| Electronic pulse physiotherapy instrument is a kind of medical equipment that simulates Chinese massage and acupuncture to achieve treatment, through outputting electronic pulses with width, space, and amplitude changing. Designing and implementing a convenient and portable physiotherapy instrument with many treatment functions and flexible configuration is important to meet the customers'demands of massage therapy and health care.Physiotherapy instrument and research status are introduced. Improved methods using the step-down switching power supply circuit to improve power efficiency and output power and using waveform control program to achieve the treatment waveform's diversity are proposed. The parameters'save function for reuse, and custom treatment modes to meet the specific needs of different users are designed.The principle of electrical pulses medical treatment is introduced. Based on modulating mid frequency electrical therapy, the treatment waveforms are designed. It is a kind of bidirectional and symmetric pulse with the frequency of 1 kHz-10 kHz. The mid frequency pulse's amplitude is modulated by six low-frequency periodic signals of sine, exponential, square, triangle, sawtooth and trapezoidal waveforms in 1 Hz-50 Hz. Seven traditional treatment modes,30 modulation wave modes and 12 combination treatment modes are designed. According to the principle of isolated flyback switching power supply,±16.5V dual output switching power supply with wide input voltage range, high stability and efficiency is designed. And 3.6V output DC-DC converter power supply circuit is also designed. The design of power supply circuit parameter and isolation transformer parameters is introduced in detail. Based on MSP430F4250 microcontroller, the control circuit including key response, DAC output and LCD display is designed. The TDA2030A amplifier circuit is designed to ensure the mid frequency pulse transmission without distortion and to increase drive capability. Key response by I/O interrupt and key shake-proof function by timer interrupt are achieved by programming. Waveform control program is designed to achieve the control of mid frequency pulse, low-frequency modulation wave and the pulse's amplitude calculation. Flash reading and writing function achieved the parameters'save and custom treatment modes.Experimental results show that the switching power supply circuit's efficiency is 82% to 87%, output voltage ripple coefficient is 3.18%, load regulation is 3.45%, and the output waveform is the same with the low-frequency modulation waveform, which really has obvious Chinese massage effect. |
