Electric vehicles as a new means of transport, has actually been accepted by the masses. Especially in the current high oil prices, restricted motorcycle license issuance, the car unattainable dream of the case, the electric car more and more people of all ages. In China, a "bicycle kingdom", the Utility Vehicles market space is worth the wait. Insiders predict that the next few years, almost equivalent to the capacity of the electric car market capacity bikes, bike 450 million users nationwide at least 300 million users will be users of electric vehicles. With the electric vehicle market to mature, gradually brushless electric cars account for 80% market share, brushless motor controller is also continuous technological progress was loved by the majority of users, and will continue to emerge, to enrich capabilities to adapt to market changes.

Cypress Semiconductor PSoC microprocessor in the United States has introduced a field-programmable system on chip. Generic chip with analog and digital modules, users can develop needs, free call to the module, a dynamic mixed-signal array configuration. Text to CY8C24423, for example, introduced PSoC brushless motor controllers in electric vehicles on the application, it will signal to the voltage and current amplification, processing, analog-digital conversion, and integration of all the PWM signal output to the internal microprocessor to complete reduce the chip peripheral devices to improve the overall system integration performance and reliability.

Programmable System on Chip

Cypress Semiconductor Corp. initiated by the United States and launched entirely based on a common IP blocks, selected by a programmable SoC idea to form the product, and to the development of single-chip SoC from the MCU to promote a new stage. This programmable SoC named Programmable System on Chip (PSoC), from the basic CPU core and default peripheral device composed of a proprietary MCU is integrated in and around the PSoC blocks (configurable analog and digital peripherals device arrays), the use of programmable interconnect array chip, the chip can be effectively configured analog and digital circuits resources to achieve the purpose programmable system on chip.

Compared with the traditional MCU, a fundamental sense, the PSoC family is a micro-controller and a programmable system on chip micro-controller, which allows designers to gradually get rid of the emergence of a board-level electronic system level design methodology and into the chip-level electronic system design, reduce chip varieties and specifications, and more conducive to new product development and upgrading. With the same price of an ordinary single-chip comparison, its rich internal resources, innovative design interface, flexible design methods, and simple programming skills are so highly characteristic. PSoC completely different from the conventional microprocessor. PSoC developers do not need to build their own ADC, DAC and other peripheral devices, PSoC's configurable through the deployment of resources, and the success of PSoC to control the introduction of dynamic re-configuration feature, the real line programmable, we can see, a PSoC microcontroller can replace many types of microcontrollers.

PSoC's internal block diagram of the structure and resources

Cypress CY8C21 × × × ~ 29 × × × series of internal structure shown in Figure 1. The resources include:
1 processor core

PSoC microprocessor CY8C21 × × × ~ 29 × × × series devices use a powerful 8-bit Harvard architecture processor core (M8C CPU), it has separate program memory and data memory bus, the processor speeds up to 24MHz. Rich M8C architecture instruction, and the I / O and memory operations. In addition, the system provides a convenient way of addressing.

CPU core has a perfect ability to rapidly multiply, PSoC family of all processors have a multiplier / adder (MAC). MAC system as a separate component, and mapped to a specific register address space, the input register and output register, can perform 8 × 8 signed 32-bit multiplication and addition operations. As long as the input register data to the next instruction cycle, the output register can be result of the operation. Register memory speed data exchange, greatly improving the data processing speed.

2 internal memory

The PSoC family's flexible on-chip memory, including 4 ~ 16KB of program memory quickly (Flash Program Memory) and 256 bytes of on-chip SRAM data memory, memory speed rewritable 100,000 times, and can block real-time changes, different The capacity of different types of flash memory chips. In addition, the system has a serial programming (ISSP), which in the program header (Programme Pod) or user-board flash memory via the serial approach, the curing process to the internal program Flash memory. PSoC offers a variety of on-chip memory protection encryption. Sensitive information to ensure the safety of the user. This feature allows the user to selectively read and write operations on the memory module lock and write protection. This allows for some code upgrades, and will not leak important data.

3. PSoC block

In each there are a number of PSoC chip digital PSoC block. PSoC chip digital micro-controller module to reduce a variety of types and peripheral components. Digital PSoC blocks can be configured into a variety of user modules, such as timer, real-time clock, pulse-width modulation (PWM) and pulse-width modulation dead (DB PWM), cyclic redundancy check module, full-duplex (UARTS ), a serial master-slave communication (SPI) function. PSoC PSoC Software Development Kit module provides automatic configuration, users simply select the desired function blocks, PSoC software development kit will be able to generate the correct preparation of information and the device data sheet.

In each there are a number of PSoC chip analog PSoC block, chip analog PSoC blocks can reduce the CPU complex series of numbers and the demand for peripherals. Analog PSoC blocks can be configured in many peripheral functions, such as 12 PSoC blocks can provide 11 △-Σ ADC, 8-bit successive approximation analog-digital converter, 8-bit direct digital conversion, 12 incremental analog-digital conversion, programmable gain amplifier, sample and hold function, programmable filter, a differential comparator and the on-chip temperature sensors. PSoC analog system contains three types of modules: a continuous clock module (CT), A Class and B switched capacitor (SC) module.

4 general I / O

PSoC microcontroller's general-purpose I / O counts ranging from 6-44, depending on different models to determine. Each I / O functions are programmable options. In the output mode selectable output drive, analog output drive up to 40mA. By internal pull-up or pull-down resistor output, high output, you can set the maximum output drive current of 25mA. All power supply pins can be used as an interrupt, the interrupt generated by changes in the signal pin. Select the bit edge triggered and terminal, falling edge trigger. Pin can be connected to the analog module. In addition, as a Schmitt trigger TTL, I / O.

5 Oscillator

PSoC family of devices to choose from a variety of oscillator, the total for the CPU clock, analog and digital PSoC block PSoC block clock to find a suitable oscillator. There are internal to 24/48MHz master oscillator, a 32.768MHz external crystal oscillator and internal low speed oscillator. The main oscillator error of ± 2.5%, with no external compensation, the external crystal oscillator PLL can be selected for accuracy, the internal low speed oscillator PSoC block and general as watchdog / sleep timer clock. Clock divider can be used to optimize code execution speed and reduce power consumption.

6-specific peripheral

PSoC devices also provide some special peripherals, including watchdog / sleep mode clock (Watchdog / Sleep Timer), the threshold voltage can be set to power low-voltage detection (LVD / POR), interrupt controller, sample extractor ( Decimator), on-chip temperature sensor and on-chip voltage reference and so on.

7 Static COMS device

PSoC microcontroller family using advanced Flash technology is a fully static CMOS devices to achieve a high degree of low-voltage function. Voltage is usually maintained at 3.0 to 5.5V DC, using the on-chip voltage mercury switch voltage can be reduced to 1.0V DC, working at -40 ℃ ~ +85 ℃.

Brushless electric vehicle control system

Constituted by the CY8C24423 brushless chinese electric bikes controller system block diagram shown in Figure 2.
Shown in the figure to make up the motor rotation, the first control unit to be based on Hall induction motor rotor to the current location, and then decide on (or off) MOSFET in the order, such as on the image above the A, B, and C, (these are called to the bridge power transistors) and A under, B next, C next (these are called the bridge power transistors), the current flowing through the motor windings in sequence to produce cis-(or reverse) rotating magnetic field, and interaction with the rotor magnet, so you can make the motor clockwise / counterclockwise rotation. When the motor rotor to the Hall sensor sensing the position of another group of signals, the controller again on the next set of MOSFET, so the cycle can be in the same direction the motor continues to rotate until the controller decided to stop the rotor, then then turn off MOSFET, the MOSFET to turn the rotor back in reverse order.

A basic brushless motor controllers for electric vehicles to achieve the functionality required to include in addition to switch to the governor, but also should include undervoltage protection, overcurrent protection, power brakes, etc. In recent years, there are some other useful and popular features such as cruise control, ABS brakes regenerative braking, 1:1 help and so on. From the above block diagram can clearly see that the system only uses a PSoC chip will be realized above all control functions. Figure 3 shows the design of the brushless controller this semi-physical map.
In addition to these functions, the system is powerful and flexible PSoC chip with the allocation of resources, but also with ordinary controllers do not have the following advantages:

1 ultra-quiet: the whole process of moving the start and very low noise, far beyond the traditional brushless controller, reduce motor vibration and greatly extend the life of the motor;

(2) Low heat: the use of advanced synchronous rectification technology to significantly reduce heat loss controllers to improve vehicle energy efficiency, extend the driving range;

3 Multi-limiting: not only did the average current limit, and so the peak current limit. Peak current limit in each PWM period of the current waveform to detect, prevent more than the maximum allowable current of the MOSFET, in any case will not be burned;

4 Average: limiting the controller to the motor in a variety of different limiting values ??remain the same, and light and heavy loads, and even lower stall current value of the same. This greatly facilitate debugging and OEM production test;

5 Anti-Speed ??function: to solve the brushless controller or line failure due to switch to the phenomenon caused by Speed, improve system security;

6 stall protection: Stall 3 seconds or more controller automatically protection against burning the motor;

7 Short circuit protection: motor three phase output short circuit or any three-terminal ends of the whole circuit, the controller is not burning.

Not increase the hardware cost of these features, the PSoC programmable system-on-chip peripheral devices will minimize most of the functions done by the chip, reducing hardware costs, and reduce the failure point. The system used in the SoC chip and pin functions shown in Figure 4.
The chip module structure shown in Figure 5.
As can be seen from Figure 5, the system uses a total of seven types of PSoC internal modules, which include the AD converter simulation module ADCINC_1, programmable amplifier PGA_1, comparator CMPPRG_1, four analog switches AMUX4_1, DAC DAC6_1. AD converter module including digital ADCINC_1, 8-bit PWM module dead PWMDB8_1, 8-bit timer module Timer8_1. Such good use of the CY8C24423's internal resources, but also save a lot had to be used in the chip external peripheral chips.

The system control software flow shown in Figure 6.
As the PSoC Designer PSoC development system supports the C programming language, with a powerful C compiler, so the main program using C language, so simple, intuitive, good portability.
Conclusion

This article describes the electric car through brushless motor controller system, you can briefly glimpse the powerful PSoC chip can be configured to function, to connect the chip configuration like the design a new chip. The entire system with minimal components, the program than other brushless controllers have a huge cost advantage.

PSoC convenient, efficient interface design, object-oriented design and development system, mixed-signal arrays can be modular and dynamic configuration capabilities to applications in embedded systems design with a more flexible approach, allowing designers to create new system functions. With PSoC can quickly and easily complete the development of appropriate procedures, to shorten product development cycles, reduce development costs and production costs. Programmable System-on-chip mixed-signal array of integrated applications and dynamic configuration, which greatly improved work efficiency, reduce development costs 1 / 2, PCB board space reduction of the l / 3, lower production costs by 1 / 5 .