# US 2011/0216565 A1 · One-cycle controlled power factor correction method

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- Number: US 2011/0216565 A1
- Document ID: US20110216565A1
- Status: Published application
- Kind: A1
- Application number: 13/128,610
- Filed: 2009-09-14
- Published: 2011-09-08
- Earliest claimed: 2008-11-11
- Assignees: Gree Electric Appliances, Inc. of Zhuhai
- Inventors: Xuetao Mi; Qingfeng Guo; Min Xu
- Web page: https://patentgrep.com/patent/US20110216565A1

## CPC

- H02M 1/4225: {using a non-isolated boost converter}
- 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
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A one cycle control method for power factor correction based on a boost circuit and a main control chip of system comprises the steps of: (1) Determining whether soft-start ends or not; if the soft-start ends, processing step (2) directly, if not, increasing reference value Uref of output voltage and then processing step (2); (2) Reading sampling output voltage Uo, and sampling inductive current ig according to A/D sampling triggering instant; (3) Calculating duty ratio of PWM signal for driving the switch transistor; (4) Outputting PWM signal; (5) Calculating the next A/D sampling triggering instant according to the duty ratio of PWM signal; (6) Returning to step (2). The present invention can implement the function of power factor correction by integrating the software of the method into the main control chip of the existing system and cooperating with the simple boost circuit, without using the traditional circuit for power factor correction and the specific one cycle control chip for PFC, which reduces the cost of the system. Also the present invention ensures the sampling data true and correct, and the stable operation of system, by simple processing of the sampling triggering instant.

## Claims

### Claim 1

A one cycle control method for power factor correction based on a boost circuit and a main control chip of system, the boost circuit comprising an AC input, a rectifying circuit, an inductor, fast recovery diodes, a capacitor, a DC output, an inductive current sampling circuit, an output voltage sampling circuit, a switch transistor and a driving circuit of the switch transistor; the control method comprises the steps of:
(1) Determining whether soft-start ends or not; if the soft-start ends, processing step (2) directly, if not, increasing reference value Uref of output voltage and then processing step (2);
(2) Reading sampling output voltage U0 and sampling inductive current ig according to A/D sampling triggering instant;
(3) Calculating as follows duty ratio of PWM signal for driving the switch transistor:
Calculating u1 and u2 according to Equation of
{
u
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R
s
u
m
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u
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(
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)
=
1
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0
t
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1
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τ
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in which Rs is an equivalent current detection resistance, um is an output of a PI regulator by regulating difference between the reference value Uref of the output voltage and the sampling output voltage Uo; obtaining the duty ratio of PWM signal;
(4) Outputting PWM signal;
(5) Calculating the next A/D sampling triggering instant according to the duty ratio of PWM signal;
(6) Returning to step (2).

### Claim 2 (depends on 1)

The one cycle control method for power factor correction according to claim 1, wherein calculating the duty ratio of PWM signal for driving the switch transistor in step (3) further comprises the steps of:
determining whether u1 is greater than or equal to the maximum turn-off duty ratio for the switch transistor of 1 or not; if u1 is greater than or equal to 1, pr_duty being the maximum of 1; or else, pr_duty being equal to u1, determining whether pr_duty is less than the minimum turn-off duty ratio for the switch transistor of 0.05 or not, if pr_duty is less than the minimum, pr_duty being the minimum of 0.05; in which pr_duty is the turn-off duty ratio for the switch transistor.

### Claim 3 (depends on 1)

The one cycle control method for power factor correction according to claim 1, wherein calculating the duty ratio of PWM signal for driving the switch transistor in step (3) further comprises the steps of:
determining whether u1 is less than or equal to the minimum turn-on duty ratio for the switch transistor of 0 or not; if u1 is less than or equal to 0, p_duty being the minimum of 0; or else, p_duty being equal to u1, determining whether p_duty is greater than the maximum turn-on duty ratio for the switch transistor of 0.95 or not, if p_duty is greater than the maximum, pr_duty being the maximum of 0.95; in which p_duty is the turn-on duty ratio for the switch transistor.

### Claim 4 (depends on 2)

The one cycle control method for power factor correction according to claim 2, wherein calculating the next A/D sampling triggering instant according to the duty ratio of PWM signal in step (5) further comprises the steps of:
determining the turn-on time of the switch transistor according to the duty ratio of PWM signal for driving the switch transistor; if the turn-on time of the switch transistor is longer than that of the turn-off time, the sampling triggering instant being selected between 50 percent and 80 percent of the turn-on time; or else, the sampling triggering instant being selected between 50 percent and 80 percent of the turn-off time.

### Claim 5 (depends on 1)

The one cycle control method for power factor correction according to claim 1, wherein u2 in step (3) is generated by a counter of a main control chip of system such as DSP.

### Claim 6 (depends on 3)

The one cycle control method for power factor correction according to claim 3, wherein calculating the next A/D sampling triggering instant according to the duty ratio of PWM signal in step (5) further comprises the steps of:
determining the turn-on time of the switch transistor according to the duty ratio of PWM signal for driving the switch transistor; if the turn-on time of the switch transistor is longer than that of the turn-off time, the sampling triggering instant being selected between 50 percent and 80 percent of the turn-on time; or else, the sampling triggering instant being selected between 50 percent and 80 percent of the turn-off time.