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  1. (Dept. of Electrical Engineering, Ulsan National Institute of Science and Technology (UNIST), Korea.)
  2. (Dept. of Electrical Engineering, Ulsan National Institute of Science and Technology (UNIST), Korea.)



IH(Induction Heating), SRI(Series Resonant Inverter), Impedance measurement, Temperature estimation

1. ์„œ ๋ก 

์œ ๋„ ๊ฐ€์—ด (Induction Heating; IH) ๊ธฐ์ˆ ์€ ๋‹ค๋ฅธ ๊ฐ€์—ด ๋ฐฉ๋ฒ•์— ๋น„ํ•ด ๊ณ ํšจ์œจ, ๊ณ ์† ๊ฐ€์—ด, ๋น„์ ‘์ด‰์‹ ๊ฐ€์—ด ๋ฐ ์ฒญ๊ฒฐ์„ฑ์œผ๋กœ ์ธํ•ด ์‚ฐ์—…๊ณ„์™€ ๊ฐ€์ • ๋ฐ ์˜๋ฃŒ๊ณ„์—์„œ ๋„๋ฆฌ ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋Š” ๊ธฐ์ˆ ์ด๋‹ค(1). ์œ ๋„ ๊ฐ€์—ด๊ธฐ๋Š” ๊ทธ๋ฆผ 1๊ณผ ๊ฐ™์ด ๋‹ค์ด์˜ค๋“œ ์ •๋ฅ˜๊ธฐ, ์Šค์œ„์นญ ํšŒ๋กœ, ๊ณต์ง„ ํƒฑํฌ, ์›Œํ‚น ์ฝ”์ผ๋กœ ๊ตฌ์„ฑ๋œ๋‹ค. ์œ ๋„ ๊ฐ€์—ด๊ธฐ์— ์ „์›์ด ์ธ๊ฐ€๋จ์— ๋”ฐ๋ผ ์›Œํ‚น ์ฝ”์ผ์— ๊ณ ์ฃผํŒŒ ์ „๋ฅ˜๊ฐ€ ํ๋ฅด๊ฒŒ ๋œ๋‹ค. ์ด์— ๋”ฐ๋ผ ์›Œํ‚น ์ฝ”์ผ ์ฃผ๋ณ€์— ๋ฐœ์ƒํ•˜๋Š” ์ž๊ณ„์— ์˜ํ•ด ๋ฐœ์ƒํ•˜๋Š” ์™€์ „๋ฅ˜(Eddy current)์˜ ์ €ํ•ญ ์†์‹ค(Ohmic Loss)๋กœ ์šฉ๊ธฐ๊ฐ€ ๊ฐ€์—ด๋˜๋Š” ๋ฐฉ์‹์ด๋‹ค. ์ตœ๊ทผ ๊ฐ€์ •์—์„œ ์‚ฌ์šฉํ•˜๊ณ  ์žˆ๋Š” ์ธ๋•์…˜ ๋ ˆ์ธ์ง€๋Š” ์‚ฌ์šฉ์ž์—๊ฒŒ ํŽธ์˜์„ฑ ๋ฐ ์•ˆ์ •์„ฑ์„ ๊ฐ•ํ™”ํ•˜๊ธฐ ์œ„ํ•ด ์ž๋™ ์กฐ๋ฆฌ ๊ธฐ๋Šฅ๊ณผ ์ •์˜จ ๊ธฐ๋Šฅ ๊ฐœ๋ฐœ์ด ํ™œ๋ฐœํ•˜๊ฒŒ ์ด๋ฃจ์–ด์ง€๊ณ  ์žˆ๋‹ค(2). ์œ ๋„ ๊ฐ€์—ด๊ธฐ๋ฅผ ์‚ฌ์šฉํ•จ์— ์žˆ์–ด ์ผ๋ฐ˜์ ์œผ๋กœ ์‚ฌ์šฉ์ž๋Š” ์˜จ๋„๊ฐ€ ์–ผ๋งˆ๋‚˜ ๋†’์€์ง€์— ๋Œ€ํ•œ ์‹ค์‹œ๊ฐ„ ์ •๋ณด๊ฐ€ ์—†๊ธฐ ๋•Œ๋ฌธ์— ํ•„์š”์น˜๋ณด๋‹ค ๋” ๋งŽ์€ ์ „๋ ฅ์„ ์‚ฌ์šฉํ•˜๋Š” ๊ฒฝํ–ฅ์ด ์žˆ๋‹ค. ์ „๋ ฅ ์ „์ž ์žฅ์น˜์˜ ํšจ์œจ์„ฑ์€ ๋งค์šฐ ๋†’์ง€๋งŒ ์ด๋Ÿฌํ•œ ์—๋„ˆ์ง€ ๋‚ญ๋น„๋Š” ์ „์ฒด ์กฐ๋ฆฌ ๊ณผ์ •์˜ ์—๋„ˆ์ง€ ํšจ์œจ์„ฑ์„ ๊ฐ์†Œ์‹œํ‚จ๋‹ค.

๊ทธ๋ฆผ. 1. IH ์‹œ์Šคํ…œ์˜ ๋ธ”๋ก๋„์™€ ํŒŒํ˜•

Fig. 1. Block Diagram and Waveforms of an IH System

../../Resources/kiee/KIEE.2022.71.9.1230/fig1.png

๋”ฐ๋ผ์„œ ์šฉ๊ธฐ์˜ ์‹ค์‹œ๊ฐ„ ์˜จ๋„ ์ •๋ณด๋Š” ์—๋„ˆ์ง€ ํšจ์œจ์„ฑ ์ธก๋ฉด์—์„œ๋„ ํ•„์ˆ˜์ ์ด๋‹ค. ๊ธฐ์กด ์˜จ๋„ ์ธก์ • ๋ฐฉ์‹์€ NTC ์ €ํ•ญ์„ ์‚ฌ์šฉํ•˜์—ฌ ์˜จ๋„์— ์˜ํ•ด ๋ณ€ํ™”๋œ NTC ์ €ํ•ญ๊ฐ’์— ์˜ํ•ด ๊ฐ„์ ‘์ ์œผ๋กœ ์ธก์ •ํ•˜์˜€๋‹ค(3). ๊ทธ๋Ÿฌ๋‚˜ ์šฉ๊ธฐ์˜ ์˜จ๋„๋ฟ๋งŒ ์•„๋‹ˆ๋ผ IH ์ฝ”์ผ ์˜จ๋„์˜ ์˜ํ–ฅ๋„ ๋ฐ›๊ธฐ ๋•Œ๋ฌธ์— ์˜จ๋„ ์ถ”์ • ์˜ค์ฐจ์œจ์ด ๋†’์€ ๋ฌธ์ œ์ ์ด ์žˆ๋‹ค. ๊ทธ๋ฆฌ๊ณ  ์ ์™ธ์„  ์„ผ์„œ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ์šฉ๊ธฐ์˜ ์˜จ๋„๋ฅผ ์™ธ๋ถ€ ์ ์™ธ์„  ์„ผ์„œ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ์ง์ ‘์ ์œผ๋กœ ์ธก์ •ํ•˜๋Š” ๋ฐฉ์‹๋„ ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์™ธ๋ถ€ ์„ผ์„œ๋ฅผ ์‚ฌ์šฉํ•จ์— ๋”ฐ๋ผ ์‹œ์Šคํ…œ ๋น„์šฉ์„ ์ฆ๊ฐ€์‹œํ‚ค๊ณ , ์‚ฌ์šฉ์ž์— ์˜ํ•ด ์™ธ๋ถ€์— ๋Œ์ถœ๋œ ์„ผ์„œ๊ฐ€ ์†์ƒ๋  ์ˆ˜ ์žˆ์–ด ์„ผ์„œ ํŒŒ์†์— ๋Œ€ํ•œ ์ธก์ • ์˜ค์ฐจ ๋ฐ ์œ ์ง€๊ด€๋ฆฌ ๋น„์šฉ์ด ๋ฐœ์ƒํ•  ์ˆ˜ ์žˆ๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ์™ธ๋ถ€ ์„ผ์„œ ์—†์ด IH ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก์„ ํ†ตํ•ด ์˜จ๋„๋ฅผ ์ถ”์ •ํ•œ๋‹ค. ์˜จ๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜๋ฉด ๊ธˆ์† ์•ˆ์˜ ์ž์œ ์ „์ž์˜ ์ด๋™์„ฑ์ด ๋†’์•„์ ธ ์ „๋ฅ˜์˜ ํ๋ฆ„์„ ๋ฐฉํ•ดํ•˜๊ฒŒ ๋˜์–ด ์˜จ๋„๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์ €ํ•ญ์ด ์ฆ๊ฐ€ํ•˜๊ฒŒ ๋œ๋‹ค. ๋”ฐ๋ผ์„œ ์‹ค์‹œ๊ฐ„ ์ž„ํ”ผ๋˜์Šค ์ธก์ •์„ ํ†ตํ•ด ์˜จ๋„์™€ ์ž„ํ”ผ๋˜์Šค ๊ฐ„์˜ ๊ด€๊ณ„์„ฑ์„ ํŒŒ์•…ํ•˜์—ฌ ์šฉ๊ธฐ์˜ ์˜จ๋„๋ฅผ ์ถ”์ •ํ•œ๋‹ค. IH ๋ถ€ํ•˜์˜ ์‹ค์‹œ๊ฐ„ ์ž„ํ”ผ๋˜์Šค ์ธก์ •์„ ํ†ตํ•ด ์ •ํ™•ํ•˜๊ฒŒ ์ ์ • ์ถœ๋ ฅ ์ „๋ ฅ์„ ์ œ์–ดํ•  ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ๋ถ€ํ•˜ ์ž„ํ”ผ๋˜์Šค์™€ ์˜จ๋„์™€์˜ ๊ด€๊ณ„๋ฅผ ํ†ตํ•ด ์ž๋™ ์กฐ๋ฆฌ ๊ธฐ๋Šฅ์˜ ๊ตฌํ˜„์„ ๊ธฐ๋Œ€ํ•  ์ˆ˜ ์žˆ๋‹ค.

์œ ๋„ ๊ฐ€์—ด ์‹œ์Šคํ…œ์€ ์ตœ์†Œ 20 kHz ์ด์ƒ์˜ ์Šค์œ„์นญ ์ฃผํŒŒ์ˆ˜๋กœ ๋™์ž‘ํ•˜์—ฌ ์ƒ˜ํ”Œ๋ง๋œ ์‹ ํ˜ธ๋ฅผ ์›์‹ ํ˜ธ ์ •๋ณด๋กœ ๋ณต์›ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ๊ณ ์ฃผํŒŒ ADC(Analog-to-Digital Converter) ๋ฅผ ํ•„์š”๋กœ ํ•œ๋‹ค. ์ฐธ๊ณ ๋ฌธํ—Œ (5),(6),(7)์—์„œ๋Š” 10 MHz ์ด์ƒ์˜ ์ƒ˜ํ”Œ๋ง ์ฃผํŒŒ์ˆ˜๋กœ ์ž„ํ”ผ๋˜์Šค๋ฅผ ๊ณ„์ธกํ•˜์˜€์œผ๋ฉฐ, ์ด๋กœ ์ธํ•ด FPGA์™€ ๊ฐ™์€ ๋†’์€ ์„ฑ๋Šฅ์˜ ์ œ์–ด๊ธฐ๊ฐ€ ์š”๊ตฌ๋˜์–ด ์œ ๋„ ๊ฐ€์—ด ์‹œ์Šคํ…œ์˜ ๋น„์šฉ์„ ์ฆ๊ฐ€์‹œํ‚ค๋Š” ๋ฌธ์ œ๊ฐ€ ์žˆ๋‹ค.

๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ์ € ์„ฑ๋Šฅ ์ œ์–ด๊ธฐ์—์„œ๋„ ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก์ด ๊ฐ€๋Šฅํ•œ Time-Split ๋ฐฉ์‹์— ๊ธฐ๋ฐ˜ํ•œ ์˜จ๋„ ์ถ”์ •๊ธฐ๋ฒ•์„ ์ œ์•ˆํ•œ๋‹ค. ๊ธฐ์กด ์—ฐ๊ตฌ์— ๋น„ํ•ด ๋‚ฎ์€ ์ƒ˜ํ”Œ๋ง ์ฃผํŒŒ์ˆ˜๋ฅผ ์‚ฌ์šฉํ•˜์ง€๋งŒ ์ž„ํ”ผ๋˜์Šค๋ฅผ ์ •ํ™•ํ•˜๊ฒŒ ๊ณ„์ธกํ•œ๋‹ค. ๊ฒฐ๊ณผ์ ์œผ๋กœ ๊ธฐ์กด ๋ฐฉ์‹์— ๋น„ํ•ด ์œ ๋„ ๊ฐ€์—ด ์‹œ์Šคํ…œ์˜ ๋น„์šฉ์„ ์ ˆ๊ฐํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋ฆผ 2์™€ ๊ฐ™์ด 2-kW ํ•˜ํ”„ ๋ธŒ๋ฆฌ์ง€ ์ง๋ ฌ ๊ณต์ง„ํ˜• ์ธ๋ฒ„ํ„ฐ ์‹œ์ž‘ํ’ˆ์„ ํ†ตํ•ด ์ œ์•ˆํ•˜๋Š” Time-Split ๊ธฐ๋ฒ•์„ ์‚ฌ์šฉํ•˜์—ฌ ์‹ค์‹œ๊ฐ„ ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก์„ ํ†ตํ•ด ํŠน์ • ์šฉ๊ธฐ์— ๋Œ€ํ•œ ์˜จ๋„ ์ถ”์ •์˜ ํƒ€๋‹น์„ฑ์„ ๊ฒ€์ฆํ•˜๊ณ ์ž ํ•œ๋‹ค.

2. ์‹ค์‹œ๊ฐ„ ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก

2.1 IH ๋ถ€ํ•˜

IH ๋ถ€ํ•˜๋Š” ์ผ๋ฐ˜์ ์œผ๋กœ ๊ทธ๋ฆผ 3๊ณผ ๊ฐ™์ด ๋“ฑ๊ฐ€ ์ธ๋•ํ„ฐ์™€ ๋“ฑ๊ฐ€ ์ €ํ•ญ์˜ ์ง๋ ฌ์—ฐ๊ฒฐ๋กœ ๋ชจ๋ธ๋ง์ด ๋œ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ IH ๋ถ€ํ•˜๋Š” ์šฉ๊ธฐ์˜ ์žฌ์งˆ, ์ฃผํŒŒ์ˆ˜, ์˜จ๋„, ์ธ๋•ํ„ฐ์™€ ์šฉ๊ธฐ์˜ ์ƒ๋Œ€์  ์œ„์น˜์— ๋”ฐ๋ผ ๋ณ€ํ™”ํ•œ๋‹ค. ์ธ๋ฒ„ํ„ฐ์˜ ์ถœ๋ ฅ ์ „๋ ฅ ๋ฐ ํšจ์œจ์€ ๋™์ž‘์ ์— ๋”ฐ๋ผ ์ขŒ์šฐ๋œ๋‹ค. ์ด๋กœ ์ธํ•ด ์ •ํ™•ํ•œ ์ „๋ ฅ ์ œ์–ด ๋ฐ ์˜์ „์•• ์Šค์œ„์นญ(Zero Voltage Switching; ZVS) ๋™์ž‘์ด ๋ณด์žฅ๋˜์ง€ ์•Š์•„ IH ์‹œ์Šคํ…œ์˜ ์‹ ๋ขฐ์„ฑ์ด ์ €ํ•ด๋  ์ˆ˜ ์žˆ๋‹ค. ๋˜ํ•œ, ์ด๋ฅผ ํšŒํ”ผํ•˜๊ธฐ ์œ„ํ•ด ๊ณผ๋„ํ•˜๊ฒŒ ๊ณ ์ฃผํŒŒ ์˜์—ญ์—์„œ ๋™์ž‘ํ•˜๋ฉด ์ถฉ๋ถ„ํ•œ ์ „์•• ์ด๋“์„ ์–ป์„ ์ˆ˜ ์—†๊ณ , ์Šค์œ„์นญ ์†์‹ค๋„ ์ฆ๊ฐ€ํ•œ๋‹ค. ๋”ฐ๋ผ์„œ IH ์‹œ์Šคํ…œ์˜ ๋†’์€ ์‹ ๋ขฐ๋„์™€ ํšจ์œจ ๋ฐ ์ถฉ๋ถ„ํ•œ ์ „๋ ฅ์„ ์–ป๊ธฐ ์œ„ํ•ด์„œ๋Š” ๋™์ž‘์ ์— ๋”ฐ๋ฅธ ์‹ค์‹œ๊ฐ„ ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก์€ ํ•„์ˆ˜์ ์ด๋‹ค.

2.2 ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก ๊ธฐ๋ณธ ์›๋ฆฌ

๊ทธ๋ฆผ 4์™€ ๊ฐ™์ด LCR Meter๋ฅผ ์ด์šฉํ•˜์—ฌ ์˜คํ”„๋ผ์ธ ์ƒํƒœ์—์„œ ์ „์ฒด ๋ถ€ํ•˜ ์ž„ํ”ผ๋˜์Šค๋กœ๋ถ€ํ„ฐ ๋ถ€ํ•˜์˜ ๋“ฑ๊ฐ€ ์ €ํ•ญ๊ณผ ๋“ฑ๊ฐ€ ๋ฆฌ์•กํ„ด์Šค๋ฅผ ๊ณ„์ธกํ•  ์ˆ˜ ์žˆ๋‹ค. ์šฉ๊ธฐ์™€ ๊ณต์ง„ ์ปคํŒจ์‹œํ„ด์Šค๊ฐ€ ๊ฒฐํ•ฉ๋œ IH Inverter์˜ ๋ถ€ํ•˜ ์ž„ํ”ผ๋˜์Šค๋ฅผ ์ˆ˜์‹์œผ๋กœ ๋‚˜ํƒ€๋‚ด๋ฉด ์‹(1)๊ณผ ๊ฐ™๋‹ค.

๊ทธ๋ฆผ. 2. IH ์ธ๋ฒ„ํ„ฐ ํšŒ๋กœ๋„

Fig. 2. Circuit Diagram of an IH Inverter

../../Resources/kiee/KIEE.2022.71.9.1230/fig2.png

๊ทธ๋ฆผ. 3. IH ๊ณต์ง„ ๋„คํŠธ์›Œํฌ์˜ ๋“ฑ๊ฐ€ ํšŒ๋กœ

Fig. 3. Equivalent Circuit of an IH Resonant Network

../../Resources/kiee/KIEE.2022.71.9.1230/fig3.png

๊ทธ๋ฆผ. 4. ๋™์ž‘ ์ฃผํŒŒ์ˆ˜์— ๋”ฐ๋ฅธ IH ๋ถ€ํ•˜์˜ ์ €ํ•ญ๊ณผ ์ธ๋•ํ„ด์Šค

Fig. 4. Resistance and Inductance Curves of an IH Loads According to the Operating Frequency

../../Resources/kiee/KIEE.2022.71.9.1230/fig4.png

(1)
Zload =Rload +jXload 

Rload ์€ ์ฝ”์ผ๊ณผ ์šฉ๊ธฐ์˜ ํ•ฉ์„ฑ์ €ํ•ญ, Xload ๋Š” ๋ถ€ํ•˜์˜ ๋ฆฌ์•กํ„ด์Šค ์ด๋‹ค. Rload,Xload  ์€ '์˜ด์˜ ๋ฒ•์น™'์— ์˜ํ•ด ํ•˜๊ธฐ์˜ ์‹(2), (3)๊ณผ ๊ฐ™์ด ๋‚˜ํƒ€๋‚œ๋‹ค.

(2)
Rload =PtrI2r(rms)

(3)
Xload =QtrI2r(rms)

Ir(rms) ๋Š” ์ธ๋ฒ„ํ„ฐ ๋ถ€ํ•˜์˜ ๊ณต์ง„ ์ „๋ฅ˜์˜ RMS ์ „๋ฅ˜์ด๊ณ , ์€ ์ € ํ•ญ์— ์ „๋‹ฌ๋˜๋Š” ์œ ํšจ ์ „๋ ฅ, Qtr ๋Š” ๋ฆฌ์•กํ„ด์Šค์— ์ „๋‹ฌ๋˜๋Š” ๋ฌดํšจ์ „ ๋ ฅ์ด๋‹ค. ๊ทธ๋ฆผ 2 ๋Š” IH ์ธ๋ฒ„ํ„ฐ์˜ ์ „์••, ์ „๋ฅ˜ ์ธก์ • ์ง€์ ์„ ๋ณด์—ฌ์ค€ ๋‹ค. IH ์ธ๋ฒ„ํ„ฐ์˜ ์ž„ํ”ผ๋˜์Šค ๋””์ง€ํ„ธ ์ถ”์ •์€ ๊ทธ๋ฆผ 2 ์˜ ์ „์••๊ณผ ์ „ ๋ฅ˜ ์ธก์ • ์ง€์ ์—์„œ DSP์— ์˜ํ•ด ์ƒ˜ํ”Œ๋งํ•˜์—ฌ ์‹(4), (5)์™€ ๊ฐ™์ด ์–ป์„ ์ˆ˜ ์žˆ๋‹ค.

(4)
Vsw(rms)=โˆš1nnโˆ‘k=1V2sw[k]

(5)
Ir(rms)=โˆš1nnโˆ‘k=1I2sw[k]

์‹(6)-(8)์€ ์ „๋ ฅ ๊ณต์‹์— ๋”ฐ๋ผ Str ๋Š” ํ”ผ์ƒ์ „๋ ฅ, Ptr ๋Š” ์œ ํšจ ์ „๋ ฅ, Qtr ๋Š” ๋ฌดํšจ์ „๋ ฅ์ด๋‹ค.

(6)
Str=VrmsIrms

(7)
Ptr=1nnโˆ‘k=1Vsw[k]Isw[k]

(8)
Qtr=โˆšS2trโˆ’P2tr

์‹(4)-(8)์„ ํ†ตํ•ด Ir(rms),Ptr,Qtr ๋ฅผ ๊ณ„์‚ฐํ•˜๊ณ  ์‹(2), (3) ์— ๋Œ€์ž…ํ•˜์—ฌ ์ €ํ•ญ๊ณผ ๋ฆฌ์•กํ„ด์Šค ๊ฐ’์„ ๊ณ„์ธกํ•  ์ˆ˜ ์žˆ๋‹ค.

2.4 Time-Split ๊ธฐ๋ฒ•

๊ธฐ์กด์˜ ๋””์ง€ํ„ธ ์‹ ํ˜ธ ์ธก์ • ๋ฐฉ์‹์€ ๋†’์€ ์ƒ˜ํ”Œ๋ง ์ฃผํŒŒ์ˆ˜๊ฐ€ ์š”๊ตฌ๋˜์–ด ๋†’์€ ์„ฑ๋Šฅ์˜ ์ œ์–ด๊ธฐ์™€ ์‹ ํ˜ธ์ฒ˜๋ฆฌ๊ธฐ๊ฐ€ ํ•„์š”ํ•˜๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” Time-Split ๊ธฐ๋ฒ•์„ ํ†ตํ•ด ๋‚ฎ์€ ์ƒ˜ํ”Œ๋ง ์ฃผํŒŒ์ˆ˜๋กœ๋„ ๋น„๊ต์  ์ •ํ™•ํžˆ ์ž„ํ”ผ๋˜์Šค๋ฅผ ๊ณ„์ธกํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋ฆผ 5์™€ ๊ฐ™์ด, Time-Split ๊ธฐ๋ฒ•์€ ๋งŽ์€ ํŒŒํ˜•์œผ๋กœ๋ถ€ํ„ฐ ์ƒ˜ํ”Œ๋ง ๋ฐ์ดํ„ฐ๋ฅผ ์–ป๋Š” ๊ธฐ๋ฒ•์ด๋‹ค. ์Šค์œ„์นญ ์ฃผํŒŒ์ˆ˜์™€ ์ƒ˜ํ”Œ๋ง ์ฃผํŒŒ์ˆ˜ ๊ฐ„์˜ ์ฐจ์ด๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ํŒŒํ˜•์ด ์ƒ˜ํ”Œ๋ง๋˜๋Š” ํšŸ์ˆ˜๋ฅผ ๊ฒฐ์ •ํ•œ๋‹ค. ์ƒ˜ํ”Œ๋ง ์ฃผํŒŒ์ˆ˜๋Š” ์‹(9)์™€ ๊ฐ™์ด ๋„์ถœํ•œ๋‹ค. ์—ฌ๊ธฐ์„œ k๋Š” ํŒŒํ˜• ์ˆ˜, kโˆ’1์€ ์ƒ˜ํ”Œ๋ง ์ˆ˜, fsw๋Š” IH ์ธ๋ฒ„ํ„ฐ์˜ ์Šค์œ„์นญ ์ฃผํŒŒ์ˆ˜์ด๋‹ค.

๊ทธ๋ฆผ. 5. Time-Split ๊ธฐ๋ฒ•

Fig. 5. Time-Split Method

../../Resources/kiee/KIEE.2022.71.9.1230/fig5.png

๊ทธ๋ฆผ. 6. ์—ฐ์†์ ์ธ ๊ณต์ง„ ์ „๋ฅ˜์˜ FFT ํŒŒํ˜•

Fig. 6. FFT Waveform of Continuous Resonant Curren

../../Resources/kiee/KIEE.2022.71.9.1230/fig6.png

๊ทธ๋ฆผ. 7. ์ƒ˜ํ”Œ๋œ ๊ณต์ง„ ์ „๋ฅ˜์˜ FFT ํŒŒํ˜•

Fig. 7. FFT Waveform of Sampled Resonant Current

../../Resources/kiee/KIEE.2022.71.9.1230/fig7.png

๊ทธ๋ฆผ. 8. ๊ณต์ง„ ์ „๋ฅ˜์˜ FFT ํŒŒํ˜•

Fig. 8. Magnitude Plot of the Band-Pass Filter

../../Resources/kiee/KIEE.2022.71.9.1230/fig8.png

(9)
fsample=kโˆ’1kfsw

๊ทธ๋ฆผ 6์€ ์Šค์œ„์นญ ์ฃผํŒŒ์ˆ˜๊ฐ€ 50 kHz์ธ ๊ณต์ง„ ์ „๋ฅ˜์˜ FFT(Fast Fourier Transform) ํŒŒํ˜•์ด๊ณ , ๊ทธ๋ฆผ 7์€ Time-Split ๊ธฐ๋ฒ•์„ ํ†ตํ•ด ์ƒ˜ํ”Œ๋ง ๋œ ๊ณต์ง„ ์ „๋ฅ˜์˜ FFT ํŒŒํ˜•์ด๋‹ค. ์‹(10)์€ Time-Split ๊ธฐ๋ฒ•์„ ํ†ตํ•ด ์ƒ˜ํ”Œ๋ง๋œ ์ž„์˜์˜ ํ™€์ˆ˜์ธ X์ฐจ ์ฃผํŒŒ์ˆ˜ ์„ฑ๋ถ„์ด๋‹ค.

(10)
fharmonic (X)=X(fsw ยฑfsample )

์˜ˆ๋ฅผ ๋“ค์–ด ์Šค์œ„์นญ ์ฃผํŒŒ์ˆ˜๊ฐ€ 50 kHz์ธ ํŒŒํ˜•์„ 100๊ฐœ์˜ ํŒŒํ˜• ์ค‘์— 99๋ฒˆ ์ƒ˜ํ”Œ๋ง ํ•ด์•ผ ํ•˜๋Š” ๊ฒฝ์šฐ ์› ์‹ ํ˜ธ์˜ 1/100์ธ ์ฃผํŒŒ์ˆ˜ ์„ฑ๋ถ„์„ ๊ฐ€์ง„๋‹ค. ์ œ์•ˆํ•˜๋Š” ์•Œ๊ณ ๋ฆฌ์ฆ˜์€ ๊ณต์ง„์  ๊ทผ์ฒ˜์—์„œ ๋™์ž‘ํ•˜๋ฏ€๋กœ ์œ ํšจ ์ „๋ ฅ์€ ๋Œ€๋ถ€๋ถ„ ๊ธฐ๋ณธํŒŒ ์„ฑ๋ถ„์— ์˜ํ•ด ์ „๋‹ฌ๋œ๋‹ค. ๋”ฐ๋ผ์„œ ์ƒ˜ํ”Œ๋ง๋œ ํŒŒํ˜•์—์„œ ๊ธฐ๋ณธํŒŒ ์ถ”์ถœ์„ ํ†ตํ•ด ์ž„ํ”ผ๋˜์Šค๋ฅผ ์ถ”์ •ํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜, AC ์ž…๋ ฅ์˜ ๊ฒฝ์šฐ ๊ทธ๋ฆผ 7๊ณผ ๊ฐ™์ด ์ „ํŒŒ ์ •๋ฅ˜๋œ

120 Hz์˜ Side Band๊ฐ€ ์กด์žฌํ•œ๋‹ค. ๋”ฐ๋ผ์„œ Side Band๋ฅผ ํฌํ•จํ•˜๋Š” ๋‹ค๋ฅธ ๊ณ ์กฐํŒŒ ์„ฑ๋ถ„์— ์˜ํ•œ ์™œ๊ณก์„ ๋ฐฉ์ง€ํ•˜๊ธฐ ์œ„ํ•ด ๋Œ€์—ญํ†ต๊ณผํ•„ํ„ฐ๊ฐ€ ์š”๊ตฌ๋œ๋‹ค. 3์ฐจ ๊ณ ์กฐํŒŒ ์ด์ƒ์˜ ์ฃผํŒŒ์ˆ˜ ์„ฑ๋ถ„์€ ๊ธฐ๋ณธํŒŒ ์„ฑ๋ถ„์— ๋น„ํ•ด ๋งค์šฐ ์ž‘์œผ๋‚˜ Side Band ์ฃผํŒŒ์ˆ˜ ์„ฑ๋ถ„์€ ์•ฝ ๊ธฐ๋ณธํŒŒ์˜ ์•ฝ 3/10์˜ ํฌ๊ธฐ๋ฅผ ๊ฐ€์ง„๋‹ค. ๋”ฐ๋ผ์„œ ๊ธฐ๋ณธํŒŒ๋งŒ์„ ์ถ”์ถœํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” Side Band ์„ฑ๋ถ„์„ ํ•„ํ„ฐ๋งํ•ด์•ผ ํ•œ๋‹ค.

์ด๋ฅผ ์œ„ํ•ด ๊ณ ์กฐํŒŒ๋กœ ์ธํ•œ ํŒŒํ˜•์˜ ์™œ๊ณก์˜ ์ •๋„๋ฅผ ๋‚˜ํƒ€๋‚ด๋Š” ์ง€ํ‘œ์ธ ์ „๊ณ ์กฐํŒŒ ์™œ์œจ(Total Harmonic Distortion; THD)์„ ๊ณ„์‚ฐํ•˜์˜€๋‹ค.

(11)
THD=โˆšK21ยฑ120Hz+K23+K25+โ‹ฏ+K2nK1

THD๋Š” ๊ธฐ๋ณธํŒŒ ํฌ๊ธฐ ๋Œ€๋น„ ํƒ€ ์ฃผํŒŒ์ˆ˜ ์„ฑ๋ถ„์˜ ํฌ๊ธฐ์ด๋ฉฐ, ์€ n์ฐจ ๊ณ ์กฐํŒŒ์˜ RMS ๊ฐ’์„ ์˜๋ฏธํ•œ๋‹ค. ๊ทธ๋ฆผ 7์˜ FFT ํŒŒํ˜•์„ ํ†ตํ•ด ์‹(11)์— ๋”ฐ๋ผ ๊ณ„์‚ฐํ•˜์˜€๋‹ค. ๊ธฐ๋ณธํŒŒ ๋Œ€๋น„ Side Band ์ฃผํŒŒ์ˆ˜์˜ ํฌ๊ธฐ๋ฅผ ๊ณ ๋ คํ•˜์˜€์„ ๋•Œ THD๋Š” 42%์ด๋‹ค. ์˜ˆ๋ฅผ ๋“ค์–ด THD๋ฅผ 7% ์ด๋‚ด๋กœ ๋‹ฌ์„ฑํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์‹(11)์— ๋”ฐ๋ผ ๊ธฐ๋ณธํŒŒ ์„ฑ๋ถ„์ด โ€“26dB ๋ณด๋‹ค ํฌ๊ฒŒ ๊ฐ์‡„ํ•˜๋Š” ์˜์—ญ์„ ๋Œ€์—ญํญ์œผ๋กœ ์„ค๊ณ„ํ•ด์•ผ ํ•œ๋‹ค. ๊ทธ๋ฆผ 8์€ ๋Œ€์—ญํญ์„ ์ค‘์‹ฌ ์ฃผํŒŒ์ˆ˜์˜ 2% ์ด๋‚ด๋กœ ์„ค๊ณ„ํ•œ 2์ฐจ ๋Œ€์—ญํ†ต๊ณผํ•„ํ„ฐ์˜ Bode Plot ํฌ๊ธฐ ์„ ๋„๋กœ, ์ค‘์‹ฌ ์ฃผํŒŒ์ˆ˜์™€ Side Band ๊ณ ์กฐํŒŒ ์„ฑ๋ถ„ ํฌ๊ธฐ ์„ฑ๋ถ„์„ ๋ณด์—ฌ์ค€๋‹ค. Side Band ์ฃผํŒŒ์ˆ˜ ์„ฑ๋ถ„์ด โ€“26dB๋ณด๋‹ค ํฌ๊ฒŒ ๊ฐ์‡„ํ•˜์˜€์œผ๋ฏ€๋กœ, ๋Œ€์—ญํ†ต๊ณผํ•„ํ„ฐ๋ฅผ ํ†ตํ•ด THD 7%๋ฅผ ๋งŒ์กฑํ•  ์ˆ˜ ์žˆ๋‹ค. ๋”ฐ๋ผ์„œ ๊ธฐ๋ณธํŒŒ์™€ Side Band ์ฃผํŒŒ์ˆ˜ ์„ฑ๋ถ„์„ ํฌํ•จํ•˜์—ฌ ํ•„ํ„ฐ๋ง ๋œ ์ƒ˜ํ”Œ๋ง ์ „์•• ๋ฐ ์ „๋ฅ˜๋ฅผ ํ™œ์šฉํ•˜์—ฌ ์™œ๊ณก์ด ์ ์€ ์ž„ํ”ผ๋˜์Šค๋ฅผ ๊ณ„์ธกํ•  ์ˆ˜ ์žˆ๋‹ค.

3. ์šฉ๊ธฐ ์ž„ํ”ผ๋˜์Šค์™€ ์˜จ๋„์˜ ์ƒ๊ด€๊ด€๊ณ„ ๋ถ„์„

3.1 IH ๋ถ€ํ•˜ ํŠน์„ฑ ๋ถ„์„

์šฉ๊ธฐ์˜ ์žฌ์งˆ์— ๋”ฐ๋ผ ๊ณ ์œ ์˜ ๋น„์ €ํ•ญ, ํˆฌ์ž์œจ์„ ๊ฐ€์ง€๊ณ  ์žˆ์–ด ๋ถ€ํ•˜ ์ €ํ•ญ์ด ๋‹ฌ๋ผ์ง€๋ฏ€๋กœ ํŠน์ • ์šฉ๊ธฐ ์กฐ๊ฑด์—์„œ ๋ถ„์„์„ ์ง„ํ–‰ํ•˜์˜€๋‹ค. ์ฐธ๊ณ ๋ฌธํ—Œ (4)์™€ ๊ฐ™์ด ์šฉ๊ธฐ์˜ ๊ฐ€์—ด์‹œ๊ฐ„์— ๋”ฐ๋ผ ์šฉ๊ธฐ์˜ ์ €ํ•ญ์€ ์ฆ๊ฐ€ํ•œ๋‹ค. ์˜จ๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜๋ฉด ์ž์œ ์ „์ž์˜ ์ด๋™์„ฑ์ด ์ฆ๊ฐ€ํ•˜์—ฌ ์ „๋ฅ˜ ํ๋ฆ„์„ ๋ฐฉํ•ดํ•˜๊ฒŒ ๋˜์–ด ์ €ํ•ญ์„ ์ฆ๊ฐ€์‹œํ‚จ๋‹ค. ์‹(12)์— ๋”ฐ๋ผ ๊ธˆ์†์˜ ๋น„์ €ํ•ญ(resistivity)์€ ์˜จ๋„์— ๋Œ€ํ•ด ์„ ํ˜•์ ์œผ๋กœ ์ฆ๊ฐ€ํ•จ์„ ๋ณด์—ฌ์ค€๋‹ค. ๋น„์ €ํ•ญ๊ณผ ์ €ํ•ญ๊ฐ’์€ ๋น„๋ก€ํ•˜๋ฏ€๋กœ ์‹(13)๊ณผ ๊ฐ™์ด ์˜จ๋„์— ๋”ฐ๋ฅธ ์ €ํ•ญ์˜ ๋ณ€ํ™”๋ฅผ ๋‚˜ํƒ€๋‚ผ ์ˆ˜ ์žˆ๋‹ค.

๊ทธ๋ฆผ. 9. IH ์šฉ๊ธฐ์˜ ์ €ํ•ญ๊ณผ ์˜จ๋„ ๊ณก์„ 

Fig. 9. Resistance and Temperature Curves of an IH Pot

../../Resources/kiee/KIEE.2022.71.9.1230/fig9.png

๊ทธ๋ฆผ. 10. IH ์šฉ๊ธฐ์˜ ์˜จ๋„ ์ธก์ • ์ง€์ 

Fig. 10. Temperature Measuring Points of IH Pot

../../Resources/kiee/KIEE.2022.71.9.1230/fig10.png

(12)
ฯ=ฯ0[1+ฮฑ(Tโˆ’T0)โŒ‰

(13)
R=R0[1+ฮฑ(Tโˆ’T0)]=ฯฯ0R0

์—ฌ๊ธฐ์„œ, ฯ๋Š” ์šฉ๊ธฐ์˜ ๋น„์ €ํ•ญ, ฯ0๋Š” ํ‘œ์ค€ ์˜จ๋„์—์„œ์˜ ์ €ํ•ญ๋ฅ , ฮฑ๋Š” ์˜จ๋„๊ณ„์ˆ˜, R์€ ์ž„์˜์˜ ์˜จ๋„์—์„œ์˜ ์ €ํ•ญ, R0์€ ํ‘œ์ค€ ์˜จ๋„์—์„œ์˜ ์ €ํ•ญ์ด๋‹ค.

3.1 IH ๋ถ€ํ•˜ ํŠน์„ฑ ๋ถ„์„

์ฝ”์ผ์˜ ๋™์ž‘ ์ฃผํŒŒ์ˆ˜ ๋Œ€์—ญ๋ณ„๋กœ IHใ€€๋ถ€ํ•˜ ์ €ํ•ญ์„ ๊ณ„์ธกํ•˜๊ณ , ์˜จ๋„์™€ ๋ถ€ํ•˜ ์ž„ํ”ผ๋˜์Šค์˜ ๊ฒฝํ–ฅ์„ฑ์„ ํŒŒ์•…ํ•˜๊ธฐ ์œ„ํ•ด ์„ ํ˜• ํšŒ๊ท€ ๋ถ„์„ ๋ชจ๋ธ์„ ๋„์ถœํ•œ๋‹ค. ๊ทธ๋ฆผ 9๋Š” ๋™์ž‘ ์ฃผํŒŒ์ˆ˜ 50 kHz๋กœ ๊ตฌ๋™ํ•˜์˜€์„ ๋•Œ ์‹œ๊ฐ„์— ๋”ฐ๋ฅธ ์˜จ๋„์™€ ์ €ํ•ญ ๊ทธ๋ž˜ํ”„์ด๋‹ค. ๊ทธ๋ฆผ 10๊ณผ ๊ฐ™์ด 3๊ฐœ์˜ ์˜จ๋„ ์ธก์ • ์ง€์ ์˜ ํ‰๊ท ๊ฐ’์œผ๋กœ ์šฉ๊ธฐ์˜ ์˜จ๋„๋ฅผ ์ธก์ •ํ•˜์˜€๋‹ค. ๊ทธ๋ฆผ 9์™€ ๊ฐ™์ด IH ์‹œ์Šคํ…œ์˜ ๊ฐ€์—ด ํŠน์„ฑ์œผ๋กœ ์ธํ•ด ์˜จ๋„ ์šฉ๊ธฐ์˜ ์˜จ๋„๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์ €ํ•ญ์ด ํŠน์ • ๊ตฌ๊ฐ„์—์„œ ์‹œ๊ฐ„์— ๋”ฐ๋ผ ์„ ํ˜•์ ์œผ๋กœ ์ฆ๊ฐ€ํ•จ์„ ํ™•์ธํ•˜์˜€๋‹ค. ์ด๋ฅผ ์„ ํ˜• ํšŒ๊ท€ํ•˜์—ฌ ์‹(14)์™€ ๊ฐ™์ด ๊ธฐ์šธ๊ธฐ a์™€ y ์ ˆํŽธ์— ๋”ฐ๋ผ ์˜จ๋„์™€ ์ €ํ•ญ ๊ฐ„์˜ ์„ ํ˜• ํšŒ๊ท€ ๋ชจ๋ธ์‹์„ ๋„์ถœํ•  ์ˆ˜ ์žˆ๋‹ค.

(14)
T=aR+b

ํšŒ๊ท€ ๋ถ„์„์„ ํ†ตํ•ด ์‹(14)์˜ a์™€ b๋ฅผ ๊ตฌํ•˜๋ฉด ํŠน์ • ์šฉ๊ธฐ์—์„œ ์ž„์˜์˜ ์ €ํ•ญ๊ฐ’์œผ๋กœ ์˜จ๋„๋ฅผ ์ถ”์ •ํ•  ์ˆ˜ ์žˆ๋‹ค.

4. ๋ชจ์˜์‹œํ—˜ ๋ฐ ์‹คํ—˜ ๊ฒฐ๊ณผ

๋ณธ ์žฅ์—์„œ๋Š” ๋ชจ์˜์‹œํ—˜๊ณผ ์‹คํ—˜์„ ๋น„๊ต ๋ถ„์„ํ•˜์—ฌ ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก์„ ์œ„ํ•œ Time-Split ๊ธฐ๋ฒ•๊ณผ ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก์„ ํ†ตํ•œ ์˜จ๋„ ์ถ”์ •์˜ ์‹คํšจ์„ฑ์„ ๊ฒ€์ฆํ•œ๋‹ค. ๊ทธ๋ฆผ 11๊ณผ ๊ฐ™์ด Time-Spilt์„ ๊ฒ€์ฆํ•˜๊ธฐ ์œ„ํ•ด PSIM ์‹œ๋ฎฌ๋ ˆ์ด์…˜์œผ๋กœ ํšŒ๋กœ๋„๋ฅผ ๊ตฌ์„ฑํ•˜๊ณ  ๊ทธ๋ฆผ 12๊ณผ ๊ฐ™์ด 2-kW ์ง๋ ฌ ๊ณต์ง„ ์ธ๋ฒ„ํ„ฐ ์‹œ์ž‘ํ’ˆ์„ ๊ตฌ์„ฑํ•˜์—ฌ ์‹คํ—˜ํ•˜์˜€๋‹ค. ์šฉ๊ธฐ์˜ ์ง€๋ฆ„์€ 220mm, ๋ฌผ์˜ ์–‘ 2L๋กœ, IEC standard 60335-2-9 ๊ทœ๊ฒฉ์˜ ์ˆ˜๋ถ€ํ•˜๋Ÿ‰์œผ๋กœ ์‹คํ—˜์„ ์ง„ํ–‰ํ•˜์˜€๋‹ค. ํ‘œ 1์€ ์ง๋ ฌ ๊ณต์ง„ ์ธ๋ฒ„ํ„ฐ์˜ ์„ค๊ณ„ ์‚ฌ์–‘์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

๊ทธ๋ฆผ. 11. IH ์ธ๋ฒ„ํ„ฐ์˜ ์‹œ๋ฎฌ๋ ˆ์ด์…˜ ํšŒ๋กœ

Fig. 11. Simulated Circuit Diagram of an IH Inverter

../../Resources/kiee/KIEE.2022.71.9.1230/fig11.png

๊ทธ๋ฆผ. 12. 2-kW๊ธ‰ IH ์ธ๋ฒ„ํ„ฐ ์‹œ์ž‘ํ’ˆ

Fig. 12. 2-kW IH Inverter Prototype

../../Resources/kiee/KIEE.2022.71.9.1230/fig12.png

ํ‘œ 1. ์ง๋ ฌ ๊ณต์ง„ํ˜• ์ธ๋ฒ„ํ„ฐ์˜ ์„ค๊ณ„ ์‚ฌ์–‘

Table 1. Design Specification of the Series Resonant Inverter

Parameter

Mark

Value

Unit

Input Voltage

Vin,AC

220

V

Resonant Capacitor

Cr

660

ฮผF

Resonant Inductor

Lr

18

ฮผH

Coil Turn Number

n

16

turn

Sampling Frequency

fsample

49.5

kHz

Switching Frequency

fsw

50

kHz

Pot Material

SUS304 18-10

ํ‘œ 2. ์ „๋ ฅ ๋ณ„ ์ถ”์ • ํšŒ๊ท€ ๋ฐฉ์ •์‹

Table 2. Estimated Regression Equations According to Power

1 kW

2 kW

The number of experiments

3

3

Slope (a)

85.2191

206.38

Y-Intercept (b)

-266.8924

-683.1

๊ทธ๋ฆผ. 13. Time-Split ์‹œ๋ฎฌ๋ ˆ์ด์…˜

Fig. 13. Time-Split Simulation

../../Resources/kiee/KIEE.2022.71.9.1230/fig13.png

๊ทธ๋ฆผ. 14. ์ €ํ•ญ ๊ณ„์ธก ์‹œ๋ฎฌ๋ ˆ์ด์…˜

Fig. 14. Resistance Measurement Simulation

../../Resources/kiee/KIEE.2022.71.9.1230/fig14.png

4.1 ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก ๋ชจ์˜์‹œํ—˜

LCR Meter๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ์ธก์ •ํ•œ ๋ถ€ํ•˜ ์ž„ํ”ผ๋˜์Šค ํŒŒ๋ผ๋ฏธํ„ฐ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ IH Inverter๋ฅผ ๋ชจ์˜์‹œํ—˜ํ•˜์˜€๋‹ค. PSIM ์‹œ๋ฎฌ๋ ˆ์ด์…˜์—์„œ ์˜จ๋„์˜ ์˜ํ–ฅ์„ฑ์„ ๊ณ ๋ คํ•  ์ˆ˜ ์—†์œผ๋ฏ€๋กœ ๊ณ ์ • ์ €ํ•ญ์„ ์‚ฌ์šฉํ•˜์—ฌ ์‹œ๋ฎฌ๋ ˆ์ด์…˜์„ ์ง„ํ–‰ํ•˜์˜€๋‹ค. ๊ทธ๋ฆผ 13๊ณผ ๊ฐ™์ด ์‹(10)์—์„œ ๋„์ถœํ•œ ์ƒ˜ํ”Œ๋ง ์ฃผํŒŒ์ˆ˜๋กœ Time-Split ๊ธฐ๋ฒ•์˜ ์ •์ƒ ์ž‘๋™์„ ํ™•์ธํ•˜์˜€๋‹ค. ๊ทธ๋ฆผ 14์—์„œ Time-Split ๊ธฐ๋ฒ•์„ ์‚ฌ์šฉํ•˜์—ฌ ๊ณ„์ธก๋œ ์ €ํ•ญ์ด ๊ณ ์ • ์ €ํ•ญ์— ๋Œ€ํ•ด ์˜ค์ฐจ์œจ 1% ์ด๋‚ด๋กœ ๊ณ„์ธก๋จ์„ ํ™•์ธํ•˜์˜€๋‹ค.

๊ทธ๋ฆผ. 15. ์ „๋ ฅ ๋ถ„์„๊ธฐ๋กœ ๊ณ„์ธกํ•œ ์ €ํ•ญ๊ณผ Time-Split ๊ธฐ๋ฒ•์„ ์ ์šฉํ•œ DSP ๊ณ„์ธก ์ €ํ•ญ ๋ฐ์ดํ„ฐ ๋น„๊ต

Fig. 15. Comparison between Power Analyzer Data and DSP Measurement data Using Time-split: (a) 1 kW, (b) 2 kW

../../Resources/kiee/KIEE.2022.71.9.1230/fig15.png

4.2 ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก ์‹คํ—˜ ๊ฒฐ๊ณผ

๊ทธ๋ฆผ 15๋Š” ์ „๋ ฅ ๋ถ„์„๊ธฐ์— ์˜ํ•ด ์ธก์ •๋œ ๊ฐ’๊ณผ ์ œ์–ด๊ธฐ์— ์˜ํ•ด ๊ณ„์ธก๋œ ์ €ํ•ญ๊ฐ’์„ ๋ณด์—ฌ์ค€๋‹ค. ์šฉ๊ธฐ ์•ˆ์˜ ๋ฌผ์ด ๋“๋Š” ๊ตฌ๊ฐ„, ์ฆ‰ ์ •์ƒ ์ƒํƒœ ๊ตฌ๊ฐ„์—์„œ ์ž„ํ”ผ๋˜์Šค ์ถ”์ • ํŒŒํ˜•์ด๋‹ค. ํ•˜ํ”„ ๋ธŒ๋ฆฌ์ง€ ์ง๋ ฌ ๊ณต์ง„ํ˜• ์ธ๋ฒ„ํ„ฐ๋Š” ๋™์ž‘์ฃผํŒŒ์ˆ˜์˜ ๋ณ€๋™์„ ํ†ตํ•ด ์ „๋ ฅ์„ ์ œ์–ดํ•œ๋‹ค. ๋”ฐ๋ผ์„œ ๋™์ž‘ ์ฃผํŒŒ์ˆ˜์— ๋”ฐ๋ผ ์ž„ํ”ผ๋˜์Šค๊ฐ€ ๋ณ€๋™ํ•˜๋ฏ€๋กœ ๋“๋Š” ๊ตฌ๊ฐ„์—์„œ ์ „๋ ฅ ์šฉ๋Ÿ‰ ๋ณ„ ์ž„ํ”ผ๋˜์Šค๋Š” ๋‹ค๋ฅด๊ฒŒ ๋‚˜ํƒ€๋‚œ๋‹ค. ๊ฒฐ๊ณผ์ ์œผ๋กœ ์ €ํ•ญ์€ ์˜ค์ฐจ์œจ 1.2% ์ด๋‚ด๋กœ ๊ณ„์ธก๋œ๋‹ค.

๊ทธ๋ฆผ. 16. ์ €ํ•ญ-์˜จ๋„ ํšŒ๊ท€ ๊ณก์„ 

Fig. 16. Resistance-Temperature Regression Curves: (a) 1 kW, (b) 2 kW

../../Resources/kiee/KIEE.2022.71.9.1230/fig16.png

๊ทธ๋ฆผ. 17. ์šฉ๊ธฐ ์˜จ๋„ ์ถ”์ • ํŒŒํ˜•

Fig. 17. Experimental Curves of Pot Temperature Estimation: (a) 1 kW, (b) 2 kW

../../Resources/kiee/KIEE.2022.71.9.1230/fig17.png

4.3 ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก์„ ํ†ตํ•œ ์˜จ๋„ ์ถ”์ • ๋ถ„์„

IHใ€€์‹œ์Šคํ…œ์€ ์šฉ๊ธฐ์˜ ์œ„์น˜, ์ฝ”์ผ์˜ ์ดˆ๊ธฐ ์˜จ๋„์— ๋”ฐ๋ผ ์ฐจ์ด๊ฐ€ ์žˆ์œผ๋ฏ€๋กœ ๊ทธ๋ฆผ 16๊ณผ ๊ฐ™์ด 3ํšŒ ์‹คํ—˜์„ ํ†ตํ•ด ํšŒ๊ท€ ๋ถ„์„ ๋ชจ๋ธ์‹์„ ๋„์ถœํ•œ๋‹ค. ํšŒ๊ท€ ๋ถ„์„์„ ํ†ตํ•ด ๋„์ถœํ•œ ์‹์„ ํ‘œ 2์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ํ‘œ 2๋ฅผ ํ†ตํ•ด ๋†’์€ ์ „๋ ฅ์ผ์ˆ˜๋ก ๊ธฐ์šธ๊ธฐ๊ฐ€ ํฌ๋ฏ€๋กœ ๋น ๋ฅด๊ฒŒ ๊ฐ€์—ด๋จ์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋ฆผ 17์€ ์‹œ๊ฐ„์— ๋”ฐ๋ฅธ ์šฉ๊ธฐ์˜ ์‹ค์ œ ์˜จ๋„์™€ ์ถ”์ • ์˜จ๋„๋ฅผ ๋น„๊ตํ•œ ๊ทธ๋ž˜ํ”„์ด๋‹ค. ๊ทธ๋ฆผ 17๊ณผ ๊ฐ™์ด ์˜จ๋„ ์ฆ๊ฐ€ ๊ตฌ๊ฐ„ ์ตœ๋Œ€ ยฑ7โˆ˜C, ์˜จ๋„ ์œ ์ง€ ๊ตฌ๊ฐ„ ์ตœ๋Œ€ ยฑ5โˆ˜C ์˜ ๋‚ฎ์€ ์˜ค์ฐจ๋กœ ์˜จ๋„ ์ถ”์ •์ด ๊ฐ€๋Šฅํ•˜๋‹ค. ๋”ฐ๋ผ์„œ ์ •ํ™•ํ•œ ์ž„ํ”ผ๋˜์Šค ์ถ”์ •์œผ๋กœ๋ถ€ํ„ฐ ์˜จ๋„ ์ถ”์ •์˜ ์‹คํšจ์„ฑ์„ ๊ฒ€์ฆํ•˜์˜€๋‹ค.

5. ๊ฒฐ ๋ก 

๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ์ €ํ•ญ-์˜จ๋„ ํšŒ๊ท€ ๋ถ„์„์„ ํ†ตํ•ด ์˜จ๋„ ์ถ”์ •์ด ๊ฐ€๋Šฅํ•œ ์•Œ๊ณ ๋ฆฌ์ฆ˜์„ ์ œ์•ˆํ•˜์˜€๋‹ค. ๋˜ํ•œ, ๋‚ฎ์€ ์ƒ˜ํ”Œ๋ง ์ฃผํŒŒ์ˆ˜๋กœ๋„ IH ๋ถ€ํ•˜์˜ ์ž„ํ”ผ๋˜์Šค๋ฅผ ๊ณ„์ธกํ•  ์ˆ˜ ์žˆ๋Š” Time-Split ๊ธฐ๋ฒ•์„ ์ œ์•ˆํ•˜์˜€๋‹ค. ์ตœ์ข…์ ์œผ๋กœ 2-kW ์ง๋ ฌ ๊ณต์ง„ ์ธ๋ฒ„ํ„ฐ ์‹œ์ž‘ํ’ˆ์„ ํ†ตํ•ด ์‹คํ—˜์ด ์ˆ˜ํ–‰๋˜์—ˆ๋‹ค. ์‹ค์ œ ์ธก์ •๋œ ๊ฐ’ ๋Œ€๋น„ ์ €ํ•ญ์ด ์˜ค์ฐจ์œจ 1.2% ์ด๋‚ด๋กœ ๊ณ„์ธก๋จ์— ๋”ฐ๋ผ Time-split ๊ธฐ๋ฒ•์˜ ํƒ€๋‹น์„ฑ์ด ๊ฒ€์ฆ๋˜์—ˆ๋‹ค. ์ž„ํ”ผ๋˜์Šค ๊ณ„์ธก์„ ํ†ตํ•˜์—ฌ ํŠน์ • ์šฉ๊ธฐ์—์„œ ์˜จ๋„์™€ ์ €ํ•ญ ๊ฐ„์˜ ํšŒ๊ท€ ๋ถ„์„ ๋ชจ๋ธ์‹์„ ๋„์ถœํ•˜์—ฌ ์˜จ๋„ ์ƒ์Šน ๊ตฌ๊ฐ„์—์„œ์˜ ์šฉ๊ธฐ ์˜จ๋„๋Š” ยฑ7โˆ˜C ์ด๋‚ด์˜ ์˜ค์ฐจ, ๋ฌผ์ด ๋“๋Š” ๊ตฌ๊ฐ„์—์„œ์˜ ์šฉ๊ธฐ ์˜จ๋„๋Š” ยฑ5โˆ˜C ์ด๋‚ด์˜ ์˜ค์ฐจ๋กœ ์ •ํ™•ํ•˜๊ฒŒ ์˜จ๋„๋ฅผ ์ถ”์ •ํ•  ์ˆ˜ ์žˆ๋‹ค.

Acknowledgements

์ด ๋…ผ๋ฌธ์€ 2022 ๋…„๋„ ์ •๋ถ€(์‚ฐ์—…ํ†ต์ƒ์ž์›๋ถ€)์˜ ์žฌ์›์œผ๋กœ ํ•œ๊ตญ์—๋„ˆ์ง€๊ธฐ์ˆ ํ‰๊ฐ€์›์˜ ์ง€์›์„ ๋ฐ›์•„ ์ˆ˜ํ–‰๋œ ์—ฐ๊ตฌ์ž„(2019381010001A, ์ˆ˜์šฉ๊ฐ€์šฉ LVDC ์ „์›๊ณต๊ธ‰ ๋ฐ ๋ถ„์‚ฐ์ „์› ์—ฐ๊ณ„์šฉ ํ•ต์‹ฌ๊ธฐ๊ธฐ ๊ฐœ๋ฐœ)

References

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O. Lucia, P. Maussion, E. J. Dede., J. M. Burdio, May 2014, Induction heating technology and its application: Past developments, current technology, and future challenges, IEEE Trans. Ind. Electron., Vol. 61, No. 5, pp. 2509-2520DOI
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J. Lasobras, R. Alonso, C. Carretero, E. Carretero, E. Imaz, Mar 2014, Infrared Sensor-Based Temperature Control for Domestic Induction Cooktops, Sensors, Vol. 14, No. 3, pp. 5278-5295DOI
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D. Paesa, S. Llorente, C. Sagues, O. Aldana, May-june 2009, Adaptive Observers Applied to Pan Temperature Control of Induction Hobs, in IEEE Transactions on Industry Applications, Vol. 45, No. 3, pp. 1116-1125DOI
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D. Paesa, C. Franco, S. Llorente, G. Lopez-Nicolas, C. Sagues, Sept-Oct 2011, Adaptive Simmering Control for Domestic Induction Cookers, in IEEE Transactions on Industry Applications, Vol. 47, No. 5, pp. 2257-2267DOI
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O. Jimenez, O. Lucia, L. A. Barragan, D. Navarro, J. I. Artigas, I. Urriza, Aug 2013, FPGA-Based Test-Bench for Resonant Inverter Load Characterization, in IEEE Transactions on Industrial Informatics, Vol. 9, No. 3, pp. 1645-1654DOI
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O. Jimenez, O. Lucia, I. Urriza, L. A. Barragan, D. Navarro, May 2014, Analysis and implementation of FPGA-based online parametric identification algorithms for resonant power converters, IEEE Trans. on Industrial Informatics, Vol. 10, pp. 1144-1153DOI
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H. Sarnago, O. Lucia, J. M. Burdio, Mar 2018, A Versatile Resonant Tank Identification Methodology for Induction Heating Systems, in IEEE Transactions on Power Electronics, Vol. 33, No. 3, pp. 1897-1901DOI
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, Safety standards for household electrical products-IEC 60335-2-9, Table 101, Figure 103 and 104Google Search

์ €์ž์†Œ๊ฐœ

๊น€ํ˜„์ง€(Hyun-Ji Kim)
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She received her B.S. degree in electronic engineering from Hanbat National University, Daejeon, South Korea, in 2020.

She is currently working toward a MS. degree in electrical engineering from the Ulsan National Institute of Science and Technology, Ulsan, South Korea.

ํ—ˆ๊ฒฝ์šฑ(Kyung-Wook Heo)
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He received his B.S. degree in electronic engineering from the Kumoh National Institute of Technology, Gumi, South Korea, in 2019.

He is currently working toward a Ph.D. degree in electrical engineering from the Ulsan National Institute of Science and Technology, Ulsan, South Korea.

์ •์ง€ํ›ˆ(Jee-Hoon Jung)
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He received his B.S., M.S., and Ph.D. degrees in Electrical and Computer Engineering Program from the Department of Electronics and Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, South Korea, in 2000, 2002 and 2006, respectively.

From 2006 to 2009, he was a Senior Research Engineer in the Digital Printing Division, Samsung Electronics Company Ltd., Suwon, South Korea.

From 2009 to 2010, he was a Postdoctoral Research Associate in the Department of Electrical and Computer Engineering, Texas A&M University at Qatar (TAMUQ), Doha, Qatar.

From 2011 to 2012, he was a Senior Researcher in the Power Conversion and Control Research Center, HVDC Research Division, Korea Electrotechnology Research Institute (KERI), Changwon, South Korea.

From 2013 to 2017, he was an Assistant Professor in the School of Electrical and Computer Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea.

From 2017 to 2022, he was an Associate Professor in the Department of Electrical Engineering, UNIST where he is presently working as a Professor.