CN206195602U - UPS power with active power filter function - Google Patents

Abstract

The utility model relates to a UPS power supply with an active filtering function, comprising: an AC/DC rectifier circuit, a DC/AC inverter circuit, a drive circuit, a charge and discharge circuit, a main control circuit, and a detection circuit. The charge and discharge circuit The output end of the detection circuit is connected to the input end of the DC/AC inverter circuit; the main control circuit controls the UPS power supply through the driving circuit; the input end of the detection circuit is connected to the output end of the charging and discharging circuit, and the output end of the detection circuit is connected to the main The input end of the control circuit; the input end of the AC/DC rectification circuit is connected to the power grid, and the output end of the AC/DC rectification circuit is respectively connected to the input ends of the charging and discharging circuit and the DC/AC inverter circuit. The utility model solves the harmonic problem of the off-line UPS power supply under the nonlinear load by adding a detection circuit of the load current in the system, and makes it work in the APF mode in the bypass state, greatly improving the utilization rate.

Description

A kind of UPS power supply with active filtering function

technical field

The utility model relates to the field of an uninterrupted power supply, in particular to a UPS power supply with an active filtering function.

Background technique

Nowadays, problems such as mains voltage drop or power interruption often occur due to the overload of mains power or sudden accidents. Especially in hospitals, banks, data management centers, etc., the sudden interruption of the power supply of working equipment will cause serious economic losses and even safety accidents. On the other hand, the power supply system of these devices usually contains nonlinear power electronic devices, which will introduce harmonics into the mains. The existence of harmonics in the mains will cause the control system of the equipment to malfunction, which will affect the life of the equipment for a long time and cause irreparable losses.

At present, the uninterruptible power supply UPS on the market can solve the problem of power interruption and maintain continuous power supply to equipment. However, nothing can be done about harmonic problems. Especially the widely used offline UPS has a single function, and when the mains power is normal, it is in a bypass state, and the utilization rate is poor. The utility model improves the off-line UPS and adds the function of harmonic control under the condition of hardly increasing the hardware cost.

According to statistics, the offline UPS power supply currently on the market has the following two problems:

(1) Part of the load of the offline UPS is usually a nonlinear power electronic device, and the current harmonics generated by the nonlinear power electronic device will distort the UPS output voltage waveform, thereby generating voltage harmonics. The existence of voltage harmonics will affect the normal work of other loads. However, UPS does not deal with harmonic problems.

(2) The offline UPS provides power to the load when the mains voltage is interrupted, and is in a bypass state after charging the battery when the mains is normal. In practice, the mains is normal when the mains is normal, that is to say, the bypass state is the normal state of the offline UPS. In this way, the utilization rate of UPS is greatly reduced.

Contents of the invention

The purpose of the utility model is to provide a UPS power supply with an active filter function, which is used to solve the harmonic problem in the offline UPS application occasion. To improve the offline UPS, without affecting its uninterrupted power supply, it has an active filtering function to control harmonics. The technical problem to be solved in the utility model is realized through the following technical solutions:

A UPS power supply with an active filtering function, comprising: a DC/AC inverter circuit, a charge and discharge circuit, and an AC/DC rectifier circuit, the output end of the charge and discharge circuit is connected to the input end of the DC/AC inverter circuit; The input end of the AC/DC rectifier circuit is connected to the power grid, and the output end of the AC/DC rectifier circuit is respectively connected to the input end of the charging and discharging circuit and the DC/AC inverter circuit. The special feature is that it also includes:

main control circuit;

A drive circuit, the input end of the drive circuit is connected to the output end of the main control circuit, and the output end of the drive circuit is connected to the UPS power supply;

A detection circuit, the input end of the detection circuit is connected to the output end of the charging and discharging circuit, and the output end of the detection circuit is connected to the input end of the main control circuit.

The above-mentioned UPS power supply with active filtering function is special in that a third switch for controlling filtering is provided between the AC/DC rectifying circuit and the DC/AC inverter circuit.

The above-mentioned UPS power supply with active filter function is special in that the charging and discharging circuit includes a storage battery and a bidirectional DC/DC circuit, and the input end of the bidirectional DC/DC circuit is connected to the AC/DC rectifying circuit. The output terminal, the output terminal of the bidirectional DC/DC circuit is connected to the input terminal of the DC/AC inverter circuit; the input and output terminals of the storage battery are respectively connected to the bidirectional DC/DC circuit.

The above-mentioned UPS power supply with active filter function is special in that an isolation transformer is provided between the AC/DC rectification circuit and the power grid.

The above-mentioned UPS power supply with active filtering function is special in that the AC/DC rectification circuit adopts three-phase natural rectification.

The above-mentioned UPS power supply with active filtering function is special in that the DC/AC inverter circuit adopts a three-phase bridge inverter.

The above-mentioned UPS power supply with active filter function is special in that the main control circuit adopts a digital signal processor DSP.

The above-mentioned UPS power supply with active filter function is special in that the detection circuit uses voltage and current Hall sensors and an operational amplifier conditioning circuit.

The above-mentioned UPS power supply with active filtering function is special in that it also includes an auxiliary power supply circuit that provides the required operating power for the drive circuit, charge and discharge circuit, main controller circuit and detection circuit.

The above-mentioned UPS power supply with active filter function is special in that the auxiliary power supply circuit adopts a flyback switching power supply.

The above-mentioned UPS power supply with active filter function is special in that the flyback switching power supply includes a first switch arranged between the power grid and the load, and is arranged between the DC/AC inverter circuit and the load. the second switch between the AC/DC rectifier circuit and the DC/AC inverter circuit, the third switch is arranged between the DC/AC inverter circuit and the bidirectional DC/DC circuit; if the first When the first switch, the second switch and the third switch are closed, the system is in the APF mode; if the second switch and the fourth switch are closed, the system is in the UPS mode.

The beneficial effects of the utility model:

The utility model solves the harmonic problem of the off-line UPS power supply under the nonlinear load by adding a detection circuit of the load current in the system, and makes it work in the APF mode in the bypass state, greatly improving the utilization rate. Compared with the current off-line UPS, its hardware cost hardly increases, but its functions are richer, and it has a good cost performance.

The utility model will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Figure 1 is a schematic diagram of the structure of a UPS power supply system with an active filtering function.

detailed description

In order to further illustrate the technical means and effects of the utility model to achieve the intended purpose, the specific implementation, structural features and effects of the utility model will be described in detail below in conjunction with the accompanying drawings and examples.

Referring to Figure 1, a UPS power supply with active filtering function, including: AC/DC rectification circuit, DC/AC inverter circuit, drive circuit, charge and discharge circuit, main control circuit, detection circuit, output terminal of charge and discharge circuit Connect to the input end of the DC/AC inverter circuit;

The main control circuit controls the UPS power supply through the driving circuit;

The input end of the detection circuit is connected to the output end of the charging and discharging circuit, and the output end of the detection circuit is connected to the input end of the main control circuit;

The input end of the AC/DC rectification circuit is connected to the grid, and the output end of the AC/DC rectification circuit is respectively connected to the input end of the charging and discharging circuit and the DC/AC inverter circuit.

Among them, a third switch for controlling filtering is provided between the AC/DC rectifier circuit and the DC/AC inverter circuit. When the third switch is closed, the AC/DC rectifier circuit and the DC/AC inverter circuit are connected, so that the whole circuit has Active filtering function, so that the UPS power supply will control the harmonics when it is offline.

Among them, the charging and discharging circuit includes a battery and a bidirectional DC/DC circuit, the input end of the bidirectional DC/DC circuit is connected to the output end of the AC/DC rectifier circuit, and the output end of the bidirectional DC/DC circuit is connected to the input end of the DC/AC inverter circuit ; The input and output terminals of the storage battery are respectively connected to a bidirectional DC/DC circuit. The above-mentioned bidirectional DC-DC circuit is used to charge the storage battery when the mains power is normal and work in the charging state; when the mains power fails, it works in the discharging state to provide voltage to the inverter DC bus.

Wherein, an isolation transformer is also provided between the AC/DC rectification circuit and the power grid.

Among them, the AC/DC rectification circuit adopts three-phase natural rectification, and the three-phase natural rectification converts the AC mains power into DC. On the one hand, it provides voltage for the inverter DC bus, and on the other hand, it serves as the input DC voltage of the battery charging circuit.

Among them, the DC/AC inverter circuit is the core of the whole system, and is the shared main circuit of APF and UPS. The DC/AC inverter circuit adopts a three-phase bridge inverter to convert the DC voltage into AC to realize the output of active power, compensation current and compensation voltage.

Among them, the drive circuit adopts a power-type drive optocoupler to realize the safety isolation between the main controller and the inverter main circuit and the power amplification of the control signal.

Among them, the main control circuit adopts digital signal processor DSP, which is the core processing unit of the whole system, collects and calculates voltage and current signals, and outputs appropriate control signals.

Among them, the detection circuit adopts voltage and current Hall sensors and operational amplifier conditioning circuit, which is responsible for converting the actual voltage and current to the range that the main controller AD can collect.

Among them, it also includes an auxiliary power circuit that provides the required operating power for the drive circuit, charge and discharge circuit, main controller circuit and detection circuit. The auxiliary power supply circuit preferably adopts a flyback switching power supply. The flyback switching power supply includes a first switch arranged between the power grid and the load, a second switch arranged between the DC/AC inverter circuit and the load, and a second switch arranged between the AC/AC inverter circuit and the load. The third switch between the DC rectifier circuit and the DC/AC inverter circuit, the fourth switch arranged between the DC/AC inverter circuit and the bidirectional DC/DC circuit; if the first switch, the second switch, and the third switch Closed, the system is in APF mode; if the second switch and the fourth switch are closed, the system is in UPS mode.

With reference to Fig. 1, technical scheme of the present utility model is as follows:

The UPS power supply with active filtering function includes the following circuit units: AC/DC rectification circuit, DC/AC inverter circuit, drive circuit, battery and its charging and discharging circuit, main control circuit, detection circuit and auxiliary power supply circuit.

The AC/DC rectifier circuit adopts three-phase natural rectification to convert the AC mains power into DC. On the one hand, it provides voltage for the inverter DC bus, and on the other hand, it serves as the input DC voltage of the battery charging circuit.

DC/AC inverter circuit, the core of the whole equipment, is the shared main circuit of APF and UPS. Three-phase bridge inverter is used to convert DC voltage into AC to realize the output of active power, compensation current and compensation voltage.

The drive circuit adopts a power-type drive optocoupler to realize the safety isolation between the main controller and the inverter main circuit and the power amplification of the control signal.

The battery and its charging and discharging circuit adopt a bidirectional DC-DC circuit. When the mains is normal, it works in the charging state to charge the battery; when the mains fails, it works in the discharging state to provide voltage to the inverter DC bus.

The main controller circuit adopts digital signal processor DSP, which is the core processing unit of the whole system, collects and calculates voltage and current signals, and outputs appropriate control signals.

The detection circuit uses voltage and current Hall sensors and an operational amplifier conditioning circuit, which is responsible for converting the actual voltage and current to the range that the main controller AD can collect.

The auxiliary power supply circuit adopts a flyback switching power supply to provide the required operating power for the drive circuit, charge and discharge circuit, main controller circuit and detection circuit.

The UPS power supply with active filtering function of the utility model has two working modes:

(1) When the mains is normal, it works in APF (Active Power Filter) mode, which charges the battery on the one hand and compensates the current harmonics in the mains on the other hand.

(2) When the mains voltage drops or is interrupted, it works in UPS (uninterruptible power supply) mode, on the one hand to provide power to the load, and on the other hand to compensate for voltage harmonics.

The schematic diagram of the UPS power system structure with active filtering function is shown in Figure 1, where:

Real-time detection of mains voltage. When the voltage is normal, K1, K2, and K3 are closed. The device works in APF mode, collects mains current, extracts harmonic current signals, and outputs compensation current as a reference signal for inverter current closed-loop. Harmonics are compensated; at the same time, K4 is closed to control the bidirectional DC-DC circuit to work in the BUCK state, and the supercapacitor is charged after the mains voltage is rectified, and K4 is disconnected after the charging is completed.

When the mains voltage drops or is interrupted, control the bidirectional DC/DC circuit to work in the BOOST state, close K4, disconnect K1, K3, and supply power to the inverter DC bus after the battery is boosted. At this time, the device works at In UPS mode, it outputs three-phase AC voltage to provide power to the load equipment to ensure its continuous operation. At the same time, the voltage harmonics are detected and synthesized with the output three-phase AC voltage as the total output voltage command, so that the UPS can compensate the voltage harmonics under the condition of outputting active power.

The above content is a further detailed description of the utility model in combination with specific preferred embodiments, and it cannot be assumed that the specific implementation of the utility model is only limited to these descriptions. For a person of ordinary skill in the technical field to which the utility model belongs, without departing from the concept of the utility model, some simple deduction or substitutions can also be made, which should be regarded as belonging to the protection scope of the utility model.

Claims (10)

1. A UPS power supply with active filter function, comprising: DC/AC inverter circuit, charging and discharging circuit, AC/DC rectifying circuit, the output end of said charging and discharging circuit is connected to the input end of DC/AC inverter circuit The input end of the AC/DC rectifier circuit is connected to the power grid, and the output end of the AC/DC rectifier circuit is respectively connected to the input end of the charging and discharging circuit and the DC/AC inverter circuit. It is characterized in that it also includes: main control circuit; A drive circuit, the input end of the drive circuit is connected to the output end of the main control circuit, and the output end of the drive circuit is connected to the UPS power supply; A detection circuit, the input end of the detection circuit is connected to the output end of the charging and discharging circuit, and the output end of the detection circuit is connected to the input end of the main control circuit. 2. A UPS power supply with active filtering function according to claim 1, characterized in that a third switch for controlling filtering is provided between the AC/DC rectifying circuit and the DC/AC inverter circuit. 3. A kind of UPS power supply with active filter function according to claim 1 or 2, it is characterized in that, described charging and discharging circuit comprises accumulator and bidirectional DC/DC circuit, the input end of described bidirectional DC/DC circuit The output end of the AC/DC rectification circuit is connected, the output end of the bidirectional DC/DC circuit is connected to the input end of the DC/AC inverter circuit; the input and output ends of the storage battery are respectively connected to the bidirectional DC/DC circuit. 4. A UPS power supply with active filter function according to claim 1 or 2, characterized in that an isolation transformer is also provided between the AC/DC rectifier circuit and the power grid. 5. The UPS power supply with active filter function according to claim 1 or 2, characterized in that, the AC/DC rectification circuit adopts three-phase natural rectification. 6. A UPS power supply with active filter function according to claim 1 or 2, characterized in that the DC/AC inverter circuit adopts a three-phase bridge inverter. 7. A UPS power supply with active filter function according to claim 1 or 2, characterized in that said main control circuit adopts a digital signal processor. 8. A UPS power supply with active filter function according to claim 1 or 2, characterized in that the detection circuit adopts voltage and current Hall sensors and an operational amplifier conditioning circuit. 9. A kind of UPS power supply with active filter function according to claim 2, is characterized in that, also comprises the auxiliary power supply circuit that provides required operating power supply for drive circuit, charge and discharge circuit, main controller circuit and detection circuit . 10. A kind of UPS power supply with active filter function according to claim 9, it is characterized in that, described auxiliary power supply circuit adopts flyback switching power supply; Said flyback switching power supply comprises The first switch between the DC/AC inverter circuit and the load, the second switch installed between the AC/DC rectifier circuit and the DC/AC inverter circuit, the third switch installed between the DC/AC inverter circuit The fourth switch between the transformer circuit and the bidirectional DC/DC circuit; if the first switch, the second switch, and the third switch are closed, the system is in APF mode; if the second switch and the fourth switch are closed, the system is in UPS mode.