AU2015258260A1

AU2015258260A1 - A control method of starting a locomotive cooling fan motor

Info

Publication number: AU2015258260A1
Application number: AU2015258260A
Authority: AU
Inventors: Zhiwei Cai; Lu LU; Yang Song; Chaolin XU; Xiliang YANG
Original assignee: CNR Dalian Locomotive and Rolling Stock Co Ltd
Current assignee: CRRC Dalian Co Ltd
Priority date: 2015-05-28
Filing date: 2015-10-08
Publication date: 2016-12-15
Anticipated expiration: 2035-10-08
Also published as: NZ714326A; CN104868795A; AU2015258260B2; WO2016188007A1; ZA201700519B; CN104868795B

Abstract

Abstract The invention discloses a control method of starting the locomotive cooling fan motor, which is characterized in that, the output frequency target value of inverter is set to the lower value Fl, the inverter output frequency is controlled based on the lower loading rate Rpl; when the inverter output frequency reaches F1, it can be maintained till Ti. From the time of motor starting to Ti, The smaller value output from output current limit and intermediate DC voltage limit (double closed-loop control) is multiplied by the degree of modulation to obtain the new degree of modulation ML. Then ML is applied to control the output voltage of the inverter, to make the output voltage limit fall within the given Max. starting current range and the intermediate DC voltage limit within the DC voltage limit range. At T1 time, if the output frequency target value of the inverter is set as the higher value F2, the inverter output frequency is controlled based on the higher loading rate Rp2, then F2 can be reached at T2. Therefore, the invention can achieve steady starting of fan motor at any initial speed and in any rotation direction, and can prevent over-voltage of the intermediate voltage of the inverter.

Description

_Description_ A method of starting the locomotive cooling fan motor

Technical Field

The invention relates to a motor starting control method, in particular to a method of starting the locomotive cooling fan motor, which belongs to the technical field of railway locomotive vehicles.

Background Art

With the rapid development of power electronic technologies, the application of inverters becomes wider. In the industry control field, inverters are usually used to drive fan motors, thus to achieve accurate control of the fan motor rotation speed. However, when the inverters are applied in railway locomotives vehicles, due to the constraints of cost and installation space, rotary encoder cannot be installed in the shaft head of the fan motor. In most case, when the inverter is started, the fan motor is provided with a high initial rotation speed but the direction of rotation is not determined. If the inverter outputs three-phase AC current under certain frequency and voltage rise rate to the fan motor since it is started, the starting current of motor might too high, which will cause vibration and impact to the mechanical and electrical system, and even trigger over-current protection. And thus the reliable operation of the system can be impacted.

Contents of the Invention

The invention is intended to provide a method of starting the locomotive cooling fan motor that can ensure steady starting of fan motor at any initial speed and in any rotation direction.

The invention adopts the following technical scheme to solve the technical problems:

The invention relates to a method of starting the locomotive cooling fan motor. An inverter is adopted to drive the cooling fan motor, which is characterized in that, the first target value FI and the second target value F2 of inverter output frequency are set with F1<F2; the first loading rate Rpl and the second loading rate Rp2 are also set with Rpl< Rp2; in case of starting, the inverter output frequency Fd is controlled based on the first loading rate Rpl; When the inverter output frequency Fd reaches the first target value FI at TO, maintain the inverter output frequency FI till Tl; From T1 on, the inverter output frequency Fd is controlled based on the loading rate Rp2 to gradually reach the second target value F2; from the time of motor starting to Tl, output current limit and intermediate DC voltage limit are adopted for double closed-loop control. The output current limit loop has a control valve of VDlout, and the limit, is 0<VDlout<100%; while the intermediate DC voltage limit loop has a control valve of VD2out, and the limit is 0<VD2out<100%. If the control value, which is smaller out of VDlout and VD2out is taken as the control value VDout, given the modulation degree ML=VDout*Mi (wherein Mi means the fan inverter open-loop control modulation degree). ML is applied to control the output voltage of the inverter, to make the output voltage limit fall within the given max. starting current range and the intermediate DC voltage limit within the DC voltage limit range.

In order to better realize the object of the invention, T1 time can be determined by the following steps: set the output current valid value threshold Icmp, the set value Ccmpl of timer Cntl and the set value Ccmp2 of timer Cnt2, with Ccmpl>Ccmp2, timer Cntl starts work when the inverter output frequency Fd reaches FI; while timer Cnt2 starts work when the output current valid value Ifdb is smaller than the current valid value threshold, and the time that first reaches the set value is deemed as T1 time.

The invention has the advantages that, the fan motor starting control method can ensure steady low-frequency brake control of fan motor at the initial speed and with uncertain rotation direction through application of output current limit and intermediate DC current limit (double closed-loop) control; considering the determination method of T1 time, output circuit detection and delay control links are additional applied on the basis of preset low-frequency brake time, so as to enter the speed acceleration and regulation mode immediately after low-frequency brake. The control method can eliminate the impact caused by high starting current of fan motor to the electrical and mechanical systems, and prevent intermediate DC over-voltage of the inverter caused by brake.

Description of Figures

Figure 1 is the schematic diagram of the main power supply of the cooling fan motor.

Figure 2 is the frequency VS time Fd-t curve of the cooling fan motor during the starting process;

Figure 3 is the subprogram flowchart for timer 1 interrupt;

Figure 4 is the subprogram flowchart for fan motor start-up;

Figure 5 is the subprogram flowchart for T1 time flag judgment;

Embodiment

To clarify the objects, technical scheme and advantages of the invention, a clear and complete description of the technical scheme of the invention is given below in consideration of the figures herein. Obviously, the embodiments described represent part but not all. On the basis of the embodiment in the invention, all other embodiments obtained by the ordinary technical personnel skilled in this field without completing any creative work, are under the protection of the invention.

See Figure 1 for the schematic diagram of the main power supply of the cooling fan motor. The three-phase AC voltage is wired from U, V and W connection terminals. Through the three-phase AC contactor CTT1, the voltage is input in the three-phase rectifier circuit composed of diodes D1 to D6, and changes to DC current. Through the middle filter circuit Cl, the DC current is input in the three-phase inverter circuit composed of SI to S6, and changes to three-phase AC current with adjustable voltage and frequency and is then output to cooling fan motor Ml.

See Figure 2 for the frequency VS time Fd-t curve of the cooling fan motor during the starting process; Given the motor starting time t=0 and Fd=0, the inverter output frequency Fd is controlled based on the loading rate Rpl, when the inverter output frequency Fd reaches the target value FI at time of TO, the output frequency FI is maintained till Tl. From the time of motor starting to Tl, output current limit and intermediate DC voltage limit are adopted for double closed-loop control. The Min. value output by the double closed-loop control is multiplied by the inverter open-loop control Mi to obtain the degree of modulation ML. Then ML is applied to control the output voltage of the inverter, to make the output voltage limit fall within the given Max. starting current range and the intermediate DC voltage limit within the DC voltage limit range. At the time of Tl, when the target value of inverter output frequency is set as the working frequency F2, the inverter output frequency Fd is controlled based on the loading rate Rp2 to gradually reach the working frequency F2.

See Figure 3 for the subprogram flowchart of timer 1 interrupt; Interrupt of the timer 1 used for this embodiment causes lOmS timing interrupt. The interrupt subprogram is interrupted when timer 1 is first closed in box 1.1, and the timer 1 interrupt flag is removed in box 1.2. Then, enter box 1.3, judge the starting command is true or false: if it is true, enter box 1.4, execute the subprogram for starting the fan motor; otherwise, enter box 1.5, execute the subprogram for stopping the fan motor. Then, enter box 1.6, open the timer 1 interrupt, to prepare for the next interrupt of timer 1. And then, end of the interrupt subprogram.

See Figure 4 for the subprogram flowchart for fan motor start-up. Subprogram 1.4 for fan motor starting: first, execute calculation of frequency target F2 in box 1.4.1, then enter box 1.4.2, execute use of Tl time flag judgment subprogram; next, enter box 1.4.3, judge whether TlFlag==l: if yes, enter the right box 1.4.6, judge whether Fd<F2; if yes, enter box 1.4.7, execute Fd=Fd+Rp2; next, enter box 1.4.11, execute "set the modulation control value Vdout=l"; then, enter box 1.4.13, execute calculation of modulation control value VDout = The smaller value out of VDlout and VD2out; enter box 1.4.6, judge whether Fd<F2: if no, enter box 1.4.8, execute Fd=F2, then enter box 1.4.11, execute "set the modulation control value Vdout=l"; and then enter box 1.4.13, execute calculation of modulation control value VDout = the smaller value out of VDlout and VD2out; enter box 1.4.3, judge if the program is TlFlag==l: if no, enter 1.4.4, judge if the program is Fd=Fl; if no, enter box 1.4.9, execute Fd=Fl, next, enter 1.4.10, execute "send Iref and Ifdb to output current PID controller VD1 and output control value VDlout", and ensure 0<VDlout<l; in box 1.4.4, judge if the program is Fd=Fl, if yes, enter box 1.4.5, execute Fd=Fd+Rpl, and then enter box 1.4.10, execute "send Iref and Ifdb to output current PID controller VD1 and output control value VDlout" and ensure 0<VDlout<l; enter box 1.4.12, execute "send VdcRef and VdcFdb to medium voltage PID controller VD2 and output control value VD2out" and ensure 0<VD2out<l; then enter box 1.4.13, execute calculation of modulation control value VDout = The smaller value out of VDlout and VD2out; enter box 1.4.14, execute calculation of initial degree of modulation Mi=Fd/Fmax; next, enter box 1.4.15, execute calculation of the final degree of modulation ML=VoutxMi, and then end the program.

See Figure 5 for the subprogram flowchart for T1 time flag judgment; Ti time flag judgment subprogram 1.4.2: first, in box 1.4.2.1, judge whether Fd<Fl: if yes, enter box 1.4.2.3, execute Cntl=0, then enter box 1.4.2.8, execute TlFlag=0; enter box 1.4.2.1, judge whether Fd<Fl: if no, enter box 1.4.2.2, execute Cntl=Cntl+l; then enter box 1.4.2.4, judge whether Ifdbdcmp: if no, enter 1.4.2.10, execute Cnt2=0, then enter box 1.4.2.8, execute TlFlag=0; enter 1.4.2.4, judge whether Ifdbdcmp: if yes, enter box 1.4.2.5, execute Cnt2=Cnt2+l, and then enter box 1.4.2.6, judge whether Cntl==Ccmpl: if yes, enter 1.4.2.9, execute TlFlag=l; enter 1.4.2.6, judge whether Cntl==Ccmpl: if no, enter 1.4.2.7, judge whetherCnt2==Ccmp2: if yes, run box 1.4.2.9, execute TlFlag=l; enter 1.4.2.7, judge whether Cnt2==Ccmp2: if no, run box 1.4.2.8, execute TlFlag=0, and then end the program.

Claims

_Claims_

1. A control method of starting the locomotive cooling fan motor. An inverter is adopted to drive the cooling fan motor, which is characterized in that, the first target value FI and the second target value F2 of inverter output frequency are set with F1<F2; the first loading rate Rpl and the second loading rate Rp2 are also set with Rpl< Rp2; in case of starting, the inverter output frequency Fd is controlled based on the first loading rate Rpl; When the inverter output frequency Fd reaches the first target value FI at TO, maintain the inverter output frequency FI till Tl; From T1 on, the inverter output frequency Fd is controlled based on the loading rate Rp2 to gradually reach the second target value F2; from the time of motor starting to Tl, output current limit and intermediate DC voltage limit are adopted for double closed-loop control. The output current limit loop has a control valve of VDlout, and the limit is 0<VDlout<100%; while the intermediate DC voltage limit loop has a control valve of VD2out, and the limit is 0<VD2out<100%. If the control value, which is smaller out of VDlout and VD2out is taken as the control value VDout, given the modulation degree ML=VDout* Mi (wherein Mi means the fan inverter open-loop control modulation degree). ML is applied to control the output voltage of the inverter, to make the output voltage limit fall within the given Max. starting current range and the intermediate DC voltage limit within the DC voltage limit range.
2. The method according to Claim 1 is characterized in that the Tl time is determined by the following steps: set the output current valid value threshold Icmp, the set value Ccmpl of timer Cntl and the set value Ccmp2 of timer Cnt2, with Ccmpl>Ccmp2, timer Cntl starts work when the inverter output frequency Fd reaches FI; while timer Cnt2 starts work when the output current valid value Ifdb is smaller than the current valid value threshold, and the time that first reaches the set value is deemed as Tl time.