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Three key features of improving energy efficiency technology of electric vehicles

the world's leading semiconductor solution supplier Renesas Electronics Co., Ltd. (hereinafter referred to as "Renesas Electronics") announced that it has successfully developed a special circuit technology for motor control, which can help the car factory meet more stringent carbon emission standards

this newly developed technology is called "intelligent motor timer system (IMTS)", which is a special circuit module that can be integrated into the microcontrollers of future electric vehicles and hybrid electric vehicles. For field oriented control (FOC), which is very important in electric vehicle motor control, its operating time is only 0.8 microseconds( μ s) , the fastest speed in the world, less than one tenth of the software processing time on CPUs running at the same operating frequency. This will help to develop high-speed electric vehicle motors with excellent energy efficiency such as qei and inverter systems with high-speed switching performance

in addition, this unique circuit can also provide functional safety support for automotive powertrain

in recent years, with the continuous improvement of fuel efficiency requirements, the share of electric vehicles, hybrid electric vehicles and plug-in hybrid electric vehicles in the automotive market has gradually expanded. In order to further improve the application range of electric vehicles, it is necessary to enhance the energy efficiency of motor control

therefore, it is not only necessary to improve the mechanical performance of the motor, but also very important to improve the function and performance of the electronic control unit of the motor. The electronic control units that can be used to support the next generation of electric vehicles, hybrid electric vehicles and plug-in hybrid electric vehicles require very advanced functions and complex control software, which is bound to significantly increase the processing load of the micro controller in these electronic control units. The full name of the project is plasticpackagingrecyclingusingintelligentseparationtechnologiesformaterials (PRISM) controller

at the same time, in order to ensure high reliability in high temperature environment, it is also necessary to limit the heat generated by the automobile microcontroller. Therefore, it is necessary to keep the operating frequency of the internal circuit of the microcontroller (including the CPU core) at a relatively low level, which will hinder the improvement of its performance

in order to meet the above requirements, among the numerous motor controls executed by the microcontroller, Renesas electronics takes IMTS as a special circuit module for static processing, because the processing process usually requires high response performance, such as collecting sensor data, calculating and outputting control values on this basis. IMTS is independent of CPU and can run autonomously, which can significantly reduce the CPU load of motor control microcontroller. The saved CPU performance can be allocated to the advanced motor control algorithm, so as to improve the energy efficiency of electric vehicles, hybrid electric vehicles and plug-in hybrid electric vehicles in the future

key characteristics of special motor control circuit technology:

(1) developing special circuit module for static motor control processing and circuit technology supporting independent operation

motor control requires a series of static processing involving field oriented control (FOC). In each control cycle, MCU will collect motor current value and angle value and calculate the control value of the next cycle; PWM output is generated based on the control value

when a variety of motor control programs are running at the same time, the total processing load generated by Renesas 40nm automotive MCU operating at 320 MHz frequency can account for up to 90% of its CPU performance. The newly developed IMTS is a special circuit module supporting FOC operation, which can share the processing load of CPU to a large extent. It is configured in the form of a special motor control timer circuit, and the link is compact. Therefore, a series of processing performed in the control cycle managed by each timer circuit - from obtaining the current value and angle value to PWM signal output, can run independently of the CPU

thus, the load that should have been handled by the CPU has been eliminated, and the released CPU performance can now be allocated to this forum to focus on the innovative development and utilization of automotive lightweight technology and plastic parts, including software with advanced control algorithms, to improve energy efficiency. By configuring dedicated circuits for FOC, IMTS can reduce the operation processing time to 0.8 μ s. Compared with the software configured on the CPU, it takes less than one tenth of its time

for power supply equipment made of new materials, the processing performance achieved by the new technology can meet the inverter control requirements with high-speed switching performance (performance example: 100kHz switching frequency, control cycle 10 μ s) Including inverters using power supply equipment made of silicon carbide and other new materials

(2) the development of professional technology provides functional safety guarantee for automotive power system control

automotive power system control must be able to ensure functional safety, so as to timely detect component failures and automatically convert the system to a safe state. This is generally achieved by using two microcontrollers to provide system redundancy, or MCU with internal redundant circuit can be used, but the cost of the latter will be relatively high

the MCU used by the new technology is equipped with two dual core step locked CPUs, which can regularly monitor the internal operation of IMTS circuit. This method can not only reduce the cost, but also realize high-speed control and functional safety. Functional safety will increase the load of CPU, but in actual use, it only accounts for 2.4% of the total processing capacity of CPU (Note 5)

(3) the circuit technology can flexibly correct the signal error of external sensors

in order to achieve the accurate processing performance of high-precision microcontroller, it is necessary to collect high-precision sensor signal values. However, in actual operation, there will be errors caused by various reasons, such as errors caused by the installation position of the sensor. The newly developed IMTS can load user developed software to correct errors in real time. In addition, the IMTS can perform the correction process independently without causing additional load to the CPU. Correct sensor signal value can achieve more accurate processing performance and higher energy efficiency during motor operation

Renesas electronics is currently testing a 40 nm MCU prototype (with on-chip flash memory) using the technology that must jointly create the most cost-effective solution. It uses a real motor drive system to confirm the operation in the real system. Through this special motor control circuit technology, Renesas electronics aims to achieve higher energy efficiency for electronic control units of electric vehicles, hybrid electric vehicles and plug-in hybrid electric vehicles

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