JP2000270539A - Power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously attain two functions where both switching noise and electromagnetic noise can be suppressed to a low level by connecting resistors in series, and mounting a gate drive circuit, where switches for shortening both ends of the resistor are parallel-connected on each of the resistors other excluding one resistor. SOLUTION: This converter consists of voltage drive type switching elements 1 to 4 where diodes are connected back to back, a DC power source 5, gate drive circuits 6 to 9, two-serial gate resistors 101 to 102, and a gate resistor short shorting switch 103. A gate signal is generated which operates so as to alternately-repeat an on-condition of the voltage drive type switching elements 1, 4 and an off condition of the voltage drive type switching elements 2, 3, and an off-condition of the voltage drive type switching elements 1, 4 and an on condition of the voltage drive type switching elements 2, 3. The gate signal is transmitted to the voltage drive type switching elements 1 to 4 through the gate drive circuits 6 to 9 for driving.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention simultaneously has two functions of minimizing switching noise generated at the time of switching by a switching element or minimizing electromagnetic noise generated at the time of switching due to a switching frequency. The present invention relates to a power converter.

[0002]

2. Description of the Related Art In a conventional power conversion device using a voltage-driven semiconductor switching element, it is general that the gate resistance of the voltage-driven semiconductor switching element is fixed to a predetermined resistance value. Further, the resistance value of the gate resistor is determined in consideration of the contents described below.

To turn on or off a voltage-driven semiconductor switching element, a charge / discharge current is applied to the gate input capacitance of the switching element, and a positive voltage is applied to the gate when the switching element is on and a negative voltage is applied to the gate when the switching element is off. There is a need to. Further, it is necessary to insert a gate resistor for limiting the charging / discharging current to the gate into the gate terminal of the voltage-driven semiconductor switching element. The smaller the gate resistance value, the shorter the switching time, and the main current di / dt during switching.
Although the switching noise increases due to the increase in the voltage dv / dt of the voltage across the switching element, the switching loss generated when switching is suppressed.

On the other hand, when the gate resistance value is large, the switching time becomes long, and the main current di /
Since dt and dv / dt of the voltage across the switching element are reduced, the switching noise is reduced, but the switching loss generated when switching is increased.

As described above, the switching noise and the switching loss at the time of switching depend on the gate resistance value and are in a trade-off relationship with each other. Alternatively, after deciding which type of low-noise type power converter that can operate at a high switching frequency with a small switching loss, a gate resistance value suitable for it is selected.

[0006]

In the conventional power converter, the gate resistance is a fixed fixed value.
Only a power converter of a type that suppresses switching noise generated at the time of switching as low as possible or a power converter of a low noise type that can operate at a high switching frequency with small switching loss can be realized.

Therefore, a power converter equipped with a gate resistor having a resistance value that satisfies the requirement is installed in an environment where there is a demand to suppress the switching noise as low as possible. It is necessary to prepare two types of power converters having different gate resistances, that is, installing a power converter equipped with a gate resistor having a resistance value satisfying the requirement.

In addition, the two types of power converters differ only in the gate resistance value and are otherwise the same, and when the type of the gate resistance value is small, that is, when the switching loss is small, the operation of the power conversion device at the maximum switching frequency is performed. If it is designed to be cooled as much as possible, if you are going to change this to a type of power converter that increases only the gate resistance value and keeps switching noise as low as possible,
Since the switching loss increases due to the increase in the gate resistance value, operation at the highest switching frequency becomes impossible due to the problem of cooling performance, and a function that can change the switching frequency as a power converter is required, and the gate resistance value is further increased. If so, the maximum switching frequency must be limited.

On the other hand, when the cooling design is made so that the power converter can be operated at the maximum switching frequency when the type having a large gate resistance, that is, the type in which the switching noise is suppressed as low as possible and the switching loss is large, If it is attempted to change to a low-noise type power converter that can operate at a high switching frequency by reducing only the gate resistance value, the switching loss is reduced due to the reduced gate resistance value, so there is sufficient cooling performance. The power conversion device has too much power. The present invention has been made in view of the above points, and an object of the present invention is to provide a power converter that eliminates these disadvantages.

[0010]

[Means for Solving the Problems] That is, means for achieving the object are as follows: 2. The power converter according to claim 1, wherein at least two or more resistors are connected in series as a gate resistance of the voltage-driven semiconductor switching element, and one resistor is connected to the power-switching semiconductor switching element. A power converter characterized in that a gate drive circuit in which a switch for short-circuiting both ends of the resistor is connected to each of all the remaining resistors except for the resistor is mounted.

2. In claim 2, the maximum switching frequency of the switching element can be set arbitrarily, and there is provided means for determining the open / close state of a switch for short-circuiting both ends of the resistor according to the set switching frequency. Power conversion device.

3. Claim 3 has means for arbitrarily setting the open / close state of a switch for short-circuiting both ends of the resistor, and further has means for determining the maximum switching frequency of the switching element according to the open / close state of the switch. Item 6. The power converter according to item 1. Less than,
An embodiment of the present invention will be described in detail with reference to the drawings.

[0013]

FIG. 1 is a circuit diagram of a single-phase output inverter device as an example of a power converter to which the present invention is applied. Here, 1 to 4 are voltage-driven switching elements having diodes connected in antiparallel, 5 is a DC power supply, 6 to 9 are gate drive circuits, and two series gate resistors 101 to 1 in this example.
02 and a gate resistance short-circuit switch 103. Reference numeral 10 denotes a control circuit, and reference numeral 11 denotes an output terminal of the power conversion device.

With the above configuration, the control circuit 10 turns on the voltage-driven switching elements 1, 4 and turns off the voltage-driven switching elements 2, 3; A gate signal is generated so that the drive type switching elements 2 and 3 operate to alternately repeat the ON state, and this gate signal is supplied to the voltage drive type switching elements 1 to 4 via gate drive circuits 6 to 9.
To drive the voltage-driven switching elements 1-4. With the above operation, the output terminal 11 of the power converter is
To output a single-phase inverter.

The voltage-driven switching elements 1 to 4
FIG. 2 shows the relationship between the gate resistance value and the switching loss of the voltage-driven switching elements 1 to 4 when the switching frequency is constant. Gate resistance short circuit switch 103
Is the value of the gate resistance 102 when the switch is on, the gate resistance when the gate resistance short-circuit switch 103 is off is the value of the gate resistance 101 + 102, and the gate resistance when the gate resistance short-circuit switch 103 is on. As a result, the gate resistance increases, and the switching loss of the voltage-driven switching elements 1 to 4 increases, but the switching noise decreases.

The voltage-driven switching elements 1 to 4
FIG. 3 shows the relationship between the gate resistance value and the maximum switching frequency of the voltage-driven switching elements 1 to 4 when the switching loss of FIG. Gate resistance short-circuit switch 1
Since the gate resistance is small when the switch 03 is on, the maximum switching frequency of the voltage-driven switching elements 1 to 4 can be set high (H in FIG. 3), and when the gate resistance short-circuit switch 103 is off, the gate resistance is low. Because the value is large,
In order to keep the switching loss constant, the highest switching frequency of the voltage-driven switching elements 1 to 4 needs to be set low (L in FIG. 3).

Here, the voltage-driven switching elements 1 to
When the switching frequency of No. 4 is set in the range of L to H in FIG. 3, the gate resistance short-circuit switch 103 is turned on by a command of software or the like of the control circuit 10 to provide a low-noise type power converter. If the switching frequency of the voltage-driven switching elements 1 to 4 is set within the range of L or less in FIG.
By turning off the gate resistance short-circuit switch 103 in accordance with a command of software or the like, a power conversion device of a type that suppresses switching noise as low as possible can be obtained.

Conversely, when the gate resistance short-circuit switch 103 is set to ON, the maximum switching frequency of the voltage-driven switching elements 1 to 4 can be raised to H in FIG. When the gate resistance short-circuit switch 103 is set to OFF, the maximum switching frequency of the voltage-driven switching elements 1 to 4 can be determined by a command of software or the like of the control circuit 10 as shown in FIG. In this case, the switching noise limited by L can be minimized.

[0019]

As described above, according to the present invention, the gate resistance can be varied in the power converter, so that the switching noise generated at the time of switching is suppressed as low as possible, or at a high switching frequency with a small switching loss. What can correspond to any of the low noise types that can operate can be realized with one power conversion device. Further, in the power conversion device of the present invention, the ON / OFF command of the gate resistance short-circuit switch 103 or the determination of the limit value of the maximum switching frequency of the voltage-driven switching elements 1 to 4 can be performed to the full extent of the cooling performance of the power conversion device. This can be performed automatically by software or the like of the control circuit 10 so that it is extremely useful in practical use.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between switching losses.

FIG. 3 is a characteristic diagram showing a relationship between maximum switching frequencies.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Voltage-driven switching element 2 Voltage-driven switching element 3 Voltage-driven switching element 4 Voltage-driven switching element 5 DC power supply 6 Gate drive circuit 7 Gate drive circuit 8 Gate drive circuit 9 Gate drive circuit 10 Control circuit 11 Output terminal 101 Gate resistance 102 Gate resistance 103 Gate resistance short-circuit switch

Claims (3)

[Claims] 1. A power conversion device using a voltage-driven semiconductor switching element, wherein at least two or more resistors are connected in series as a gate resistance of the voltage-driven semiconductor switching element, and the remaining resistors except for one resistor are connected. A power converter characterized in that a gate drive circuit in which switches for short-circuiting both ends of a resistor are connected in parallel is mounted on each of all the resistors. 2. The switching device according to claim 1, wherein a maximum switching frequency of the switching element can be arbitrarily set, and a means for determining an open / close state of a switch for short-circuiting both ends of the resistor according to the set switching frequency. Power converter. 3. A switching means for arbitrarily setting an open / close state of a switch for short-circuiting both ends of a resistor, and further comprising means for determining a maximum switching frequency of a switching element according to the open / close state of the switch. Item 7. The power converter according to Item 1.