CN101567573A - Uninterrupted power and control method thereof - Google Patents

Abstract

The invention discloses an uninterruptible power supply and a control method thereof. The uninterruptible power supply includes a boosting module and an inverter module, and the boosting module includes a first switch tube, a second inductor, a first diode, a first capacitor, a second capacitor, a second diode, a first inductor, a second switch tube, a third switch tube and a fourth switch tube; the source of the third switch tube is coupled to the source of the first switch tube and the second switch tube Between the drains of the switch tubes, the drain of the third switch tube is coupled between the second inductor and the anode of the first diode, and the drain of the fourth switch tube is coupled between the source of the first switch tube and the anode of the second switch tube Between the drains, the source of the fourth switching tube is coupled between the first inductor and the cathode of the second diode; the drain of the first switching tube is coupled between the positive pole of the battery and the second inductor, and the source of the second switching tube is coupled Between the negative terminal of the battery and the first inductor. The invention has simple circuit structure and high efficiency.

Description

An uninterruptible power supply and its control method

technical field

The invention relates to an uninterruptible power supply, and also relates to a control method of the uninterruptible power supply.

Background technique

The existing uninterruptible power supply circuit has a complex structure and low efficiency.

Contents of the invention

The technical problem to be solved by the present invention is to propose a simple uninterruptible power supply and its control method in order to overcome the above deficiencies.

The technical problem of the present invention is solved by the following technical solutions: an uninterruptible power supply, including a boost module and an inverter module, the boost module boosts the battery voltage and outputs it to the inverter module in battery mode, so The inverter module inverts the received DC voltage signal into an AC signal, and the step-up module includes a first switch tube, a second inductor, a first diode, a first capacitor, a second capacitor, and a second capacitor connected in sequence. Two diodes, a first inductor and a second switch tube, and a third switch tube and a fourth switch tube; the source of the third switch tube is coupled between the source of the first switch tube and the second switch tube Between the drains, the drain of the third switching tube is coupled between the second inductor and the anode of the first diode, and the drain of the fourth switching tube is coupled between the source of the first switching tube and the second Between the drains of the switching tubes, the source of the fourth switching tube is coupled between the first inductor and the cathode of the second diode; the drain of the first switching tube is coupled between the positive pole of the battery and the second inductor, The source of the second switching tube is coupled between the negative pole of the battery and the first inductor.

The uninterruptible power supply also includes a first current transformer and a second current transformer, and the drain of the third switching tube is connected between the second inductor and the anode of the first diode through the primary side of the first current transformer Between, the source of the fourth switching tube is connected between the first inductor and the second diode cathode via the primary side of the second current transformer; the secondary side of the first current transformer and the second current transformer respectively coupled to the current acquisition module, the current acquisition module is coupled with the boost module controller, the current acquisition module collects the current flowing through the first inductor or the second inductor and outputs it to the boost module controller, the The boost module controller compares the current flowing through the first inductor or the second inductor with the current loop setting, and then generates a corresponding control signal through proportional control and outputs it to the fourth switch tube or the third switch tube.

A control method for the above-mentioned uninterruptible power supply, judging whether the modulation signal of the controller of the inverter module is greater than the first preset value, and if so, outputting a turn-on signal to the second switch tube and a turn-off signal to the first switch tube ; If otherwise, it is judged whether the modulation signal of the controller of the inverter module is less than the second preset value, and if so, output a turn-on signal to the first switch tube and a turn-off signal to the second switch tube, if otherwise, output a turn-off signal to the second switch tube The first switch tube and the second switch tube.

The control method further includes: the second switching tube is turned on before the third switching tube, and the third switching tube is turned off before the second switching tube; the first switching tube is turned on before the fourth switching tube, so The fourth switching tube is turned off prior to the first switching tube.

The control method also includes collecting the current flowing through the first inductance and the second inductance, comparing the current flowing through the first inductance or the second inductance with the current loop setting, and then generating a corresponding control signal through proportional control and outputting it to the fourth The switching tube or the third switching tube, so that the current flowing through the first inductor and the second inductor can be locked at the given current loop.

Compared with the prior art, the present invention has the beneficial effects that: the uninterruptible power supply circuit of the present invention has simple structure and high efficiency. The control method of the invention can reduce the stress of the switch tube and improve the efficiency of the whole machine in the battery mode.

Description of drawings

Fig. 1 is the structural representation of the uninterruptible power supply of the specific embodiment of the present invention;

Fig. 2 is a schematic diagram of the inductive charging process of the uninterruptible power supply of the specific embodiment of the present invention working in the negative half cycle of the inverter;

Fig. 3 is a schematic diagram of the inductance discharge process of the uninterruptible power supply of the specific embodiment of the present invention working in the negative half cycle of the inverter;

Fig. 4 is a schematic diagram of the inductive charging process of the uninterruptible power supply of the specific embodiment of the present invention working in the negative and positive cycles of the inverter;

Fig. 5 is a schematic diagram of the inductance discharge process of the uninterruptible power supply of the specific embodiment of the present invention working in the positive half cycle of the inverter;

Fig. 6 is a schematic diagram of the inductance discharge process of the uninterruptible power supply of the specific embodiment of the present invention working in the positive half cycle of the inverter;

Fig. 7 is a schematic diagram of the control of the uninterruptible power supply in the battery mode according to the specific embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings.

As shown in Figure 1, an uninterruptible power supply includes a boost module and an inverter module. In battery mode, the boost module boosts the battery voltage and outputs it to the inverter module, and the inverter module will receive The DC voltage signal is inverted into an AC signal. The boost module includes a first switch tube Q1, a second inductor L2, a first diode D1, a first capacitor C1, a second capacitor C2, a second diode D2, a first inductor L1, and a second switch tube Q2, the third switching tube Q3 and the fourth switching tube Q4.

As shown in Figure 1, the first switching tube Q1, the second inductor L2, the first diode D1, the first capacitor C1, the second capacitor C2, the second diode D2, the first inductor L1 and the second The switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are connected in sequence.

The source of the third switching transistor Q3 is coupled between the source of the first switching transistor Q1 and the drain of the second switching transistor Q2, and the drain of the third switching transistor Q3 is coupled between the second inductor L2 and the second inductor L2. Between the anodes of a diode D1, the drain of the fourth switching tube Q4 is coupled between the source of the first switching tube Q1 and the drain of the second switching tube Q2, and the source of the fourth switching tube Q4 The pole is coupled between the first inductor L1 and the cathode of the second diode D2.

The drain of the first switching transistor Q1 is coupled between the positive pole of the battery and the second inductor L2 , and the source of the second switching transistor Q2 is coupled between the negative pole of the battery and the first inductor L1 . Specifically, the drain of the first switching tube Q1 is connected to the positive pole of the battery through the third relay RY3 and the fuse F4, and the source of the second switching tube Q2 is connected to the negative pole of the battery.

As shown in FIG. 1 , the uninterruptible power supply further includes a first current transformer CT1 and a second current transformer CT2 , a current acquisition module and a boost module controller (not shown in the figure). The drain of the third switching tube Q3 is connected between the second inductor L2 and the anode of the first diode D1 through the primary side of the first current transformer CT1, and the source of the fourth switching tube Q4 is connected between the second inductor L2 and the anode of the first diode D1 through the second current transformer CT1. The primary side of the transformer CT2 is connected between the first inductor L1 and the cathode of the second diode D2. The secondary side of the first current transformer CT1 is coupled to the current acquisition module, the secondary side of the second current transformer CT2 is also coupled to the current acquisition module, and the current acquisition module is coupled to the boost module controller. The current collection module collects the current flowing through the first inductor L1 or the second inductor L2 and outputs it to the boost module controller, and the boost module controller collects the current flowing through the first inductor L1 or the second inductor L2 Compared with the given current loop, a corresponding control signal is generated through proportional control and output to the fourth switching tube Q4 or the third switching tube Q3. The control signal is a pulse width modulation (Pulse Width Modulation, PWM for short) signal, and the current flowing through the first inductor L1 or the second inductor L2 can be changed by adjusting the duty cycle of the PWM signal.

The uninterruptible power supply shown in Figure 1 is a single-phase output. The single-phase output of the inverter module is to make the energy of the UPS relatively stable from rectification to inverter.

The working principle of the above uninterruptible power supply is as follows:

As shown in Figure 2, when the inverter is in the negative half cycle, the first switching tube Q1 is turned on, the switching frequency can be 100HZ, and the fourth switching tube Q4 performs high-frequency chopping. When the fourth switching tube Q4 is turned on, the first The inductor L1 stores energy, and its current flow direction is shown in Fig. 2 .

As shown in FIG. 3 , when the first switching tube Q1 is turned on and the fourth switching tube Q4 is turned off, the first inductor L1 discharges to charge the negative bus ( C2 ), and its current flow is shown in FIG. 3 .

As shown in Figure 4, when the inverter is in the positive half cycle, the second switching tube Q2 is turned on, the switching frequency can be 100HZ, and the third switching tube Q3 performs high-frequency chopping. When the third switching tube Q3 is turned on, the The second inductor L2 stores energy, and its current flow is shown in FIG. 4 .

As shown in Figure 5, when the second switching tube Q2 is turned on and the third switching tube Q3 is turned off, the second inductor L2 discharges to charge the positive bus (C1), and its current flow is shown in Figure 5

In order to maintain the stability of the bus in the battery mode, it is more important to control the first switching tube Q1 and the second switching tube Q2. As shown in Figure 6, the above-mentioned UPS can adopt the following control method: judge whether the modulation signal of the controller of the inverter module is greater than the first preset value a, and if so, output a turn-on signal to the second switch tube Q2, turn off the signal to the first switch tube Q1; if otherwise, it is judged whether the modulation signal of the controller of the inverter module is less than the second preset value -b, and if so, the turn-on signal is output to the first switch tube Q1, and the turn-off signal is sent to the second switch The tube Q2, otherwise, outputs a shutdown signal to the first switching tube Q1 and the second switching tube Q2. In Fig. 6, the sine wave is the reference waveform of the modulation signal of the controller of the inverter module. During the period from a1 to a2, the second switch tube Q2 is turned on, and the first switch tube Q1 is turned off; during the period from b1 to b2, Q1 is turned on, the first switch tube Q1 is turned on, and the second switch tube Q2 is turned off. A dead zone is naturally generated during the period from a2 to b1.

According to the analysis of the working principle of UPS, the positive half cycle of the inverter should be composed of the second switching tube Q2 and the third switching tube Q3; the negative half cycle of the inverter should be the first switching tube Q1 and the third switching tube Q3. A loop composed of four switching tubes Q4. Therefore, the control of the first switching tube Q1 and the second switching tube Q2 must be synchronized with the positive and negative alternation of the inverter, and because Q1 and Q2 are connected in parallel at the positive and negative ends of the battery, the first switching tube Q1 and the second switching tube Q2 cannot be directly connected, otherwise it will short-circuit the battery, so there must be a dead time between the first switch tube Q1 and the second switch tube Q2, but the dead time should not be left too long, otherwise it will affect inverted waveform.

In addition, during the working process of the UPS, the inverter module has a phase-locked adjustment process. For example, when the input is switched from the mains to the battery, the tracking object of the inverter changes from the bypass to the local oscillator. During the phase adjustment process, in order to maintain the stability of the bus, we selected the modulation signal of the controller of the inverter module as the control reference waveform of the first switching tube Q1 and the second switching tube Q2. During the inverter phase-locking process, the phase shift of the inverter waveform is relatively large, and the control of the first switching tube Q1 and the second switching tube Q2 by the method of the present invention can ensure a smooth transition of the inverter output during the entire phase-locking process, Ensuring the balance of input and output energy will not cause large fluctuations in the bus.

In the present invention, the dead zone is generated without using the method of leaving a fixed delay time in the prior art, because it is difficult to ensure the transient change of the inverter under various working conditions, we directly use the positive and negative half cycle gate The limits a, -b naturally generate a dead zone. Although this kind of dead zone will cause no control waveform to be issued at the zero-crossing point of the inverter, at this time, whether it is a resistive load or a rectified load, the current is zero or close to zero, so the energy of the bus capacitor It can be fully supported without causing distortion of the inverter waveform.

In the present invention, the working sequence of the step-up module should coincide with the inverter sequence, which can ensure the smooth flow of energy of the whole machine and reduce bus ripple and reactive power loss.

The above UPS also adopts the following control method:

The second switch tube Q2 is turned on before the third switch tube Q3, and the third switch tube Q3 is turned off before the second switch tube Q2; the first switch tube Q1 is turned on before the fourth switch tube Q4, and the The fourth switching tube Q4 is turned off prior to the first switching tube Q1. This avoids high voltage stress at both ends of the first switching tube Q1 and the second switching tube Q2,

As shown in Figure 7, the above UPS also adopts the following control method:

Collect the current flowing through the first inductor L1 and the second inductor L2, compare the current flowing through the first inductor L1 or the second inductor L2 with the current loop setting, and then generate a corresponding control signal through proportional control and output it to the fourth switch tube Q4 or the third switch tube Q3, so that the current flowing through the first inductor L1 and the second inductor L2 is locked at a given current loop. Since there is a dead time between the first switching tube Q1 and the second switching tube Q2, when the UPS output is fully loaded, the battery current will change from the rated value to zero every once in a while and then change again at the other end. To the rated value, in this case, the battery current will have relatively large distortion in the power frequency cycle, which will affect the efficiency of the whole machine in battery mode. The present invention can avoid the above situation, improve the dynamic response capability of the UPS in the battery mode, and improve the efficiency of the whole machine.

The present invention has a very good battery current effect for improving the topology of the positive and negative busbars generated by a single battery in the UPS, because generally for the positive and negative bipolar busbars, a group of batteries is generally used for the positive and negative busbars, so that The current of the battery is basically in a continuous state, but when a single battery is used, the battery current needs to be controlled artificially to achieve smoothness.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be assumed that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deduction or replacement can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (5)

1. An uninterruptible power supply, comprising a boost module and an inverter module, in battery mode, the boost module boosts the battery voltage and outputs it to the inverter module, and the inverter module receives the DC voltage signal Inversion into an AC signal, characterized in that: the step-up module includes a first switch tube (Q1), a second inductor (L2), a first diode (D1), a first capacitor (C1), The second capacitor (C2), the second diode (D2), the first inductor (L1), the second switch tube (Q2), and the third switch tube (Q3) and the fourth switch tube (Q4); the The source of the third switching tube (Q3) is coupled between the source of the first switching tube (Q1) and the drain of the second switching tube (Q2), and the drain of the third switching tube (Q3) is coupled between Between the second inductor (L2) and the anode of the first diode (D1), the drain of the fourth switching tube (Q4) is coupled between the source of the first switching tube (Q1) and the second switching tube ( Between the drains of Q2), the source of the fourth switching tube (Q4) is coupled between the first inductor (L1) and the cathode of the second diode (D2); the drain of the first switching tube (Q1) The pole is coupled between the positive pole of the battery and the second inductor (L2), and the source of the second switching tube (Q2) is coupled between the negative pole of the battery and the first inductor (L1). 2. The uninterruptible power supply according to claim 1, characterized in that: it also includes a first current transformer (CT1) and a second current transformer (CT2), and the drain of the third switching tube (Q3) is passed through the first current transformer (CT1). The primary side of a current transformer (CT1) is connected between the second inductance (L2) and the anode of the first diode (D1), and the source of the fourth switching tube (Q4) passes through the second current transformer (CT2) ) is connected between the first inductor (L1) and the cathode of the second diode (D2); the secondary sides of the first current transformer (CT1) and the second current transformer (CT2) are respectively coupled to A current collection module, the current collection module is coupled with the boost module controller, the current collection module collects the current flowing through the first inductor (L1) or the second inductor (L2) and outputs it to the boost module controller , the boost module controller compares the current flowing through the first inductor (L1) or the second inductor (L2) with the given current loop, and then generates a corresponding control signal through proportional control and outputs it to the fourth switch tube (Q4) or the third switching tube (Q3). 3. A control method for the uninterruptible power supply according to claim 1, characterized in that: it is judged whether the modulation signal of the controller of the inverter module is greater than the first preset value, and if so, the conduction signal is output to the second Switch tube (Q2), turn off signal to the first switch tube (Q1); if otherwise, judge whether the modulation signal of the controller of the inverter module is less than the second preset value, and if so, output the conduction signal to the first switch tube (Q1), the shutdown signal is sent to the second switch tube (Q2), if otherwise, the shutdown signal is output to the first switch tube (Q1) and the second switch tube (Q2). 4. The control method according to claim 3, characterized in that: the second switching tube (Q2) is turned on before the third switching tube (Q3), and the third switching tube (Q3) is turned on before the second switching tube (Q3) The tube (Q2) is turned off; the first switch tube (Q1) is turned on before the fourth switch tube (Q4), and the fourth switch tube (Q4) is turned off before the first switch tube (Q1). 5. The control method according to claim 3, characterized in that: it also includes collecting the current flowing on the first inductance (L1) and the second inductance (L2), and converting the first inductance (L1) or the second inductance (L2) to ) is compared with the given current loop, and then the corresponding control signal is generated through proportional control and output to the fourth switching tube (Q4) or the third switching tube (Q3), so that the first inductor (L1), the second inductor The current flowing on (L2) is locked at the given current loop.

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