverter of a constant frequency generated by itself so that the envelope of the inverter current repeating the increase and decrease is equal to the reference signal, So that the power path between the battery and the load is interrupted.

According to the above operation, the current of the inverter circuit compensates for the reactive power and harmonic power of the load in a steady state, and supplies power to the load from the battery at the time of a power failure. In addition, the reference signal generated by the reference signal generating means in the steady state is adjusted so that the active power flows through the inverter circuit, so that a current larger than the current required in the load from the commercial power source flows into the inverter circuit, The battery is trickle charged.

Hereinafter, the configuration and operation of a preferred embodiment of the single-phase small uninterruptible power supply according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows a configuration of a preferred embodiment of a single-phase small uninterruptible power supply apparatus according to the present invention, in which a field effect transistor (FET) is connected in a full- Second, third, and fourth diodes D1, D2, and D4 connected in parallel to the switches F1, F2, F3, and F4, Second, third and fourth capacitors C1, C2, C3 and C4 connected in parallel to the switches F1, F2, F3 and F4, respectively, ); A battery 4 for charging and supplying electric power; A triac 5 composed of one control electrode (gate) and two main electrodes, and receiving a control signal during a power failure; A capacitor C connected in parallel to the battery 4; A smoothing circuit 120 composed of an inductor L2 and a capacitor C _p for smoothing the output power of the inverter circuit 110; A DC side voltage current detection circuit (10) for detecting a DC side voltage and current; A dc side control circuit (20) for outputting an adjustment signal for adjusting the charging of the battery (4) from the detected dc voltage and current; A power filter 70 for filtering the power supply voltage signal; A phase synchronization circuit (PLL) 80 for outputting a signal synchronized with the frequency of the filtered signal; A power supply current control circuit (30) for outputting a reference voltage signal for controlling the phase and magnitude of an input current based on the synchronized signal and the adjustment signal; A load voltage control circuit (40) for selecting the reference voltage signal according to the presence or absence of a power failure to generate an output current reference signal corresponding to a difference from a specific load voltage; An open / close control circuit (50) for supplying a signal for opening / closing the switches (F1, F2, F3, F4) compared with a triangular wave signal of a constant frequency generating the output current reference signal by itself; A driving circuit 51 for power-amplifying the switching signal to drive the gates of the switches F1, F2, F3 and F4; An electrostatic detector (90) for rectifying the difference between the reference voltage and the input voltage and detecting the electrostatic charge in the magnitude; And a control unit (100) for controlling the respective components to replace the gate signal of the triac (5) and the reference signal in accordance with the detection of the electrostatic condition of the electrostatic detector (90).

The overall operation of the single-phase small uninterruptible power supply according to the present invention will now be described. First, the apparatus has two operation modes, a by-pass mode and a backup mode. The triac 5 is in the ON state and the power is almost directly transferred from the power supply 3 to the load 3 and the apparatus is capable of improving the power supply current waveform and charging the battery 4 And the output voltage V ₂ in this mode is determined by the power supply voltage V ₁ . However, in the backup mode, the triac 5 is in the OFF state, and the present apparatus receives the DC power from the battery 4 and supplies the AC power to the load 3, Is maintained at a constant voltage of a certain frequency.

In the bypass mode in which power is supplied, the single-phase small uninterruptible power supply apparatus of Fig. 2 controls the current (i ₁ ) flowing in the power supply side to be in phase with the voltage (V ₁ ) and to be sinusoidal. Referring to the phaser diagram of FIG. 4, the principle will be described as follows.

When the battery 4 is in a trickle charge state and this fine charge current is relatively small and is neglected, all the power input from the power source side is transmitted to the load 3 side, so that the input current i ₁ is It has the same size as the expression.

Equation (1)

Power supply side is a, as shown in I Fig page 4 in order to prevent the reactive power flow through the load (3) reactive current component (I ₂ sin θ) and invalid current component (I ₂ sinφ) required for the inductor (L1) of The output current reference signal is generated in the load voltage control circuit 40 so that the differential current of the current flowing from the sum to the capacitor C _p flows into the inverter circuit 110.

In order to place the battery 4 in the charged state, the power supplied to the load 3 must be greater than the power used for the load 3. That is, V ₁ I ₁ = V ₂ I ₂ cos φ + 1) and its value is given by

Equation (2)

Therefore, the single-phase small uninterruptible power supply apparatus of FIG. 2 controls the charge current of the battery 4 by controlling the magnitude of the input current i ₁ without a separate charger, And the magnitude of the input current is controlled by the variation of the reference voltage signal of the power supply current control circuit 30 that reflects the adjustment signal by the control signal.

When the above control is normally performed, the input side current i ₁ becomes a sinusoidal wave, and the low harmonic of the load 3 side is supplied from the inverter circuit 110, and a high harmonic current flows through the parallel capacitor C _p , And the harmonic current generated during the switching operation of the inverter circuit 110 also flows to the capacitor C _P to operate as an active power filter to remove harmonic components.

Hereinafter, the operation of the single-phase small uninterruptible power supply of FIG. 2 will be described in detail with reference to a circuit diagram of each constitution.

First, the power filter 70 is constructed as shown in FIG. 5 (a) to remove noise introduced from a power source and provide a power synchronization signal to the phase synchronization circuit 80 in the subsequent stage. , It is possible to detect an erroneous detection point of a synchronous signal to be used by detecting a power point of a normal power source. In the power supply filter 70 shown in Fig. 5 (A), the resistive-capacitor circuit and the differential amplifier in the preceding stage delay the input signal by 45 [deg], respectively, and the synchronous signal SYNCH obtained in the above- The voltage controlled oscillator (VCO) 801 in the phase synchronization circuit 80 outputs a signal synchronized with the applied synchronization signal SYNCH.

Since the output signal of the voltage-controlled oscillator 801 includes a direct current component, the direct current component is removed through the AC coupling amplifier, the noise is removed through the low-pass filter, and the output signal is output as a reference signal Sine by 45 [deg] do. The reference signal Sine is delayed by 45 [deg] again for the voltage command in the backup mode, so that a phase delay of 180 [deg.] Is generated with the power source and is used as a signal synchronized with the power source. It is delayed by 45 [deg] after the multiplier described later and is used as a signal synchronized with the power supply.

The signal filtered by the power filter 70 and the output signal of the phase synchronizing circuit 80 are inputted to the electrostatic detector 90 connected to the circuit as shown in FIG. 5 (c) The upper circuit 901 rectifies the difference between the reference voltage and the input voltage and judges the power failure by the magnitude thereof. In order to obtain the difference between the two voltages, an instantaneous value is used. Therefore, even when the phase is out of order, a power failure is determined so that the phase synchronization circuit 80 performs a normal recovery procedure after the phase synchronization circuit 80 completes synchronization. The circuit comparator 902 of the lower circuit sets the value of the circuit element so that the circuit 901 is judged to be a blackout if the voltage difference is out of 15% The value is small, and there may be an error in the determination. Therefore, the determination section is set excluding the vicinity of the zero crossing, and the determination section is applied to the control section 100. The comparator 903 in the electrostatic detector 90 outputs a synchronous clock synchronized with the zero crossing to the controller 100 so that the switching of the controller 100 synchronizes with the zero crossing of the reference signal V _ref2 .

The control unit 100 immediately removes the gate signal of the triac 5 and outputs the gate signal of the triac 5 when the synchronous clock signal is input to the control unit 100 in accordance with the determination value of the upper circuit 901 of the electrostatic detector 90. [ The load voltage control circuit 40 switches the reference voltage of the load voltage control circuit 40 so as to maintain the voltage at a constant voltage and constant frequency, The reference voltage of the circuit 40 is synchronously switched.

On the other hand, the DC voltage-current detection circuit 10 detects the voltage (E _b ) of the battery 4 using a resistive voltage divider, detects a current using a voltage drop by a resistor, To the circuit (30). The power supply current control circuit 30 configured as shown in FIG. 5 (D) compares the reference voltage adjusted by the diode D6 with the sum of the voltage by the feedback DC voltage V _fb and the current I _fb And the adjustment signal I * according to the comparison is output to simultaneously perform the function of charging the battery 4 by the feedback voltage V _fb and the function of floating charge by the feedback DC current I _fb To the power supply current control circuit 30 so that the power supply current can be controlled.

The power supply current control circuit 30 configured as shown in FIG. 5 (e) outputs two reference voltages V _ref and V _ref2 . One signal is a constant current (2) for charging the battery 4, and the other signal is a signal V _{ref2 for} outputting a signal that freely oscillates in frequency with a delay of 45 [ The output signal Sine of the phase synchronizing circuit 80 is multiplied by the signal I * by the multiplier 301 and then the output signal Sine of the phase synchronizing circuit 80 as described in the description of the phase synchronizing circuit 80 Likewise, it is a 45 ° delayed signal (V _ref ).

The two signals V _ref and V _ref2 are applied to the load voltage control circuit 40 and selected by a control signal according to the presence or absence of a power failure of the control unit 100 and used as a reference voltage.

The two reference voltages V _ref and V _ref2 are applied to the load voltage control circuit 40 to act as target values of the different detection voltages, respectively. As shown in (bar) of FIG. 5, The voltage V _ref used as the reference voltage is compared with the voltage V _ser across both ends of the inductor L1 through which the power supply current flows and the voltage V _ref2 used as the reference voltage during the power failure is compared with the voltage applied to the smoothing capacitor C _p (V _ser2 ).

The pair (V _ser , V _ref or V _ser2 , V _ref2 ) to be compared is determined by the switch 401 in the circuit by the electrostatic discrimination signal of the controller 100. When the pair to be compared is determined, circuit detection voltage (an inductor (L1) the voltage across or the capacitor (C _P), the voltage across) the reference voltage (V _ref, V _ref2), the output current reference signal to be provided by the inverter circuit 110 to ensure close proximity to (I _ref ) to be applied to the open / close control circuit 50.

When the output current reference signal I _ref is input to the open / close control circuit 50 configured as shown in FIG. 5 (D), the output current reference signal I _ref is clamped to positive and negative voltages by the diodes D1 and D2, In the section where the voltage exists, the positive voltage signal is outputted as the upper limit signal (U_limit) and the negative certain voltage is outputted as the lower limit signal (L_limit). In the section where the negative voltage exists, And a negative voltage signal is output as a lower limit signal. 3 (A) shows an example in which an upper limit signal and a lower limit signal according to the circuit operation are outputted.

When the upper limit signal U_limit and the lower limit signal L_limit obtained as described above are input to the comparator 501 in the circuit, the comparator 501 compares the frequency of the self-generated triangle wave Outputs an open / close signal for opening / closing the switches F1, F2, F3, and F4 in the inverter circuit 110 according to a result of comparison between the signal R _i and the limit signals U_limit and L_limit, Is amplified by the driving circuit 51 and applied to the gates of the switches F1, F2, F3 and F4. The opening and closing operation of the above-described switching device performs the zero voltage switching. Hereinafter, the zero voltage switching process will be described in detail.

First, it is assumed that the first and fourth switches F1 and F4 of the switches F1, F2, F3 and F4 are turned on. In this state, the inverter circuit 110 supplies reactive power and harmonics to the load 3 or supplies the constant power of the commercial frequency from the battery 4 to the load 3 by the above-described operation. The output current i ₃ of the inverter circuit 110 also increases when the first and fourth switches F1 and F4 are turned on and the self-generated triangular wave signal R _i increases. When the magnitude of the increasing triangular wave signal R _i exceeds the upper limit signal U_limit described above, the triangular wave signal R _i is immediately reduced, and the comparator 501 compares the triangular wave signal R _{i with} the first switch F1) and the fourth switch F4 to turn off the corresponding switch (t1). Since the first capacitor C10 and the fourth capacitor C4 are connected to both ends of the first switch F1 and the fourth switch F4 respectively, the voltage does not change abruptly and the first switch F1 and the fourth switch The switch F4 is turned off at zero voltage.

It said first switch (F1) and the fourth switch drive current (i ₃₎ (F4) that flows through the turn is off after the smoothing inductor (L2) is to flow, while charging the first and the fourth capacitor (C1, C4) gradually At this time, the voltages at both ends of the parallel capacitors C2 and C3 of the second and third switches F2 and F3 decrease at the same ratio. When the voltage across both ends of the second and third capacitors C2 and C3 is completely discharged, the current flowing through the inductor L2 flows through the second and third switches F2 and F3, And the third diodes D2 and D3 to make the voltage between both ends of the second and third switches F2 and F3 zero. After the second and third diodes (D2, D3) the conduction is the there is the drive current (i _a) is urgently reduced, the current decreases after the conduction of the second and third diodes (D2, D3) polarized A turn-on voltage is applied to the gates of the second and third switches F2 and F3 within a period Ta from when the first and second switches F2 and F3 turn on at zero voltage do.

Meanwhile, while the inverter current i _a is decreasing, the triangular wave signal R _i is maintained at a constant rate, and when the polarity of the triangular wave signal R _i is changed to reach the lower limit signal L_limit, And the triangular wave signal R _i is immediately increased. As the operation is repeated, the inverter circuit 110 performs the zero voltage switching and outputs the output current i _a , In the form of an output current reference signal I _ref required by the load voltage control circuit 40. [

6 to 8 are waveforms of experimental results of the single-phase small uninterruptible power supply according to the present invention, which are obtained by using a simple rectifying circuit as a load. FIG. 6 is a waveform diagram for illustrating a switching process of the single-phase small uninterruptible power supply apparatus of the present invention during power failure and recovery, showing switching between modes without changing the phase of the output voltage. FIG. 7 is a graph showing waveforms of respective modes at the time of load. In the backup mode, all the load currents are provided by the inverter circuit. In the bypass mode, the ineffective and harmonic components of the load current are supplied to the inverter circuit To show that the supply current is a clean sinusoidal wave.

8 shows that the voltage across the uppermost stage of the switch F2 gradually decreases for two seconds after the gate signal is removed and the gate signal is applied to the other switch F1 after the voltage across both ends thereof becomes zero, It shows that the operation is done at zero voltage.

Accordingly, in the single-phase small uninterruptible power supply apparatus according to the present invention configured as described above, the input power factor is improved by supplying the ineffective component and the harmonic component of the load current in the supply state of the power source, and a separate rectifier, a charger and a transformer It is a very useful and cost-effective invention that not only can be manufactured in a small size because it is not used, but also can reduce power loss by implementing zero voltage switching that reduces switching loss.

Claims (7)

An inverter circuit that forms an intermittent power path between the connection point of the commercial power supply and the load and the battery; A smoothing circuit connected between the inverter circuit and the load; Detecting means for detecting presence / absence of power failure of the commercial power supply; A current control element for disconnecting the commercial power supply path when the detection means senses a power failure; A reference signal generating means for generating a different reference signal according to whether or not the sensing means senses a power failure; And And a control means for comparing an output current control signal of a self-generated constant frequency with the reference signal and for interrupting the power path of the inverter circuit accordingly. The method according to claim 1, The inverter circuit includes: Four switching elements constituted of a full bridge and controlled by the control means to be opened and closed; Four rectifying elements connected in parallel in the reverse direction of the switching elements; And And four capacitive elements connected in parallel with the switching elements. 3. The method of claim 2, Wherein the reference signal generating means comprises: A target signal output means for selecting one of a load voltage and a supply current according to the presence or absence of the detection of a blackout of the sensing means and outputting a target signal according to the selection; And And limit signal output means for inverting the upper limit signal and the lower limit signal to be output and outputting the upper limit signal and the lower limit signal when the target signal is inverted, Wherein the control means opens a pair of switching elements short-circuited when a triangular wave signal of a self-generated frequency exceeds the upper limit signal or the lower limit signal, and after the capacitive element connected in parallel to the open switching element is charged And short-circuits the other pair of switching elements before the current flowing in the inverter circuit is inverted. The method of claim 3, Wherein the upper limit signal and the lower limit signal are composed of a pair of the target signal and a DC signal having a constant value. The method of claim 3, Wherein the target signal output means outputs a target signal for causing a power supply current larger than the load current to flow in a non-operating state. The method of claim 3, And the target signal outputting means outputs a target signal corresponding to the ineffective component of the load current at the time of the uninterruptible power supply. An inverter circuit that forms an intermittent power path between the connection point of the commercial power supply and the load and the battery; A smoothing circuit connected between the inverter circuit and the load; A power filter for outputting a power supply voltage through a filter; A phase synchronization circuit outputting a signal synchronized with the frequency of the filtered signal; An electrostatic detector for rectifying the difference between the synchronized signal and the input voltage, determining a power failure by the magnitude thereof, and outputting a determination signal in synchronization with the synchronized signal; A current control element for maintaining / blocking the commercial power path according to the discrimination signal; A DC voltage current detection circuit for detecting a voltage and a current of the battery; A DC side control circuit for outputting an adjustment signal for adjusting charging of the battery from the detected DC voltage and current; A reference voltage signal for controlling the phase and magnitude of the input current based on the synchronized signal and the adjustment signal and a power supply current control for outputting a reference voltage signal obtained by phase- Circuit; A load voltage control circuit for selecting one of the two reference voltages according to the determination signal to generate an output current reference signal corresponding to a difference from the specific load voltage; And And an open / close control circuit for opening / closing the inverter circuit by comparing the output current reference signal with a triangular wave signal having a constant frequency that generates the output current reference signal.