Refrigerator control evaluation board user manual
Contents
1. CONCLUSION Appendix 4 Bill of Materials N DESCRIPTION R1 Resistor 2 W Through_Hole 33 Qhm 5 R2 R3 Resistor 1 8 W SMD 160 Qhm 5 0805 R4 Resistor 1 8 W SMD 360 Qhm 5 0805 R5 Resistor 1 8 W SMD 1 5 KQhm 5 0805 R6 Resistor 1 4 W Through_Hole 470 KQhm 5 R7 Resistor 1 8 W SMD 33 KQhm 5 0805 R8 Resistor 1 8 W SMD 62 kQhm 5 0805 R9 Resistor 1 8 W SMD 47 KQhm 5 0805 R10 Resistor Le W Through_Hole 0 05 Qhm 5 R11 Resistor Y2 W Through_Hole 47 Qhm 5 R12 Resistor 1 8 W SMD 1 KQhm 5 0805 R13 Resistor 1 8 W SMD 51 Qhm 5 0805 R14 Resistor 1 8 W SMD 51 Qhm 5 0805 C1 Cond 250 V X2 470 nF 20 Ref EPCOS B81130C1474M C2 Cond SMD 6V3 100 nF C3 Cond Radial 10 V 2200 uF 20 Ref EPCOS B41821A3228 M C4 Cond 250 V X2 10 nF 20 Ref EPCOS B81130C1 103M C5 C6 Cond 250 VAC 1 nF 20 GE Get Cond SMD 6V3 2 2 nF C11 Cond SMD 6V3 680 pF C12 Cond SMD 10V 1 uF 1206 F1 Fuse 5x20 mm 6 A 250 V 1 Switch POT Potentiometer Single Turn 100 K D1 Red LED diameter 5 mm 5V 2mA D2 Zener 6V2 1 3 W SMD D3 Rectifier 1N4148 SMD TS ASCT6 7ST T0220 TR ASCT6 7ST T0220 TB ASC102 5T1 S08 U1 Microcontroller ST62T00C DIP16 Through Hole 18 20 www BDTIC com ST CONCLUSION Appendix 5 Procedure for IEC61000 4 4 Voltage Burst Test Fast transient voltage tests have been performed according to the E2. Figure 7 Compressor starter If you want to keep the PTC acting inside the starter then the RUN pin must not be connected to the RUN connector of the THERMO1EVAL board If you remove the PTC it is better to put an insulation layer in its place in order to avoid spu rious short circuits between the RUN and START windings d 16 20 www BDTIC com ST CONCLUSION Appendix 3 THERM01EVAL Schematics Figure 8 THERMO1EVAL schematic S00LZILS ED ZN ZW Ju es 15 M 2 4 WoS if Z old A uz 89 ce ds e ESCH S Le L e ep EE ZH L 25 A PPA f ST Sy dub md gt zorsov ging H SCH ces qL z FH EIER YLS ey FLH g1soy uny e AL GEI EZ 9LSOV HEJS MZ L HEE uny LH YOLOW WW z Hng gina YLS ely 4384S aod 1 L z SSA NIV S d NIV Z d NIV 98d NIV Ead NIV L d NIV 0 d Vd evd Wd LSAL ddA aaa Any SL PPA SNIVIV T MEL ng za sr 1SH dogg LLO TN e MZ L YZ GN 2004 LI o KEN SSC In ei st LNOOSO Niosof x HH zZ 7 17 20 www BDTIC com ST
3. REFRIGERATOR CONTROL EVALUATION BOARD Ah 8 User Manual July 2001 DOC THERMOSTAT Evaluation Board i t www BDTIC com ST USE IN LIFE SUPPORT DEVICES OR SYSTEMS MUST BE EXPRESSLY AUTHORIZED STMicroelectronics PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF STMicroelectronics As used herein 1 Life support devices or systems are those 2 A critical component is any component of a life which a are intended for surgical implant into support device or system whose failure to the body or b support or sustain life and perform can reasonably be expected to cause whose failure to perform when properly used in the failure of the life support device or system accordance with instructions for use provided or to affect its safety or effectiveness with the product can be reasonably expected to result in significant injury to the user www BDTIC com ST TT REFRIGERATOR CONTROL YI EVALUATION BOARD USER MANUAL 1 INTRODUCTION 1 1 TARGET APPLICATION The THERMO1EVAL board is designed to be a complete MCU controlled thermostat applica tion when used with a M2020 12k NTC thermal sensor from EPCOS supplied with the kit This thermostat can be used to control a single phase induction motor and works with a 220 240 V RMS 50 Hz mains voltage The board can operate in an ambient temperature range of 0 to 60 C T
4. Vs varies according to Equa tion 4 for a 5 V supply Equation 3 Equation 4 Vs T T 50 1 15 625 Figure 5 gives the variation of Vs and the linear value given by Equation 4 refer to VI versus the temperature sensed by the CTN Zar 13 20 www BDTIC com ST CONCLUSION Figure 5 Linear voltage response of the NTC resistor for a 5 V supply NI Vv 5 40 30 20 10 0 10 T CC 20 14 20 d www BDTIC com ST CONCLUSION Appendix 2 Wiring connections For the NTC you only have to cut its connector standard connector for M2020 sensors and to screw the wires in the NTC connector It can be connected in both ways as it is just a re sistor For the motor things are more complex Figure 6 shows how the wires are generally accessible in compressor motors These three pins may be connected directly to the THERM0O1EVAL connector Figure 6 Compressor connections Often compressor motors are used with a starter that includes a thermal protection against excessively high currents or overheating This protection is called a klixon and is shown in Figure 7 When you are using the THERMO1EVAL board its better to keep this starter in order to let the klixon work In this case the motor connections can still be accessible this depends on the starter model as shown in Figure 7 Zar 15 20 www BDTIC com ST CONCLUSION
5. the board is able to withstand bursts of more than 3 kV during IEC61000 4 4 standard tests without any operational problems and up to 4 5 kV without any damage Surge tests have also been performed IEC61000 4 5 standard 2 kV bursts can be applied without any damage to the semiconductors Safety standards have also been taken into account Hence a 2mm creepage is ensured between all high voltage parts and low voltage parts to achieve the functional insulation level The thermal sensor is a class II sensor Zar 7 20 www BDTIC com ST FUNCTIONAL DESCRIPTION 2 2 MAIN FEATURES 2 2 1 Temperature control The thermal sensor is an NTC resistor from EPCOS M2020 12 k 2 It should be placed on the evaporator of the fridge or the freezer The controlled temperature range should be be tween 30 to 0 C The range can be modified by changing the value of the resistor placed in series with the NTC see Appendix 1 lts resistance value decreases following an exponential variation when the temperature in creases Then to get back the temperature data the MCU could use a numerical table In the THERMO1EVAL board a simple resistor has been added in series with the NTC in order to lin earize its thermal response refer to Appendix 1 Two advantages come from this choice Memory area savings Easy way to measure the temperature refer to Appendix 1 Temperature regulation is performed by hysteresis control The linear te
6. current from a real overcurrent caused by a stalled rotor After an overcurrent detection the D1 LED is switched on for 10 seconds The overcurrent is detected by measuring the RUN current through the 0 05 Q shunt resistor R10 in Appendix 3 Each measurement is performed approximately 7 ms after ZCS when the Vy voltage is negative If the current peaks at a different time this delay can be changed by software see AN1353 The overcurrent detection is based on an average of four measurements in order to reduce measurement noise The motor will then be stopped at least 80 ms after an overcurrent has appeared 3 4 MEASUREMENT POINTS Figures 3 and 4 show where the Vpp and Vgs planes are placed and also the measurement points that can be used Zar 11 20 www BDTIC com ST CONCLUSION Figure 3 Top layer view from component side Vss plane Vss Measurement point Von Measurement point Vu Measurement point V measurement point Figure 4 Bottom layer view from component side Vss plane 4 CONCLUSION The guidelines provided in this document have been given to help you use the THERMO1EVAL board properly The board is designed for conventional monophase induction motors in fridge and freezer applications especially for 1 5 horse power compressors The main thing to check is that your loads especially the compressor load correspond to pro grammed data pulse delay for detecting the over
7. eee eee eee 17 Appendix 4 Bill of Materials 0 0 ccc eee 18 Appendix 5 Procedure for IEC61000 4 4 Voltage Burst Test 055 19 4 20 d www BDTIC com ST INTRODUCTION 1 2 BLOCK DIAGRAM Figure 1 shows the block diagram of the THERMO01EVAL board Figure 1 Thermostat evaluation board block diagram Ai 4 NTC e connector Ts protective inductor DOOR connector Door Switch Capacitive Power Supply Start ST62T00C ACST6 RC Overcurrent snubber Waming LED ACS102 Run ACST6 R Compressor C BULB MAINS comnector snubber connector connector Temperature order potentiometer l lt gt Lu oc Lu L j resistor 1 3 LIST OF CONTENTS The following items are supplied in this package A thermostat board ref THERMO01 EVAL including the ST62T00C MCU programmed with the software described in Application Note AN1353 A M2020 12 k EPCOS NTC A CD ROM including ST and EPCOS product presentations and datasheets and the SOFTWARE programmed in the ST62T00C microcontroller demov1r3 st6 file A User Manual this document 1 4 GETTING STARTED To operate the THERMO1EVAL board correctly use the following procedure 1 Check that the programmed pulses for generating the current for the ACS ACST gates are compatible with the motor to be controlled see Section 3 2 This means that the START and RUN winding currents must
8. of the ST62X00C in the DIL16 socket Unused memory space must be filled with a NOP instruction 04H The three last bytes must be filled with 0D D8 01 hex in order to generate a RESET if the PC points to unused locations 2 3 3 Capacitive power supply In order to reduce the board price as much as possible a capacitive power supply is used on the board instead of a transformer based supply This supply can only source an average cur rent lower than 10 mA For higher current the C1 capacitor see Appendix 3 can be replaced by one with a higher value One particularity of this power supply is to be a negative one Indeed the Vpp terminal is connected to Neutral This means that the Vss voltage is 5V below Neutral This type of con nection is mandatory when the MCU drives ACS devices directly In fact ACSs can only be triggered by a negative current i e sourced from the gate hi 9 20 www BDTIC com ST USING THE EVALUATION BOARD 3 USING THE EVALUATION BOARD 3 1 CURRENT LOADS Initially there is no heat sink mounted on the TO220 AB of the ACST6 7ST devices In this case Figure 2 2 of their datasheet shows that the maximum permanent allowed current is 1 5 A RMS for an ambient temperature of under 40 C If the RUN triac has to sink a higher cur rent or work at a higher temperature a heat sink can be added As the START triac works for a short time only no heat sink is normally required For example reliab
9. LB connector b Connect the NTC to the NTC connector and put the sensor terminal on the evap orator in the fridge or freezer to be controlled c Connect the switch of the appliance door if it is not connected to any electrical po tential to the DOOR connector Alternatively instead of using an external switch you can use the DOORSWITCH on the board to switch the bulb ON or OFF d Connect the Compressor to the MOTOR connector Take care to connect the START RUN and LINE properly to the right terminals on the motor see ap pendix 2 and AN1354 e Warning all the following actions have to be done by a electrically skilled techni cian because the board has to be plugged to the MAINS voltage and because NO INSULATION is implemented between the MAINS voltage and the accessible con ductive parts d www BDTIC com ST FUNCTIONAL DESCRIPTION When all safety precautions have been taken the mains voltage can be plugged into the MAINS connector Note The Protective Earth PE pin is not connected to any part of the board but just to a floating pad in case it is needed 6 Use an insulated screw driver to switch the motor ON by turning the TEMP ORDER potentiometer towards the COLD indication Note that the temperature order is refreshed every 5 seconds The potentiometer should so not be turned too fast in order to let the microprocessor take the new order into account The potentiometer should not b
10. N61000 4 4 standard on THERMO1EVAL boards connected to a compressor and three 25 W light bulbs One of these bulbs is the fridge internal lamp The two other ones are placed in parallel with the motor wind ings This enables any spurious device firing to be easily detected In fact as soon as one switch conducts a few milliseconds the bulb will emit some light The test layout shown on Figure 9 have been done in order to implement very high stress tests but still in accordance with the EN61000 4 4 standard The main characteristics of the setup are a THERMO1EVAL Board loads and mains wires are placed 10 cm above the ground reference a The mains wire is shorter than 1 m a The compressor protective earth is linked to the PE of the board through a 30 cm cable Each operating cycle has been tested all loads OFF lamp ON Motor ON lamp motor ON The burst withstanding level is in the range of 3 to more than 4 5 kV maximum generator ca pability depending on the coupling mode to L N PE etc Figure 9 EN61000 4 4 test layout PE connector Bursts generator er 19 20 www BDTIC com ST CONCLUSION Notes Information furnished is believed to be accurate and reliable However STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use No license is granted by implicatio
11. be lower than the ACST6 holding and latching currents 25 and 50 mA respectively in a 2 8 ms window starting ISA 5 20 www BDTIC com ST INTRODUCTION 0 45 ms after the Zero Crossing point of the mains voltage see Figure 2 To change the pulse timing refer to Application Note AN1353 Two motor control parameters should also be checked i e the length of the START wind ing conduction and the delay after which the overcurrent subroutine operates cf AN1353 amp AN1354 These two times can be lengthened if they are too short and do not meet the require ments of the motor you are using Check that the power of the motor and the bulb to be controlled is not too high see Sec tion 3 1 Bulb power lt 25 W Compressor power lt 150 W Check that the programmed threshold level 4 C by default of the temperature Hystere sis control is compatible with the temperature variation of the evaporator to be controlled If not you can change this threshold by modifying the THRES variable in the software see Appendix 1 and AN1353 If you have changed the software in steps 1 and 3 above don t forget to program the Option Byte as follows in your MCU D1 1 Hardware Watchdog activation D6 1 RC network oscillator selection D8 1 LVD reset activation Unused memory should also be filled as described in Section 2 3 2 5 Connect the board as follows see Figure 1 6 20 a Connect the bulb to the BU
12. current etc Then after some adjustment to your software and using the EPROM version of the ST6200 MCU you can perform tests with a freezing system One interesting measurement to carry out would be to see how much the temperature regulation is improved and how much the power consumption is reduced by removing the PTC and decreasing the motor operation duty cycle Information on these two last points is also given in Application Note AN1354 12 20 d www BDTIC com ST CONCLUSION Appendix 1 Thermal Sensor Linearization A NTC thermistor is a resistor whose value decreases when its temperature increases The thermal law is exponential as presented in Equation 1 1 1 B EE T To To build a simple voltage sensor it is better to linearize the temperature response using a con stant resistor R1 added in series with the NTC Rc This creates a voltage divider The voltage across R1 will follow the supply voltage Vpp according to the relationship below Equation 1 Re T Ro exp S Rc T Equation 2 Vs Re T RI VDp To make the relationship of Equation 2 to vary linearly it s enough to ensure that the second order derivative will be zero Equation 3 gives the R1 value to ensure this condition 2 2 RAT Ri dI Rc T ae Rc T d T2 To linearize the voltage response of a M2020 12 k from EPCOS between 30 and 5 C a 62 kQ resistor should be chosen for R1 In this temperature range
13. de da penceeaeeeendeeaateneeaeeeanaas 3 1 1 TARGET APPLICATION ec cecescecasateceivareeanae cn decn ance bean ne 3 1 2 BLOCK DIAGRAM so c2ctade secede nndioee TEE 5 1 3 LIST OF CONTENTS rgere eet Sege jetta etd Sr ede deco eedetused 5 1 4 GETTING STARTED 24426 3442555 55 45650945 3661404 chu sisoetateeet 5 2 FUNCTIONAL DESCRIPTION 02 0 c eee eee eee 7 2 1 PERFORMANCE s 45 345i 003505540500655404404o adie ged fe ed 7 2 2 MAIN FEATURES 2sncadiie Send eg ee Ser red BE Eet rer gege 8 2 2 1 Temperature control cedsse eseiNaereawdees Coe ae SR ae eee e PERSE 8 SE ai crates E ik het ee eel eet eee ie ese a Sok ee 8 SEENEN 3 3 stn Soa eT eee BERS FORE REET GREEN he Se le SERS Se 8 2 3 HARDWARE DESCRIPTION 2000 cece eee eee eee 8 2 3 1 ACS amp ACSI devices coo sn dhe E Reeg EE EE a ed 8 2 3 2 ST6200C Microcontroller naasna EE ee Bhs wees eee 9 2 3 3 Capacitive power supply ANEN REINER EE EE EE EE EELER 9 3 USING THE EVALUATION BOARD 10 3 1 CURRENT LOADS o Aa NR 0550 ER bee C855 Eer Ee bed eee eae 10 3 2 CONTROL PULSES 234s cc ecebesw nese eee nee eaeee eee Chee es ee eee 10 3 3 OVERCURRENT DETECTION 0 02 eee eee eee 11 3 4 MEASUREMENT POINTS 11 4 CONCLUSION sees Hoes ue eeae CNS eGo ie ON 5G 6 He REES 12 Appendix 1 Thermal Sensor Linearization 00 0c cece eee eee eee 13 Appendix 2 Wiring connections 0 00 c eee eee 15 Appendix 3 THERMO1EVAL Schematics 0 000 e
14. e turned completely to the COLD position in order to avoid the fridge cooling excessively and the motor operating too long It is recommended to check the evaporator temperature with a second temperature sensor Check that the motor is being controlled properly for example by using an oscilloscope to display the START and RUN winding currents their waveforms should be sinusoidal 7 lf there are problems Ifthe overcurrent LED is switched on several times at each motor start up this means that the START winding conduction and or the overcurrent subroutine start delay are too short and must be changed Check that the board is correctly powered on by changing the DOORSWITCH position The bulb should go ON and OFF Check if the FUSE is blown disconnect the mains voltage before unplugging the fuse Reset the MCU by unplugging the mains voltage and waiting for Vpp to drop below 0 7 V Then apply the mains voltage and try again to see if the board operates 2 FUNCTIONAL DESCRIPTION 2 1 PERFORMANCE The THERMO1EVAL board is designed to meet the following requirements Low cost the complete board material plus the sensor can reach a cost close to electro mechanical solutions for high volume ranges 1 Million units per year a lower target can also be reached if all the options are removed only one triac to drive the compressor no LED no ACS to drive the bulb smaller PCB area Electromagnetic Compatibility
15. he exact maximum temperature will depend on the power of the loads see Sec tion 3 1 This type of motor used to drive a compressor usually has an auxiliary winding that only works during the first 0 5 s of operation in order to apply a higher torque at start up Tradition ally a PTC resistor is used to switch off this winding after start up The THERM01EVAL board allows this PTC to be switched off after motor turn on or to be completely removed in order to reduce the power consumption caused by the PTC heating up In fact the two windings can be controlled by two triacs However only one triac can be used to drive the compressor if the PTC is to be left working Warning The MCU is directly linked to the mains voltage No insulation is ensured between the accessible parts and the high voltage The THERMO1EVAL board must be used with care and only by persons qualified for working with electricity at mains voltage levels This document gives all the information needed to make the board work how to connect it how it works To have specific information at design level in order to modify certain parame ters please refer to the two following Application Notes a AN1353 ST6200C Software Description for Cooling Thermostat Applications a AN1354 Single phase Induction Motor Drive for Refrigerator Compressor Applications Rev 1 1 July 2001 3 20 www BDTIC com ST Table of Contents TINTRODUCTION sscctensaaeeadaceede
16. ility tests have shown that ACST6 7ST can withstand 11 A RMS for half a second for more than 300 k cycles refer also to AN1354 The ACS102 5T1 which has an SO8 package can withstand a 0 2 A RMS permanent current in an ambient temperature of up 90 C And this is reached with a very low copper area on the COM terminals approx 2 mm Based on this information we can assume that the ACS102 5T1 can drive the common types of light bulb found in fridges or freezers without any problem In fact a 25 W bulb will always sink a current lower than 150 mA 3 2 CONTROL PULSES Figure 2 shows how the gate current pulses are defined for the two loads The choice of these durations is explained in Application Note AN1354 If the loads used sink a different current or with a different power factor there is the risk of missing firing the triac for one or several half cycles So you should check that the pro grammed angles are compatible with the loads connected to the board If not refer to AN1353 and AN1354 to change these values d 10 20 www BDTIC com ST USING THE EVALUATION BOARD Figure 2 Gate current pulses NMIL ee ee ee E PAS ACS102 control ACSTE control 5 00 che 5 00V ch3 Sony D I 200v 3 3 OVERCURRENT DETECTION The overcurrent detection is active one second after motor start up This delay is needed to differentiate a start up transient
17. mperature information is then simply compared to the voltage given by the TEMP ORDER potentiometer The hys teresis threshold can be changed by software see Application Note AN1353 2 2 2 Motor control The motor is driven by two ACST6 7ST devices Tr RUN Switch ON when the temperature is too high OFF when the temperature is low enough or when an overcurrent has been detected Ts START Switch only ON for the first 0 5 seconds of each start up i e each time Tr is switched ON Ts can be not used refer to Appendix 2 In this case only Tr controls the mo tor Both ACSTs are turned on whenever a Zero Voltage Crossing ZVC event occurs In order to reduce the power supply rating the ACSTs are triggered by a pulsed gate current 2 2 3 Light bulb A light bulb is driven by the ACS102 5T1 called Tb This device is ON or OFF when the DOORSWITCH is opened or closed respectively Instead of using the switch on the board S1 you can connect an external switch via the DOOR connector The ACS is turned on whenever a ZVC event occurs In order to reduce the power supply rating the ACS is triggered by a pulsed gate current 2 3 HARDWARE DESCRIPTION 2 3 1 ACS amp ACST devices The THERMO1EVAL board has an on board ACS102 5T1 plus two ACST6 7ST devices The datasheet of these devices can be found on the ST website go to http www st com ston line discretes index shtml and click on Thyristors Table 1 sums
18. n or otherwise under any patent or patent rights of STMicroelectronics Specifications mentioned in this publication are subject to change without notice This publication supersedes and replaces all information previously supplied STMicroelectronics products are not authorized for use as critical components in life support devices or systems without the express written approval of STMicroelectronics The ST logo is a registered trademark of STMicroelectronics 2001 STMicroelectronics All Rights Reserved Purchase of C Components by STMicroelectronics conveys a license under the Philips DC Patent Rights to use these components in an IC system is granted provided that the system conforms to the BC Standard Specification as defined by Philips STMicroelectronics Group of Companies Australia Brazil China Finland France Germany Hong Kong India Italy Japan Malaysia Malta Morocco Singapore Spain Sweden Switzerland United Kingdom U S A http www st com d 20 20 www BDTIC com ST
19. up the main differences between ACS amp ACST and traditional triacs d 8 20 www BDTIC com ST FUNCTIONAL DESCRIPTION Table 1 Differences between ACS ACST and TRIACS Parametei TRIAC ACS102 TRIAC ACST6 min 1A 5mA 0 2A 5mA 6A 10 mA 6A 10mA sensitivity sensitivity sensitivity sensitivity VBR io Clamped at 600 V if voltage ee Clamped at 900 V dV dt 20 V us 300 V us 100 V us 200 V us dl dt at turn on 10 A us 100 A us 20 A us 100 A us 2 3 2 ST6200C Microcontroller The MCU used in the THERMO1EVAL board is the ST62TOOC It is a basic ST6 microcon troller that embeds a large number of features at minimum cost The peripheral hardware requirements have been reduced to the minimum No quartz crystal or external resonator is used In fact the internal RC oscillator of the ST62TOOC is used to generate the clock No external RESET circuit is required as the ST62TOOC has an internal circuit When programming the MCU EPROM you have to set the following three options D1 Hardware Watchdog Activation as it is not done by software D6 RC network oscillator selection D8 Low Voltage Detection option in order to start a RESET subroutine when the board is plugged to the mains The ST62T00C program memory size is 1024 bytes The size of the implemented software is 974 bytes In order to test longer programs the ST62X01C with 2K bytes of program memory can be installed instead
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