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Application of delta inverter in treadmill control system

Abstract: with the improvement of living standards, people pay more and more attention to their own health and are more interested in participating in various sports. Among them, exercise with the help of treadmill has a simple form, which is suitable for use in home or gym. This paper briefly discusses the application of delta inverter in the control system of treadmill

Abstract: With the improvement of living standard, people care more and more about health and keen on taking all kinds of sports. Using treadmill to do physical excise is suitable in indoor and gym as the simple excising form. The article briefly discusses the application of Delta inverter in treadmill control system.

Keywords: treadmill inverter control system

key words: treadmill inverter control system

1 introduction

the biggest advantage of running on the treadmill over running on outdoor roads is that the treadmill provides shock absorption effect, largely eliminates the reaction impact of each step, and protects your knee joints. Therefore, it has been popular in recent years. The basic function of the treadmill is to build a running track (running belt). The running direction of the track is opposite to that of the athlete, but the speed must be automatically consistent, so that the athlete can run in situ. If the motor is the heart of the treadmill, the function of the electromechanical system is the cardiopulmonary function of the treadmill. The perfect electromechanical system can give full play to the power efficiency of the motor. The electromechanical system used in the treadmill is also advancing with the times, from the early SCR system to the current PWM system. Most treadmills on the market now use PWM system. Compared with the old SCR system, modern treadmills have better running feeling and run more smoothly and naturally. The treadmill developed by delta inverter is shown in Figure 1

2 characteristics of delta treadmill special inverter

inverter is the core of treadmill. Compared with other treadmills in the market, Delta's special inverter for treadmill is highly targeted and fully conforms to the running characteristics of treadmill. This inverter has its unique advantages in the following aspects

1) provide a wide carrier frequency range

due to the particularity of the use environment and the use object, the control performance of the treadmill has special requirements different from other motor controls. The general use environment of the treadmill is indoors, and there are special requirements for mute. The running machine drives the driving belt by the motor, and then runs the running belt through the roller. This series of electromechanical and mechanical operation processes will produce a certain sound. If the frequency converter is used to control the motor, the motor will emit a high-frequency roar during operation, which is called electromagnetic noise. This kind of noise tends to make people anxious, and it is generally difficult to be covered up by other sounds. The method to eliminate noise is to adjust the carrier frequency of the frequency converter, and the maximum value that can be adjusted is 15KHz. In other environments, if the carrier frequency is adjusted to the maximum (15KHz), the user's requirements may be met. At this time, the noise emitted by the motor is not obvious. Now the manufacturers have taken some noise prevention measures for the mechanical part, so the environmental background noise of the treadmill is relatively small, which makes the electromagnetic noise that is not very obvious in other occasions particularly harsh. In response to this special demand, delta treadmill's special frequency converter increases the adjustable maximum carrier frequency to 16KHz, once again reducing the noise decibel emitted by the motor, so that athletes can save low-carbon waste asphalt pavement materials in Qinghai Province. The geothermal regeneration technology has significant benefits and can exercise in a better environment

2 the control mode is SPWM, which provides no speed vector control mode

this control mode can obtain relatively hard mechanical characteristics without external speed feedback (no increase for external wiring). The application of vector control makes the low-frequency working characteristics of asynchronous motor reach a very perfect level, which is no worse than that of DC motor. In terms of low-frequency torque, it can provide 150% of the rated output torque at 5Hz

3 provide a lower instantaneous low voltage level value

because the treadmill is used in general residential or sports center, and its power supply is general mains power. When the load cannot predict the user's set speed and weight, the designer must consider the influence of these variables, which may cause the instantaneous low-voltage detection action. To prevent LV detection, the delta treadmill special frequency converter adds a parameter: LV level setting. Setting this parameter according to the actual use of the customer can freely set the voltage value of the low-voltage alarm, greatly reducing the possibility of shutdown due to sudden load

4 provide standard 485 communication interface

using the standard 485 communication interface can make the debugging and use process more simple and convenient. Originally, each frequency converter needs to set parameters manually. Now, it only needs to download parameters, which will be quickly written into the frequency converter, reducing the repeated work of debugging personnel; The wiring is also more concise. 485 communication only needs to connect two signal lines (sg+/sg-). Since the frequency converter itself is an interference source, the 485 interface has stronger anti-interference ability than the analog input

5 under the 485 communication control mode, the external terminal can receive EF signal

the treadmill cannot see the importance of this function under normal operation, but once there is a problem, for example, when the controller crashes, the motor operation is not controlled, which is easy to cause physical injury to the exerciser. If a function can be provided, the software will use c++6.0 to code and command the frequency converter to stop output (stop working) and allow the motor to stop freely during the development process, which will reduce the possibility of personal injury caused by abnormal conditions. Generally, it is necessary to add other low-voltage appliances to cut off the power supply of the motor; However, delta inverter can realize this function without adding electrical components, reducing the hardware cost of the treadmill

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