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-1R09 | 1 | 9 | 0.032 | 13 | ≥13 | ≤63 | SCD-1R39 | 1.3 | 9 | 0.042 | 13 | ≥13 | ≤63 | SCD-1R59 | 1.5 | 9 | 0.043 | 13 | ≥13 | ≤63 | SCD-2R58-13 | 2.5 | 8 | 0.048 | 13 | ≥13 | ≤63 | SCD-3R08 | 3 | 8 | 0.052 | 13 | ≥13 | ≤ 63 | SCD-4R07 | 4 | 7 | 0.068 | 13 | ≥ 13 | ≤63 | SCD-5R07 | 5 | 7 | 0.078 | 13 | ≥13 | ≤63 | SCD-6R06 | 6 | 6 | 0.090 | 13 | ≥ 13 | ≤63 | SCD-7R06 | 7 | 6 | 0.098 | 13 | ≥13 | ≤63 | SCD-8R06 | 8 | 6 | 0.104 | 13 | ≥13 | ≤63 | SCD-10R06 | 10 | 6 | 0.126 | 13 | ≥13 | ≤ 63 | SCD-12R05 | 12 | 5 | 0.146 | 13 | ≥ 13 | ≤63 | SCD-15R04 | 15 | 4 | 0.155 | 13 | ≥13 | ≤63 | SCD-16R04 | 16 | 4 | 0.158 | 13 | ≥13 | ≤63 | SCD-20R04 | 20 | 4 | 0.192 | 13 | ≥ 13 | ≤63 | SCD-30R3.5 | 30 | 3.5 | 0.237 | 13 | ≥13 | ≤63 | SCD-47R03 | 47 | 3 | 0.340 | 13 | ≥13 | ≤63 | SCD-60R2.5 | 60 | 2.5 | 0.420 | 13 | ≥13 | ≤63 | SCD-121R2.5 | 120 | 1.8 | 0.994 | 13 | ≥13 | ≤63 | SCD-2R58-15 | 2.5 | 8 | 0.086 | 15 | ≥21 | ≤75 | SCD-1R310 | 1.3 | 10 | 0.034 | 15 | ≥22 | ≤75 | SCD-1R510 | 1.5 | 10 | 0.036 | 15 | ≥22
| ≤75 | SCD-2R59.5 | 2.5 | 9.5 | 0.044 | 15 | ≥22 | ≤75 | SCD-3R09 | 3.0 | 9.0 | 0.046 | 15 | ≥22 | ≤75 | SCD-5R08 | 5.0 | 8.0 | 0.058 | 15 | ≥22 | ≤75 | SCD-6R07 | 6.0 | 7.0 | 0.069 | 15 | ≥22 | ≤75 | SCD-7R07 | 7.0 | 7.0 | 0.078 | 15 | ≥22 | ≤75 | SCD-8R07 | 8.0 | 7.0 | 0.084 | 15 | ≥22 | ≤75 | SCD-10R07 | 10.0 | 7.0 | 0.098 | 15 | ≥22 | ≤75 | SCD-12R06 | 12.0 | 6.0 | 0.116 | 15 | ≥22 | ≤75 | SCD-15R06 | 15.0 | 6.0 | 0.125 | 15 | ≥22 | ≤75 | SCD-16R06 | 16.0 | 6.0 | 0.129 | 15 | ≥22 | ≤75 | SCD-20R06 | 20.0 | 6.0 | 0.136 | 15 | ≥22 | ≤75 | SCD-30R05 | 30.0 | 5.0 | 0.165 | 15 | ≥22 | ≤ 75 | SCD-47R04 | 47.0 | 4.0 | 0.257 | 15 | ≥22 | ≤ 75 | SCD-121R2.5 | 120 | 2.5 | 0.652 | 15 | ≥22 | ≤75 | SCD-0R716 | 0.7 | 16 | 0.026 | 20 | ≥29 | ≤110 | SCD-1R016 | 1.0 | 16 | 0.027 | 20 | ≥29 | ≤110 | SCD-1R020-20 | 1.0 | 20 | 0.020 | 20 | ≥29 | ≤113 | SCD-1R515 | 1.5 | 15 | 0.030 | 20 | ≥29 | ≤110 | SCD-2R014 | 2.0 | 14 | 0.035 | 20 | ≥29 | ≤110 | SCD-2R512 | 2.5 | 12 | 0.060 | 20 | ≥29 | ≤110 | SCD-2R513 | 2.5 | 13 | 0.055 | 20 | ≥29 | ≤110 | SCD-2R515-20 | 2.5 | 15 | 0.046 | 20 | ≥29 | ≤110 | SCD-3R012 | 3.0 | 12 | 0.040 | 20 | ≥29 | ≤110 | SCD-4R012 | 4.0 | 12 | 0.043 | 20 | ≥29 | ≤110 | SCD-4R712 | 4.7 | 12 | 0.046 | 20 | ≥29 | ≤110 | SCD-5R010 | 5.0 | 10 | 0.049 | 20 | ≥29 | ≤110 | SCD-5R012 | 5.0 | 12 | 0.047 | 20 | ≥29 | ≤110 | SCD-6R011 | 6.0 | 11 | 0.052 | 20 | ≥29 | ≤110 | SCD-6R810 | 6.8 | 10 | 0.055 | 20 | ≥29 | ≤110 | SCD-7R09 | 7.0 | 9 | 0.080 | 20 | ≥29 | ≤110 | SCD-7R010 | 7.0 | 10 | 0.075 | 20 | ≥29 | ≤110 | SCD-8R09 | 8.0 | 9 | 0.058 | 20 | ≥29 | ≤110 | SCD-10R08 | 10.0 | 8 | 0.085 | 20 | ≥29 | ≤110 | SCD-12R07.5 | 12.0 | 7.5 | 0.112 | 20 | ≥29 | ≤110 | SCD-15R07 | 15.0 | 7 | 0.123 | 20 | ≥29 | ≤110 | SCD-18R07 | 18.0 | 7 | 0.122 | 20 | ≥29 | ≤110 | SCD-20R06 | 20.0 | 6 | 0.132 | 20 | ≥29 | ≤110 | SCD-20R07 | 20.0 | 7 | 0.122 | 20 | ≥29 | ≤110 | SCD-25R06 | 25.0 | 6 | 0.168 | 20 | ≥29 | ≤110 | SCD-30R06 | 30.0 | 6 | 0.195 | 20 | ≥29 | ≤110 | SCD-47R05 | 47.0 | 5 | 0.325 | 20 | ≥29 | ≤110 | SCD-121R3 | 120.0 | 3 | 0.658 | 20 | ≥29 | ≤110 | SCD-0R522 | 0.5 | 22 | 0.017 | 25 | ≥30 | ≤130 | SCD-0R722 | 0.7 | 22 | 0.018 | 25 | ≥30 | ≤130 | SCD-1R020-25 | 1.0 | 20 | 0.021 | 25 | ≥30 | ≤130 | SCD-1R519 | 1.5 | 19 | 0.024 | 25 | ≥30 | ≤130 | SCD-2R018 | 2.0 | 18 | 0.026 | 25 | ≥30 | ≤130 | SCD-2R516 | 2.5 | 16 | 0.029 | 25 | ≥30 | ≤130 | SCD-3R015.5 | 3.0 | 15.5 | 0.032 | 25 | ≥30 | ≤130 | SCD-4R015 | 4.0 | 15 | 0.039 | 25 | ≥30 | ≤130 | SCD-4R714 | 4.7 | 14 | 0.044 | 25 | ≥30 | ≤130 | SCD-5R014 | 5.0 | 14 | 0.047 | 25 | ≥30 | ≤130 | SCD-6R812 | 6.8 | 12 | 0.061 | 25 | ≥30 | ≤130 | SCD-7R011 | 7.0 | 11 | 0.064 | 25 | ≥30 | ≤130 | SCD-8R010 | 8.0 | 10 | 0.079 | 25 | ≥30 | ≤130 | SCD-10R10 | 10.0 | 10 | 0.084 | 25 | ≥30 | ≤130 | SCD-12R09 | 12.0 | 9 | 0.102 | 25 | ≥30 | ≤130 | SCD-15R08 | 15.0 | 8 | 0.117 | 25 | ≥30 | ≤130 | SCD-18R08 | 18.0 | 8 | 0.125 | 25 | ≥30 | ≤130 | SCD-20R08 | 20.0 | 8 | 0.132 | 25 | ≥30 | ≤130 | SCD-0R530 | 0.5 | 30 | 0.013 | 30 | ≥40 | ≤190 | SCD-1R030 | 1.0 | 30 | 0.014 | 30 | ≥40 | ≤190 | SCD-1R525 | 1.5 | 25 | 0.016 | 30 | ≥40 | ≤190 | SCD-2R023 | 2.0 | 23 | 0.019 | 30 | ≥40 | ≤190 | SCD-2R520 | 2.5 | 20 | 0.023 | 30 | ≥40 | ≤190 | SCD-3R019.5 | 3.0 | 19.5 | 0.026 | 30 | ≥40 | ≤190 | SCD-4R019 | 4.0 | 19 | 0.031 | 30 | ≥40 | ≤190 | SCD-4R718 | 4.7 | 18 | 0.035 | 30 | ≥40 | ≤190 | SCD-5R017 | 5.0 | 17 | 0.037 | 30 | ≥40 | ≤190 | SCD-6R017 | 6.0 | 17 | 0.042 | 30 | ≥40 | ≤190 | SCD-6R816 | 6.8 | 16 | 0.043 | 30 | ≥40 | ≤190 | SCD-7R015 | 7.0 | 15 | 0.044 | 30 | ≥40 | ≤190 | SCD-8R014 | 8.0 | 14 | 0.049 | 30 | ≥40 | ≤190 | SCD-10R13 | 10.0 | 13 | 0.056 | 30 | ≥40 | ≤190 | SCD-12R12 | 12.0 | 12 | 0.067 | 30 | ≥40 | ≤190 | SCD-15R11 | 15.0 | 11 | 0.078 | 30 | ≥40 | ≤190 | SCD-18R10 | 18.0 | 10 | 0.092 | 30 | ≥40 | ≤190 | SCD-20R09 | 20.0 | 9 | 0.113 | 30 | ≥40 | ≤190 | SCD-0R532 | 0.5 | 32 | 0.010 | 35 | ≥55 | ≤280 | SCD-1R032 | 1.0 | 32 | 0.011 | 35 | ≥55 | ≤280 | SCD-1R528 | 1.5 | 28 | 0.013 | 35 | ≥55 | ≤280 | SCD-2R025 | 2.0 | 25 | 0.017 | 35 | ≥55 | ≤280 | SCD-2R523 | 2.5 | 23 | 0.020 | 35 | ≥55 | ≤280 | SCD-3R022 | 3.0 | 22 | 0.023 | 35 | ≥55 | ≤280 | SCD-4R021 | 4.0 | 21 | 0.026 | 35 | ≥55 | ≤280 | SCD-4R720 | 4.7 | 20 | 0.029 | 35 | ≥55 | ≤280 | SCD-5R019 | 5.0 | 19 | 0.030 | 35 | ≥55 | ≤280 | SCD-6R818 | 6.8 | 18 | 0.035 | 35 | ≥55 | ≤280 | SCD-7R017 | 7.0 | 17 | 0.037 | 35 | ≥55 | ≤280 | SCD-8R016 | 8.0 | 16 | 0.041 | 35 | ≥55 | ≤280 | SCD-10R15 | 10.0 | 15 | 0.045 | 35 | ≥55 | ≤280 | SCD-12R14 | 12.0 | 14 | 0.051 | 35 | ≥55 | ≤280 | SCD-15R13 | 15.0 | 13 | 0.060 | 35 | ≥55 | ≤280 | SCD-18R11 | 18.0 | 11 | 0.072 | 35 | ≥55 | ≤280 | SCD-20R10 | 20.0 | 10 | 0.089 | 35 | ≥55 | ≤280 | SCD-0R240 | 0.2 | 40 | 0.005 | 40 | ≥60 | ≤350 | SCD-0R540 | 0.5 | 40 | 0.008 | 40 | ≥60 | ≤350 | SCD-1R040 | 1 | 40 | 0.010 | 40 | ≥60 | ≤350 | SCD-1R536 | 1.5 | 36 | 0.012 | 40 | ≥60 | ≤350 | SCD-2R032 | 2 | 32 | 0.014 | 40 | ≥60 | ≤350 | SCD-2R530 | 2.5 | 30 | 0.018 | 40 | ≥60 | ≤350 | SCD-3R028 | 3 | 28 | 0.020 | 40 | ≥60 | ≤350 | SCD-4R027 | 4 | 27 | 0.022 | 40 | ≥60 | ≤350 | SCD-4R726 | 4.7 | 26 | 0.023 | 40 | ≥60 | ≤350 | SCD-5R025 | 5 | 25 | 0.028 | 40 | ≥60 | ≤350 | SCD-6R823 | 6.8 | 23 | 0.030 | 40 | ≥60 | ≤350 | SCD-8R020 | 8 | 20 | 0.034 | 40 | ≥60 | ≤350 | SCD-10R019 | 10 | 19 | 0.038 | 40 | ≥60 | ≤350 | SCD-12R018 | 12 | 18 | 0.040 | 40 | ≥60 | ≤350 | SCD-15R016 | 15 | 16 | 0.050 | 40 | ≥60 | ≤350 | SCD-18R014 | 18 | 14 | 0.062 | 40 | ≥60 | ≤350 | SCD-20R013 | 20 | 13 | 0.075 | 40 | ≥60 | ≤350 | SCD-0R250 | 0.2 | 50 | 0.004 | 45 | ≥70 | ≤480 | SCD-0R550 | 0.5 | 50 | 0.007 | 45 | ≥70 | ≤480 | SCD-1R048 | 1 | 48 | 0.009 | 45 | ≥70 | ≤480 | SCD-1R545 | 1.5 | 45 | 0.011 | 45 | ≥70 | ≤480 | SCD-2R040 | 2 | 40 | 0.012 | 45 | ≥70 | ≤480 | SCD-2R537 | 2.5 | 37 | 0.015 | 45 | ≥70 | ≤480 | SCD-3R035 | 3 | 35 | 0.018 | 45 | ≥70 | ≤480 | SCD-4R034 | 4 | 34 | 0.020 | 45 | ≥70 | ≤480 | SCD-4R732 | 4.7 | 32 | 0.022 | 45 | ≥70 | ≤480 | SCD-5R030 | 5 | 30 | 0.025 | 45 | ≥70 | ≤480 | SCD-6R828 | 6.8 | 28 | 0.028 | 45 | ≥70 | ≤480 | SCD-8R026 | 8 | 26 | 0.030 | 45 | ≥70 | ≤480 | SCD-10R024 | 10 | 24 | 0.032 | 45 | ≥70 | ≤480 | SCD-12R022 | 12 | 22 | 0.034 | 45 | ≥70 | ≤480 | SCD-15R020 | 15 | 20 | 0.042 | 45 | ≥70 | ≤480 | SCD-18R018 | 18 | 18 | 0.061 | 45 | ≥70 | ≤480 | SCD-20R016 | 20 | 16 | 0.070 | 45 | ≥70 | ≤480 | SCD-02R60 | 0.2 | 60 | 0.003 | 50 | ≥90 | ≤650 | SCD-0R560 | 0.5 | 60 | 0.006 | 50 | ≥90 | ≤650 | SCD-1R056 | 1 | 56 | 0.008 | 50 | ≥90 | ≤650 | SCD-1R550 | 1.5 | 50 | 0.010 | 50 | ≥90 | ≤650 | SCD-2R045 | 2 | 45 | 0.011 | 50 | ≥90 | ≤650 | SCD-2R542 | 2.5 | 42 | 0.012 | 50 | ≥90 | ≤650 | SCD-3R040 | 3 | 40 | 0.015 | 50 | ≥90 | ≤650 | SCD-4R038 | 4 | 38 | 0.018 | 50 | ≥90 | ≤650 | SCD-4R736 | 4.7 | 36 | 0.021 | 50 | ≥90 | ≤650 | SCD-5R035 | 5 | 35 | 0.022 | 50 | ≥90 | ≤650 | SCD-6R832 | 6.8 | 32 | 0.025 | 50 | ≥90 | ≤650 | SCD-8R029 | 8 | 29 | 0.028 | 50 | ≥90 | ≤650 | SCD-10R027 | 10 | 27 | 0.030 | 50 | ≥90 | ≤650 | SCD-12R025 | 12 | 25 | 0.033 | 50 | ≥90 | ≤650 | SCD-15R023 | 15 | 23 | 0.040 | 50 | ≥90 | ≤650 | SCD-18R020 | 18 | 20 | 0.055 | 50 | ≥90 | ≤650 | SCD-20R018 | 20 | 18 | 0.065 | 50 | ≥90 | ≤650 |
注:若非特別指出,R25的允許偏差為±20%。 華巨電子熱敏電阻廠家:www.vtt-mtb.com
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