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  Date: 29/10/2014

ST India's Sapna Mongia on power semiconductor market trends

With the fast-growing market of solar power, energy efficient power sources and electric car, the power semiconductor market is going to be as hot as mobile communication market in very near future. One of the leading vendor in power semiconductor market is ST Microelectronics. In an email interview with EE Herald, Sapna Mongia, Technical Marketing Head, IPG Group, STMicroelectronics India, answers to some of the latest technology and market trends related questions on power semiconductor domain. Below is the full Q and A session:

What are the global market trends in power semiconductor area?

Sapna Mongia: The ever-increasing demand for electricity is driving developments in the power domain to optimize energy generation, distribution, and management. The Smart Grid aims to optimize a utility’s electric distribution network by monitoring, communicating, and increasing consumer awareness of usage while Smart energy meters, Solar inverters, solar charge controller, solar LED lights, digital power supply are creating innovation in the global power market.Meanwhile, applications with smart-power features ensure that those applications operate as efficiently as possible.

The Semiconductor industry is developing products which are helping the power sector in generation and distribution of power through Smart Grid and Smart Metering solutions. Consumers are benefiting from products like LED lights (low cost high efficiency), higher efficiency gadget chargers with much lower standby power and higher efficiency domestic equipment that can operate more efficiently and therefore don’t need to consume as much energy. And in the Industrial segment, semiconductors offer better and more efficient HVAC, motor drives, and industrial control systems.

Efficient energy generation, distribution, conversion and consumption are all critical components in meeting our growing energy needs. In addition to performance and cost, power consumption has become an important factor in benchmarking an IC design. Also power awareness levels are escalating and the semiconductor industry’s involvement in reducing global energy consumption has turned out to be progressively more significant.

Is India also in line with global trend? Any India specific power semiconductor trends?

Sapna Mongia: As in other markets, India is moving to more efficient and reliable power systems with the use of more efficient power inverters, solar charge controller, LED lighting, induction cooking, Brushless-motor Direct Current ceiling fans, power supplies for set-top box, metering systems, and communication modules for smart energy meters. There are enormous opportunities in both existing and emerging applications.

For instance, we believe the smart grid will benefit the Indian power sector on many levels. The technology optimizes power delivery and facilitates two-way communication across the grid, enabling end-user energy management, minimizing power disruptions and transporting only the required amount of power. The result better balances power demand through the day, lowers costs for the utility and the customer, and ensures more reliable power and reduced carbon emissions. This is precisely what ST is working toward.

In case of smart power, where the power device need to be smart?

Sapna Mongia: Smart power enhances innovative solutions for handling power in various applications like Switched-Mode Power Supplies, lighting, and handheld equipment. With the integration of smart controls and power together, devices for power management are being developed. ST, among others, is integrating smart controls and power –transistors and-converters as well as industrial ICs that will meet the needs of applications and industries from HVAC, home appliances, robotics, healthcare, home automation, factory automation, POS terminals and power supply and management. ST has developed a new family dual in line intelligent power modules with optional extra features called small low–loss intelligent molded module which will provide higher efficiency in power to the customers.
Smart energy is particular important to India because it will allow the country to leapfrog more than developed countries that have to replace infrastructure. In power generation, new power technologies improve the output efficiency of solar panels; new communication devices for smart metering and smart grid solutions improve distribution and remote management of energy. Efficient Power MOSFET transistors are already in Uninterrupted Power Supplies (UPS) in countless homes and offices across India. Finally at end consumption, the millions of Smart LED modules and motorized appliances optimize energy use. In Solar applications, Smart integrated PV power converter with inbuilt Maximum Power Point tracking (MPPT) algorithm makes the solar solution more efficient and controlled.

With solar getting nearly main stream, what are the design issues ST addressing related to devices which work both with solar as well as mains?

Sapna Mongia: In photovoltaic applications, the DC electricity produced by the PV panel array is converted into the alternating AC current electricity suitable for grid insertion by a centralized power converter device, named also “inverter.” The inverter also manages the MPPT (Maximum Power Point Tracker) algorithm to maximize the DC power produced by PV panels at any temperature and cloud conditions. The inverter also tracks power output from the PV modules while maintaining continuous grid connectivity. Overall performance of the inverter impacts the efficiency of the whole PV system. That’s why a monolithic power converter device, such as the SPV1020, embedded in the panel which implements the MPPT algorithm, maximizes the power extracted from the panel and maximizes the overall system efficiency. The SPV1020 breaks with the paradigm of the centralized power conversion by moving part of the electronics from the inverter into the panel. In this new distributed architecture one or more power converter devices are integrated into the panel, the PV cells are connected in a few strings and each cell-string supplies one converter. By computing the maximum power point for each cells-string, the SPV1020 delivers greater efficiency in a distributed architecture than the conventional topology where the MPPT is computed in the main centralized inverter.

For Mains-based applications, ST has added two miniature motor drivers to its range of SLLIMM (Small Low-Loss Intelligent Molded Modules). These motor drivers enable domestic appliances to deliver better energy ratings. Energy marking and labeling schemes, such as the ENERGY STAR mark and in-store energy rating labels, which are mandatory in many countries and communities worldwide, give consumers the tools to identify energy efficient products and intelligent motor controllers provide the key to using less energy, while enabling new features and quieter operation in dishwashers, refrigerators, air conditioners and fans, and industrial drives. ST’s new SLLIMM nano family extends the portfolio of SLIMM intelligent power modules for appliance motor drivers in a single module that connect directly between the central microcontroller and the motor. Compared to a conventional driver, which typically requires more than 30 individual components, ST’s modular solution reduces costs by simplifying design and significantly reducing component count while saving space, improving reliability and lowering electromagnetic emissions (EMI). The modules are also ideal for small built-in motor applications where assembly space is limited.

There is good demand for compound semiconductor based discrete power semiconductors such as SiC, GAN? Are they really threatening silicon?

Sapna Mongia: The smart grid and renewable energy are pushing Power electronics to solve new challenges. For certain high-power applications Silicon Carbide devices will find a niche and Gallium Nitride will find use in high-speed applications. In general, though, silicon will continue to be used widely since it is scalable in power and phases. And monolithic ICs will be used in low power applications.

ST trials, using the Company’s latest 1200V silicon carbide diodes, have delivered a 2% increase in overall inverter yield, even when operating at high load and high frequency. ST has introduced several innovative technologies that improve efficiency in solar-power converters, include our proprietary MDmesh and STripFET VII DeepGATE power MOSFETs which ensure ultra-low loss performance, the trench-gate field-stop IGBTs, and the second generation of silicon carbide (SiC) Schottky diodes for minimizing switching losses and improving thermal performance in solar-power systems, where capturing every fractional improvement in energy efficiency is valuable.
New dual-configuration Schottky silicon-carbide (SiC) diodes from ST are the first such devices in the industry with a voltage rating of 650V per diode in a choice of common-cathode or series configurations allowing use in interleaved or bridgeless power-factor correction (PFC) circuits.

We are a leading innovator of SiC power semiconductors that have inherently higher energy efficiency and ruggedness compared to ordinary silicon alternatives. ST’s STPSC6/8/10TH13TI and STPSC8/12/16/20H065C devices1 combine SiC performance advantages with the space savings and EMI reduction of dual integrated diodes. They are ideal for interleaved or bridgeless PFC topologies that enhance energy efficiency of equipment such as server and telecom power supplies, solar inverters or electric-vehicle charging stations. The industry-unique diodes eliminate energy losses due to reverse recovery at turn-off, thereby optimizing switching efficiency, and the 650V voltage rating provides increased safety margin against hazardous reverse-voltage spikes. In addition, ceramic isolation built into the package of the STPSCxxTH13TI devices simplifies attachment to an external heatsink, allowing the removal of the usual external isolation

Do you see 2014 an important year for LED lighting? Is the cost coming down?

Sapna Mongia: Consumers are benefiting from products like LED lights, higher efficiency gadget chargers with much lower standby power, and higher efficiency domestic equipment that operates more efficiently and consumes less energy. The ongoing revolution in lighting with the move to more energy efficient Compact Fluorescent, Halogen and LED lamps has led to big growth in power semiconductors for lighting applications. A key factor contributing to this success is the declining price of LEDs. ST's long-term partnerships with the major lighting suppliers combined with our leadership discrete and integrated power devices enable us to offer high efficiency, low-cost, small solutions for all lighting applications. These include industrial, residential, commercial, architectural and street lighting.

What are latest topologies for energy efficiency in switching power supplies now?

Sapna Mongia: In a switched-mode power supply (SMPS), the AC mains input is directly rectified and then filtered to obtain a DC voltage. The resulting DC voltage is then switched at a high frequency (typically 10 kHz — 1 MHz), by electronic switching circuitry, producing an AC current that can pass through a high-frequency transformer or inductor. Higher switching frequencies enable the use of transformers and filter capacitors that are much smaller, lighter, and less expensive. After the inductor or transformer secondary, the high frequency AC is rectified and filtered to produce the stabilized DC output voltage. Depending on the power range, input voltage range, output voltages, space constraints and efficiency goals of the power supply, different topologies provide better trade-offs. ST’s key products for AC–DC converters are the VIPer II range of integrated high-voltage converters, PWM, PFC and Synchronous rectification controllers and high-voltage MOSFETFly-back converters are mainly used in AC-to-DC power supplies. This kind of converter is a galvanically isolated version of the buck-boost converter where the inductor has been replaced by a transformer. A positive output is obtained by an appropriate coupling of the transformer windings.
Forward converters are mainly used in AC-to-DC power supplies, and are a form of galvanic isolated buck converter. These converters are used for offline applications requiring higher output power than flyback circuits. Compared to flyback converters, forward converters are more energy efficient. Our VIPer series high-voltage converters from the mains are monolithic ICs integrating a PWM controller and a 700 V vertical power MOSFET, offering a compact and cost-effective solution suitable for a wide range of applications.

Sapna Mongia ST

Pic above: Sapna Mongia
Author: Srinivasa Reddy N
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