No. OBT16
SERVICE TECHNICAL GUIDE
??
CONTENTS
1.MS MICROPROCESSOR CONTROL ????????????????????
2.MSZ,MSY MICROPROCESSOR CONTROL ??????????????
3.MXZ MICROPROCESSOR CONTROL ????????????????????
No. OBT16
SERVICE TECHNICAL GUIDE
??
CONTENTS
1.MS MICROPROCESSOR CONTROL ????????????????????
2.MSZ,MSY MICROPROCESSOR CONTROL ??????????????
3.MXZ MICROPROCESSOR CONTROL ????????????????????
1. MS MICROPROCESSOR CONTROL ??????????????????????????????????????????????????????????????????????????3
Indoor unit models Outdoor unit models
2. MSZ, MSY MICROPROCESSOR CONTROL ??????????????????????????????????????????????????????????????????6
Indoor unit models
Outdoor unit models
3. MXZ MICROPROCESSOR CONTROL ????????????????????????????????????????????????????????????????????????20
Outdoor unit models
2
Room temperature minus set temperature : 3.1 degrees or more ??????????????????????????????????????????????????????????????High
Room temperature minus set temperature : Between 1.8 and 3.1 degrees ??????????????????????????????????????Med. 
Room temperature minus set temperature : less than 1.8 degrees ????????????????????????????????????????????????????????Low
5.4 deg.
1.8 deg. 3.1 deg.
3.Coil frost prevention
???Temperature control
When the indoor coil thermistor RT12 reads 37 ??F or below the coil frost prevention mode starts immediately. However, the coil frost prevention doesn???t work for 5 minutes since the compressor has started.
The indoor fan operates at the set speed and the compressor stops for 5 minutes.
After that, if RT12 still reads below 37 ??F this mode prolonged until the RT12 reads over 37 ??F.
???Time control
When the three conditions as follows have been satisfied for 1 hour and 45 minutes, compressor stops for 3 minutes.
a.Compressor has been continuously operating.
b.Indoor fan speed is Low or Med.
c.Room temperature is below 79 ??F.
When compressor stops, the accumulated time is cancelled and when compressor restarts, time counting starts from the beginning.
Time counting also stops temporarily when the indoor fan speed becomes High or the room temperature exceeds 79 ??F. However, when two of the above conditions (b.and c.) are satisfied again. Time accumulation is resumed.
) OPERATION
Set temperature is as shown on the right chart.
The system for dry operation uses the same refrigerant circuit as the cooling circuit.
The compressor and the indoor fan are controlled by the room tem- perature.
By such controls, indoor flow amounts will be reduced in order to lower humidity without much room temperature decrease.
3
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature.
Initial temperature differenceThermostat Room temperature minus set temperature :
Set temperature
2.Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button. When thermostat OFF (compressor OFF) fan speed becomes Very Low.
In AUTO the fan speed is as follows.
Initial temperature difference Fan speed
Room temperature minus set temperature : 3.1 degrees or more ??????????????????????????????????????????????????????????????High
Room temperature minus set temperature : Between 1.8 degrees and 3.1 degrees??????Med.
Room temperature minus set temperature : less than 1.8 degrees ??????????????????????????????????????????????????????????Low
3.The operation of the compressor and indoor/ outdoor fan
Compressor operates by room temperature control and time control. Set temperature is controlled to fall 4??F from initial room temperature. Indoor fan and outdoor fan operate in the same cycle as the compressor. ???When the room temperature is 73??F or over:
When the thermostat is ON, the compressor repeats 8 minutes ON and 3 minutes OFF. When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
???When the room temperature is under 73??F.
When the thermostat is ON, the compressor repeats 2 minutes ON and 3 minutes OFF. When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
Difference between room temperature and set temper- ature during operation ( 
T)
4.5 deg.
1.8 deg. 3.1 deg.
4.Coil frost prevention
Coil frost prevention is as same as COOL mode.
The indoor fan maintains the actual speed of the moment. However ,when coil frost prevention works while the compressor is not operating it???s speed becomes the set speed.
4
1. Horizontal vane
ECONO COOL ( 
) operation (ECONOmical operation)
When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 3.6 degrees higher than that in COOL mode.
Also the horizontal vane swings in various cycle according to the temperature of indoor heat exchanger (RT12). SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher than that in COOL mode, the air conditioner can keep comfort. As a result, energy can be saved.
ECONO COOL operation is cancelled when ECONO COOL button is pressed once again or VANE CONTROL button is pressed or change to other operation mode.
<SWING operation>
In swing operation of ECONO COOL operation mode, the initial air flow direction is adjusted to ???Horizontal???. According to the temperature of indoor coil thermistor RT12 at starting of this operation, next downward blow time is decided. Then when the downward blow has been finished, next horizontal blow time is decided.
For initial 10 minutes the swing operation is performed in table G~H for quick cooling.
Also, after 10 minutes when the difference of set temperature and room temperature is more than 3.6 degrees, the swing operation is performed in table D~H for more cooling.
The air conditioner repeats the swing operation in various cycle as follows.
5
3.Coil frost prevention
Temperature control
When indoor coil thermistor detects following temperature for 90 seconds, operational frequency of compressor is controlled according to the following table.
The indoor fan maintains the actual speed of the moment.
4.Low outside temperature operation
If the outside temperature falls to 64??F or less during operation in COOL mode, the unit enters the low outside temperature operation mode.
<Operation>
(1)If the unit enters the low outside temperature operation mode, the outside fan rotation speed gets slow down.
(2)Even when the unit is in the
(3)In this mode to detect the exact outside temperature the compressor turns OFF with the outdoor fan ON for 3 minutes once 1 hour; if the outside temperature rises over 64??F, the unit goes back to the normal COOL mode, and if the outside temperature is still 64??F or less, the unit stays in the low outside temperature operation mode.
(4)Dew drop prevention
When the ambient temperature thermistor RT65 reads 10??F or less, as coil frost or dew drop from indoor unit may occur, the compressor turns OFF with the outdoor fan ON for prevention of them.
WOther protections work as well as in the normal COOL mode.
6
) OPERATION
Set temperature is as shown on the right chart.
The system for dry operation uses the same refrigerant circuit as the cooling circuit.
The compressor and the indoor fan are controlled by the room tem- perature.
By such controls, indoor flow amounts will be reduced in order to lower humidity without much room temperature decrease.
2.Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button. When thermostat OFF (compressor OFF) fan speed becomes Very Low.
In AUTO the fan speed is as follows.
Room temperature minus set temperature : 3.1 degrees or more ??????????????????????????????????????????????????????????????High
Room temperature minus set temperature : Between 1.8 and 3.1 degrees ??????????????????????????????????????Med.
Room temperature minus set temperature : less than 1.8 degrees ????????????????????????????????????????????????????????Low
3.Coil frost prevention
Coil frost prevention is as same as COOL mode.
Difference between room temperature and set temper- ature during operation ( 
T)
4.5deg.
1.8deg. 3.1deg.
The indoor fan maintains the actual speed of the moment. However ,when coil frost prevention works while the compressor is not operating it???s speed becomes the set speed.
4.Low outside temperature operation
Low outside temperature operation is as same as COOL mode.
) OPERATION (MSZ)
2.Indoor fan speed control
(1)Indoor fan operates at the set speed by FAN SPEED CONTROL button. In Auto the fan speed is as follows.
Set temperature minus room temperature: 3.6 degrees or more???????????????????????????????????????????????????????????????????????????? High
Set temperature minus room temperature: Between 0.4 and 3.6 degrees ???????????????????????????????????????? Med.
Set temperature minus room temperature: less than 0.4 degrees???????????????????????????????????????????????????????????????????????? Low
Difference between room temperature and set temper- ature during operation
3.6deg. 7.2deg.
0.4deg. 3deg.
7
(2)Cold air prevention control
1 When the compressor is not operating,
(1) if the temperature of room temperature thermistor RT11 is less than 66??F, the fan stops. (2) if the temperature of room temperature thermistor RT11 is 66??F or more and
(1) if the temperature of RT12 is less than 32??F, the fan stops.
(2) if the temperature of RT12 is 32??F or more, the fan operates at Very Low. 2 When the compressor is operating,
(1) if the temperature of RT12 is 104??F or more, the fan operates at set speed. (2) if the temperature of RT12 is less than 104??F and
(1) if heating operation starts after defrosting, the fan stops.
(2) if the temperature of room temperature thermistor RT11 is 66??F or less, the fan stops.
(3) if the temperature of room temperature thermistor RT11 is more than 66??F, the fan operates at Very Low. NOTE : When 3 minutes have passed since the compressor started operation, this control is released regardless of the
temperature of RT11 and RT12.
1 When the compressor is not operating,
(1) if the temperature of room temperature thermistor RT11 is 59??F or less, or RT12 is less than 64??F, the fan stops.
(2) if the temperature of room temperature thermistor RT11 is more than 59??F, or RT12 is more than 64??F, the fan operates at Very Low.
2 When the compressor is operating,
(1) if the temperature of RT12 is 64??F or more, the fan operates at set speed. (2) if the temperature of RT12 is less than 64??F and
(1) if heating operation starts after defrosting, the fan stops.
(2) if the temperature of room temperature thermistor RT11 is 59??F or less, the fan stops.
(3) if the temperature of room temperature thermistor RT11 is more than 59??F, the fan operates at Very Low.
NOTE : When 3 minutes have passed since the compressor started operation, this control is released regardless of the temperature of RT11 and RT12.
3. Overload starting
When the room temperature thermistor RT11 reads 64??F or more, the compressor runs with its maximum frequency regulated for 10 minutes after the
4.Defrosting
(1)Starting conditions of defrosting
When the following conditions a) ~ c) are satisfied, the defrosting starts.
a)The defrost thermistor reads 27??F or less.
b)The cumulative operation time of the compressor has reached any of the set valuesw (40, 45, 55, 65, 75, 85, 95, 105, 115, 125, 150
c)More than 5 minutes have passed since the
wSet value of compressor operation time (here in after referred to as defrost interval)
This is decided by the temperature of defrost thermistor and ambient temperature thermistor, the previous defrosting time. For example, the first defrost interval is 40 minutes long, and the second is 45 minutes long. The third and subse-
quent intervals are set to be longer, and less frequent, depending on defrosting time.
The third and subsequent defrost intervals follow any of the three patterns ???5 or 10 to 20 minutes longer, the same, or 5 or 10 to 20 minutes shorter compared with the previous defrost interval ??? with the longest 125 minutes and the shortest 40 minutes.
(2)Releasing conditions of defrosting
Defrosting is released when any of the following conditions is satisfied:
a)The defrost thermistor continues to read 50??F or more
b)Defrosting time has exceeded 10 minutes.
c)Any other mode than HEAT mode is set during defrosting.
8
Time chart of defrosting in HEAT mode (reverse type)
<indoor unit>
Once desired temperature is set, unit operation is switched automatically between COOL and HEAT operation.
1.Mode selection
(1)Initial mode
At first indoor unit operates only indoor fan with outdoor unit OFF for 3 minutes to detect present room temperature. Following the conditions below, operation mode is selected.
1 If the room temperature thermistor RT11 reads more than set temperature, COOL mode is selected. 2 If the room temperature thermistor RT11 reads set temperature or less, HEAT mode is selected.
(2)Mode change
In case of the following conditions the operation mode is changed.
1COOL mode changes to HEAT mode when 15 minutes have passed with the room temperature 4 degrees below the set temperature.
2HEAT mode changes to COOL mode when 15 minutes have passed with the room temperature 4 degrees above the set temperature.
In the other cases than the above conditions, the present operation mode is continued.
NOTE1: Mode selection is performed when multi standby (refer to NOTE2) is released and the unit starts operation with
NOTE2: If two or more indoor units are operating in multi system, there might be a case that the indoor unit, which is operating in AUTO ( 
), cannot change over the other operating mode (COOL 
HEAT) and becomes a state of standby.
9
(3)Indoor fan control/ Vane control
As the indoor fan speed and the horizontal vane position depend on the selected operation mode, when the operation mode changes over, they change to the exclusive ones.
Fan speed is switched according to the compressor frequency.
Fan speed
High
Low
Down Up
Min. Compressor frequency Max.
<Relation between compressor frequency and fan speed.>
1. Horizontal vane
(1) Cold air prevention in HEAT operation. (MUZ)
When any of the following conditions occurs in HEAT operation, the vane angle changes to Horizontal position automati- cally to prevent cold air blowing on users.
??? Compressor is not operating.
??? Defrosting is performed.
??? Indoor coil thermistor RT12 temperature does not exceed 102??F within about 3 minutes after compressor starts.
NOTE: When 2 or more indoor units are operated with multi outdoor unit, even if any indoor unit turns thermostat off, this control doesn???t work in the indoor unit.
(2)ECONO COOL ( 
) operation (ECONOmical operation)
When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 3.6 degrees higher than that in COOL mode.
Also the horizontal vane swings in various cycle according to the temperature of indoor heat exchanger (RT12). SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher than that
in COOL mode, the air conditioner can keep comfort. As a result, energy can be saved.
ECONO COOL operation is cancelled when ECONO COOL button is pressed once again or VANE CONTROL button is pressed or change to other operation mode.
10
<SWING operation>
In swing operation of ECONO COOL operation mode, the initial air flow direction is adjusted to ???Horizontal???. According to the temperature of indoor coil thermistor RT12 at starting of this operation, next downward blow time is decided. Then when the downward blow has been finished, next horizontal blow time is decided.
For initial 10 minutes the swing operation is performed in table G~H for quick cooling.
Also, after 10 minutes when the difference of set temperature and room temperature is more than 3.6 degrees, the swing operation is performed in table D~H for more cooling.
The air conditioner repeats the swing operation in various cycle as follows.
11
Function of main parts
1.At the start of operation
Main power supply circuit is formed when X64 (Relay) is turned ON at compressor startup. To prevent rush current from running into the circuit when power supply is turned ON, R64A and R64B
2.At normal operation
1 When AC runs into POWER P.C. board, its external noise is eliminated in the noise filter circuit. 2 After noise is eliminated from AC, it is rectified to DC by DB61 (Diode module).
3 DC voltage, to which AC has been rectified by process 2, is stabilized by C63A, C63B and C63C (Smoothing capacitor) and supplied to IPM (Intelligent power module).
4 DC voltage, which has been stabilized in process 3, is converted to
5 CT761 and CT781 (Current Transformer), which are placed in the power supply circuit to compressor, are used to measure the value of phase current and locate the polar direction of rotor with algorithm. PWM (Pulse width modulation) controls impressed voltage and frequency with those information.
12
3. Purpose of PAM adoption
PAM : Pulse Amplitude Modulation
PAM has been adopted for the efficiency improvement and the adaptation to IEC harmonic current emission standard.
Outline of simple partial switching method
In conventional inverter models, diode module rectifies AC voltage to DC voltage, smoothing capacitor makes its DC waveform smooth, and IPM converts its DC voltage to imitated AC voltage again in order to drive the compressor motor.
However, it has been difficult to meet IEC harmonic current emission standard by above circuit because harmonic gets generated in the input current waveform and power factor gets down. The simple partial switching method with PAM, which has been adopted this time, places and utilizes the booster chopper circuit (L61, DB65 and TR821) before rectifying AC voltage in the general
Input current waveform without PAM
Due to the time of no electricity;
??Power factor gets worse.
??Harmonic gets increased.
Energized time is short in case L inductance is small.
No electricity runs into diode module because the
voltage at both sides of smoothing capacitor is higher than input voltage.
Input current waveform with PAM
Owing to the increase of energized time;
??Power factor gets better.
??Harmonic gets suppressed.
Release of energy stored in L
Peak gets down.
Energized time is extended by optimization of L inductance.
Compulsory energizing by switching.
4.Intelligent power module
IPM consists of the following components
Since the above components are all integrated in IPM, IPM has a merit to make the control circuit simplify and miniaturize.
5.Smoothing capacitor
C63A, C63B and C63C stabilize the DC voltage and supply it to IPM.
6.Elimination of electrical noise
Noise filter circuit, which is formed by *CMC COILS capacitors placed on the POWER P.C. board, eliminates electrical noise of AC power that is supplied to main power supply circuit. And this circuit prevents the electrical noise generated in the inverter circuit from leaking out.
*CMC COILS; Common mode choke coils
13
Function of main parts
1.At the start of operation
Main power supply circuit is formed when X64 (Relay) is turned ON at compressor startup.
To prevent rush current from running into the circuit when power supply is turned ON, R64A and R64B
2.At normal operation
1 When AC runs into noise filter P.C. board, its external noise is eliminated in the noise filter circuit.
2 After noise being eliminated from AC, it is rectified to DC by L (Reactor) and PFC (Power factor controller). If the operating frequency becomes 25Hz or more, DC voltage rises to 370V.
3 DC voltage, to which has AC been rectified by process 2, is stabilized by CB1~3 (Smoothing capacitor) and supplied to IPM (Intelligent power module).
4 The DC (Bus voltage), which has been stabilized in process 3, is converted to
5 CT1 and CT2 (Current Transformer), which are placed in the power supply circuit to compressor, are used to measure the value of phase current and locate the polar direction of rotor with algorithm. PWM (Pulse width modulation) controls impre- ssed voltage and frequency with those information.
3.Power factor improvement
Booster coil L (Reactor) and PFC rectify AC to DC and control its voltage.
In the motor drive system of sine wave control, power factor can be improved by reducing harmonics PFC and L (Reactor) stabilize the voltage of DC supplied to inverter circuit and make its waveform smooth.
4. Power transistor module
IPM consists of the following components.
?? Power Transistors (x6): Converts DC waveform to
Since the above components are all integrated in IPM, IPM has a merit that can get the control circuit simplified and mini- aturized.
5.Smoothing capacitor
CB1, CB2 and CB3 stabilize the DC voltage and supply it to IPM.
6.Elimination of electrical noise
Noise filter circuit, which is formed by *CMC COILS and capacitors placed on the noise filter P.C. board, eliminates electrical noise of AC power that is supplied to main power supply circuit. In short, common mode noise is absorbed in this circuit. Moreover, normal mode noise is absorbed in another noise filter circuit which is formed by *NMC COILS and capacitors. Both noise filter circuit exists for preventing the electrical noise generated in the inverter circuit from leaking out.
*CMC COILS; Common mode choke coils *NMC COILS; Normal mode choke coils
14
In these air conditioners, compressor equips brushless DC motor which doesn't have Hall element.
In short, the motor is sensorless. However, it's necessary to locate the polar direction of rotor in order to drive brushless DC motor efficiently. The general detection method of the polar direction for such a DC motor is to locate it from the voltage induced by unenergized stator.
Therefore, It is necessary to have a certain period of time in which the stator is being unenergized for the rotor position detection when the voltage of supplied power is impressed.
So the motor has been driven by square wave control (the conventional motor drive system) which energizes the motor only when the range of electrical angle is within 120_ because it is forced to be unenergized within 30_ at start & end of one heap in one waveform cycle (180_) when the voltage is impressed.
However, torque pulsation occurs at rotation in this method when the
???Although ordinary
???This control provides the most efficient waveform corresponding to the rotation times of compressor motor.
???The rotation can be set to higher compared to the conventional motor drive system. So, the time in which air conditioner can be operated with energy saved is longer than conventional models. This can save annual electric consumption.
???Compared to square wave control, the torque pulsation is reduced at rotation so that the motor operates more quietly.
???Since response and efficiency of motor are enhanced in sine wave control, finer adjustment can be provided.
wIn brushless DC motor, permanent magnet is embedded in the rotor. Therefore, it doesn't require energy to excite the rotor like AC motor does. However, it's necessary to control the frequency of
Sine wave control makes the current transformers conduct real time detection of the value of the current running into the motor, locates the rotor position from the detected value, and decides if voltage should be impressed and if frequency should be chan- ged.
Compared to the conventional control and rotor position detection method, sine wave control can provide finer adjustment of the voltage of supplied power. The value of the current running into the motor is determined by each motor characteristic.
15
1.Outline
The operational frequency is as following:
First, the target operational frequency is set based on the difference between the room temperature and the set tem- perature.
Second, the target operational frequency is regulated by discharge temperature protection, high pressure protection, electric current protection and overload protection and also by the maximum/minimum frequency.
2.Maximum/minimum frequency in each operation mode.
wThe operation frequency in COOL mode is restricted the upper limit frequency after 1 hour as shown below for dew prevention.
It is rated frequency or less.
Maximum frequency
Upper limit
frequency
1 hour
Rated frequency or less
Time
16
(1) Outline of LEV control
The LEV basic control is comprised of setting LEV opening degree to the standard opening degrees set for each opera- tional frequency of the compressor. However, when any change in indoor/outdoor temperatures or other factors cause air conditioning load fluctuation, the LEV control also works to correct LEV opening degree based on discharge temper- ature (Shell temperature) of the compressor, developing the unit???s performance.
general operation
17
(2) Time chart
Operational frequency of the compressor
(3)Control data
(a)Reference value of target discharge temperature (COOL/HEAT (MUZ)??F)
F
Operational frequency of the compressor
18
In COOL operation, the two indoor coil thermistors (one main and one sub) sense temperature ununiformity (super heat) at the heat exchanger, and when temperature difference have developed, the indoor coil thermistors adjust LEV opening degree to get approximate 10 degrees lower temperature than the target temperature in the table above, thus diminishing super heat.
(b)Reference value of LEV standard opening degree (COOL/ HEAT (MUZ) pulse)
19
3 
MXZ MICROPROCESSOR CONTROL
Function of main parts
1.At the start of operation
Main power supply circuit is formed when X64 (Relay) is turned ON at compressor startup.
To prevent rush current from running into the circuit when power supply is turned ON, R64A and R64B
2.At normal operation
1 When AC runs into noise filter P.C. board, its external noise is eliminated in the noise filter circuit.
2 After noise being eliminated from AC, it is rectified to DC by L (Reactor) and PFC (Power factor controller). If the operating frequency becomes 25Hz or more, DC voltage rises to 370V.
3 DC voltage, to which has AC been rectified by process 2, is stabilized by CB1~3 (Smoothing capacitor) and supplied to IPM (Intelligent power module).
4 The DC (Bus voltage), which has been stabilized in process 3, is converted to
5 CT1 and CT2 (Current Transformer), which are placed in the power supply circuit to compressor, are used to measure the value of phase current and locate the polar direction of rotor with algorithm. PWM (Pulse width modulation) controls impre- ssed voltage and frequency with those information.
20
3. Power factor improvement
Booster coil L (Reactor) and PFC rectify AC to DC and control its voltage.
In the motor drive system of sine wave control, power factor can be improved by reducing harmonics PFC and L (Reactor) stabilize the voltage of DC supplied to inverter circuit and make its waveform smooth.
4. Power transistor module
IPM consists of the following components.
?? Power Transistors (x6): Converts DC waveform to
Since the above components are all integrated in IPM, IPM has a merit that can get the control circuit simplified and mini- aturized.
5. Smoothing capacitor
CB1, CB2 and CB3 stabilize the DC voltage and supply it to IPM.
6. Elimination of electrical noise
Noise filter circuit, which is formed by *CMC COILS and capacitors placed on the noise filter P.C. board, eliminates electrical noise of AC power that is supplied to main power supply circuit. In short, common mode noise is absorbed in this circuit. Moreover, normal mode noise is absorbed in another noise filter circuit which is formed by *NMC COILS and capacitors. Both noise filter circuit exists for preventing the electrical noise generated in the inverter circuit from leaking out.
*CMC COILS; Common mode choke coils *NMC COILS; Normal mode choke coils
In these air conditioners, compressor equips brushless DC motor which doesn'thave Hall element.
In short, the motor is sensorless. However, it's necessary to locate the polar direction of rotor in order to drive brushless DC motor efficiently. The general detection method of the polar direction for such a DC motor is to locate it from the voltage induced by unenergized stator.
Therefore, it is necessary to have a certain period of time in which the stator is being unenergized for the rotor position detection when the voltage of supplied power is impressed.
So the motor has been driven by square wave control (the conventional motor drive system) which energizes the motor only when the range of electrical angle is within 120_ because it is forced to be unenergized within 30_ at start & end of one heap in one waveform cycle (180_) when the voltage is impressed.
However, torque pulsation occurs at rotation in this method when the
???Although ordinary
???This control provides the most efficient waveform corresponding to the rotation times of compressor motor.
???The rotation can be set to higher compared to the conventional motor drive system. So, the time in which air conditioner can be operated with energy saved is longer than conventional models. This can save annual electric consumption.
???Compared to square wave control, the torque pulsation is reduced at rotation so that the motor operates more quietly.
???Since response and efficiency are enhanced in sine wave control, finer adjustment can be provided.
wIn brushless DC motor, permanent magnet is embedded in the rotor. Therefore, it doesn't require energy to excite the rotor like AC motor does. However, it's necessary to control the frequency of
Sine wave control makes the current transformers conduct real time detection of the value of the current running into the motor, locates the rotor position from the detected value and decides if voltage should be impressed and if frequency should be chan- ged.
Compared to the conventional control and rotor position detection method, sine wave control can provide finer adjustment of the voltage of supplied power. The value of the current running into the motor is determined by each motor characteristic.
21
Linear expansion valve (LEV) is controlled by "Thermostat ON" commands given from each unit.
w1 LEV opening when the outdoor unit is operating: Upper limit 500 pulse, Lower limit 53pulse.
Determination of LEV standard opening in each indoor unit
???The standard opening is on the straight line, which connects an each standard point in the section where divided into seven according to the operation frequency of compressor as shown in the figure below.
(LEV opening is controlled in proportion to the operation frequency.)
Note: Opening is adjusted at the standard opening according to the indoor unit conditions.
However, inclination of standard opening in each point of opening does not change with the original curve.
???Add opening provided in Difference in Capacity in the table below to the standard opening from 1 to 8, when capacity of the indoor unit is excluding code 1.
???Add opening provided in Difference in Operation number in the table below to determined LEV opening for each indoor unit, when 2 or 3 indoor units are operated at the same time.
Note: Even when the adjusted standard opening exceeds the driving range from 59 to 500 pulse, actual driving output opening is in a range from 59 to 500 pulse.
22
The table below shows the role of Exclusive LEV and Receiver LEV in each operation mode.
Receiver
Receiver
LEV
wIn COOL mode, the two indoor coil thermistor (one main and one sub) sense temperature ununiformity (super heat) at the heat exchanger, and when temperature difference have developed, the indoor coil thermistors adjust LEV opening to dimin- ish the super heat.This action is called Evaporation Temperature Protection.
The opening pulse of the Receiver LEV is fixed to the standard No.3 in cooling operation, and so is that of each Exclusive LEV in heating operation.
However the opening pulse will be changed to the standard No.4 or No.5 when the discharge temperature protection or high- pressure protection is working.
In addition to that, it will also be changed to standard No.2 or No.1 when the opening pulse of the each Exclusive LEV becomes 100 pulse or less in cooling operation or so does that of Receiver LEV in heating operation.
23
Compressor operating frequency (Hz)
24
<Correction>
(1)LEV opening correction by discharge temperature
The target discharge temperature is determined according to frequency zone and number of operation unit of the compressor.
25
Correct the LEV opening according to the difference between target discharge temperature and discharge temperature.
(2)Separate correction (COOL,DRY) (Correction by the separate super heat)
a)Correct the LEV separately by temperature difference between each gas pipe temperature and the minimum gas pipe temperature of all.
1 Calculate each super heat of the unit from the expression below;
(Super heat) = (Each gas pipe temperature) - (Minimum gas pipe temperature)
2 Separate correction is performed according to each super heat in the table below.
26
b) Correct the LEV separately by temperature difference ??? 
RT??? between main/sub indoor coil thermistor.
In addition, decrease the target discharge temperature corresponding 
RT.
27
(1) Conditions to enter defrosting mode
1. When temperature of defrosting thermistor is 26.6??F or less.
2. When specified
Going to defrosting mode at both condition of 1 and 2.
(2) Defrosting operation
1. Compressor stops for 50 seconds, Indoor fan is off, Defrosting lamp lights.
2.
(3) Conditions to finish defrosting mode
1. When the defrosting thermistor temperature is 55.76??F or more. 2. When it has spent 10 minutes for defrosting.
Defrosting finishes at condition of 1 or 2.
This protection controls the compressor ON/OFF and operation frequency according to temperature of the discharge temperature thermistor.
(1) Compressor ON/OFF
When temperature of the discharge temperature thermistor exceeds 240.8??F, the control stops the compressor. When temperature of the discharge temperature thermistor is 176??F or less, the controls starts the compressor.
(2) Compressor operation frequency
When temperature of the discharge temperature thermistor is expected to be higher than 240.8??F, the control decreases 12Hz from the current frequency.
When temperature of the discharge temperature thermistor is expected to be higher than 231.8??F and less than 240.8??F, the control decreases 6Hz from the current frequency.
When temperature of the discharge temperature thermistor is expected to be higher than 219.2??F and less than 231.8??F, the control is set at the current frequency.
Fan speed is switched according to the number of operating indoor unit and the compressor frequency.
Fan speed
High
Low
Down Up
Min. Compressor frequency Max.
<Relation between compressor frequency and fan speed.>
Note
???When the indoor coil thermistor is 134.6??F or more on HEAT operation, fan speed is fixed to Low speed. Or, the indoor coil thermistor is 113??F or less on HEAT operation, fan speed is back to normal.
HEAD OFFICE: TOKYO