DC-BANK variable frequency motor control method without disturbance

Abstract

The application relates to a DC-BANK variable-frequency undisturbed motor control method; the method comprises the following steps: calculating the battery capacity and quantity of a DC-BANK device; a double-power supply LTS is used for variable-frequency cabinet control power supply; PC-level switch control is adopted; one 220V power supply is introduced from the cabinet commercial power supply; another 220V power supply is introduced from an UPS power supply; when the commercial power supply is faulty, a phase sequence relay sends a signal to the DC-BANK device; a KM2 contactor of the DC-BANK device is attracted and contacted; full voltage of the DC-BANK device is supplied to a variable-frequency converter DC bus through the KM2 contactor; full voltage of the DC-BANK device is supplied to a variable-frequency converter DC / AC inverter; after the commercial power supply is restored to normal, a J13 relay is electrified, the KM2 contactor is disconnected, the DC-BANK DC is controlled by a DC-STC and connected to the variable-frequency converter DC bus side, the commercial AC / DC rectifier and the DC / AC inverter supply power to the motor, and the normal operation of the equipment is continuously ensured. The application provides a commercial power supply and DC-BANK combined variable-frequency undisturbed control technology, realizes continuous, stable and safe operation of the motor, and thus ensures continuous operation of a production line.

Description

Technical Field

[0001] This invention relates to the field of power technology, and in particular to power supply technology for devices in large equipment and production lines, specifically a method for controlling a DC-BANK frequency converter without disturbance. Background Technology

[0002] In some critical production lines and process equipment applications, such as the PCW and exhaust systems associated with cleanrooms in chip manufacturing plants, dynamic generators and static UPS power supplies are typically used to ensure power reliability in order to guarantee product quality and production continuity.

[0003] However, this involves a power outage period and high costs: generators require startup time and cannot meet the continuous operation of equipment; UPS systems have relatively high investment costs, system complexity, maintenance difficulties, and high energy loss. For example, if a 300KVA UPS is configured with a total load power of 100kW and an efficiency of 90%, the power loss is 100kW / 90%-100kW=11.11KW; based on 365 days a year and an electricity cost of RMB 0.65 per kWh, the annual electricity cost for UPS losses is 11.11*24*365*0.65=63260 yuan. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned defects and provide a variable frequency non-disruptive control technology that combines mains power and DC-BANK to achieve continuous, stable and safe operation of the motor, thereby ensuring the continuous operation of the production line.

[0005] To achieve the above objectives, the present invention is implemented as follows: A method for controlling a disturbance-free motor with DC-BANK frequency conversion, including Step 1: Calculate the battery capacity and quantity of the DC-BANK device. The calculation formula is as follows: Taking a power supply time of 10 minutes and a load of 110kW as an example, the battery selected is a certain product HR4000(A) battery. Battery constant power calculation formula (W): W = (P*1000*COSφ) ÷ (η*N*6); P: UPS power capacity; COSφ: Power factor (taken as 1 as required) η: Inverter efficiency (taken as 0.94 as required); N: Number of cells in a single battery pack; W=(P*1000*COSφ) ÷(η*N*6 )=(110*1000*1) ÷(0.94*41*6)=475.6W; Checking the constant power discharge parameter table of the product battery: HR4000(A) series, the battery capacity is 506W after a discharge time of 10 minutes, that is: 475.6W / 506W=0.94. Considering the safety margin, a set of HR4000(A) batteries of a certain product is selected, that is, 41 batteries. Step 2: The frequency converter cabinet control power supply adopts dual power supply LTS, PC-level switch control. One 220V is drawn from the mains power of this cabinet, (L1) and (N); the other is drawn from the UPS power supply, (UL1) and (UN). The two live wires must be in phase. When the mains power fails, the control power supply switches to point U in milliseconds to ensure the normal operation of the circuit. Step 3: Under normal mains power conditions, the frequency converter AC / DC rectifier and DC / AC inverter supply power to the motor; Step 4: During the operation of the frequency converter, the intermediate relay of the DC-BANK device (J11) is energized and the contactor of the DC power supply terminal (KM1) is energized. At this moment, the DC power supply is supplied to the DC terminal of the frequency converter DC / AC inverter. Step 5: The inverter's mains power is normal. It is controlled by the DC-BANK device DC-STS. The DC power supply of the device is connected in parallel to the DC bus side of the inverter. At this time, the DC-BANK DC power supply belongs to the inverter's redundant power supply. Step 6: When there is a mains power failure, that is, when the phase sequence relay detects a phase loss, low voltage, overvoltage, or reverse phase sequence, the phase sequence relay sends a signal to the DC-BANK device, that is, the intermediate relay (J13). Step 7: After a mains power failure, the node disconnects, and the normally open auxiliary node of the (J13) intermediate relay closes. Step 8: The DC-BANK device (KM2) contacts and engages, supplying full voltage from the device's DC positive bus to the inverter's DC bus via the (KM2) contactor; Step 9: The DC-BNAK DC power supply is supplied to the DC / AC inverter of the frequency converter, thereby ensuring the smooth switching of the frequency converter power supply and ensuring the continuous operation of the motor. Step 10: After the mains power is restored to normal, relay (J13) is energized, contactor (KM2) is disconnected, DC-BNAK DC power is controlled by DC-STS and connected to the DC bus of the frequency converter, and the AC / DC rectifier and DC / AC inverter supply power to the motor to ensure the normal operation of the equipment.

[0006] The principle of this method is as follows: The DC-BANK device collects data from the phase sequence relays installed in the frequency converter cabinet (which can detect mains power problems such as reverse phase sequence, phase loss, low voltage, overvoltage, and frequency drift) to determine whether to fully switch DC-BANK power to the DC / AC inverter of the frequency converter. Because the KM1 contactor of the DC-BANK device is in the energized state after the frequency converter starts running, the DC power of the device is always in a redundant standby state. Therefore, if a mains power fault is detected, KM2 will activate, and the DC power of the device will be fully switched on in milliseconds, thus ensuring a smooth switching of power supply and equipment. Therefore, in loads with frequency converters, DC-BANK can effectively solve power quality problems. Its backup power supply mode determines its advantages of high energy utilization and high safety.

[0007] This invention also inherits the advantages of DC-BANK devices: DC-BANK is normally in standby mode, with a load of 6-10kW only during charging, so the resulting losses are negligible. Furthermore, DC-BANK features a parallel connection and a simple system structure, making maintenance quick and easy. While UPS systems have relatively low load reliability, DC-BANK systems only require redundancy in battery capacity. Their parallel connection provides independent, isolated power protection for each load, and the inverter has both AC and DC redundant power supplies, resulting in higher reliability.

[0008] In summary, the power distribution method combining DC-BANK devices and frequency converter control cabinets is adopted. The DC power of the DC-BANK device is a redundant power supply for the frequency converter, so even if the mains power fails, there will be no equipment shutdown or downtime. Attached Figure Description

[0009] Figure 1 This is the original control diagram for a frequency converter.

[0010] Figure 2 This is a diagram showing the connection system between the frequency converter cabinet and the DC-BANK.

[0011] Figure 3 This is a schematic diagram of a DC-BANK system. Detailed Implementation

[0012] The present invention will be further illustrated below through specific embodiments.

[0013] Step 1: To ensure the power supply capacity and duration for the load, the battery capacity and quantity of the DC-BANK device must first be calculated. The specific calculation formula is as follows: Taking a power supply time of 10 minutes and a 110kW load as an example, a certain product HR4000(A) battery is selected.

[0014] Battery constant power calculation formula (W): W = (P * 1000 * COSφ) ÷ (η * N * 6) P: UPS power capacity; COSφ: Power factor (taken as 1 as required) η: Inverter efficiency (taken as 0.94 as required) N: Number of cells in a single battery pack W=(P*1000*COSφ) ÷(η*N*6 )=(110*1000*1) ÷(0.94*41*6)=475.6W Checking the constant power discharge parameter table of a certain product's battery: HR4000(A) series, discharge time 10min, battery capacity is 506W. That is: 475.6W / 506W=0.94. Considering the safety margin, a set of HR4000(A) batteries from a certain product is selected, that is, 41 batteries.

[0015] Step 2: Figure 1 As shown: The inverter cabinet control power supply adopts dual power supply (LTS PC-level switch) control. One 220V power supply is drawn from the mains power of this cabinet, L1 and N; the other power supply is drawn from the UPS power supply, UL1 and UN. The two live wires must be in phase. When the mains power fails, the control power supply switches to point U in milliseconds to ensure the normal operation of the circuit.

[0016] Step 3: Figure 2 As shown: Under normal mains power conditions, the motor is powered by a frequency converter, an AC / DC rectifier, and a DC / AC inverter.

[0017] Step 4: Inverter in operation Figure 3 When the intermediate relay J11 of the DC-BANK device is energized, the contactor KM1 at the DC power supply terminal is energized, and at this moment, the DC power supply is supplied to the DC / AC inverter terminal of the frequency converter. Figure 2 (As indicated by the label).

[0018] Step 5: With the inverter's mains power normal, the DC-BANK device DC-STS is controlled. The device's DC power supply is connected in parallel to the inverter's DC bus side. At this time, the DC-BANK DC power supply belongs to the inverter's redundant power supply.

[0019] Step 6: When a mains power fault occurs (the phase sequence relay detects a phase loss, low voltage, overvoltage, or reverse phase sequence), the phase sequence relay sends a signal to the DC-BANK device. Figure 3 Intermediate relay J13).

[0020] Step 7: After a mains power failure, the node disconnects and the normally open auxiliary node of the J13 intermediate relay closes.

[0021] Step 8: The KM2 contact of the DC-BANK device is engaged, and the DC positive bus of the device supplies power to the DC bus of the frequency converter through the full voltage of the KM2 contactor.

[0022] Step 9: DC-BNAK DC power supply to the frequency converter DC / AC inverter ( Figure 2 As shown in the figure, this ensures smooth switching of the inverter power supply and continuous operation of the motor.

[0023] Step 10: After the mains power is restored, relay J13 is energized, contactor KM2 is disconnected, and DC-BNAK DC power is connected to the DC bus side of the frequency converter via DC-STS control. The AC / DC rectifier and DC / AC inverter supply power to the motor, ensuring continuous normal operation of the equipment.

[0024] In this application's technical solution, the dual-power switching of the control power supply 220 is first implemented. To ensure the system can resume normal operation in the shortest possible time, a millisecond-level dual-power automatic transfer switch employs fast switching technology. It can complete the switching from the main power supply to the backup power supply within milliseconds, ensuring that the load equipment does not experience any interruption.

[0025] In this invention, the phase sequence relay operates as follows: the device is a phase sequence comparator composed of operational amplifiers, comparing voltage amplitude, frequency, and phase. If the conditions are met, the amplifier conducts. Typically, the three-phase power supply (A, B, and C) corresponds to the input terminals of the phase sequence protector. The relay output is connected to either a normally closed or normally open terminal depending on your circuit requirements. When the circuit is normal, the phase sequence relay's output does not operate. When a fault occurs (phase sequence error, phase loss, low voltage, etc.), the normally closed terminal opens, and the normally open terminal closes, thus providing an on / off signal to the control circuit.

Claims

1. A method for controlling a disturbance-free motor with DC-BANK frequency conversion, characterized in that: include Step 1: Calculate the battery capacity and quantity of the DC-BANK device. The calculation formula is as follows: Taking a power supply time of 10 minutes and a load of 110kW as an example, a certain product battery is selected. Battery constant power calculation formula (W): W = (P*1000*COSφ) ÷ (η*N*6); P: UPS power capacity; COSφ: Power factor, set to 1 as required; η: Inverter efficiency, set to 0.94 as required. N: Number of cells in a single battery pack; W=(P*1000*COSφ) ÷(η*N*6 )=(110*1000*1) ÷(0.94*41*6)=475.6W; Checking the constant power discharge parameter table of the product's battery: the battery capacity is 506W after a discharge time of 10 minutes, that is: 475.6W / 506W=0.

94. Considering the safety margin, a set of batteries of a certain product is selected, that is, 41 cells. Step 2: The frequency converter cabinet control power supply adopts dual power supply LTS, PC-level switch control. One 220V is drawn from the mains power of this cabinet, L1 and N; the other is drawn from the UPS power supply, UL1 and UN. The two live wires must be in phase. When the mains power fails, the control power supply switches to point U in milliseconds to ensure the normal operation of the circuit. Step 3: Under normal mains power conditions, the frequency converter AC / DC rectifier and DC / AC inverter supply power to the motor; Step 4: During the operation of the frequency converter, the intermediate relay J11 of the DC-BANK device is energized and the contactor KM1 at the DC power supply terminal is energized. At this moment, the DC power supply is supplied to the DC terminal of the frequency converter's DC / AC inverter. Step 5: The inverter's mains power is normal. It is controlled by the DC-BANK device DC-STS. The DC power supply of the device is connected in parallel to the DC bus side of the inverter. At this time, the DC-BANK DC power supply belongs to the inverter's redundant power supply. Step 6: When there is a mains power failure, that is, when the phase sequence relay detects a phase loss, low voltage, overvoltage, or reverse phase sequence, the phase sequence relay sends a signal to the DC-BANK device, that is, the intermediate relay J13. Step 7: After a mains power failure, the node disconnects and the normally open auxiliary node of the J13 intermediate relay closes. Step 8: The KM2 contact of the DC-BANK device is engaged, and the DC positive bus of the device supplies power to the DC bus of the frequency converter through the full voltage of the KM2 contactor; Step 9: The DC-BNAK DC power supply is supplied to the DC / AC inverter of the frequency converter, thereby ensuring the smooth switching of the frequency converter power supply and ensuring the continuous operation of the motor. Step 10: After the mains power is restored to normal, relay J13 is energized, contactor KM2 is disconnected, and DC-BNAK DC power is connected to the DC bus side of the frequency converter via DC-STS control. The AC / DC rectifier and DC / AC inverter supply power to the motor, ensuring the normal operation of the equipment.

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