Heavy: There are several classifications of commonly used UPS power supplies, and what are the components of UPS? Up

From the perspective of the main circuit structure and the uninterrupted power supply operation mechanism, there are four main types of UPS power supplies that are mature in technology and have formed products: backup UPS, online interactive UPS , Double conversion UPS, and two-way conversion series-parallel compensation online UPS (Delta conversion UPS).

　　UPS is usually composed of input rectifier filter circuit, power factor correction circuit, battery pack, charging circuit, inverter circuit, static switch circuit, control detection The insight and protection circuit consists of 7 parts.

1. Input rectifier filter circuit

　　 In the UPS power supply, the commonly used rectifier circuit has single-phase uncontrollable and controllable Rectifier circuit, three-phase uncontrollable and controllable rectifier circuit. Filters can be divided into two types: capacitive input or inductive input. The output voltage of the capacitor input filter is relatively high, but the peak current output by the transformer is required to be relatively large, and the load adjustment is crossed. Inductive input filters have better output characteristics, but require larger chokes and higher cost. At present, LC filters composed of capacitors and inductors are usually used in UPS.

Second, power factor correction circuit

　　In UPS, the AC mains is rectified and used large-capacity capacitors for filtering And the output terminal of the rectifier circuit is also connected in parallel with a battery. A pulse current will be formed during the charging of the capacitor or battery. The current peak value is very high, which will produce high-order harmonic currents and cause the power factor to drop. The power factor correction circuit can make the grid input current into a sine wave with the same phase as the input voltage.

3. Battery pack

　　The battery pack is the heart of UPS. When the mains power is normal, the battery is charged to convert the electrical energy into chemical energy and stored. When the mains is interrupted, the power in the UPS battery maintains the inverter operation. Currently, valve-regulated lead-acid batteries are widely used in small and medium-sized UPSs. In a UPS with a long delay (4h or 8h), the cost of the battery even exceeds the cost of the host. The correct use of battery packs is only important for prolonging the service life of the battery. When used correctly, the life of valve-regulated lead-acid batteries can reach more than 10 years.

Four. Charging circuit

　　 In the UPS power supply system, the general charging circuit works independently, that is, Even if the inverter is not used, as long as the AC power supply is connected, the charging circuit will start to work. During the charging process, first use constant current charging. When the battery voltage reaches the float voltage, it will be switched to constant voltage charging until the battery Was sufficient. Therefore, the charging circuit generally has two feedback loops, one for current feedback and one for voltage feedback. The main circuit generally adopts a switch-type rectifier circuit. In order to shorten the charging time, various fast charging circuits are also used in UPS.

Five. Inverter circuit

　　The function of the inverter is to rectify the DC voltage or battery voltage of the mains Converted to AC voltage. In the backup UPS, the inverter output voltage waveform is generally a quasi-square wave; in the online UPS, the inverter output voltage is mostly a sine wave pulse width modulation (SPWM) waveform, which is filtered by an LC filter. Standard sine wave can be obtained.

VI. Static switch circuit

　　The function of the static switch is to protect the UPS and the load, and to realize the mains bypass power supply And the conversion of inverter power supply. When the UPS is overloaded, in order to protect the inverter, when the mains power is normal, the UPS uses a static switch to convert the output of the inverter to the mains; when the inverter fails, in order to ensure that the load is uninterrupted, the output of the UPS is also passed The static switch output is switched to the mains. Because there is generally a synchronous phase lock circuit inside the UPS, and a static switch conversion time period, there will be no power supply interruption during the conversion process. Small UPS generally use fast relays as static switches, and large and medium-sized UPSs use anti-parallel fast thyristors as static switches.

Seven, monitoring, detection, display protection circuit

　 UPS output voltage accuracy, waveform distortion and working reliability Both are closely related to the control circuit. The control circuit mainly includes SPWM generating circuit, closed loop voltage regulating circuit, synchronous phase lock circuit and so on. In order for the UPS to work reliably, it should also have a more complete protection circuit. In general UPS, there are automatic protection circuits for low battery voltage, automatic protection circuits for high mains voltage and UPS delay start. In order to grasp and understand the working status and operating conditions at any time, the UPS is also equipped with a monitoring circuit, a display circuit and an alarm circuit.