JP2006081382A - Drive device and control method of element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for driving an element, capable of reducing the drive power for the element, and is capable of reducing the weight and the volume of the drive device. <P>SOLUTION: A power supply B1 that can both supply and charge electric power has two kinds of states, depending on switches Q1 and Q2 connected to the power supply B1: a state 1, where the switch Q1 is closed and the switch Q2 is opened and a state 2, where the switch Q1 is opened and the switch Q2 is closed. At transition when the electric charge charged in the gate capacitance of a driven element is discharged, the electric charge charged in the gate capacitance in the state 2 is discharged via an inductance element L1, while energy is stored in the inductance element L1. After that, the energy stored in the inductance element L1 in the state 1 discharges the electric charge charged in the gate capacitance of IGBT1, while a current is regenerated and charged in the power supply B1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a device for driving an element (such as a MOS-FET or IGBT) having a capacitance (gate capacitance or mirror capacitance) at a drive signal input terminal, and a method for controlling the drive of the device.

An element (such as a MOS-FET or IGBT) having a capacitance (gate capacitance or mirror capacitance) at the drive signal input terminal is connected to the drive signal input terminal (gate), and a gate capacitance (in the case of MOS-FET: between gate and source) Capacitance in IGBT, IGBT: capacitance between gate and emitter) and Miller capacitance (for MOS-FET: capacitance between gate and drain, for IGBT: capacitance between gate and collector) Etc. Conventionally, there is a device composed of a push-pull circuit equipped with a power source and a gate resistor that limits the current to the drive signal input terminal for driving such an element having a capacitance at the gate. This device outputs a drive voltage to the gate of the element by a push-pull circuit. During a transient that changes the driving state of the device, the gate resistance limits the current supplied to the gate of the device.
(For example, see Patent Document 1).
JP 08-27550 A

By the way, MOS-FET, IGBT, etc. are known as elements having capacitance at the drive signal input terminal. These elements have a drive signal input terminal (gate) and the other terminals of the element, electrostatic capacity (gate capacity and mirror capacity) created by the element configuration, and between the drive signal input terminal of the element and the element case. There is a capacitance between the drive signal input terminal of the element and the ground or other conductors (hereinafter, this capacitance is referred to as the capacitance of the drive signal input terminal).
The element is driven by changing the element resistance (in the case of MOS-FET: drain-source resistance, in the case of IGBT: collector-emitter resistance) by changing the drive signal input terminal voltage. For this purpose, a charge current or a discharge current is generated with respect to the capacitance of the drive signal input terminal of the element by a device composed of a push-pull circuit having a power source and a gate resistor for limiting the current to the drive signal input terminal. It is necessary to change the voltage of the sink drive signal input terminal.

  Conventionally, however, Joule heat is generated in the gate resistance due to the charging current or discharging current that flows to the capacitance of the drive signal input terminal during the transition that changes the driving state of the element, resulting in large energy consumption, deteriorating the efficiency of the driving device. In addition, there was a problem that the power supply of the power supply provided in the drive unit was large and the weight and volume increased.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for improving element drive efficiency that contributes to improvement in efficiency of an element drive device and reduction in weight and volume.

  In order to solve the above problems, an element driving device according to the invention of claim 1 includes a control device (for example, the third embodiment) that generates an element driving signal, and is capable of supplying power and storing power (for example, State 1 (for example, Q1 of the embodiment is conducted, Q2 of the embodiment is conducted, Q2 of the embodiment is provided, and B2) of the embodiment is provided and the power supply and the output are conducted by the structure in which two switches (for example, Q1 and Q2 of the embodiment) are connected to the totem pole. The push-pull circuit (for example, 2 of the embodiment) that can be switched between the state 2 (for example, Q1 of the embodiment is shut off and Q2 is turned on), which disconnects the power source and the output and short-circuits the output terminal. L1) of the embodiment is a device driving apparatus (for example, 1 of the embodiment) having a structure connected in series, and the electric charge charged in the capacitance existing in the driving signal input terminal of the device is In the state 2, the push-pull circuit (for example, 2 in the embodiment) is set to the state 2 to discharge the charged charge of the capacitance existing at the drive signal input terminal of the element through the inductance element (for example, L1 in the embodiment). At the same time, a state in which a discharge current flows through the inductance element (for example, L1 of the embodiment) and energy is stored in the inductance element (for example, L1 of the embodiment), and the push-pull circuit (for example, 2 of the embodiment) is changed to the state 1 The energy stored in (for example, L1 in the embodiment) is regenerated and charged in a power source (for example, B1 in the embodiment).

  The drive device having the above configuration is in the state 1 or the state 2 set by the push-pull circuit (for example, 2 in the embodiment) when charging and discharging the capacitance existing in the drive signal input terminal of the element. It has schedule information regarding the driving contents and the time during which the driving contents are held and the time transition of the driving conditions, and performs the state setting of the push-pull circuit (for example, embodiment 2) based on the schedule, The current flowing through the input terminal and the drive signal input terminal voltage of the element can be adjusted.

  The present invention not only has the advantage that the driving power of the element can be kept small and the driving efficiency of the entire apparatus is improved, but also the weight and volume of the power source provided in the driving apparatus of the element can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
(overall structure)
The drive device according to the present embodiment is a device that is useful when driving elements such as MOS-FETs and IGBTs constituting a power converter, for example. FIG. 1 is a block diagram showing the configuration of an element driving apparatus according to an embodiment of the present invention. In FIG. 1, the driven element is an element such as a MOS-FET or IGBT having a gate capacitance or a mirror capacitance between the drive signal input terminals.

(Element drive unit)
In FIG. 1, a power source B1 is a device that can supply and charge electric power, and is a power source constituted by a chemical battery, a capacitor, a power storage device, a power conversion device, or a combination thereof. Switches Q1 and Q2 are connected to the totem pole between the positive terminal and the negative terminal of the power supply B1 to constitute a push-pull circuit 2. The control signal to the switches Q1 and Q2 is given by the control device 3. The output of the push-pull circuit 2 has two states depending on the states of the switches Q1 and Q2. The state where the switch Q1 is conductive and the switch Q2 is cut off is referred to as state 1, and the state where the switch Q1 is cut off and the switch Q2 is conductive is referred to as state 2. Therefore, in the state 1, the push-pull circuit 2 is in a state where the power source B1 is connected to the gate which is a drive signal input terminal of an element such as a MOS-FET or IGBT via the inductance element L1. In the state 2 of the push-pull circuit 2, the power source B1 and the inductance element L1 are disconnected, and the drive signal input terminals of elements such as MOS-FET and IGBT are short-circuited via the inductance element L1.

(Control method)
FIG. 2 is a circuit diagram showing the operation of the embodiment of the drive device for the IGBT element. FIG. 2 shows the operation of regeneratively charging the power supply B1 in a transient that changes the driving state of the IGBT1 by discharging the charge charged in the gate capacitance of the IGBT1. In a state where the switch Q1 is cut off and the switch Q2 is turned on, a current loop (A) is formed in which the charge charged in the gate capacitance of the IGBT 1 is turned on through the inductance element L1. Then, the charge charged in the gate capacitance of the IGBT 1 is discharged through the inductance element L1. At the same time, energy is stored in the inductance element L1 by a current flowing through the inductance element L1. Through this state, the switch Q2 is electrically cut off and the switch Q1 is in a conductive state (however, there are cases of either or both of conduction by a diode parasitic on the MOS-FET and conduction by making the MOS-FET conductive). Thus, a current loop (B) composed of the gate capacitance of the IGBT 1 and the switch Q1 conducting to the inductance element L1 and the power source B1 is formed, and the charge charged in the gate capacitance of the IGBT 1 by the energy stored in the inductance element L1. And the power source B1 is charged with current.

  FIG. 3 is a circuit diagram showing the operation of the embodiment of the drive device for the IGBT element. FIG. 3 shows a transient operation that changes the driving state of the IGBT 1 by charging the gate capacitance of the IGBT 1. As a state in which the switch Q1 is turned on and the switch Q2 is turned off, a current loop (D) is formed that includes the gate capacitance of Q1, the inductance element L1, and the IGBT 1 that are connected to the power source B1. Then, the gate capacitance of the IGBT 1 is charged from the power source B1 through the inductance element L1. At the same time, energy is stored in the inductance element L1 by a current flowing through the inductance element L1. Through this state, the switch Q1 is electrically cut off and the switch Q2 is in a conductive state (however, there are cases of either or both of conduction by a diode parasitic on the MOS-FET and conduction by making the MOS-FET conductive). Thus, a current loop (C) composed of the gate capacitance of the IGBT 1 and the switch Q2 conducting with the inductance element L1 is formed, and the gate capacitance of the IGBT 1 is charged by the energy stored in the inductance element L1.

  FIG. 4 is a waveform diagram showing the relationship between the switching state of the switches Q1 and Q2 and the current and voltage of the gate of the IGBT 1 in a transition that changes the driving state of the IGBT 1 by charging or discharging the gate capacitance of the IGBT 1. .

  Table 1 is provided in advance in the driving apparatus of the present embodiment, and suppresses an excessive current from flowing to the gate of IGBT 1 due to LC resonance caused by the gate capacitance of IGBT 1 and the inductance of inductance element L1, and an excessive voltage is applied to the gate of IGBT 1. This is a switch drive schedule table showing the state of the switches Q1 and Q2 and the transition time to the next sequence with the drive information of the switches Q1 and Q2 that can be suppressed.

  For example, when charging the gate capacity of the IGBT 1, the switches Q1 and Q2 according to Q1 and Q2 shown in the state (1) of the schedule table (charging of the gate capacity) are set, and after the time Tc1 has elapsed, the next item of the state of the schedule table Transition to (2), switch setting and time holding are performed in the same manner, and the current and voltage flowing through the gate of the IGBT 1 can be adjusted by sequentially performing the state terms (1) to (n). However, the transition times Tc1 to Tcn and n are arbitrary values.

  For example, in the transition when the gate capacitance of the IGBT 1 is discharged, the switches Q1 and Q2 shown in the state (1) of the schedule table (gate capacitance discharge) are set to the driving state, and after the time Td1 has elapsed, It is possible to adjust the current and voltage flowing through the gate of the IGBT 1 by making the transition to the next term (2) and performing the setting of the switch and the time holding in the same manner and sequentially performing the state terms (1) to (m). However, the transition times Td1 to Tdm and m are arbitrary values.

(overall structure)
The driving device of the present embodiment includes, for example, a low-voltage power source necessary for controlling and driving these elements in driving of elements such as MOS-FETs and IGBTs constituting a high-voltage power converter. There is a need to electrically insulate these two power sources in a system using two power sources with a high-voltage power source conducted by an element such as a MOS-FET or IGBT driven by a driving device of the form This device is useful for driving certain elements. FIG. 5 is a block diagram showing the configuration of the element driving apparatus according to the embodiment of the present invention. In FIG. 5, the IGBT 1 is shown as an example of an element having a gate capacity or a mirror capacity between the drive signal input terminals, and can also drive an element such as a MOS-FET. The power transfer to the gate which is the drive signal input terminal of the IGBT 1 is performed by the element drive device 1 through a transformer composed of the inductance elements L2 and L3.

(Trance)
The transformer T1 composed of the inductance elements L2 and L3 is a transformer capable of transmitting power from the inductance elements L2 to L3 and transmitting power from the inductance elements L3 to L2 by mutual induction. The number of turns of the inductance element L2 of this transformer is N2, and the number of turns of the inductance element L3 is N3. Further, assuming that the voltage applied to the inductance element L2 is VL2 and the voltage applied to the inductance element L3 is VL3, the relationship between the voltage and the number of turns is represented by the formula (A).

VL2: VL3≈N2: N3 (N2 and N3 are arbitrary numbers) (A)

Since a voltage charged to the gate capacitance of the IGBT 1 is always connected to VL3, a voltage (proportional relationship with VL3) corresponding to the equation (A) appears in VL2, and a change in the voltage charged to the gate capacitance of the IGBT 1 occurs. VL2 also varies in proportion to

(Element drive unit)
The power source B1 constituting the element driving device 1 is a device that can charge and discharge electric energy, and is a power source constituted by a chemical battery, a capacitor, a power storage device, a power conversion device, and the like, or a combination thereof. Switches Q1 and Q2 are connected to the totem pole between the positive terminal and the negative terminal of the power supply B1 to constitute a push-pull circuit 2. The control signal to the switches Q1 and Q2 is given by the control device 3. The output of the push-pull circuit 2 has two states depending on the states of the switches Q1 and Q2. The state where the switch Q1 is conductive and the switch Q2 is cut off is referred to as state 1, and the state where the switch Q1 is cut off and the switch Q2 is conductive is referred to as state 2. Therefore, in the state 1, an annular electric circuit is formed by the power source B1, the conductive switch Q1, and the inductance elements L1 and L2. Then, the power source B1 transmits and receives power to the gate of the IGBT 1 by electromagnetic induction between the inductance elements L2 and L3 via the inductance element L1. In state 2, the power source B1 and the inductance element L1 are disconnected, and a conductive switch Q2 and the inductance elements L1 and L2 form an annular electric circuit. Then, the gate of the IGBT 1 can transmit and receive power by mutual induction between the inductance elements L2 and L3, and the voltage appearing on the inductance element L2 is short-circuited via the inductance element L1.

  The transformer T1 has a self-inductance that is not mutually induced in addition to the inductance that is mutually induced between the inductance elements L2 and L3 due to the leakage magnetic flux. The inductance element L1 in FIG. 5 can also be realized by self-inductance due to the leakage magnetic flux of the transformer T1. It can also be installed separately from the transformer T1.

(Control method)
FIG. 6 is a circuit diagram showing the operation of the embodiment of the drive device for the IGBT element. FIG. 6 shows the operation of regeneratively charging the power supply B1 in a transient that changes the driving state of the IGBT1 by discharging the charge charged in the gate capacitance of the IGBT1. In a state where the switch Q1 is cut off and the switch Q2 is turned on, a current loop (E) is formed in which the voltage appearing on the inductance element L2 is turned on through the inductance element L1. Then, energy is stored in the inductance element L1 by a current flowing through the inductance element L1. At the same time, the charge charged in the gate capacitance of the IGBT 1 is discharged through the inductance element L3. Through this state, the switch Q2 is electrically cut off and the switch Q1 is in a conductive state (however, there are cases of either or both of conduction by a diode parasitic on the MOS-FET and conduction by making the MOS-FET conductive). Thus, a current loop (F) composed of the inductance element L2 and the switch Q1 conducting to the inductance element L1 and the power source B1 is formed, and the current is charged to the power source B1 by the energy stored in the inductance element L1. At the same time, the electric charge charged in the gate capacitance of the IGBT 1 is discharged through the inductance element L3.

  FIG. 7 is a circuit diagram showing the operation of the embodiment of the drive device for the IGBT element. FIG. 7 shows a transient operation that changes the driving state of the IGBT 1 by charging the gate capacitance of the IGBT 1. As a state in which the switch Q1 is turned on and the switch Q2 is turned off, a current loop (H) composed of Q1, the inductance element L1, and the inductance element L2 connected to the power source B1 is formed. At the same time, the electric power supplied to the inductance element L2 is charged to the gate capacitance of the IGBT 1 through the inductance element L3 by mutual induction. At the same time, the current flows through the inductance element L1, whereby energy is stored in the inductance element L1. Through this state, the switch Q1 is electrically cut off and the switch Q2 is in a conductive state (however, there are cases of either or both of conduction by a diode parasitic on the MOS-FET and conduction by making the MOS-FET conductive). Thus, a current loop (G) composed of the inductance element L1 and the switch Q2 that conducts with the inductance element L2 is formed, and the energy stored in the inductance element L1 is supplied to the inductance element L2. At the same time, the gate capacitance of the IGBT 1 is charged from the inductance element L3 by mutual induction.

  It is a block diagram which shows the structure of the element drive of embodiment of this invention.   It is a circuit diagram which shows operation | movement of the drive device of the embodiment.   It is a circuit diagram which shows operation | movement of the drive device of the embodiment.   It is a waveform diagram showing the drive operation of the same embodiment.   It is a block diagram which shows the example of the structure of the element drive of one embodiment of this invention   It is a circuit diagram which shows operation | movement of the drive device of the Example.   It is a circuit diagram which shows operation | movement of the drive device of the Example.

Explanation of symbols

1 device drive device 2 push-pull circuit 3 control device B1 DC power supply Q1, Q2 switch (MOS-FET including parasitic diode)
L1 Inductance element T1 Transformer L2, L3 Inductance element IGBT1 element constituting transformer (drive signal input terminal has capacitance)

Claims (2)

  A control device for generating a drive signal for the element, and a power source capable of supplying and storing power, wherein the power source and the output are connected by a structure in which two switches are connected to the totem pole; An element driving device having an inductance element connected in series to a push-pull circuit capable of switching between a state 2 in which an output is disconnected and an output terminal is short-circuited, and a capacitance existing at a driving signal input terminal of the element When the push-pull circuit is in state 2 and the electrostatic charge charged at the drive signal input terminal of the element is discharged through the inductance element, a discharge current is simultaneously applied to the inductance element. After the energy is stored in the flow inductance element, the energy stored in the inductance element is changed to the push-pull circuit in state 1. Apparatus characterized by regenerated ghee to power charger.   The driving device according to claim 1, wherein the push-pull circuit sets the driving contents and driving contents in the state 1 or 2 when charging and discharging the capacitance existing in the driving signal input terminal of the element. The schedule information about the time during which the state is held and the time transition of the driving state are held, the state of the push-pull circuit is set based on the schedule, the adjustment of the current flowing through the drive signal input terminal of the device, and the drive signal of the device A control method characterized by the ability to adjust the input terminal voltage.

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