Overview of Existing Technologies The design of drive circuits for high-power devices in switching power supplies has always been one of the key technologies in the power supply field. Ordinary high-power transistors and insulated-gate power devices (including VMOS field-effect transistors and IGBT insulated-gate bipolar high-power transistors, etc.) have vastly different drive requirements and technologies due to their different device structures. The former are current-controlled devices, requiring a suitable current waveform for drive; the latter are electric field-controlled devices, requiring a certain voltage for drive. This article only introduces the latter. The source and gate of a VMOS field-effect transistor (and IGBT insulated-gate bipolar high-power transistors, etc.) are insulated silicon dioxide structures, preventing DC current from passing through, thus the low-frequency static drive power is close to zero. However, a gate capacitance Cgs is formed between the gate and source, thus requiring a certain amount of dynamic drive power during high-frequency alternating turn-on and turn-off. The Cgs of low-power VMOS transistors is generally within 10-100pF. For high-power insulated-gate power devices, due to the larger gate capacitance Cgs, ranging from 1-100nF or even larger, a larger dynamic drive power is required. Furthermore, due to the Miller capacitance Cdg from the drain to the gate, the gate drive power is not negligible. Many mature circuits are currently available for reliably driving insulated-gate devices. When isolation between the drive signal and the power device is not required, the design of the drive circuit is relatively simple, and some excellent driver integrated circuits, such as the IR2110, are available. When electrical isolation between the input and output of the driver is required, there are generally two approaches: using an optocoupler or using a pulse transformer to provide electrical isolation. The advantage of an optocoupler is its small size, but its disadvantages are: A. Slow response, resulting in a large delay time (even high-speed optocouplers generally have a delay greater than 500ns); B. The output stage of the optocoupler requires an isolated auxiliary power supply. There are three methods for using a pulse transformer to isolate and drive insulated-gate power devices: passive, active, and self-powered drive. The passive method directly drives the insulated-gate device (IGD) using the output of the transformer's secondary winding. This method is simple and does not require a separate drive power supply. However, because the gate-source capacitance (Cgs) of the IGD is generally large, the waveform (Vgs) between the gate and source will be significantly distorted unless the primary input signal is changed to a high-power signal, and the corresponding pulse transformer should be larger. In the active method, the transformer only provides an isolated signal, and a shaping and amplifying circuit is used on the secondary winding to drive the IGD. This results in a better drive waveform, but requires an additional isolated auxiliary power supply to the amplifier. Improper handling of the auxiliary power supply can introduce parasitic interference. Existing self-powered methods involve high-frequency (above 1MHz) modulation of the PWM drive signal. This signal is applied to the primary winding of the isolation pulse transformer, and the self-powered signal is obtained through direct rectification on the secondary winding. The original PWM modulation signal needs to be demodulated. Obviously, this method is not simple, and the price is also higher. The advantage of modulation is that the duty cycle that can be transmitted is unlimited. Time-sharing self-contained power supplies are an innovative technology from Beijing Luomuyuan Company. Their characteristic is that the transformer only transmits PWM information on the rising and falling edges of the input PWM signal, and transmits the energy required for driving during the flat-top phase of the input signal, resulting in very low waveform distortion. The disadvantage of this technology is that the duty cycle can generally only reach 5-95%. Market Driver Product Overview Currently, finished drivers on the market can be divided into two types according to the electrical relationship between the drive signal and the driven insulated-gate device: direct drive and isolated drive. Isolated drive uses optocouplers and pulse transformers as isolation components. Non-isolated Direct Drivers In Boost, full-wave, forward, or flyback circuits, the source of the power switch is located at the lower rail of the input power supply. The drive signal output by the PWM IC generally does not need to be isolated from the switch and can be directly driven. If a larger drive capability is required, an amplifier stage can be added or a finished driver can be connected in series. Direct drive finished drivers generally use thin-film technology to fabricate the IC circuit, with the regulating resistor and a large capacitor connected via external pins. There are many types of commercially available drivers, such as TI's UCC37XXX series, TOSIBA's TPS28XX series, Onsemi's MC3315X series, SHARP's PC9XX series, IR's IR21XX series, and so on. This article will not go into detail about them; readers can consult relevant materials. Isolation Drivers Using Optocouplers Most isolation driver products use optocouplers to isolate the input drive signal from the driven insulated gate device (IGDD). They employ thick-film technology to fabricate the HIC circuit, and some resistors and capacitors are also connected via pins. Currently available optocoupler-type drivers mainly include FUJI's EXB8XX series, MITSUBISHI's M579XX series, INDA's HR065, Xi'an Aipake Power Electronics Co., Ltd.'s HL402B, and Beijing Luomuyuan Electronic Technology Co., Ltd.'s TX-KA series. The TX-KA series drivers have comprehensive protection functions, high operating frequencies, low prices, and are compatible with many other types of drivers. These types of products, due to the speed limitations of optocouplers, generally operate at frequencies below 50kHz (TX-KA101 can reach 80kHz). Their advantages include overcurrent protection in most cases, with the overcurrent signal derived from the IGBT's voltage drop. A common disadvantage is the need for one or two independent auxiliary power supplies, making them somewhat cumbersome to use. Due to cost considerations, these products are relatively expensive and therefore only suitable for driving IGBT modules in high-power power supplies, making them difficult to promote in low-to-medium power applications. Transformer-isolated drivers with a single power input and built-in DC/DC auxiliary power supply: Currently, there are drivers such as CONCEPT's 2SD315A and SEMIKRON's SKHI22, which use two pulse transformers to transmit the half-bridge drive signal. They require a single power input and have a built-in DC/DC power supply to provide the two auxiliary power supplies needed for the drive. The output drive signal quality is good, and the drive capability is strong, but due to the complex structure, they are large and expensive, making them only suitable for ultra-high power supplies. The signal transmission of the above two types of driver boards uses modulation technology. Beijing Luomuyuan Company has also developed a transformer-isolated driver, model KB101, which can operate at higher frequencies but requires an auxiliary power supply from the user. Transformer-isolated, Modulated Self-Powered Drivers Modulated self-powered drivers use a transformer for electrical isolation, transmitting the energy required for drive through a carrier frequency and transmitting PWM information through a modulation signal. Therefore, they can handle PWM signals with a duty cycle of 0-100%. Many current driver boards use this technology, such as Semikron's SKHI27. Monolithic modulation drivers are not currently available for sale overseas. However, there is a two-chip combination, such as the UNITRODE UC3724/25 integrated circuit pair. The 3724 is connected to the driver source, and the 3725 is connected to the driven insulated-gate device (IGAD). A pulse transformer is connected between the 3724 and 3725 by the user. The PWM signal is modulated onto a carrier wave of approximately 1MHz in the UC3724 and sent to the primary winding of the isolation pulse transformer. The secondary output signal is directly rectified in the UC3725 to obtain its own power supply, and the original PWM signal is obtained through demodulation. Domestically, there are single-chip modulation drivers such as the TX-KE series drivers from Beijing Luomuyuan. Modulation drivers, besides not requiring an auxiliary power supply from the user, also have the characteristic of high isolation voltage, but the price is relatively high. Transformer-isolated, time-sharing self-powered drivers The advantages of time-sharing self-powered drivers are: low price, applicable to power supplies of various sizes; the driver itself does not require a separate power supply, simplifying the circuit; minimal delay in the output drive pulse, and steep rise and fall edges; high operating frequency; and the ability to operate within a duty cycle range of 5-95%. The disadvantages of time-sharing self-powered drivers are: at lower operating frequencies, the transformer is larger, making thick-film transformers difficult to manufacture; and due to the limited energy provided by the self-powered supply, it is difficult to drive IGBTs above 300A/1200V. TX Series Driver Introduction Our company offers seven series of IGBT and MOSFET drivers, including five series of driver products, one series of driver boards, and one series of driver power supplies. TX-KA Series IGBT Drivers: Employ high-speed optocoupler isolation, providing comprehensive protection measures and signal blocking functionality to maximize IGBT protection. Several models are compatible with foreign products. The KA101 features comprehensive three-stage short-circuit protection. TX-KB Series IGBT Drivers: Employ transformer isolation, operate at higher frequencies, and offer comprehensive protection functions, including signal blocking. TX-KC Series IGBT Drivers: Provide comprehensive protection functions, including signal blocking functionality. Employ transformer isolation, and the secondary side uses a time-sharing self-powered supply, eliminating the need for a user-provided isolation power supply. TX-KD Series IGBT Drivers A variety of types are available. They employ transformer isolation, with a time-sharing self-powered secondary winding. Duty cycles can reach 5-95%. They are easy to use and relatively inexpensive, capable of driving various single-transistor and half-bridge, dual-forward, and dual-transistor circuits in synchronous rectifier circuits. However, they are generally not suitable for very low frequency applications. TX-KE Series MOSFET and IGBT Drivers Transformer isolation, using modulation technology. The secondary winding uses a modulated self-powered winding, eliminating the need for a user-provided isolation power supply. PWM switching information is transmitted to the secondary winding through modulation. They have a wide operating frequency range, with duty cycles between 0-100%. Driver Board Series Integrates the driver and its peripheral components (as well as auxiliary power supplies). Combined with the user's main control board and power devices, it forms a complete power supply system, capable of driving IGBTs with a maximum current of 1000A or more. Onboard auxiliary power supplies are available in AC/DC, DC/DC, and self-powered types. Driver Power Supplies Specifically designed for drivers, with high isolation voltage, available in both AC/DC and DC/DC versions.