TECHNICAL TRAINING 2008

Inverter Mini Chiller System and Control

Content 1. Introduction 2. Basic Inverter Technology 3. Components 4. Control Algorithm 5. Protection

Introduction

Introduction 5ACV100/135/210 CR 5ACV55/75 CR 5ACV30 CR

Introduction Model Capacity (kW) Cooling Heating 5ACV030CR 7.94 9.66 14.65 16.12 5ACV075CR 20.52 21.99 5ACV100CR 27.80 29.30 5ACV135CR 38.54 41.47 5ACV210CR 58.62 61.55

Introduction New Technology BPHE- True Dual Circuits Conventional Back to Back Circuits BPHE Secondary Circuit Primary Circuit 1 Primary Circuit 2 5ACV True Dual Circuits BPHE Primary Circuit 1 Primary Circuit 2

Introduction Inverter Compressor Conventional System Inverter System

Introduction Elimination of Water Tank Modular Installation Inverter system provide constant Water Temperature band, or much lesser water temperature fluctuation. With this, water tank of mini chiller system can be eliminated Modular Installation A network up to 50 chillers in a system is possible. Control on the operation of chillers will be done through the microprocessor controller. The external water piping connection can be made either from the left or right side of the unit. Safety Protection High & Low Pressure Switches Anti Freeze Protection Sensor Discharge Temperature Sensor Over Pressure Relief Valve Water Pressure Differential Switch Anti Freeze Heater on BPHE Compressor, Water Pump Overload Protector

Basic Inverter Technology

Basic Inverter Technology The system:- Power supply Input frequency 50Hz Inverter t1 u AC/DC Rectifier DC/AC Inverter t t 50 Hz 15 Hz 100 Hz (compressor motor input) PWM

Basic Inverter Technology Three-phase inverter PWM control Power supply unit Compressor (Waveform formation) AC Inverter Unit Three-phase induction motor AC DC Temperature detection signal Operating frequency signal

Basic Inverter Technology Inverter Basic Structure Inversion PLC Control Rectification AC DC Link Converter PWM Signal SMPS M

Basic Inverter Technology Rectification Circuit EMI filter to minimize emission effect (EMC) and raise immunity level (EMS) PTC to cushion start-up current to capacitor Diode bridge inverts AC to DC EMI Filter Rectifier Bridge PTC Starter Relay

Basic Inverter Technology DC Stage PFC capacitor acts to curb PF losses caused by DC voltage fluctuation in order to drive the asynchronous motor PFC Capacitor Reactor Stabilizing Capacitor Diode

Basic Inverter Technology Inversion Circuit Consists of 6 IGBT (Insulated Gate Bipolar Transistor) Controlling the ON/OF linkages, different frequency and voltage of 3-phase AC can be generated IPM (Intelligent power module) encased the inversion circuitry together with error detection and protection features

Soft-start. No current surge Yes, operates at high freq. Basic Inverter Technology Advantages of Inverter Air Conditioners Item Fixed Speed AC Inverter AC Energy Saving No Yes, by 30% - 40% Temp. Fluctuation ± 2°C ± 0.5°C Adjust to Load Yes Start-up Current surge of 7-11x Soft-start. No current surge Full Load Op. Yes, operates at high freq. Speed of Cool/Heat Slow Fast Defrosting Less efficient Accurate and fast Protection Features Basic Complete Auto-Mode Features

Components

Components Fan guards Coil guards fan motors Heat exchangers with gold fin as standard Expansion tank ( 8L) True dual circuits BPHE (Brazed plate heat exchanger) Control box assembly Water pump

Components High pressure switch (NC) 600 psi – open, 480psi – close. Low pressure switch (NC) 18 psi – open, 28 psi – close. Pump OLP (overload protector) Differential pressure switch Over pressure relief valve Anti freeze heater on BPHE Compressor OLP (overload protector) Chiller panel controller Fixed speed scroll compressor (R410A) Variable drive system compartment Fixed drive system compartment Variable speed scroll compressor (R410A)

Components Control box assembly 3 phase rectifier bridge diode IPM board (Intelligent power module) Main board Magnetic contactors EMI filter Capacitor board PFC capacitor (Power factor correction) Uni-directional bridge diode 3 phase rectifier bridge diode Fan capacitors Power board EMI filter - EMI filter is a device placed between the power source and control device circuit. Prevents external electromagnetic interference from getting into the controller. Prevents internally generated electromagnetic emission from polluting the supply grid. EMI filter verification - Resistance between A-A’, B-B’, C-C’ & N-N’ should be 0 ohm. Resistance between A-B, A-C, B-C should be about 1360kohm. Resistance between A-N, B-N, C-N should be about 680kohm. Resistance between A, B, C, N and casing should be infinity. 3 phase rectifier - To convert AC to DC current. Uni-Directional bridge PFC capacitor - To raise power factor to about 0.9. Testing - use dial type multimeter to measure the circuit, the resistance should gradually increase from zero to rated resistance. Capacitor board - Supply to power board. IPM - Invert DC to AC current, drive variable compressor. Electronic starter (PTC Thermistor) - PTC electronic starter and relay combination acts to cushion the excessive charge current because of high capacitor charge current during start up. Testing - Use multimeter to check the resistance of electronic starter on sheet metal at ambient temperature is 40+/-20%ohm. Resistance of electronic starter on PCB is 47+/-20%ohm. When current exceeds 10A rated level, the temperature of PTC resistor will rise and increase the resistance to restrict current increase.

Components EMI Filter Function EMI Filter is a device placed between the power source and control device circuit. Prevents external electromagnetic interference from getting into the controller. Prevents internal electromagnetic emission from polluting the supply grid. EMI filter - EMI filter is a device placed between the power source and control device circuit. Prevents external electromagnetic interference from getting into the controller. Prevents internally generated electromagnetic emission from polluting the supply grid. EMI filter verification - Resistance between A-A’, B-B’, C-C’ & N-N’ should be 0 ohm. Resistance between A-B, A-C, B-C should be about 1360kohm. Resistance between A-N, B-N, C-N should be about 680kohm. Resistance between A, B, C, N and casing should be infinity. 3 phase rectifier - To convert AC to DC current. Uni-Directional bridge PFC capacitor - To raise power factor to about 0.9. Testing - use dial type multimeter to measure the circuit, the resistance should gradually increase from zero to rated resistance. Capacitor board - Supply to power board. IPM - Invert DC to AC current, drive variable compressor. Electronic starter (PTC Thermistor) - PTC electronic starter and relay combination acts to cushion the excessive charge current because of high capacitor charge current during start up. Testing - Use multimeter to check the resistance of electronic starter on sheet metal at ambient temperature is 40+/-20%ohm. Resistance of electronic starter on PCB is 47+/-20%ohm. When current exceeds 10A rated level, the temperature of PTC resistor will rise and increase the resistance to restrict current increase.

Components Main Board For Model 55, 75, 100 & 135 For Model 30

Components Power Board To convert rectified DC current +590VDC to respective desired voltages 12VDC relay MCU +5VDC IPM +15VDC Ensure stability of above voltages within power supply voltage fluctuation range (304-480 VAC) Over voltage feedback Output short circuit protection

Components Capacitor Board

Components IPM Function Invert DC to AC current Drive variable compressor In-Built Protection Low voltage lock-out Over-heating, over-current and short-circuit protection.

Components Schematic Diagram 1. Variable drive discharge temperature sensor (Disch temp 1) variable compressor discharge temperature protection and system superheat correction sampling input. 2. Coil in temperature sensor (Cond In Temp 1) sampling input not applicable during cooling . Only for heating. 3. Coil out temperature sensor (Cond Out Temp 1) normally common sampling point for defrosting. Sampling input for over-temperature protection during cooling, and sampling input for superheat and defrost control. 4. BPHE In temperature sensor (BPHE In Temp) sampling input not applicable during cooling. During heating, inputs for superheat control and high pressure protection control. 5. BPHE Out temperature sensor (BPHE Out Temp) sampling input for low temperature evaporation point protection and sampling input for superheat control during heating. 6. Suction temperature sensor (Suct Temp) sampling input for superheat/subcool control during heating/cooling. 7. High/low pressure switch (HP1, LP1) sampling input for high/low load pressure for variable drive system. Similar for fixed drive system. 8. Fixed drive discharge pressure sensor (Disch Temp2) overheating protection for fixed drive. 9. Coil temperature sensor sampling input for high chilled temperature protection during cooling and defrosting during heating. 10.High/low pressure switch (HP2, LP2) sampling point for high/low load pressure for fixed drive system.

Control Algorithm

Clash between current & selected mode of operation? Control Algorithm General Control Flow Chart Start No Stop Inverter Comp Yes Stop pump 60s Clash between current & selected mode of operation? Cooling mode Heating? Heating mode System On? Cooling? 10s Stop Fixed Comp

Control Algorithm Variable Drive Compressor Control Cooling mode Start up condition : Pump runs normally for 3 minutes * For example : Return water temp.= 14 to 16 °C Set temp = 12°C D T = 2 to 4°C 2°C £ T water return – T set £ 4°C No irreversible errors in variable drive and the systems Satisfy a delay of 3 minutes before restart # Note : If fixed drive system starts first, the variable drive system should trail after 30 sec. * Depends on Parameter P2 (flow switch alarm delay at pump start. Min 0s, max 199s, default 180s ) # Depends on Parameter C2 (compressor min stop time. Min 0s, max 1990s, default 180s)

Control Algorithm Variable Drive Compressor Control Cooling mode Cooling mode selected  water pump starts  Outdoor fan starts  variable drive compressor starts Rated Freq. 55Hz 5Hz t 3 min 5 sec 1 min ON OFF Variable drive comp Outdoor fan Increase to rated frequency with the rate of 1Hz/s 5ACV100CR=75Hz 5ACV135CR=95Hz Inverter compressor will start from 5Hz to 55Hz and maintain this frequency for 1 min. Outdoor fan will start 5 sec before compressor start

Control Algorithm Variable Drive Compressor Control Cooling mode Shut down condition : Cooling mode terminates, OR Variable drive system error occurs, OR T water return – T set £ -2°C For example : Return water temp.= 10°C Set temp = 12°C D T = -2°C

Fixed drive starts first followed by variable drive Control Algorithm Fixed Drive Compressor Control Cooling mode Start up condition : Pump runs normally for 3 minutes * For example : Water return temp = 16°C Set temp = 12°C DT = 4°C T water return – T set > 4°C Fixed drive starts first followed by variable drive No irreversible errors in fixed drive and the systems Satisfy a delay of 3 minutes before restart # Note : If variable drive system starts first, the fixed drive system will only start after the frequency of variable drive drops to 50Hz. * Depends on Parameter P2 (flow switch alarm delay at pump start. Min 0s, max 199s, default 180s ) # Depends on Parameter C2 (compressor min stop time. Min 0s, max 1990s, default 180s)

Control Algorithm Fixed Drive Compressor Control Cooling mode Cooling mode selected  water pump starts  Outdoor fan starts  compressor starts Fixed drive compressor starts Fixed drive comp Outdoor fan 1 min 3 min 5 sec ON OFF Outdoor fan will start 5 sec before compressor start Outdoor fan will stop after compressor has stopped for 1 min

Control Algorithm Fixed Drive Compressor Control Cooling mode Shut down condition : Cooling mode terminates, OR Fixed drive system error occurs, OR T set - T water return > 2°C and variable frequency drops pass 20Hz For example : Set temp = 12°C Water return temp = 10°C DT = 2°C

Control Algorithm Variable Drive Compressor Control Heating mode Start up condition : Pump runs normally for 3 minutes * For example : Set temp = 40°C Return water temp.= 36 to 38 °C D T = 2 to 4°C 2°C £ T set - T water return £ 4°C No irreversible errors in variable drive and the systems Satisfy a delay of 3 minutes before restart # Note : If fixed drive system starts first, the variable drive system should trail after 30 sec. * Depends on Parameter P2 (flow switch alarm delay at pump start. Min 0s, max 199s, default 180s ) # Depends on Parameter C2 (compressor min stop time. Min 0s, max 1990s, default 180s)

Control Algorithm Variable Drive Compressor Control Heating mode Heating mode selected  water pump starts  Variable drive 4WV engages  Outdoor fan starts  compressor starts Increase to rated frequency with the rate of 1Hz/s Rated Freq. 45Hz 5Hz t 3 min 10 sec 1 min ON OFF Variable drive comp Outdoor fan Variable 4WV 5 sec 5ACV100CR=65Hz 5ACV135CR=90Hz Inverter compressor will start from 5Hz to 45Hz and maintain this frequency for 1 min. Variable drive 4WV start 10 sec before compressor start Outdoor fan will start 5 sec before compressor start

Control Algorithm Variable Drive Compressor Control Heating mode Shut down condition : Heating mode terminates, OR Variable drive system error occurs, OR T set - T water return £ -2°C For example : Set temp = 40°C Water return temp = 42°C DT = -2°C

Control Algorithm Fixed Drive Compressor Control Heating mode Start up condition : Pump runs normally for 3 minutes * For example : Set temp = 40°C Water return temp = 36°C DT = 4°C T set - T water return > 4°C No irreversible errors in fixed drive and the systems Satisfy a delay of 3 minutes before restart # Note : If variable drive system starts first, the fixed drive system will start after the variable drive frequency drops to 50Hz. * Depends on Parameter P2 (flow switch alarm delay at pump start. Min 0s, max 199s, default 180s ) # Depends on Parameter C2 (compressor min stop time. Min 0s, max 1990s, default 180s)

Control Algorithm Fixed Drive Compressor Control Heating mode Heating mode selected  water pump starts  Fixed drive 4WV engages  Outdoor fan starts  compressor starts Fixed drive compressor starts 3 min 10 sec 1 min ON OFF Fixed drive comp Outdoor fan Variable 4WV 5 sec Fixed drive 4WV start 10 sec before compressor start Outdoor fan and 4WV will stop after compressor has stopped for 1 min Outdoor fan will start 5 sec before compressor start

Control Algorithm Fixed Drive Compressor Control Heating mode Shut down condition : Heating mode terminates, OR Fixed drive system error occurs, OR T water return - T set > 2°C For example : Water return temp = 42°C Set temp = 40°C DT = 2°C

Control Algorithm Pump Control Pump start up Pump shut down When starting the system, pump will run for 3 minutes * before proceeding to next step. * Depends on Parameter P2 (flow switch alarm delay at pump start. Min = 0s, Max = 199s, default = 120s) Pump shut down After both compressors shut down for 1 minute, pump shuts down.

Protection

Compressor Over-Current Protection Variable drive compressor When variable drive compressor current reaches the Ib, over-current protection triggers and the compressor frequency will reduce. When the compressor current drops into Ic to Ib, frequency will not increase. When the compressor current drops below the Id, frequency variation resumes. When compressor current increase rapidly and reaches the Ia, the system will be determined as compressor overload and stop the compressor. Comp amp (A) Variable compressor stops Ia Frequency step down Ib Maintain frequency Ic Id Normal Operation

Protection Compressor Over-Current Protection Variable drive compressor Inv Comp Current M5ACV030 M5ACV055 M5ACV075 M5ACV100 M5ACV135 M5ACV210 Ia 29 20.5 Ib 27 18 Ic 25 17 Id 16

Protection Compressor Over-Current Protection Fix drive compressor When fixed compressor current > Ie. The compressor will stops and resumes after 3 minutes Note: When either drive overload protection occurs more than 3 times within 30 minutes, system triggers irreversible error protection. Comp amp (A) Fixed compressor stops Ie

Protection High Discharge Temperature Protection Variable drive system When variable drive discharge temperature reaches 110°C, system stops. When variable drive discharge temp. between 100°C and 110°C, frequency drops. When variable drive discharge temperature is less than 97°C and more than 100°C, frequency increased restricted. When discharge temperature falls below 94°C, normal operation resumes. System shuts down Frequency step down Maintain frequency Normal operation Compressor discharge temperature 110°C 100°C 97°C 94°C

Protection High Discharge Temperature Protection Fixed drive system When fixed drive discharge temperature reaches 110°C, system stops. When discharge temperature falls below 94°C for 3 minutes, system resumes. Td = Compressor discharge temperature Td 110°C Comp Cut 94°C Comp start 3 min

Protection Outdoor Coil High Temperature Protection Variable drive system During cooling, when Tcoil1 > 60 °C, frequency drops. During cooling, when Tcoil1 < 55 °C, system resumes. Fixed drive system During cooling, when Tcoil2 > 64°C, compressor stops. During cooling, when Tcoil2 < 51°C, system resumes.

Protection Low Pressure Switch Protection Alarm delayed at compressor startup : 30 sec depends on Parameter P3*. No protection during defrosting. If variable drive or fixed drive low pressure switch is activated for 5 seconds, alarm will be triggered. * Parameter P3 (Low pressure alarm delay at compressor start up. Min=0s, max=199s, default=30s) Note : If low pressure alarm occur more than 3 times within 30 minutes, system shuts down to irreversible error.

Protection High Pressure Switch Protection If fixed drive high pressure switch is activated for 30 sec, alarm will be triggered. If variable drive high pressure switch is activated, frequency of variable drive compressor will decrease at 1Hz/s. If it is re-activated for 30 sec, alarm will be triggered. Note : If high pressure alarm occur more than 3 times within 30 minutes, system shuts down to irreversible error.

Protection 3 Phase AC Phase Sequence Protection If 3 phase AC phase sequence is incorrectly connected, system will not start and controller will indicate error. System will resume after rectification. (except M5ACV030CR) 3 Phase AC Phase Missing Protection If phase missing happens, system will not operate. Controller will indicate error. System will resume after rectification.

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