A high-frequency large-current generating circuit based on gallium nitride power devices

Abstract

A high-frequency and large-current generating circuit based on gallium nitride power device, the generating circuit includes a Howland current source with voltage follower, a bias and amplification circuit, a gallium nitride power device quasi-complementary output circuit, a compensation circuit and an inductive load, based on the improved Howland current source with voltage follower, the gallium nitride power device quasi-complementary output circuit is adopted in the power amplifier output stage, the corresponding bias and amplification circuit is designed to make the power gallium nitride device in the linear amplification zone, and the bias and amplification circuit and the gallium nitride power device quasi-complementary output circuit are arranged in the feedback loop of the improved Howland current source, thereby realizing the sine wave high-voltage high-frequency large-current class A and B power amplification output, the output frequency is greater than 500KHz, the output voltage can reach ±220V, the peak output current is more than 30A, and meanwhile, the inductive load capacity is strong. It can be used for analyzing the high-frequency transient characteristics and alternating impedance of large current such as Rogowski coil, electromagnetic current transformer, cable conductor and inductor, and simulating the fault traveling wave current of power transmission line.

Description

Technical Field

[0001] This invention relates to the field of high-frequency circuit technology, and more particularly to a high-frequency generation circuit based on gallium nitride devices. Background Technology

[0002] In power systems, traveling wave-based accurate fault location for transmission lines has been developed and widely applied for many years. With technological advancements, the demand for accurate fault location in distribution networks and railway and subway cables is increasing. Accurate fault location for lines can help users quickly troubleshoot faults and shorten power outage time. In a traveling wave fault location system, a high-frequency, high-current traveling wave signal is converted into a small voltage or current signal by a Rogowski coil or a high-frequency electromagnetic current transformer, and then input to a high-speed ADC sampling system after signal processing circuitry.

[0003] Fault transient traveling waves cover a wide frequency band, from several kilohertz to several hundred kilohertz, and current traveling waves range from several amperes to several hundred amperes, placing high demands on the high-frequency, high-current transient transmission characteristics of Rogowski coils or high-frequency electromagnetic current transformers. Better high-frequency, high-current transient transmission characteristics result in higher fault location accuracy. Simulating high-frequency, high-current traveling wave signals for traveling wave ranging tests and evaluating the high-frequency, high-current transient transmission characteristics of Rogowski coils or high-frequency electromagnetic current transformers requires high-voltage, high-frequency, high-current signal generators. However, currently widely used electrical measurement instrument calibration devices, digital simulation power amplifiers, relay protection testers, and commercially available high-current output power operational amplifiers are limited by the structure, manufacturing process, and material characteristics of high-power transistors and MOSFETs. While the output AC current amplitude can reach 60A, the frequency does not exceed 10kHz, failing to meet high-frequency requirements. High-current output power operational amplifiers, such as Apex Microtechnology's PA50, can output 40A continuous current and 100A peak current, but have a full-power bandwidth of 200kHz and an operating voltage of only ±50V. When driving inductive loads such as Rogowski coils or high-frequency electromagnetic current transformers, they cannot meet the high-frequency requirements of an operating voltage of ±220V and an output current frequency of over 500kHz. Summary of the Invention

[0004] To address the aforementioned challenges, this invention proposes a high-frequency high-current generation circuit based on gallium nitride power devices. This circuit can be used to analyze the high-current high-frequency transient characteristics and AC impedance of Rogowski coils, electromagnetic current transformers, cable conductors, inductors, etc., as well as to simulate the traveling wave current of transmission line faults.

[0005] The basic scheme is based on an improved Howland current source with voltage follower. In the power amplifier output stage, a quasi-complementary output circuit of gallium nitride power devices is used. The corresponding bias and amplification circuits are designed to put the power gallium nitride devices in the linear amplification region. The bias and amplification circuits and the quasi-complementary output circuit of gallium nitride power devices are placed in the feedback loop of the improved Howland current source. Through compensation circuits and components, a sinusoidal high-voltage, high-frequency, high-current Class AB power amplifier output is achieved. The output frequency is greater than 500KHz, the output voltage can reach ±220V, and the peak output current exceeds 30A. At the same time, it has a strong ability to drive inductive loads.

[0006] A high-frequency high-current generation circuit based on gallium nitride devices, the generation circuit comprising: a Howland current source with voltage follower, a bias and amplification circuit, a quasi-complementary output circuit of gallium nitride power devices, a compensation circuit, and an inductive load, wherein the bias and amplification circuit and the quasi-complementary output circuit of gallium nitride power devices are located within the feedback loop of the Howland current source. The gallium nitride power device quasi-complementary output circuit uses two high-voltage gallium nitride power devices of the same type to form a class AB quasi-complementary power amplifier output. The bias and amplification circuit includes a high-frequency complementary power transistor, high-side and low-side constant current sources, an Ube amplification circuit, and a high-frequency power transistor. The high-side and low-side constant current sources and the high-frequency power transistor (Q3) form a common-emitter amplifier circuit with an active load. The Ube amplification circuit is located between the high-frequency power transistor (Q3) and the low-side constant current source to eliminate crossover distortion of the gallium nitride power device. The high-frequency complementary power transistor drives the gallium nitride power device to operate in the linear amplification region. The Howland current source with voltage follower includes a high-voltage high-speed operational amplifier, a resistor feedback network, a sampling resistor, and a compensation inductor. The voltage signal on the sampling resistor and the compensation inductor is input to the non-inverting and inverting input terminals of the first high-voltage high-speed operational amplifier (U1) through the voltage follower circuit and the resistor feedback network, respectively. The compensation circuit includes an RC compensation circuit, a compensation inductor, and a compensation capacitor, which improves the circuit's ability to drive inductive loads and its stability, and increases the phase margin.

[0007] In the quasi-complementary output circuit of the gallium nitride power device, two high-voltage gallium nitride power devices of the same type are used, namely the first gallium nitride power device T1 and the second gallium nitride power device T2, which constitute a class AB quasi-complementary power amplifier output. The breakdown voltage between the drain and source of the gallium nitride power device is not less than 650V, the switching frequency is greater than 10 MHz, and the drain current reaches 60A.

[0008] The bias and amplification circuit includes a high-frequency complementary power transistor, high-side and low-side constant current sources, an Ube amplifier circuit, and a high-frequency power transistor. The first high-frequency complementary power transistor Q1 and the second high-frequency complementary power transistor Q2 enable the first gallium nitride power device T1 and the second gallium nitride power device T2 in the quasi-complementary output circuit to operate in the linear amplification region. The first high-frequency complementary power transistor Q1 and the second high-frequency complementary power transistor Q2 are complementary NPN-PNP power transistors or NMOS-PMOS field-effect transistors, with an operating voltage not lower than 300V and a switching frequency greater than 10 MHz. A common-emitter amplifier circuit with an active load is used, consisting of high-side and low-side constant current sources and the high-frequency power transistor Q3. The Ube amplifier circuit is used to eliminate crossover distortion of the first gallium nitride power device T1 and the second gallium nitride power device T2. The Ube amplifier circuit includes a power transistor (Q4), a voltage divider resistor (R14), a voltage divider resistor (R15), and an adjustable resistor (Radj).

[0009] The voltage-following Howland current source includes a first high-voltage high-speed operational amplifier U1, a second high-voltage high-speed operational amplifier U2, a first feedback resistor R1, a second feedback resistor R2, a third feedback resistor R3, a fourth feedback resistor R4, a sampling resistor Rs, and a compensation inductor (Ls). The bias and amplification circuits, along with the quasi-complementary output circuit of the gallium nitride power devices, are placed within the Howland current source feedback loop. This improves the nonlinear transfer characteristics of the gallium nitride power devices, reduces crossover distortion in Class AB power amplifiers, enhances output accuracy, and reduces harmonic distortion. The first high-voltage high-speed operational amplifier U1 and the second high-voltage high-speed operational amplifier U2 operate at a power supply voltage above 450V, have a slew rate exceeding 1000V / µs, a full-power bandwidth exceeding 500kHz, and an output current of 0.2A.

[0010] The compensation circuit includes an RC compensation circuit, a compensation inductor (Ls), and a compensation capacitor (C1). The RC compensation circuit consists of a resistor Rc and a capacitor Cc connected in series, then connected in parallel with a feedback resistor (R3). The compensation inductor (Ls) and the sampling resistor (Rs) are connected in series. The compensation capacitor (C1) is located between the base and collector of the high-frequency power transistor (Q3). The compensation circuit improves the ability and stability of the high-frequency high-current generation circuit to drive inductive loads and increases the phase margin.

[0011] The high-frequency high-current generator circuit's power supply ±VCC can operate from ±24V to ±225V DC. When the input is a high-frequency sinusoidal voltage signal, it can be converted into a sinusoidal high-current output of the corresponding frequency. The output frequency is greater than 500KHz, the output voltage can reach up to ±220V, and the peak output current exceeds 30A. When the input is a DC voltage, step voltage, or other signal, the output is a corresponding DC current, step current, or other signal. When the input is a high-frequency sinusoidal voltage signal biased by DC voltage, the output is a corresponding DC current superimposed with a sinusoidal current of the corresponding frequency.

[0012] The beneficial effects of this invention are as follows: By employing a quasi-complementary output circuit of gallium nitride (GaN) power devices in the power amplifier output stage, and designing corresponding bias and amplification circuits to place the GaN power devices in the linear amplification region, and by placing the bias and amplification circuits and the quasi-complementary output circuit of the GaN power devices within a Howland current source feedback loop, this invention achieves sinusoidal high-voltage, high-frequency, high-current Class AB power amplification output. The output frequency is greater than 500kHz, the output voltage can reach ±220V, and the peak output current exceeds 30A, while also possessing a strong ability to drive inductive loads. This solves the problem that devices such as electrical measurement instrument integrated calibration devices, digital simulation power amplifiers, relay protection testers, and power operational amplifiers cannot simultaneously output high frequency, high voltage, and high current, and simultaneously drive strong inductive loads. This circuit, when used with a signal generator, high-power high-voltage DC power supply, oscilloscope, or network analyzer, can be used to analyze the high-current, high-frequency transient characteristics and AC impedance of Rogowski coils, electromagnetic current transformers, cable conductors, inductors, etc., as well as simulate the traveling wave current of transmission line faults. Attached Figure Description

[0013] Figure 1 This invention relates to a high-frequency, high-current generating circuit based on gallium nitride power devices. Figure 2 This invention relates to a high-frequency, high-current generation extension circuit based on gallium nitride power devices. Detailed Implementation

[0014] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0015] Please refer to the attached document. Figure 1 The present invention illustrates a high-frequency high-current generation circuit based on gallium nitride devices, characterized in that the generation circuit includes: a Howland current source with voltage follower, a bias and amplification circuit, a quasi-complementary output circuit of gallium nitride power devices, a compensation circuit, and an inductive load, wherein the bias and amplification circuit and the quasi-complementary output circuit of gallium nitride power devices are located within the feedback loop of the Howland current source. The gallium nitride power device quasi-complementary output circuit uses two high-voltage gallium nitride power devices of the same type to form a class AB quasi-complementary power amplifier output, namely the first gallium nitride power device T1 and the second gallium nitride power device T2. The breakdown voltage between the drain and source of the gallium nitride power device is not less than 650V, the switching frequency is greater than 10 MHz, and the drain current reaches 60A.

[0016] The gates of the first gallium nitride (GaN) power device T1 and the second GaN power device T2 are connected in series with resistors R12 and R13, respectively, to control the turn-on speed of the GaN power transistors and prevent oscillation caused by excessively fast switching. The sources of the first GaN power device T1 and the second GaN power device T2 are connected to milliohm-level high-power resistors R8 and R9, respectively. By adding protection circuits, overcurrent damage to the first GaN power device T1 and the second GaN power device T2 can be prevented. GaN power devices have faster switching speeds and better high-frequency performance than silicon carbide and superjunction silicon MOS transistors. However, the working principle of GaN power devices is different from that of transistors and power MOSFETs. When the gate-source voltage of an enhancement-mode GaN power device is greater than zero, a two-dimensional electron gas (2DEG) channel is formed between the drain and source, thereby turning on the device. Therefore, there is no PNP or PMOS type. Thus, a quasi-complementary output structure needs to be used in the power output stage, and corresponding bias and amplification circuits need to be designed.

[0017] The bias and amplification circuit includes a high-frequency complementary power transistor, high-side and low-side constant current sources, an Ube amplification circuit, and a high-frequency power transistor. The high-side and low-side constant current sources and the high-frequency power transistor (Q3) form a common-emitter amplifier circuit with an active load. The Ube amplification circuit is located between the high-frequency power transistor (Q3) and the low-side constant current source to eliminate crossover distortion of the gallium nitride power device. The circuit uses a first high-frequency complementary power transistor Q1 and a second high-frequency complementary power transistor Q2 to make the first gallium nitride power device T1 and the second gallium nitride power device T2 in the quasi-complementary output circuit work in the linear amplification region. Resistor R5 is connected to the emitter of the first high-frequency complementary power transistor Q1, and resistor R7 is connected to the collector resistor of the second high-frequency complementary power transistor Q2. The voltages on resistors R5 and R7 are used as gate voltages to drive the first gallium nitride power device T1 and the second gallium nitride power device T2, so that T1 and T2 are turned on in the positive and negative half-cycles of the sine wave, respectively. The first high-frequency complementary power transistor Q1 and the second high-frequency complementary power transistor Q2 are complementary NPN-PNP power transistors or NMOS-PMOS field-effect transistors, with an operating voltage of not less than 300V and a switching frequency greater than 10 MHz.

[0018] The Ube amplifier circuit consists of power transistor Q4, voltage divider resistors R14 and R15, and adjustable resistor Radj. As a bias circuit, the Ube amplifier circuit ensures that Q1, Q2, T1, and T2 operate in the amplification region, thereby eliminating crossover distortion between the first gallium nitride power device T1 and the second gallium nitride power device T2. The high-side and low-side constant current sources, along with the high-frequency power transistor Q3, form a common-emitter amplifier circuit with an active load, providing bias current to the Ube amplifier circuit and ensuring that Q1, Q2, and Q3 operate in the linear amplification region.

[0019] The voltage-following Howland current source includes a high-voltage high-speed operational amplifier, a load resistor, an impedance resistor, and an inductor. The voltage-following Howland current source comprises a first high-voltage high-speed operational amplifier U1, a second high-voltage high-speed operational amplifier U2, a first feedback resistor R1, a second feedback resistor R2, a third feedback resistor R3, a fourth feedback resistor R4, a sampling resistor Rs, and a compensation inductor (Ls). The feedback resistors R3 and R4 form the positive feedback network of the first high-voltage high-speed operational amplifier U1, and the first feedback resistor R1 and the second feedback resistor R2 form the negative feedback network of the first high-voltage high-speed operational amplifier U1. Typically, the ratios of R2 / R1 and R4 / R3 are the same. The sampling resistor Rs and the compensation inductor Ls form the sampling impedance. The second high-voltage high-speed operational amplifier U2, acting as a voltage follower, inputs the output voltage to the non-inverting input of the first high-voltage high-speed operational amplifier U1 through the positive feedback network formed by the feedback resistors R3 and R4. VG1 is a sinusoidal voltage signal output by instruments such as signal generators. The magnitude and frequency of the output current are determined by the first high-voltage high-speed operational amplifier U1, the second high-voltage high-speed operational amplifier U2, feedback resistors R1-R4, sampling resistor Rs, compensation inductor Ls, etc.

[0020] The first high-voltage high-speed operational amplifier U1 and the second high-voltage high-speed operational amplifier U2 operate at a power supply of 450V or higher, have a slew rate of over 1000V / µs, a full-power bandwidth of over 500kHz, and an output current of 0.2A.

[0021] The first high-voltage high-speed operational amplifier U1 and the second high-voltage high-speed operational amplifier U2 are surrounded by capacitors C2 and C3 for loop compensation, resistors Rcl1 and Rcl2 for overcurrent protection of the operational amplifier output current, and capacitors C4-C7 and C8-C11 for positive and negative power supply filtering. By placing the bias and amplification circuits and the quasi-complementary output circuit of the gallium nitride power devices within the improved Howland current source feedback loop, the nonlinear transfer characteristics of the gallium nitride power devices can be improved, and the crossover distortion of the Class AB power amplifier can be reduced.

[0022] The compensation circuit comprises an RC compensation circuit, a compensation inductor Ls, and a compensation capacitor C1. It enhances the circuit's ability to handle inductive loads and its stability, while increasing the phase margin. The RC compensation circuit consists of a resistor Rc and a capacitor Cc connected in series, then connected in parallel with the third feedback resistor R3. The compensation inductor Ls and the sampling resistor Rs are connected in series, and the compensation capacitor C1 is located between the base and collector of the high-frequency power transistor Q3. The compensation inductor Ls and the sampling resistor Rs, acting as impedance elements, simultaneously affect the magnitude of the output current Iout.

[0023] An inductive load consists of a resistor RL and an inductor LL, the specific values ​​of which depend on the Rogowski coil, the electromagnetic current transformer, the cable conductor, and the inductor itself.

[0024] The high-frequency, high-current generator circuit's power supply ±VCC is provided by a high-power, high-voltage DC power supply. The power supply operates within the range of ±24V to ±225V DC. When the circuit operates at ±225V and the input is a high-frequency sinusoidal voltage signal, it can be converted into a corresponding frequency Iout sinusoidal high-current output. The output frequency is greater than 500kHz, the maximum output voltage can reach ±220V, and the peak output current exceeds 30A. When the input is a DC voltage, step voltage, or other signal, the output Iout is the corresponding DC current, step current, or other signal. When the input is a high-frequency sinusoidal voltage signal biased by a DC voltage, the output Iout is the corresponding DC current superimposed with a sinusoidal current of the corresponding frequency. Example

[0025] like Figure 2 As shown, the example described here is based on Figure 1 The extended circuit of the "High-Frequency High-Current Generator Circuit Based on Gallium Nitride Power Devices" uses three pairs of Class AB quasi-complementary power amplifier outputs in the quasi-complementary output circuit of gallium nitride power devices: T1 and T2, T3 and T4, and T5 and T6. The peak output current of the 1-pair quasi-complementary output circuit exceeds 30A within the safe operating area of ​​the gallium nitride power devices, while the peak output current of the 3-pair quasi-complementary output circuit exceeds 90A. Resistors R12, R13, and R20-R23 are connected in series with the gates of T1-T6 to control the conduction speed of the gallium nitride power transistors and prevent oscillation due to excessively fast switching. The sources of T1-T6 are connected to milliohm-level high-power resistors R8, R9, and R24-R27, respectively. This added protection circuit prevents overcurrent damage to T1-T6.

[0026] In the bias and amplification circuit section, a high-side and low-side constant current source implementation is provided. The high-side constant current source consists of a PNP high-frequency power transistor Q5, diodes D1 and D2, and resistors R16 and R18, providing approximately 20mA of bias current. The low-side constant current source consists of an NPN high-frequency power transistor Q6, diodes D3 and D4, and resistors R17 and R19, providing approximately 15mA of bias current.

[0027] As described above, these are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the present invention without departing from the scope of the present invention are within the scope of the present invention.

Claims

1. A high-frequency, high-current generating circuit based on gallium nitride power devices, characterized in that, The generating circuit includes: a Howland current source with voltage follower, a bias and amplification circuit, a quasi-complementary output circuit of gallium nitride power devices, a compensation circuit, and an inductive load, wherein the bias and amplification circuit and the quasi-complementary output circuit of gallium nitride power devices are located within the feedback loop of the Howland current source. The gallium nitride power device quasi-complementary output circuit uses two high-voltage gallium nitride power devices of the same type to form a class AB quasi-complementary power amplifier output. The bias and amplification circuit includes a high-frequency complementary power transistor, high-side and low-side constant current sources, an Ube amplification circuit, and a high-frequency power transistor. The high-side and low-side constant current sources and the high-frequency power transistor (Q3) form a common-emitter amplifier circuit with an active load. The Ube amplification circuit is located between the high-frequency power transistor (Q3) and the low-side constant current source to eliminate crossover distortion of the gallium nitride power device. The high-frequency complementary power transistor drives the gallium nitride power device to operate in the linear amplification region. The Howland current source with voltage follower includes a high-voltage high-speed operational amplifier, a resistor feedback network, a sampling resistor, and a compensation inductor. The voltage signal on the sampling resistor and the compensation inductor is input to the non-inverting and inverting input terminals of the first high-voltage high-speed operational amplifier (U1) through the voltage follower circuit and the resistor feedback network, respectively. The compensation circuit includes an RC compensation circuit, a compensation inductor, and a compensation capacitor, which improves the circuit's ability to handle inductive loads and its stability, and increases the phase margin. In the quasi-complementary output circuit of the gallium nitride power devices, two identical high-voltage gallium nitride power devices, namely the first gallium nitride power device (T1) and the second gallium nitride power device (T2), constitute a Class AB quasi-complementary power amplifier output. The breakdown voltage between the drain and source of the gallium nitride power devices is not less than 650V, and the switching frequency is greater than 10. MHz, drain current up to 60A; the bias and amplification circuit includes a high-frequency complementary power transistor, high-side and low-side constant current sources, Ube amplification circuit, and a high-frequency power transistor, wherein the first high-frequency complementary power transistor (Q1) and the second high-frequency complementary power transistor (Q2) enable the first gallium nitride power device (T1) and the second gallium nitride power device (T2) in the quasi-complementary output circuit to operate in the linear amplification region; the first high-frequency complementary power transistor (Q1) and the second high-frequency complementary power transistor (Q2) are complementary NPN-PNP power transistors or NMOS-PMOS field-effect transistors, with an operating voltage of not less than 300V and a switching frequency greater than 10 MHz; a common-emitter amplifier circuit with active load is adopted, consisting of high-side and low-side constant current sources and a high-frequency power transistor (Q3); a Ube amplifier circuit is adopted to eliminate crossover distortion between the first gallium nitride power device (T1) and the second gallium nitride power device (T2); the Ube amplifier circuit includes a power transistor (Q4), a voltage divider resistor (R14), a voltage divider resistor (R15), and an adjustable resistor (Radj); the compensation circuit includes an RC compensation circuit, a compensation inductor (Ls), and a compensation capacitor (C1), wherein the RC compensation circuit is composed of a resistor Rc and a capacitor Cc connected in series, and then a third feedback resistor (R3) is connected in parallel; the compensation inductor (Ls) and the sampling resistor (Rs) are connected in series; and the compensation capacitor (C1) is located between the base and collector of the high-frequency power transistor (Q3).

2. The high-frequency high-current generating circuit based on gallium nitride power devices according to claim 1, characterized in that, The voltage-following Howland current source includes a first high-voltage high-speed operational amplifier (U1), a second high-voltage high-speed operational amplifier (U2), a first feedback resistor (R1) to a fourth feedback resistor (R4), a sampling resistor (Rs), and a compensation inductor (Ls). The bias and amplification circuits and the quasi-complementary output circuit of the gallium nitride power device are placed within the Howland current source feedback loop. The first high-voltage high-speed operational amplifier (U1) and the second high-voltage high-speed operational amplifier (U2) operate at a power supply of 450V or higher, have a slew rate of over 1000V / µs, a full-power bandwidth of over 500kHz, and an output current of 0.2A.

3. An application of a high-frequency, high-current generating circuit based on gallium nitride power devices, characterized in that, This includes the high-frequency high-current generating circuit based on gallium nitride power devices as described in any one of claims 1-2, and the extended application of the high-frequency high-current generating circuit based on gallium nitride power devices in the quasi-complementary output circuit consisting of multiple pairs of gallium nitride power devices.

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