Control apparatus for controlling motor of air conditioner

• US 5,663,627 A
• Filed: 04/10/1995
• Issued: 09/02/1997
• Est. Priority Date: 07/26/1994
• Status: Expired due to Fees

• Current Assignee: Fujitsu General Company Limited (Fujifilm Holdings Corporation)
• Original Assignee: Fujitsu General Company Limited (Fujifilm Holdings Corporation)
• Inventors: Ogawa, Yoshio
• Primary Examiner(s): Martin, David S.
• Application Number:
  US08/419,737
• Time in Patent Office: 876 Days
• Field of Search: 318/792-811, 363/34-41, 363/95, 363/98, 363/131, 363/135, 363/127, 363/132
• US Class Current: 318/803
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/64 using pre-stored data
• CPC Class Codes: F24F 11/85 using variable-flow pumps
• CPC Class Codes: F24F 11/86 by controlling compressors within refrigeration or heat pump circuits
• CPC Class Codes: F24F 11/88 Electrical aspects, e.g. circuits
• CPC Class Codes: F24F 2140/00 Control inputs relating to system states
• CPC Class Codes: F25B 2600/021 Inverters therefor
• CPC Class Codes: F25B 49/025 Motor control arrangements
• CPC Class Codes: G05B 11/28 using pulse-height modulation; using pulse-width modulation
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 7/53873 with digital control
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A control apparatus for controlling a motor of an air conditioner includes a converter, having switching for improving an input power factor, for converting an AC power to a DC power and an inverter for converting the DC power supplied from the converter to the AC power and supplying to a compressor. The output DC voltage of the converter is detected by a DC voltage detecting circuit. An input alternating current is detected by a current detecting circuit. A microcomputer for controlling the inverter calculates a current command from data stored on the basis of the detected voltage. The detected current is compared with the current command, an ON percentage of a PWM signal to control the switching is obtained, and the PWM signal is generated.

Claims

1. A control apparatus for controlling an air conditioner, comprising:

a converter for converting an input AC supply power into a DC power, the converter having switching means for improving an input power factor of the air conditioner;

an inverter for converting the DC power into an AC power and supplying the AC power to a compressor;

a microcomputer for controlling the converter and the inverter;

current detecting means for detecting an input current level of the AC supply power;

voltage detecting means for detecting a voltage level of the DC power output of the converter; and

DC voltage comparing means for comparing the detected DC voltage and a predetermined DC voltage;

wherein the microcomputer includes current command calculation selecting means for obtaining a current command in accordance with a comparison result of the DC voltage comparing means, and switching control means for comparing the current command and the detected input current, obtaining an ON percentage of a PWM signal to control the switching means, and outputting the PWM signal to the switching means.

2. A control apparatus for an air conditioner according to claim 1;

further comprising a memory for storing data; and

wherein the current command calculation selecting means includes means for calculating the current command in accordance with data stored in the memory and the detection result of the DC voltage comparing means.

3. A control apparatus for an air conditioner according to claim 2;

wherein the data comprises historical detected current data.

4. A control apparatus for controlling an air conditioner, comprising:

a converter for converting an input AC supply power into a DC power, the converter having switching means for improving an input power factor of the air conditioner;

an inverter for converting the DC power into an AC power and supplying the AC power to a compressor of the air conditioner;

a microcomputer for controlling the converter and the inverter;

current detecting means for detecting an input current level of the AC supply power;

voltage detecting means for detecting a voltage level of the DC power output of the converter;

DC voltage comparing means for comparing the detected DC voltage and a predetermined DC voltage; and

zero-cross detecting means for detecting a zero-cross point of the AC supply power;

wherein the microcomputer includes current command calculation selecting means for obtaining a current command corresponding to a detected input current level by controlling the current detecting means to detect an input current level at one or more predetermined time periods in an interval of at least a half period of the input current from said detected zero-cross point, storing the detected input current, and calculating the current command in accordance with previously stored input current data on the basis of a comparison result of the DC voltage comparing means, and switching control means for sequentially comparing the current command with the stored input currents, obtaining an ON percentage of a PWM signal to control the switching means, patterning the PWM signal, and outputting the patterned PWM signal synchronously with the detected zero-cross point to control the switching means.

5. A control apparatus for driving a motor, comprising:

converting means for converting an AC input supply power into a DC power;

inverter means for converting the DC voltage into a corrected AC signal for driving the motor;

control means for controlling the inverter means and the converting means;

current detecting means for detecting a current of the AC input supply power;

voltage detecting means for detecting a voltage level of the DC power;

DC voltage comparing means for comparing the detected DC voltage and a predetermined voltage level;

current correction means for generating current correction data used for correcting the detected current in accordance with a comparison result of the DC voltage comparing means;

switching means disposed in the converting means for improving a power factor of the motor; and

switching control means for comparing the current correction data and the detected input current, determining the pulse width of respective pulses in a pulse width modulation signal, and outputting the pulse width modulation signal to control the switching means.

6. A control apparatus according to claim 5;

further comprising zero-crossing detection means for detecting a zero-cross point of the AC input supply power; and

wherein the current correction means includes means for calculating current correction data corresponding to a plurality of detected input current values by controlling the current detecting means to detect an input current at a plurality of predetermined time periods in a periodic interval comprising a percentage of the period of the AC input supply power from the zero-crossing point, storing the detected input current values, and calculating the current correction data in accordance with previously stored data on the basis of a comparison result of the DC voltage comparing means; and

the switching control means includes means for sequentially comparing the current correction data with the stored input currents, determining a pulse width of respective pulses of a pulse width modulation signal in accordance with the comparison results, and outputting the pulse width modulation signal to the switching means synchronously with the detected zero-crossing point.