Application of Renesas Electronics 32-bit MCU in Servo Motor

In servo systems, AC permanent magnet synchronous motors have become the mainstream choice for servo systems because they have excellent low-speed performance, can achieve weak magnetic high-speed control, have a wide speed regulation range, and have high dynamic characteristics and efficiency. Currently, permanent magnet synchronous AC servo technology has become one of the supporting technologies for industrial automation.

This article takes the Renesas Electronics 32-bit frequency conversion MCU V850E/IX3 UPD70F3454 as an example to explain its application in AC servo systems.

About Renesas UPD70F3454

UPD70F3454 is a 32-bit high-performance MCU developed by Renesas Electronics for variable frequency control. It uses V850 core, RISC architecture, 5-stage pipeline, built-in DSP function, maximum 64MHZ, built-in 256K flash ROM and related peripheral functions, such as DMA controller, timer/counter, serial interface UART, SPI, IIC, A/D, bus controller, low voltage detection, on-chip debugging, etc. For variable frequency control, UPD70F3454 provides 2 groups of six-phase PWM outputs, two independent 12-bit AD converters, built-in comparator and op amp, two groups of encoder input counters, highly integrated peripherals required for servo motor control, and can realize the control of two servo motors with one MCU.

System Principle

1. System hardware structure:

The hardware of the servo control system based on UPD70F3454 is shown in the figure below. It mainly includes:

⑴、MCU UPD70F3454 and its peripheral circuits, 3454 is the core controller, receives external signals, determines the system's working mode, and converts them into switch signal outputs of the inverter, drives IPM after isolation, and EEPROM is used to save parameters and store user information. RS232 module is responsible for communicating with the host computer, or directly sending speed and direction control information through the host computer; programming and debugging can be done through MINICUBE, MINICUBE2, PG-FP5.

⑵. IPM drive circuit, MCU outputs 6-phase PWM signal, which is transmitted through optocoupler isolation and IPM full-bridge inverter output to drive the servo motor to work in the high-voltage circuit.

⑶. Current sampling: the system needs to sample at least two-phase currents, such as Ia and Ic. The signal of the sampling circuit is converted into digital form after passing through the operational amplifier and comparator of the internal AD module of 3454.

(4) Rotor position detection: the orthogonal encoding signals A, B, and Z output by the incremental photoelectric encoder are input into the TMT module of the MCU to determine the position of the motor rotor and the motor speed signal.

⑸. Input of sensor signals, including pulse input, analog input, switch input, etc. and communication with other MCUs.

Figure: Renesas Electronics UPD70F3454 servo control hardware structure diagram

2. Features and advantages:

①. Fine full digital control. Adopt Renesas Electronics 32-bit dedicated frequency conversion MCU, 64MHZ CPU and PWM operation clock, high-precision frequency output.

② Low system cost. UPD70F3454 is equipped with rich peripheral resources such as power-on reset, voltage detection, voltage regulator, 4 op amps, 8 comparators, encoder interface, etc.

③. Rich peripheral functions: 5V single power supply, external bus, DMA controller.

④. Provide a safe and secure high-end variable frequency motor evaluation system. There are software reference codes for each module of the system, such as PWM, AD, TMT and other modules. Users can easily carry out secondary development on the original system. And there is a strong support team for the motor group.

In addition to high-speed real-time response and single-clock instructions, UPD70F3454 also supports multiplication instructions, saturation operations, bit operations and other instructions optimized for digital servo control systems. The servo control system based on UPD70F3454 in this paper makes full use of the internal resources of MCU, with simple circuit design and few peripheral devices, meeting the real-time requirements of vector control and realizing full digital control of servo. The low-cost and high-performance MCU control characteristics make the system have a good application prospect.

Currently, UPD70F3454 has been widely used in customers' general servos, textile machinery, and sewing machines. For detailed product information and technical support, please contact Renesas Electronics' authorized distributor, Shiqiang Telecom.