POWER CONVERSION APPARATUS AND CONTROL METHOD FOR POWER CONVERSION APPARATUS

• US 20110210713A1
• Filed: 12/19/2008
• Published: 09/01/2011
• Est. Priority Date: 12/20/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kazama, Shun
• Granted Patent: US 8,767,424 B2
• Time in Patent Office: Days
• US Class Current: 323/311
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: H02M 7/53875 with analogue control of three-phase output
• CPC Class Codes: H03K 17/0822 in field-effect transistor switches
• CPC Class Codes: H03K 2217/0027 Measuring means of, e.g. currents through or voltages across the switch
• 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 power conversion apparatus includes: a MOSFET (12) which includes a channel (12b) and a body diode (12a) connected in parallel, the channel (12b) becoming conductive according to a control signal (C1), so that a flow path of a regenerative current of an inductor (16) is formed, and the body diode (12a) having the regenerative current of the inductor (16) flow in a forward direction; a shunt resistor (2) and a voltage measuring unit (9) which measure an amount of a current (Imeas) flowing into the MOSFET (12); a threshold designating unit (7) which designates a threshold current amount (Ithresh); and a synchronous rectification prohibiting circuit (4) which prohibits supplying the control signal (C1) in the case where the amount of the current (Imeas) measured by the shunt resistor (2) and the voltage measuring unit (9) is greater than the threshold current amount (Ithresh) designated by the threshold designating unit (7).

Claims

1. A power conversion apparatus which obtains either a regulated voltage or a regulated current by intermittently supplying power from a power source to an inductor, said power conversion apparatus comprising:

a switching unit which includes a field-effect transistor representing a switching element and a diode connected in parallel, said switching element becoming conductive according to a control signal to be supplied, so that a flow path of a regenerative current of the inductor is formed, said diode having the regenerative current of the inductor flow in a forward direction, and said field-effect transistor being placed so that the regenerative current of the inductor flows from a source toward a drain on said field-effect transistor;

a measuring unit configured to measure either an amount of a current flowing into said switching unit or a value of a voltage generated across said switching unit;

a threshold designating unit configured to designate a threshold which is predetermined based on a comparison between (i) on-resistance of said switching element in the case where a current in a same amount flows through said switching element in the forward direction with respect to said diode and (ii) on-resistance of said diode in the case where a current in a same amount flows through said diode; and

a prohibition control unit configured to prohibit supplying the control signal to said switching element in the case where either the amount of the current, or the amounts of the voltages measured by said measuring unit are greater than the threshold designated by said threshold designating unit.

4. The power conversion apparatus according to claim 1,

wherein said switching unit includes switching units connected in parallel and commonly controlled via the control signal, and

said measuring unit is configured to be connected to one of said switching units to measure a current flowing through said connected switching unit.

5. The power conversion apparatus according to claim 1, further comprising

a temperature measuring unit configured to measure a temperature of said switching unit,

wherein said threshold designating unit is configured to designate amounts of threshold currents to respective different temperatures, and

said prohibition control unit is configured to prohibit supplying the control signal to said switching unit in the case where the amount of the current measured by said measuring unit is greater than an amount of a threshold current corresponding to the temperature measured by said temperature measuring unit, the threshold current being one of the threshold currents designated by said threshold designating unit.

6. The power conversion apparatus according to claim 1,

wherein at least one of said switching element and said diode is made of silicon carbide.

18. The power conversion apparatus according to claim 1,

wherein said switching element is a MOSFET (metal-oxide-semiconductor field-effect transistor), and said diode is a body diode included in said MOSFET.

2. (canceled)

3. (canceled)

7. A power conversion apparatus which converts a direct current into an N-phase alternate current (N is an integer equal to 3 or greater), and supplies the converted N-phase alternate current to an inductor working as a load and provided for each phase, said power conversion apparatus comprising:

2N arms each including a switching unit having a field-effect transistor representing a switching element and a diode connected in parallel, said switching element becoming conductive according to a control signal to be supplied, so that a flow path of a regenerative current of the inductor is formed, said diode having the regenerative current of the inductor flow in a forward direction, and said field-effect transistor being placed so that the regenerative current of the inductor flows from a source toward a drain on said field-effect transistor;

N legs each provided in a corresponding one of N-phases, formed with said 2N arms serially connected in a pair, having ends connected to a direct-current power source, and having a mid point connected to an inductor of the corresponding one of the N-phases;

a load current determining unit configured to determine an amount of a current flowing into an inductor provided in each of the N-phases;

a threshold designating unit configured to designate a threshold which is predetermined based on a comparison between (i) on-resistance of said switching element in the case where a current in a same amount flows through said switching element in the forward direction with respect to said diode and (ii) on-resistance of said diode in the case where a current in a same amount flows through said diode; and

a prohibition control unit configured to prohibit supplying the control signal to said switching element included in said leg of the corresponding N-phase, in the case where the amount of the current, for each of the N-phases, determined by said load current determining unit is greater than the threshold designated by said threshold designating unit.

10. The power conversion apparatus according to claim 7,

wherein said load current determining unit includes N current measuring units each provided to an associated one of the N-phases.

11. The power conversion apparatus according to claim 7,

wherein said load current determining unit includes (i) (N−

1) current measuring units each provided in a corresponding one of (N−

1) phases included in the N-phases, and (ii) a calculator configured to calculate a current amount of an other phase included in the N-phases.

19. The power conversion apparatus according to claim 7,

wherein said switching element is a MOSFET, and said diode is a body diode included in said MOSFET.

8. (canceled)

9. (canceled)

12. (canceled)

13. (canceled)

14. A method of controlling a power conversion apparatus which obtains a regulated voltage or a regulated current by intermittently supplying power from a power source to an inductor,

wherein the power conversion apparatus includes a switching unit which has a field-effect transistor representing a switching element and a diode connected in parallel, the switching element becoming conductive according to a control signal to be supplied, so that a flow path of a regenerative current of the inductor is formed, the diode having the regenerative current of the inductor flow in a forward direction, and the field-effect transistor being placed so that the regenerative current of the inductor flows from a source toward a drain on the field-effect transistor, and

said method comprises:

measuring either an amount of a current flowing into the switching unit, or a voltage generated across said switching unit;

designating a threshold which is predetermined based on a comparison between (i) on-resistance of the switching element in the case where a current in a same amount flows through the switching element in the forward direction with respect to the diode and (ii) on-resistance of the diode in the case where a current in a same amount flows through the diode; and

prohibiting supplying the control signal to the switching element in the case where either the amount of the current, the amounts of the voltages measured in said measuring are greater than the threshold designated in said designating.

20. The method of controlling the power conversion apparatus according to claim 14,

wherein said switching element is a MOSFET, and said diode is a body diode included in said MOSFET.

15. (canceled)

16. A method of controlling a power conversion apparatus which converts a direct current into an N-phase alternate current (N is an integer equal to 3 or greater), and supplies the converted N-phase alternate current to an inductor working as a load and provided for each phase,

wherein the power conversion apparatus includes:

2N arms each including a switching unit having a field-effect transistor representing a switching element and a diode connected in parallel, said switching element becoming conductive according to a control signal which is supplied, so that a flow path of a regenerative current of the inductor is formed, the diode having the regenerative current of the inductor flow in a forward direction, and the field-effect transistor being placed so that the regenerative current of the inductor flows from a source toward a drain on the field-effect transistor; and

N legs each provided in a corresponding one of N-phases, formed with said 2N arms serially connected in a pair, having ends connected to a direct current power source, and having a mid point connected to an inductor of a phase, included in the N-phases, corresponding to the mid point, and

said method comprises;

determining an amount of a current flowing into an inductor provided in each of the N-phases;

designating a threshold which is predetermined based on a comparison between (i) on-resistance of the switching element in the case where a current in a same amount flows through the switching element in the forward direction with respect to the diode and (ii) on-resistance of the diode in the case where a current in a same amount flows through the diode; and

prohibiting supplying the control signal to the switching element included in the leg of the corresponding N-phase, in the case where the amount of the current, for each of the N-phases, determined in said determining is greater than the threshold designated in said designating.

21. The method of controlling the power conversion apparatus according to claim 16,

wherein said switching element is a MOSFET, and said diode is a body diode included in said MOSFET.

17. (canceled)