In modern motor drive systems, high efficiency and safety are core design goals, with the performance of power semiconductor devices (such as IGBTs, MOSFETs, SiC, and GaN devices) directly determining system efficiency and stability. Gate driver DC-DC power modules, as key components connecting control circuits to power circuits, not only provide stable isolated power for gate drive circuits but also significantly improve the switching speed and reliability of power devices. This article will explore how gate driver DC-DC power modules optimize power supply and isolation performance to comprehensively enhance the efficiency and safety of motor drive systems, highlighting the functional features of gate driver DC-DC power modules introduced by Murata.
Gate driver DC-DC power modules hold key role in motor drive systems
In fields such as industrial automation, electric vehicles, and renewable energy generation, efficient gate driver solutions are core technologies for achieving energy savings and safe operation. Gate driver DC-DC power modules play a key role in motor drive systems, particularly for high power density, high efficiency, and stable motor drive designs. These modules provide isolated and stable driving voltages and currents for power semiconductor devices such as IGBTs, MOSFETs, or SiC/GaN devices. Gate driver DC-DC power modules must offer isolated power to achieve electrical isolation between control and power circuits, improving system immunity to interference and ensuring safety. They provide stable power output and reliable DC voltages for gate drivers, ensuring proper operation of power devices under varying conditions, while further meeting wide voltage range requirements to support the positive and negative gate drive voltages needed for different power devices.
Motor drives require efficient and precise control of power device switching actions. Generally, motor drive systems usually adopt PWM control method, and whether it can drive power devices efficiently is critical. Gate driver DC-DC modules support high-performance motor drive control, and provide low-power, high-efficiency gate drive voltages that reduce switching losses and improve overall drive system efficiency.
SiC and GaN power devices, widely used in modern motor drives, feature high switching speeds and higher gate drive voltage requirements (e.g., +15V/-4V). Gate driver DC-DC modules can precisely supply appropriate voltages and currents to fully leverage the performance advantages of these devices.
In motor drive systems, the drive circuit must be isolated from the high-voltage power circuit to protect low-voltage control systems and ensure personnel safety. Gate driver DC-DC modules with high isolation voltage (e.g., 3-5kV) prevent electrical noise or short circuits from affecting the control system.
These gate driver DC-DC modules also can support multiphase motor drive designs. For multiphase motors such as three-phase permanent magnet synchronous motors, each bridge leg’s high-side and low-side switching devices require independent power supply. Gate driver DC-DC modules facilitate a simplified system topology with multi-channel independent power solutions.
Additionally, gate driver DC-DC modules enhance system reliability by integrating protection functions such as undervoltage and over-temperature protection. These features improve module stability and fault tolerance, effectively boosting the overall reliability of motor drive systems.
Gate driver DC-DC modules have a wide range of technical application scenarios
Gate driver DC-DC modules have a wide range of technical application scenarios, including industrial motor drives, such as servo motors, inverters, and industrial automation equipment. They can also be applied in new energy vehicles, including electric vehicle drive inverters and charging systems. In wind power generation and photovoltaic inverter applications, gate driver DC-DC modules can provide stable gate drive for power semiconductors in high-voltage, high-efficiency scenarios. In rail transit applications, gate driver DC-DC modules can supply isolated power for power devices in high-power motor drives.
In the future, gate driver DC-DC modules will develop toward higher efficiency, requiring the development of modules that support higher conversion efficiency to meet the needs of low-loss, high-frequency power devices. As products move toward miniaturization and integration, modular designs will enable the integration of gate drivers and DC-DC power supplies in smaller packages, suitable for small motor drive designs. These modules will also need to support wide temperature ranges, ensuring reliable operation in extreme environments, such as automotive and grid equipment applications.
In the future, gate driver DC-DC power modules will not only provide stable power supply but will also directly impact the performance of power devices and the efficiency of drive systems, which is crucial for optimizing the performance of modern motor drive systems.
Diversified gate driver DC-DC power modules to meet various application needs
Murata has launched a variety of gate driver DC-DC power modules for gate drive power DC-DC applications. A typical use case is providing drive power for the "High side" and "Low side" of a full-bridge motor, which can be half-bridge, full-bridge, or three-phase. The emitter of the High side switch is a high-voltage, high-frequency switching node, and it can use IGBT, MOSFET, SiC, or GaN devices. It requires a dual output voltage — +Ve and -Ve. The High side driver and related circuits must adopt an isolated design.
The power demand of the driver is met by the DC-DC module providing the average DC current to a single driver circuit, while nearby capacitors supply peak current for charging and discharging the gate capacitance each cycle. Derating and other losses in the drive must be considered. SiC and GaN devices have a lower Qg than IGBTs, but they may operate at much higher frequencies.
According to datasheets, most devices can be turned off with 0V. So why use a negative gate voltage? This is to counter parasitic inductance and the Miller capacitance effect. Negative gate drive overcomes parasitic inductance caused by the inductance of the source. When the IGBT turns off, the sudden stop of the current will cause a voltage spike that opposes the gate voltage. Regarding the Miller effect, during the turn-off period, the collector voltage rises rapidly, causing a current spike to flow through the Miller capacitance to the gate, resulting in a positive voltage across the gate resistor.
Why do gate driver DC-DC modules need isolation? Firstly, for safety. DC-DC can be part of a safety isolation system. For example, according to UL60950, a 690 VAC system needs a creepage distance and clearance of 14mm to meet reinforced insulation requirements. Additionally, isolation voltage must be supported, verified by applying a single, higher transient voltage than the operating voltage, held for one minute.
On the other hand, functional needs exist. In High-side applications, the DC-DC input-to-output must continuously switch at the PWM frequency across the entire HVDC link voltage. In this case, a one-minute transient voltage test is not a reliable isolation indicator. Compliance with partial discharge testing under IEC 60270 is the best way to ensure long-term reliability.
Partial discharge occurs because the breakdown voltage of small gaps (~3kV/mm) is much lower than that of surrounding solid insulation (~300kV/mm). This “inception voltage” can be used to measured and define the maximum operating voltage, ensuring long-term insulation reliability. While partial discharge may not cause immediate damage, it will degrade insulation performance over time.
High-performance key parameters surpassing competitors' products
Capacitance coupling is another phenomenon that requires attention. In high-side switches, the emitter is a high-voltage, high-frequency switching node. The entire HVDC link voltage continuously switches at PWM frequency from the DC-DC input to the output, with potentially high frequencies and voltage slew rates. For example, IGBTs typically reach about 30kV/μs, MOSFETs around 50kV/μs, and SiC/GaN devices can exceed 50kV/μs. The DC-DC isolation between input and output introduces capacitive coupling (Cc), across which high switching voltages cause pulse currents that may interfere with sensitive input pins. Common-mode transient immunity (CMTI) testing provides an indication of this failure level.
Murata’s gate driver DC-DC modules exhibit excellent capacitive coupling performance. For instance, the MGJ series offers the following specifications: the 1W MGJ1 has a coupling capacitance of 3pF; the 2W MGJ2 ranges from 2.8 to 4pF; and the 3W (MGJ3T) and 6W models (MGJ6T, MGJ60LP, -SIP, -DIP) feature 15pF.
There are multiple methods to achieve bipolar voltage, as different switching devices require different gate voltages depending on the manufacturer’s specifications. For example, IGBTs typically need +15V for positive voltage and -8.7V, -9V, -10V, or -15V for negative voltage. Silicon MOSFETs require +15V or +12V for positive voltage and -5V or -10V for negative voltage. SiC MOSFETs need +20V, +18V, or +15V for positive voltage and -5V, -4V, -3V, or -2.5V for negative voltage. GaN devices usually require +5V or +6V for positive voltage and -3V for negative voltage.
To meet these varying needs, Murata’s MGJ2 SIP delivers a total output power of 2W, offering traditional dual-winding methods to provide +ve and -ve gate drive voltages, including +15V/-15V, +15V/-5V, +15V/-8.7V, +20V/-5V, and +18V/-2.5V. Additional specific outputs can be achieved by adjusting the winding turns.
The MGJ3 and MGJ6 series, with output powers of 3W and 6W, respectively, use patented technology to flexibly configure triple voltage outputs, such as 20V/-5V (15V +5V, -5V) and 15V/-10V (15V, -5V -5V). The MGJ1 and MGJ2 SMD series, with 1W and 2W output powers, use internal Zener diodes for voltage division, offering specific +ve and -ve gate drive voltages, such as +15V/-5V (from a single 20V output), +15V/-9V (from a single 24V output), and +19V/-5V (from a single 24V output). Custom output can be provided by changing the Zener diodes.
Murata’s gate driver solutions are applicable in renewable energy (wind, solar, and backup batteries) inverters and high-speed, variable-speed motor drives. Key products include the MGN1, MGJ1/MGJ2, MGJ1 SIP, MGJ2B, and MGJ3/MGJ6 series. These offer a range of support for continuous barriers withstand voltage, isolation capacitance, safety certifications, CMTI, operating temperature, and power. Compared to competitors, Murata’s solutions perform well across these critical parameters.
Conclusion
The gate driver DC-DC power module plays a crucial role in motor drive systems, with its efficient power conversion, precise voltage output, and reliable electrical isolation directly impacting the performance of power semiconductor devices and the overall system efficiency. Moreover, by improving the system's anti-interference capability and operational safety, this module provides a solid technical foundation for motor drive solutions in industrial automation, electric vehicles, and renewable energy sectors. In the future, as power device technologies continue to advance, gate driver DC-DC modules will evolve towards higher efficiency, greater power density, and stronger integration, making a more significant contribution to the development of high-performance motor drive systems. Murata offers a comprehensive product line of gate driver DC-DC power modules, which can meet diverse application needs. We invite you to learn more about our related product information.