Digital Software Technology was started in the previous simulation of switching power supply on dominating the world wide popularity. LED lighting, power and industrial equipment, automotive and other fields have also begun to import digital control power supply. By adding the communication function or method to change the control method for dynamic control, in improving the power efficiency, reduce product size and shorten the development time has played an effect. DSP has long been the subject of cost issues, but also general-purpose microcontrollers with prices as low-priced products come out gradually resolved.
The digital control of power contribute to AC-DC power supplies and DC-DC converters such as small size and high efficiency of about 5 years ago attention. This “digital power,” the application of the expansion in the past year quietly.
Previously, only import the digital power supply unit with no power failure (UPS), communication products, servers and solar power conditioner, and other infrastructure part of the product.But recently, LED lighting appliances, automotive, industrial equipment and even some consumer products are beginning to use digital power supply (Figure 1).
The appearance of a low-cost opportunity for DSP
The application of digital power to expand the main reason is the unit price is only several hundred yen more than 100 yen ~ emergence of power control IC products for digital power.Digital power supply control IC’s cost down to less than 100 yen with analog power control IC match level. Microchip Technology (Microchip Technology), Texas Instruments (TI) as well as new wireless and other semiconductor manufacturers from Japan around 2008 have launched a dedicated low-cost digital power control IC. Recently, most of the digital power supply products are used by these enterprises IC.
Before the introduction of monovalent form digital power needs of thousands of yen, up from 1000′s high-performance DSP used as the control IC. The IC’s operating frequency is 100MHz or more DSP power consumption is only on for nearly 1W, the usual switching power supply for the control of the target surplus. This is the use of DSP in the digital power only over 1kW UPS and other large devices used only the main reason.
However, manufacturers should be part of the advanced power requirements, Microchip Technology and TI launched with the required number of power features, and general-purpose micro-controller prices as cheap as the DSP, also the “DSP micro-controller.” * 1,000 yen by more than the cost of a substantial drop hundreds of DSP yen, basically solved the biggest bottleneck in digital power – control IC problem of high costs.
* DSP = microcontroller microcontrollers in general common elements in the formation of integrated DSP products.Characterized by the hardware implementation of the Harvard architecture (Harvard Architecture) and loop control, etc.. From about 10 years ago, the Japanese domestic semiconductor manufacturers began to put DSP microcontrollers.
After importing the digital control, analog control and the current power than ordinary size can be reduced about 30%, 20% parts count reduction of about 2 ~ 5% efficiency (Figure 2), the basic switching power supply can enhance the performance. As the digital power supply control IC has been able to swallow the price, so in the future scope of application may be extended to AC-DC power supplies, insulation type DC-DC converters and non-insulating type DC-DC converters in the fields of switching power supply . ”Every year, saying digital power ‘will be popular this year’ in 2010, really grew out of use of products” (TI Business Technology Division in Japan, market and application of technical systems including design services by the Department of Financial Jin Chun lines).
According to the U.S. power electronics related Darnell Group research firm predicted that by 2014 digital power IC shipments will be expanded to 2.5 times the current 12.3 billion, according to the amount of conversion will maintain an average annual supply nearly 30% growth. In addition, to optimize the efficiency of energy use within the family, the wisdom of residential (Smart House) and so attention will also speed up the popularization of digital power. Through the simulation had been the power of world domination to install the software and communications capabilities, different implementations can use “wisdom” of the power of the enormous number of possibilities.
To 1MHz the following, 100W power supply for the object of more than
Although digital control has been easy to import, but it does not mean that can be applied to arbitrary power, and switching frequency of the power is still limited.
DSP digital power consumption of 200mW microcontroller will be about their own power. So, not suitable for smaller power output.Because they can not disregard the power for DSP microcontrollers resulting inefficiencies. Integrated power supply technical personnel point of view, the current power output of more than 50 ~ 100W power supply is the best target.
In addition, cost constraints are very strict, hard to find in the digital power supply function of (Ru equipped with communications functions, etc.) the value of the digital home appliances with the power supply side, “digital power supply of the import still needs time” (in LCD TV consumer products business with the power Sanken Electric).
From the switching frequency in terms of frequency around 1MHz power as the best application of the following objects (Figure 1).The digital power supply, micro-controller via DSP AD converter output voltage and output current monitoring, using software control voltage and current stability. The reason is that with the use of operational amplifier (error amplifier) Continuous detection of the output voltage and target voltage difference between the analog control different digital control will occur 1μs about the AD conversion time, and use software computing operation amount of calculation time digital control specificdelay.
Low-power non-isolated type DC-DC converters called for a thorough realization of small area, such as battery-powered portable with a DC-DC converters, etc. Therefore, the switching frequency for the 2M ~ 8MHz.Currently, the field of power is difficult to micro-controller based on DSP digital control.
However, in digital power, the use of dedicated logic circuits based on hardware rather than on DSP software to perform the PI control, control algorithms, the can supports more than 1MHz switching frequency (Figure 1). The reason is that the way the output voltage, etc. before the AD converter and DSP are the same way as the hardware used to implement PI control of digital routing device, so this part of the calculus of time and DSP approach than can be shortened.
Use of dedicated digital control logic circuit, the PI control parameters to make it easier to change, and support multi-phase composition and other uses analog control more useful than 1).But the control method is limited, unlike the DSP as a flexible way.Business-specific logic in the way of the Japanese digital control IC’s agent said that “almost no volume.” Today, the number of power changes, can be expected in future to expand the use of DSP methods.
