ALTERNATING-CURRENT DIRECT-CURRENT CONVERTER AND ELECTRIC MOTOR DRIVER

• US 20110227522A1
• Filed: 12/01/2008
• Published: 09/22/2011
• Est. Priority Date: 12/01/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Tanikawa, Makoto, Kashima, Mitsuo, Shinomoto, Yosuke, Shimomugi, Takuya
• Granted Patent: US 8,823,303 B2
• Time in Patent Office: Days
• US Class Current: 318/400.29
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 7/2176 comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output
• 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

Provided is an alternating-current direct-current converter capable of controlling a harmonic current and improving a power factor at reduced costs. The alternating-current direct-current converter includes two capacitors connected in series between output terminals of a rectifier; a first switch connected between one input terminal of the rectifier and a connection point of the capacitors; a second switch connected between the other input terminal of the rectifier and the connection point of the capacitors; a voltage detector which detects terminal voltages of the capacitors; a current detector which detects a current input from the alternating current power supply; and a control means which drives and controls the first switch and the second switch, in which the control means drives and controls the first switch and the second switch such that the terminal voltages of the capacitors are fixed and a power supply power factor is improved using an active power component and a reactive power component obtained by conversion of detection results of the current detector and detection results of voltage detector.

Claims

1. An alternating-current direct-current converter, comprising:

a rectifier connected to an alternating current power supply via a reactor;

two capacitors connected in series between output terminals of said rectifier;

a first switch connected between one input terminal of said rectifier and a connection point of said capacitors;

a second switch connected between the other input terminal of said rectifier and the connection point of said capacitors;

diodes inversely parallelly connected with said capacitors;

a voltage detector which detects terminal voltages of said capacitors;

a current detector which detects a current input from said alternating current power supply; and

control means which drives and controls said first switch and said second switch,

wherein said control means drives and controls said first switch and said second switch such that the terminal voltages of said capacitors are fixed and a power supply power factor is improved using an active power component and a reactive power component obtained by conversion of detection results of said current detector and detection results of said voltage detector.

3. The alternating-current direct-current converter of claim 1, wherein said control means drives and controls said switches such that, during a half cycle of the alternating current power supply, said rectifiers takes four rectification states that are a full-wave rectification state, a first voltage-doubler rectification state, a second voltage-doubler rectification state, and a power supply short circuit state.

4. The alternating-current direct-current converter of claim 1, wherein said control means converts the detection result of said current detector into an active power component current and a reactive power component current and performs control such that the terminal voltages of said capacitors are fixed using said active power component current.

5. The alternating-current direct-current converter of claim 1, wherein said control means controls a power supply power factor using said reactive power component current.

6. The alternating-current direct-current converter of claim 1, wherein said control means includes means that removes a pulsation component which has twice the frequency of that of said alternating current power supply and which is included in said active power component current and said reactive power component current, and drives and controls said first switch and said second switch based on said active power component and said reactive power component from which said pulsation has been removed.

7. The alternating-current direct-current converter of claim 1, wherein said control means calculates a command value of an active power component voltage of the voltage between the input terminals of said rectifiers using said active power component current, calculates a command value of a reactive power component voltage of the voltage between the input terminals of said rectifiers using said reactive power component current, calculates a command value of the voltage between the input terminals of said rectifiers using these values, and drives and controls said first bidirectional switch and said second switch such that the voltage between the input terminals of said rectifiers becomes close to the command value.

8. The alternating-current direct-current converter of claim 1, wherein said control means performs control, upon starting the driving and controlling of said switches, such that the command value of the active power component voltage of the voltage between the input terminals of said rectifiers becomes higher than the voltage of said alternating current power supply.

9. The alternating-current direct-current converter of claim 1, wherein said control means performs control, upon starting the driving and controlling of said switches, such that the command value of the reactive power component voltage of the voltage between the input terminals of said rectifiers becomes 0.

10. The alternating-current direct-current converter of claim 1, wherein said control means outputs, upon starting the driving and controlling of said switches, a voltage command value of the voltage between the input terminals of said rectifiers such that the reactive power component of the input current becomes 0 or smaller.

11. An electric motor driver, comprising:

the alternating-current direct-current converter according to claim 1;

an inverter which converts direct current power output from said alternating-current direct-current converter into alternating current power and drives a permanent-magnet electric motor; and

inverter control means which controls an operation of said inverter,

wherein said control means and said inverter control means are implemented on a single semiconductor integrated circuit.

12. The electric motor driver of claim 1,

wherein

said semiconductor integrated circuit acquires detection results of said voltage detector in synchronization with PWM control timing executed by said inverter control means and acquires detection results of said current detector in synchronization with PWM control timing executed by said control means.

2. An alternating-current direct-current converter, comprising:

a first rectifier connected to an alternating current power supply via a reactor;

a second rectifier connected in parallel to said first rectifier;

two capacitors connected in series between output terminals of said first rectifier;

two switches connected in series between output terminals of said second rectifier;

diodes inversely parallelly connected with said capacitors;

a voltage detector which detects terminal voltages of said capacitors;

a current detector which detects a current input from said alternating current power supply; and

control means which drives and controls said two switches,

wherein a connection point of said capacitors and a connection point of said switches are connected, and said control means drives and controls said first switch and said second switch such that the terminal voltages of said capacitors are fixed and a power supply power factor is improved using an active power component and a reactive power component obtained by conversion of detection results of said current detector and detection results of said voltage detector.

13. The alternating-current direct-current converter of claim 2, wherein said control means drives and controls said switches such that, during a half cycle of the alternating current power supply, said rectifiers takes four rectification states that are a full-wave rectification state, a first voltage-doubler rectification state, a second voltage-doubler rectification state, and a power supply short circuit state.

14. The alternating-current direct-current converter of claim 2, wherein said control means converts the detection result of said current detector into an active power component current and a reactive power component current and performs control such that the terminal voltages of said capacitors are fixed using said active power component current.

15. The alternating-current direct-current converter of claim 2, wherein said control means controls a power supply power factor using said reactive power component current.

16. The alternating-current direct-current converter of claim 2, wherein said control means includes means that removes a pulsation component which has twice the frequency of that of said alternating current power supply and which is included in said active power component current and said reactive power component current, and drives and controls said first switch and said second switch based on said active power component and said reactive power component from which said pulsation has been removed.

17. The alternating-current direct-current converter of claim 2, wherein said control means calculates a command value of an active power component voltage of the voltage between the input terminals of said rectifiers using said active power component current, calculates a command value of a reactive power component voltage of the voltage between the input terminals of said rectifiers using said reactive power component current, calculates a command value of the voltage between the input terminals of said rectifiers using these values, and drives and controls said first bidirectional switch and said second switch such that the voltage between the input terminals of said rectifiers becomes close to the command value.

18. The alternating-current direct-current converter of claim 2, wherein said control means performs control, upon starting the driving and controlling of said switches, such that the command value of the active power component voltage of the voltage between the input terminals of said rectifiers becomes higher than the voltage of said alternating current power supply.

19. The alternating-current direct-current converter of claim 2, wherein said control means performs control, upon starting the driving and controlling of said switches, such that the command value of the reactive power component voltage of the voltage between the input terminals of said rectifiers becomes 0.

20. The alternating-current direct-current converter of claim 2, wherein said control means outputs, upon starting the driving and controlling of said switches, a voltage command value of the voltage between the input terminals of said rectifiers such that the reactive power component of the input current becomes 0 or smaller.