CN102361391A - Power gaining circuit applicable to high-voltage field - Google Patents

Abstract

The invention discloses an energy-taking circuit device adapted to the high-voltage field, which includes a buffer circuit, a limiter circuit and a power conversion circuit, and two power poles of a switch device are connected in parallel with the buffer circuit; the buffer circuit includes a diode, a resistor and a buffer capacitor; The limiting circuit is connected in parallel at both ends of the buffer capacitor, the limiting circuit includes a current limiting circuit and a voltage limiting circuit, and the input voltage of the power conversion circuit is stabilized at a certain value through the voltage limiting circuit; the output of the limiting circuit is connected to the power converting circuit; The power conversion circuit provides the required voltage for the drive circuit. The circuit device is especially suitable for high-voltage application fields, the circuit is simple and reliable, no additional insulation equipment is needed, and it is easy to be modularized and integrated.

Description

A kind of energy harvesting circuit suitable for application in high voltage field

technical field

The invention belongs to the field of power electronics application, relates to an energy-taking circuit suitable for high-voltage field, and especially solves the energy supply problem of a gate drive circuit when fully-controlled switching devices are used in series.

Background technique

When the existing high-voltage and high-power power electronic switching devices are applied, there are mainly two ways to provide electric energy for the drive circuit, one is an external low-voltage power supply, and the other is self-capturing energy from the high-voltage side.

For the energy supply mode of external low-voltage power supply, as the voltage level increases, the equipment isolation requirements increase accordingly, and the volume and manufacturing difficulty of the commonly used magnetic isolation pulse transformers increase greatly. This is the case in applications such as power system STACOM or HVDC Flexible This option is less applicable.

For the self-energy harvesting method on the high-voltage side, the CT energy harvesting method of a special current transformer is usually used. This method is widely used in traditional DC power transmission, controllable series compensation and other occasions where thyristors are used as switching devices. When the current is too large, the secondary side of the CT obtains energy, and then outputs the required voltage through the power conversion circuit. Since the thyristor is a semi-controlled switching device, the current flows through the CT energy-taking circuit to obtain energy when it is turned on, and it is naturally turned off when the current flowing through the thyristor crosses zero when it is turned off. However, driving energy is required for fully controlled devices such as IGBT to be turned on and off, and this method of CT energy acquisition cannot meet the requirements.

For high-frequency turn-off switching devices used in series in high-voltage applications, there is currently no simple and reliable driving and energy supply method.

Contents of the invention

The main purpose of the present invention is to provide an energy supply circuit applicable to the high-voltage field, which can still drive the power switching device when the power switching device is turned off, so that the circuit is simple and reliable, and has the same reference potential as the switching device, without adding high-voltage isolation equipment.

In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an energy-taking circuit adapted to the high-voltage field, including a buffer circuit, a limiter circuit and a power conversion circuit, which is characterized in that the two power poles of the switching device are buffered in parallel circuit; the buffer circuit includes a diode, a resistor and a buffer capacitor, and the buffer circuit is connected in parallel with the buffer capacitor after the diode is connected in series with the resistor;

The limiting circuit is connected in parallel at both ends of the buffer capacitor. The limiting circuit includes a current limiting circuit and a voltage limiting circuit, and the input voltage of the power conversion circuit is stabilized at a certain value through the voltage limiting circuit. The high-voltage energy-taking circuit obtains energy from the buffer circuit of the switching device to supply power to the driving circuit. The limiter circuit output is connected to the power conversion circuit.

The power switching device is subjected to high voltage when it is turned off. In order to limit the overvoltage, a snubber circuit is usually connected in parallel at the two power poles (collector and emitter) of the switching device; the snubber circuit should include a rectifier diode, a current limiting circuit and a snubber capacitor. , the power device is subjected to high voltage during shutdown, so the snubber capacitor is charged.

The limiting circuit is connected in parallel at both ends of the buffer capacitor. The limiting circuit includes a current limiting circuit and a voltage limiting circuit. The input current of the power conversion circuit is limited by the current limiting circuit so that the input current of the power conversion circuit is not too large, and the input voltage of the power conversion circuit is controlled by the voltage limiting circuit. stable at a certain value.

The power conversion circuit is a DC/DC converter that converts the output voltage to a lower level. According to the power supply requirements of the drive circuit, the power conversion circuit can provide multiple stable output voltages.

Beneficial effects of the present invention: the present invention is a feasible energy harvesting method, which can obtain drive circuit energy from a buffer circuit connected in parallel with the power pole of the switching device. The energy harvesting circuit of the present invention is simple to implement and reliable in operation; the energy harvesting circuit of the present invention does not have the problem of high-voltage isolation, is small in size, and is easy to realize integration with the driving circuit; Energy can be obtained, and the circuit start-up is easy; the energy-taking circuit of the present invention can be applied to various power semiconductor devices, and has a wide application range.

the

Description of drawings

FIG. 1 is a schematic diagram of an energy harvesting circuit according to the present invention.

Fig. 2 is a realization circuit diagram of the buffer circuit in the present invention.

Fig. 3 is a schematic structural diagram of the limiter circuit in the present invention.

Fig. 4 is the first implementation circuit of the current limiting circuit in the present invention.

Fig. 5 is the second implementation circuit of the current limiting circuit in the present invention.

Fig. 6 is the third implementation circuit of the current limiting circuit in the present invention.

Fig. 7 is the fourth implementation circuit of the current limiting circuit in the present invention.

Fig. 8 is an implementation circuit of the voltage limiting circuit in the present invention.

Fig. 9 is an implementation circuit of the power conversion circuit in the present invention.

the

Detailed ways

The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, it is a schematic diagram of an energy harvesting circuit suitable for high-voltage fields. The switching device is selected as an IGBT. 1 in the figure is the energy harvesting circuit, and its inputs are connected to the collector (C) and emitter (E ), the output is connected to the input terminal of the power supply of the IGBT drive circuit, and 2 in the figure is the IGBT buffer circuit, and its two output terminals are respectively connected to the input of the limiting circuit 4, and the output of the limiting circuit is connected to the power conversion circuit 5, and the output of the power conversion circuit is the drive The voltage value required by circuit 6. Since the reference potential of the entire energy-taking circuit is the same as the emitter of the IGBT of the drive circuit, no additional insulation device is required to provide high-voltage isolation, which greatly reduces the size of the functional circuit.

As shown in FIG. 2 , it is an implementation circuit of the snubber circuit 2 in the energy harvesting circuit, including a diode D ₁ , a resistor R ₁ and a snubber capacitor C ₁ . When _the IGBT is turned off, a voltage is applied between the collector and the emitter, the current flows through D1 and R1 to charge the buffer capacitor, and the energy _harvesting circuit outputs the obtained energy to the limiter circuit. In the initial state, the high-voltage valve bodies connected in series are blocked, all power devices are turned off, and each series element bears high voltage. At this time, the energy harvesting circuit has established a working voltage to provide a stable output voltage for the drive circuit. Therefore, the energy harvesting described in the present invention Circuit initialization is simple and reliable. When the IGBT is turned on, the voltage between the collector and the emitter drops to the IGBT saturation turn-on voltage drop, D ₁ and R ₁ do not flow the charging current, because C ₁ does not discharge through other circuits, the voltage will not drop to zero, and basically maintain at _Near the steady-state shutdown voltage, C1 is charged again after the next shutdown pulse arrives. Therefore, when the IGBT is turned on and off at high frequency, the energy-taking circuit described in the present invention can provide a stable and reliable input power supply for the driving circuit.

As shown in FIG. 3 , it is a schematic diagram of the limiter circuit in the energy harvesting circuit, including a current limiter circuit 7 and a voltage limiter circuit 8 . The current limiting circuit limits the input current of the power conversion circuit within a fixed value range, so as to avoid damage to the voltage limiting circuit and the power conversion circuit due to overcurrent. When working, the current limiting circuit bears a certain voltage, which ensures that the voltage limiting circuit will not be damaged by overvoltage. The voltage limiting circuit provides a stable input voltage for the power conversion circuit.

As shown in Figure 4, it is the first implementation circuit of the current limiting circuit. The current limiting circuit is a Mosfet component, and the limiting circuit is connected between the source and the drain of the Mosfet. pole. Including resistors: R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , Zener diodes: Z ₁ , Z ₂ , low power Mosfet: M ₁ , M ₂ . Set the current limit value by selecting the voltage regulator value of the Zener diode and the resistance value of the Mosfet source series resistors R3 and R6 . _For example, to set the current limit value at _100mA , you can choose the Zener diode to be connected in series with the source of 150Ω resistance. Due to the limited voltage level of a single Mosfet, multiple Mosfet component units in Figure 4 can be used in series. In order to balance the voltage of each unit of the Mosfet in series, capacitors can be connected in parallel in the circuit, thus producing the second implementation circuit of the current limiting circuit shown in Figure 5.

As shown in Figure 6, it is the third implementation circuit of the current limiting circuit. It is easy to see that the low-power Mosfet in the first implementation circuit can also be replaced by a high-voltage low-power IGBT, and the working principle is similar. Similarly, a fourth implementation circuit as shown in FIG. 7 can be derived.

As shown in Figure 8, it is an implementation circuit of the voltage limiting circuit, which uses Zener diodes in series to stabilize the input voltage of the power conversion circuit within a certain range. For example, to stabilize the input voltage of the power conversion circuit at 300V, you can choose 10 voltage regulator tubes with a voltage regulation value of 30V.

The power conversion circuit can be designed according to the requirements of the driving circuit. For example, the IGBT driving circuits of companies such as Concept and Inpower usually need to provide a +16V input DC voltage with a power of 5W. Here it is necessary to design the power conversion circuit as a DC/DC converter with an output voltage of +16V, and a conventional DC/DC converter can be used.

As shown in Figure 9, it is an implementation circuit of a power conversion circuit, in which TOP-Switch chips are used: TOP-243P, optocoupler chip NEC2501LH, three-terminal voltage regulator chip LM431, transformers, inductors, resistors, capacitors, diodes, etc. device. The output voltage of the limiting circuit described in the present invention is converted to the voltage value required by the driving circuit. The power conversion circuit has a simple structure and reliable operation.

The above embodiments are only to illustrate the technical ideas of the present invention, and can not limit the protection scope of the present invention with this. All technical ideas proposed in accordance with the present invention, any changes made on the basis of technical solutions, all fall within the protection scope of the present invention. Inside.

Claims (7)

1. An energy harvesting circuit adapted to the high-voltage field, comprising a snubber circuit, a limiting circuit and a power conversion circuit, characterized in that two power poles of a switch device are connected in parallel with a snubber circuit; the snubber circuit includes a diode, a resistor and a snubber capacitor ; The limiting circuit is connected in parallel at both ends of the buffer capacitor, the limiting circuit includes a current limiting circuit and a voltage limiting circuit, and the input voltage of the power conversion circuit is stabilized at a certain value through the voltage limiting circuit; the output of the limiting circuit is connected to the power converting circuit; The power conversion circuit provides the required voltage for the drive circuit. 2. The energy harvesting circuit according to claim 1, wherein the snubber circuit is a diode connected in series with a resistor and then connected in parallel with a snubber capacitor. 3. The energy harvesting circuit as claimed in claim 1, characterized in that the current limiting circuit is a Mosfet component, the limiting circuit is connected between the Mosfet source and the drain, and the voltage regulator diode is connected to the Mosfet source and the gate . 4. The energy harvesting circuit according to claim 1, characterized in that the power conversion circuit is a DC/DC converter that converts the output voltage to a lower level. 5. The energy harvesting circuit according to claim 3, characterized in that the current limiting circuit is a multi-unit Mosfet assembly connected in series. 6. The energy harvesting circuit according to claim 3, characterized in that an IGBT component is used. 7. The energy harvesting circuit according to claim 3, wherein the voltage limiting circuit uses Zener diodes in series to stabilize the input voltage of the power conversion circuit within a certain range.

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