Converter circuit, and motor drive control apparatus, air-conditioner, refrigerator, and induction heating cooker provided with the circuit

• US 8,817,506 B2
• Filed: 03/17/2009
• Issued: 08/26/2014
• Est. Priority Date: 09/01/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Shimomugi, Takuya, Shinomoto, Yosuke, Sakanobe, Kazunori, Yamada, Michio, Hatakeyama, Kazunori
• Primary Examiner(s): Zhang, Jue
• Application Number:
  US13/058,401
• Publication Number:
  US 20110132899A1
• Time in Patent Office: 1,988 Days
• Field of Search: 323/272, 363/89
• US Class Current: 363/89
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: H02M 3/1586 switched with a phase shift, i.e. interleaved
• CPC Class Codes: H02M 7/06 using discharge tubes without control electrode or semiconductor devices without control electrode
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H05B 6/06 Control, e.g. of temperature, of power
• 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 converter circuit including a step-up converter including a rectifier, a step-up reactor, a switching element, and a reverse current prevention element; a step-up converter having a step-up reactor, a switching element, and a reverse current prevention element and connected in parallel with the step-up converter; a switching control unit that controls switching elements; and a smoothing capacitor that is provided at the output of the step-up converters. The switching control unit switches the current mode of the current flowing through the step-up reactors into any of a continuous mode, a critical mode, and a discontinuous mode based on a predetermined condition.

Claims

1. A converter circuit, comprising:

a rectifier that rectifies an AC voltage;

a first converter section that is connected with an output of said rectifier and has a first reactor, a first switching element, and a first reverse current prevention element;

a second converter section that is connected with an output of said rectifier, that has a second reactor, a second switching element, and a second reverse current prevention element, and that is connected with said first converter section in parallel;

switching control means that controls said first and second switching elements;

a smoothing capacitor that is provided at an output of said first and second converter sections; and

current detection means that detects an input current input to said first and second converter sections, wherein

said switching control means switches a current mode of a current flowing through said first and second reactors to a critical mode when the input current is equal to or larger than a threshold, and

switches the current mode of the current flowing through said first and second reactors to a discontinuous mode when the input current is less than the threshold.

2. The converter circuit of claim 1, wherein

said switching control means controls switching of said first and second switching elements so as to create a predetermined phase difference between the current flowing through said first and second reactors.

3. The converter circuit of claim 1, wherein

said switching control means controls the switching of said first and second switching elements so that the phase difference of the currents flowing through said first and second reactors randomly varies within a predetermined range.

4. The converter circuit of claim 1, further comprising:

one or two or more converter sections that is connected with the output of said rectifier, that has a reactor, a switching element, and a reverse current prevention element, and that is connected with said first and second converter sections in parallel.

5. A motor drive control apparatus, comprising:

the conversion circuit of claim 1

an inverter circuit that converts a DC output voltage of said converter circuit to an AC voltage; and

inverter drive means that drives said inverter circuit.

6. An air-conditioner, comprising:

the motor drive control apparatus of claim 5; and

a motor that is driven by said motor drive control apparatus.

7. A refrigerator, comprising:

the motor drive control apparatus of claim 5; and

a motor that is driven by said motor drive control apparatus.

8. An induction heating cooker, comprising:

the converter circuit of claim 1

an inverter circuit that converts a DC output voltage of said converter circuit to an AC voltage;

inverter drive means that drives said inverter circuit; and

a load circuit that is connected with an output point of said inverter circuit and has at least an induction heating coil and a resonance capacitor.

9. A converter circuit, comprising:

a rectifier that rectifies an AC voltage;

a first converter section that is connected with an output of said rectifier and has a first reactor, a first switching element, and a first reverse current prevention element;

a second converter section that is connected with an output of said rectifier, that has a second reactor, a second switching element, and a second reverse current prevention element, and that is connected with said first converter section in parallel;

switching control means that controls said first and second switching elements;

a smoothing capacitor that is provided at an output of said first and second converter sections, wherein

said switching control means switches a current mode of a current flowing through said first and second reactors to a critical mode when a switching frequency of said first and second switching elements is less than a threshold, and

switches the current mode of the current flowing through said first and second reactors to a discontinuous mode when the switching frequency of said first and second switching elements is equal to or larger than the threshold.

10. A converter circuit, comprising:

a rectifier that rectifies an AC voltage;

a first converter section that is connected with an output of said rectifier and has a first reactor, a first switching element, and a first reverse current prevention element;

a second converter section that is connected with an output of said rectifier, that has a second reactor, a second switching element, and a second reverse current prevention element, and that is connected with said first converter section in parallel;

switching control means that controls said first and second switching elements;

a smoothing capacitor that is provided at an output of said first and second converter sections, and

output power detection means that detects output power of said first and second converter sections, wherein

said switching control means switches a current mode of a current flowing through said first and second reactors based on said output power.

11. A converter circuit, comprising:

a rectifier that rectifies an AC voltage;

a first converter section that is connected with an output of said rectifier and has a first reactor, a first switching element, and a first reverse current prevention element;

a second converter section that is connected with an output of said rectifier, that has a second reactor, a second switching element, and a second reverse current prevention element, and that is connected with said first converter section in parallel;

switching control means that controls said first and second switching elements;

a smoothing capacitor that is provided at an output of said first and second converter sections, and

current detection means that detects an input current input to said first and second converter sections, and

output power detection means that detects an output power of said first and second converter sections, wherein

said switching control means obtains a circuit efficiency based on said input current and said output power to switch a current mode of a current flowing through said first and second reactors based on said circuit efficiency.

12. A converter circuit, comprising:

a rectifier that rectifies an AC voltage;

a first converter section that is connected with an output of said rectifier and has a first reactor, a first switching element, and a first reverse current prevention element;

a second converter section that is connected with an output of said rectifier, that has a second reactor, a second switching element, and a second reverse current prevention element, and that is connected with said first converter section in parallel;

switching control means that controls said first and second switching elements;

a smoothing capacitor that is provided at an output of said first and second converter sections,

wherein information is input to said switching control means on an output voltage command that sets an output voltage of said first and second converter sections, and

said switching control means switches a current mode of a current flowing through said first and second reactors to a continuous mode when said output voltage, said output voltage command, or a changed value of said output voltage command is a predetermined value or range and the current mode is a critical mode or a discontinuous mode.