Consumers want batteries product has excellent reliability and prolong the service life of batteries, such as portable power tools, portable medical equipment or home automation products. With the rapid growth, the market of these products manufacturers started using a new generation of lithium ion battery,Li-ion)Power supply of the brushless dc (刷)The motor. Brushless dc motor is very suitable for need of the application of high reliability, high efficiency and high power density. Since there is no brush wear and replace, the reliability of brushless dc motor is very high. Therefore, its life expectancy is significantly higher than a brush motor, thus greatly extend the service life of the product. On the other hand, the lithium battery has been widely used in all kinds of consumer electronics products, such as smart phones and tablets, etc. Lithium-ion batteries for its superior energy density and the static charge loss characteristics of slow, become one of the most widely use batteries. Lithium-ion batteries used in consumer electronics products not only, and is more and more applied in the past use lead-acid battery products, such as golf carts, electric lawn mower. New lithium-ion battery power brushless motors work long hours, product reliability is higher, so as to promote the battery-powered electric product market development. Many products are upgrading the new battery, including hand drill, battery power tools such as chain saws, blower, and small electric vehicles (Electric bicycle and wheelchair)And uninterrupted power supply, etc. These new products also need to update the MOSFET drive bridge driver, to use a variety of functions, while reducing its cooperate with integrated BLDC motor motors and the lithium-ion batteries. In particular, the innovation of the new bridge driver provides security function, can prevent the motor load regeneration reduction during the battery is out of control in lithium ion battery damage and damage, further extend the battery and the service life of the multiple class lithium battery products. Upgrade to the lithium ion battery and lithium ion battery brushless dc motor of high energy density is superior to other battery technologies (Such as nickel cadmium, nickel metal hydride, or lead acid battery)One of the main advantages. Typically, lithium battery energy density for two to three times that of other battery technologies. High energy density can decrease the size of the battery pack, reduce the weight of the hand electric tools and further miniaturization. In addition, without any increase in the original battery pack size or weight, can prolong the work time of electric bicycle or wheelchair. However, high energy density of lithium battery is not without its application problems. Lithium battery is not what we usually understand sense the battery voltage source. Lithium battery internal inductance is quite high,-nH)When using the PWM drive motor, resulting in produce clear ripple voltage. The simple solution is to add enough capacitance between the MOSFET bridge, but due to the limitation of space and cost, can't use this method. In addition to the space is limited, PCB structure constraint is also many use battery-powered handheld electric tool main problem. In some applications, the bridge arm jumper between small capacitance will also make the bridge circuit produces serious voltage ripple. In order to -V lithium-ion batteries, for example, big load conditions, the capacitance is bridged by minimal capacity of lithium battery valley value voltage could be as low as V, compared with V peak voltage. Another consideration is that during the working conditions of overload, such as the rotor stall, in this case, the battery voltage drops to a very low value. These cases, the controller (Rather than drive)To be able to decide how to respond to these extreme working conditions.
