# US 2014/0196490 A1 · System and method for controlling a variable speed drive of a compressor motor

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- Number: US 2014/0196490 A1
- Document ID: US20140196490A1
- Status: Published application
- Kind: A1
- Application number: 14/238,340
- Filed: 2012-08-31
- Published: 2014-07-17
- Earliest claimed: 2011-08-31
- Assignees: Johnson Controls Technology Company
- Inventors: Paul Nemit, JR.
- Web page: https://patentgrep.com/patent/US20140196490A1

## CPC

- F25B 49/022: {Compressor control arrangements}
- F04B 35/04: the means being electric
- F04B 49/065: {and making use of computers}
- F04C 28/08: characterised by varying the rotational speed
- F04B 2203/0202: Voltage
- F04B 2203/0204: Frequency of the electric current
- F04B 2203/0205: Temperature
- F04C 29/0085: {Prime movers}
- F04C 2240/403: with inverter for speed control
- F04C 2240/81: Sensor, e.g. electronic sensor for control or monitoring
- F04C 2270/80: Diagnostics
- F04C 2270/86: Detection
- F24F 11/85: using variable-flow pumps
- F25B 2600/021: Inverters therefor
- Y02B 30/70: Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F)
- F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A variable speed drive (VSD) can be used to vary the voltage-to-frequency ratio (V/f) supplied to a compressor motor of a heating, ventilation, air conditioning or refrigeration (HVAC&R) system to make the motor stronger or weaker to compensate for varying conditions in the HVAC&R system. The VSD and corresponding control system or algorithm can monitor an operating parameter of the HVAC&R system, such as the kW absorbed by the motor, and then raise or lower the V/f of the VSD to obtain the lowest possible power consumption from the motor.

## Claims

### Claim 1

A system comprising:
a compressor, a condenser, an expansion device and an evaporator connected in a closed refrigerant circuit;
a motor connected to the compressor to power the compressor;
a variable speed drive connected to the motor to power the motor, the variable speed drive being operable to provide a variable voltage to the motor and a variable frequency to the motor;
a control panel to control operation of the variable speed drive and one or more components of the system;
a sensor to measure an operational parameter of the system, the sensor being operable to communicate the measured operational parameter to the control panel; and
the control panel being operable to execute a control algorithm to determine a voltage-to-frequency ratio to be output by the variable speed drive using the measured operational parameter, wherein the voltage-to-frequency ratio varies based on the measured operational parameter.

### Claim 2 (depends on 1)

The system of claim 1 wherein the sensor measures power consumption of the motor.

### Claim 3 (depends on 1)

The system of claim 1 wherein the sensor measures a discharge temperature of the compressor.

### Claim 4 (depends on 1)

The system of claim 1 wherein the sensor measures a temperature of the motor.

### Claim 5 (depends on 1)

The system of claim 1 wherein the control algorithm includes a table of voltage-to-frequency ratios and corresponding operational parameter values.

### Claim 6 (depends on 1)

The system of claim 1 wherein the control algorithm includes a fuzzy logic algorithm to determine the voltage-to-frequency ratio.

### Claim 7 (depends on 1)

The system of claim 1 wherein the determined voltage-to-frequency ratio is used to optimize compressor efficiency.

### Claim 8 (depends on 1)

The system of claim 1 wherein the determined voltage-to-frequency ratio is used to optimize sound attenuation.

### Claim 9

A method for controlling a variable speed drive, the method comprising:
measuring an operational parameter of an HVAC&R system;
determining a voltage-to-frequency ratio to be output by a variable speed drive using the measured operational parameter, the variable speed drive powering a compressor motor of the HVAC&R system;
generating control instructions for the variable speed drive based on the determined voltage-to-frequency ratio; and
adjusting the output voltage-to-frequency ratio provided by the variable speed drive to the compressor motor with the generated control instructions.

### Claim 10 (depends on 9)

The method of claim 9 wherein said measuring an operational parameter includes measuring power consumption of the compressor motor.

### Claim 11 (depends on 9)

The method of claim 9 wherein said measuring an operational parameter includes measuring a discharge temperature of a compressor.

### Claim 12 (depends on 9)

The method of claim 9 wherein said measuring an operational parameter includes measuring a temperature of the compressor motor.

### Claim 13 (depends on 9)

The method of claim 9 wherein said determining a voltage-to-frequency ratio includes selecting a voltage to frequency ratio from a table of voltage-to-frequency ratios and corresponding operational parameter values.

### Claim 14 (depends on 13)

The method of claim 13 further comprising operating the HVAC&R system at varying conditions and voltage to frequency ratios to populate the table.

### Claim 15 (depends on 9)

The method of claim 9 wherein said determining a voltage-to-frequency ratio includes executing a fuzzy logic algorithm to determine the voltage-to-frequency ratio.

### Claim 16 (depends on 9)

The method of claim 9 further comprising optimizing compressor efficiency with the determined voltage-to-frequency ratio.

### Claim 17 (depends on 9)

The method of claim 9 further comprising optimizing sound attenuation with the determined voltage-to-frequency ratio.