直流電機軟啟動NTC熱敏電阻,直流電機軟啟動電阻-華巨電子


1、概述

直流馬達的工作等效電路如圖1所示。穩態運行時,電樞回路方程為:

式中,U為直流馬達供電電源電壓;E為馬達繞組上的反電動勢;IR為繞組上的壓降。起動瞬間,n=0,E=0,而R 很小,因此

式中,Ist為啟動電流,將達到很大數值,通常為額定電樞電流的十幾倍甚至更大,造成電網電壓突然降低,影響電網。供電直流電源的規格要更大,以滿足瞬間大電流沖擊,同時也使馬達本身遭受很大的電磁力沖擊,嚴重時會損壞馬達。因此,適當限制馬達的啟動電流是必要的。針對此問題,本研究提出了三種馬達軟啟動方案:NTC(Negative Temperature Coefi—cient)熱敏電阻軟啟動電路、MOSFET線性放大軟啟動電路、繼電器延時軟啟動電路。三種方案的原理:啟動瞬間,降低馬達兩端的啟動電壓,以較小的電流啟動馬達,使電機電流逐步上升到額定值,從而限制啟動瞬問的大電流沖擊。

2.1 NTC軟啟動電路

NTC thermistor是負溫度系數熱敏電阻,其電阻值隨著溫度的升高而降低,可有效抑制瞬間大電流沖擊。由其組成的直流馬達軟啟動電路如圖2所示。把合適功率、阻值與溫度系數的NTC串人馬達的供電回路。當馬達啟動時,由于NTC以一定的阻值串人馬達的供電回路,可以有效地把啟動電流限制在規定范圍之內。隨著大電流的流過,NTC熱敏電阻逐漸發熱,阻值減小。當馬達順利起動后,NTC發熱后,阻值很小,電能損耗較小。

3、實驗分析

為了驗證效果,馬達回路串接NTC電阻和不接NTC電阻在同一負載(測試時電機的扭矩為63 kg·cm)下進行了實驗,圖5、圖6分別為不接NTC、接NTC時馬達繞組的沖擊電流波形。從圖中可以看出,啟動瞬間,加了軟啟動電路的電流僅為未加軟啟動電路的1/4,可以有效抑制啟動電流。這個電路的特點是簡單、價廉,但當馬達頻繁起動時,限流效果較差,因為此時NTC溫度較高,阻值較小,達不到很好的限流效果,所以頻繁啟動的馬達不宜采用此軟啟動電路。

華巨電子推出的大功率NTC熱敏電阻已經在電機軟啟動中開始廣泛的應用主要型號有:


5.大尺寸主要技術參數
                                       

型號

R25 

最大穩態電流

25℃下最大電流時近似電阻值

片徑Φ

耗散系數      

熱時間常數

工作溫度

(Ω)

(A)

(Ω)

(mm)

(mW/℃)

(S)

(℃)

芯片直徑:(13-50)mm

-55~+250

SCD-1R09190.03213≥13≤63
SCD-1R391.390.04213≥13≤63
SCD-1R591.590.04313≥13≤63
SCD-2R58-132.580.04813≥13≤63
SCD-3R08380.05213≥13≤ 63
SCD-4R07470.06813≥  13≤63
SCD-5R07570.07813≥13≤63
SCD-6R06660.09013≥ 13≤63
SCD-7R06760.09813≥13≤63
SCD-8R06860.10413≥13≤63
SCD-10R061060.12613≥13≤ 63
SCD-12R051250.14613≥ 13≤63
SCD-15R041540.15513≥13≤63
SCD-16R041640.15813≥13≤63
SCD-20R042040.19213≥ 13≤63
SCD-30R3.5303.50.23713≥13≤63
SCD-47R034730.34013≥13≤63
SCD-60R2.5602.50.42013≥13≤63
SCD-121R2.51201.80.99413≥13≤63
SCD-2R58-152.58

0.086

15≥21≤75
SCD-1R3101.310

0.034

15≥22≤75
SCD-1R5101.510

0.036

15≥22
≤75
SCD-2R59.52.59.5

0.044

15≥22≤75
SCD-3R093.09.0

0.046

15≥22≤75
SCD-5R085.08.00.05815≥22≤75
SCD-6R076.07.00.06915≥22≤75
SCD-7R077.07.00.07815≥22≤75
SCD-8R078.07.00.08415≥22≤75
SCD-10R0710.07.00.09815≥22≤75
SCD-12R0612.06.00.11615≥22≤75
SCD-15R0615.06.00.12515≥22≤75
SCD-16R0616.06.00.12915≥22≤75
SCD-20R0620.06.00.13615≥22≤75
SCD-30R0530.05.00.16515≥22≤ 75
SCD-47R0447.04.00.25715≥22≤ 75
SCD-121R2.51202.50.65215≥22≤75
SCD-0R7160.716

0.026

20

≥29

≤110

SCD-1R0161.016

0.027

20

≥29

≤110

SCD-1R020-201.020

0.020

20

≥29

≤113

SCD-1R5151.515

0.030

20

≥29

≤110

SCD-2R0142.014

0.035

20

≥29

≤110

SCD-2R5122.512

0.060

20

≥29

≤110

SCD-2R5132.513

0.055

20

≥29

≤110

SCD-2R515-202.515

0.046

20

≥29

≤110

SCD-3R0123.012

0.040

20

≥29

≤110

SCD-4R0124.012

0.043

20

≥29

≤110

SCD-4R7124.712

0.046

20

≥29

≤110

SCD-5R0105.010

0.049

20

≥29

≤110

SCD-5R0125.012

0.047

20

≥29

≤110

SCD-6R0116.011

0.052

20

≥29

≤110

SCD-6R8106.810

0.055

20

≥29

≤110

SCD-7R097.09

0.080

20

≥29

≤110

SCD-7R0107.010

0.075

20

≥29

≤110

SCD-8R098.09

0.058

20

≥29

≤110

SCD-10R0810.08

0.085

20

≥29

≤110

SCD-12R07.512.07.5

0.112

20

≥29

≤110

SCD-15R0715.07

0.123

20

≥29

≤110

SCD-18R0718.07

0.122

20

≥29

≤110

SCD-20R0620.06

0.132

20

≥29

≤110

SCD-20R0720.07

0.122

20

≥29

≤110

SCD-25R0625.06

0.168

20

≥29

≤110

SCD-30R0630.06

0.195

20

≥29

≤110

SCD-47R0547.05

0.325

20

≥29

≤110

SCD-121R3120.03

0.658

20

≥29

≤110

SCD-0R5220.522

0.017

25

≥30

≤130

SCD-0R7220.722

0.018

25

≥30

≤130

SCD-1R020-251.020

0.021

25

≥30

≤130

SCD-1R5191.519

0.024

25

≥30

≤130

SCD-2R0182.018

0.026

25

≥30

≤130

SCD-2R5162.516

0.029

25

≥30

≤130

SCD-3R015.53.015.5

0.032

25

≥30

≤130

SCD-4R0154.015

0.039

25

≥30

≤130

SCD-4R7144.714

0.044

25

≥30

≤130

SCD-5R0145.014

0.047

25

≥30

≤130

SCD-6R8126.812

0.061

25

≥30

≤130

SCD-7R0117.011

0.064

25

≥30

≤130

SCD-8R0108.010

0.079

25

≥30

≤130

SCD-10R1010.010

0.084

25

≥30

≤130

SCD-12R0912.09

0.102

25

≥30

≤130

SCD-15R0815.08

0.117

25

≥30

≤130

SCD-18R0818.08

0.125

25

≥30

≤130

SCD-20R0820.08

0.132

25

≥30

≤130

SCD-0R5300.530

0.013

30≥40

≤190

SCD-1R0301.030

0.014

30≥40

≤190

SCD-1R5251.525

0.016

30≥40

≤190

SCD-2R0232.023

0.019

30≥40

≤190

SCD-2R5202.520

0.023

30≥40

≤190

SCD-3R019.53.019.5

0.026

30≥40

≤190

SCD-4R0194.019

0.031

30≥40

≤190

SCD-4R7184.718

0.035

30≥40

≤190

SCD-5R0175.017

0.037

30≥40

≤190

SCD-6R0176.017

0.042

30≥40

≤190

SCD-6R8166.816

0.043

30≥40

≤190

SCD-7R0157.015

0.044

30≥40

≤190

SCD-8R0148.014

0.049

30≥40

≤190

SCD-10R1310.013

0.056

30≥40

≤190

SCD-12R1212.012

0.067

30≥40

≤190

SCD-15R1115.011

0.078

30≥40

≤190

SCD-18R1018.010

0.092

30≥40

≤190

SCD-20R0920.09

0.113

30≥40

≤190

SCD-0R5320.532

0.010

35≥55≤280
SCD-1R0321.032

0.011

35≥55≤280
SCD-1R5281.528

0.013

35≥55≤280
SCD-2R0252.025

0.017

35≥55≤280
SCD-2R5232.523

0.020

35≥55≤280
SCD-3R0223.022

0.023

35≥55≤280
SCD-4R0214.021

0.026

35≥55≤280
SCD-4R7204.720

0.029

35≥55≤280
SCD-5R0195.019

0.030

35≥55≤280
SCD-6R8186.818

0.035

35≥55≤280
SCD-7R0177.017

0.037

35≥55≤280
SCD-8R0168.016

0.041

35≥55≤280
SCD-10R1510.015

0.045

35≥55≤280
SCD-12R1412.014

0.051

35≥55≤280
SCD-15R1315.013

0.060

35≥55≤280
SCD-18R1118.011

0.072

35≥55≤280
SCD-20R1020.010

0.089

35≥55≤280
SCD-0R2400.2400.00540≥60≤350
SCD-0R5400.5400.00840≥60≤350
SCD-1R0401400.01040≥60≤350
SCD-1R5361.5360.01240≥60≤350
SCD-2R0322320.01440≥60≤350
SCD-2R5302.5300.01840≥60≤350
SCD-3R0283280.02040≥60≤350
SCD-4R0274270.02240≥60≤350
SCD-4R7264.7260.02340≥60≤350
SCD-5R0255250.02840≥60≤350
SCD-6R8236.8230.03040≥60≤350
SCD-8R0208200.03440≥60≤350
SCD-10R01910190.03840≥60≤350
SCD-12R01812180.04040≥60≤350
SCD-15R01615160.05040≥60≤350
SCD-18R01418140.06240≥60≤350
SCD-20R01320130.07540≥60≤350
SCD-0R2500.2500.00445≥70≤480
SCD-0R5500.5500.00745≥70≤480
SCD-1R0481480.00945≥70≤480
SCD-1R5451.5450.01145≥70≤480
SCD-2R0402400.01245≥70≤480
SCD-2R5372.5370.01545≥70≤480
SCD-3R0353350.01845≥70≤480
SCD-4R0344340.02045≥70≤480
SCD-4R7324.7320.02245≥70≤480
SCD-5R0305300.02545≥70≤480
SCD-6R8286.8280.02845≥70≤480
SCD-8R0268260.03045≥70≤480
SCD-10R02410240.03245≥70≤480
SCD-12R02212220.03445≥70≤480
SCD-15R02015200.04245≥70≤480
SCD-18R01818180.06145≥70≤480
SCD-20R01620160.07045≥70≤480
SCD-02R600.2600.00350≥90≤650
SCD-0R5600.5600.00650≥90≤650
SCD-1R0561560.00850≥90≤650
SCD-1R5501.5500.01050≥90≤650
SCD-2R0452450.01150≥90≤650
SCD-2R5422.5420.01250≥90≤650
SCD-3R0403400.01550≥90≤650
SCD-4R0384380.01850≥90≤650
SCD-4R7364.7360.02150≥90≤650
SCD-5R0355350.02250≥90≤650
SCD-6R8326.8320.02550≥90≤650
SCD-8R0298290.02850≥90≤650
SCD-10R02710270.03050≥90≤650
SCD-12R02512250.03350≥90≤650
SCD-15R02315230.04050≥90≤650
SCD-18R02018200.05550≥90≤650
SCD-20R01820180.06550≥90≤650


注:若非特別指出,R25的允許偏差為±20%。

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