The emergency power supply automatic control system composed of frequency converter is optimized for operation.

1. Functions and types of EPS

Emergencypower supply(EPS) is a power supply device composed according to the needs of primary load power supply equipment such as fire protection facilities, emergency lighting, accident lighting, etc. The product consists of a mutual switching device, an automatic charger, an inverter and a battery pack. When the AC power grid is normal, the inverter does not work, and the important load is powered by the mutual switching device. When the AC power grid is interrupted, the mutual switching device will immediately switch to the inverter power supply. When the grid voltage is restored, the emergency power supply will resume power supply to the grid.

Emergency power supply can supply power to various electrical equipment in different occasions when the power grid is out of power. It has a wide range of applications, strong load adaptability, easy installation and high efficiency. The use of centralized emergency power supply can overcome many shortcomings of other power supply methods and reduce unnecessary waste of electricity. In emergency accidents, lighting and other power consumption places, it has a higher performance-price ratio compared with long-term continuous operation UPS.

At present, the control methods and control means adopted by EPS are different. The loads carried by EPS can be summarized into three types: the first is EPS mainly used for emergency lighting and accident lighting; the second is three-phase series EPS used for mixed loads such as air conditioners, elevators, rolling doors, exhaust fans, water pumps, etc. in addition to emergency lighting and accident lighting; the third is the variable frequency series EPS that directly supplies power to the motor. The following introduces the three-phase series EPS that supplies power to mixed loads.

This article uses Delta's emergency power inverter to develop an emergency power control system that can effectively reduce the burden on staff, improve the optimal operation of the power grid in emergency power outages, enhance the system's anti-interference ability, and avoid hardware aging losses.

2 System Analysis

The EPS solution mainly uses the inverter to drive the AC motor of the fan, water pump and rolling shutter of the fire protection system. The EPS dedicated inverter can truly realize the connection of the common DC bus, so it can be used not only in the EPS industry, but also in the chemical fiber and glass manufacturing industries. The dedicated inverter and the synchronous card can be used together to achieve the same input and output phases, so as to meet the application of special occasions. In view of the particularity of the motor drive in the EPS industry, this inverter mainly adds parameters such as automatic torque compensation, torque compensation limit, abnormal restart, etc. to meet the needs of special industries. The EPS charging module matched with the inverter reduces costs for customers, reduces heavy transformers, and reduces transportation costs.

2.1 Overview of EPS dedicated inverter

One of the main features of EPS dedicated inverter is that it can realize the shared DC bus, thus expanding the application field. At the same time, the DC conversion of the internal contactor and soft start circuit meets the demand for direct battery start. EPS dedicated inverter can form a highly reliable hybrid load dedicated inverter by matching appropriate low-pass filters and transformers, and ensure the output voltage stability and waveform smoothness of the inverter.

2.2 Functions of EPS dedicated inverter

(1) The auxiliary power supply and soft start circuit contactor of the inverter both use DC power supply, so direct DC power supply can be fully realized.

(2) Super strong hardware and software protection functions ensure the reliability of the inverter.

(3) It contains multiple modulation modes and can be applied to a variety of transformers, thus ensuring that the output voltage waveform is closer to a sine wave.

(4) EPS dedicated inverters are available in two specifications: AC380V and AC220V, with a power range from 0 to 220kW, which can meet the needs of customers in different occasions.

(5) The use of synchronization card ensures that the input and output phases are the same. 2.3 Application design of EPS dedicated inverter

(1) Working principle design

The principle of the EPS with AC and DC dual power supply is shown in Figure 1. The principle of the EPS with DC single power supply is shown in Figure 2.

(2) Definition of control terminals

The definition of the control terminals is shown in Table 1.

2.4 EPS inverter special parameter design (see Table 2)

3 Conclusion

The EPS dedicated inverter truly realizes customized service and is developed entirely according to the technical characteristics of the EPS industry to meet the needs of users in the EPS industry.