Music fountain is a comprehensive waterscape composed of different shapes, different colors, and music rhythms by the combination of computer-controlled sound, light and nozzle holes. The sound, light, color and shape of the musical fountain are beautiful, and are often used as the main scenery of landscape gardens. With the development of the national economy and the improvement of people's living standards, people pay more and more attention to the improvement and beautification of the environment. Music fountains have been widely used in residential areas, parks, and leisure squares. The control system of the musical fountain is the core of the design of the musical fountain. The following takes the application of ZVF300H series VFD inverter in a square in Kunming as an example to describe the frequency conversion control of music fountain.
Composition of fountain control system
The music fountain control system is mainly composed of audio control signal, frequency converter, water pump, multi-function valve, universal nozzle and water pipe. The fountain water pump adopts the frequency conversion speed regulation technology to realize the stepless speed regulation of the water pump, and the speed of the water pump can be adjusted at any time according to the strength of the audio signal. The multi-function valve and universal nozzle are controlled by the special controller for fountain, which can realize various patterns and shapes according to the program. We use the audio signal of music to control the inverter. The audio signal of music itself is an AC voltage signal with very little power. After rectification, filtering and voltage regulation, a corresponding DC voltage signal can be output. Relatively speaking, the signal is very weak. After power amplification of the signal, a standard DC voltage signal of 0-5V can be output, which can realize the control of the frequency converter by the audio signal, that is, the control of the water pump spray, so as to realize the control of the fountain spray by the music.
Introduction of ZVF300H VFD
ZVF300H series VFD is an economical vector inverter introduced by ZIRI Electrical. ZVF300H non-PG vector inverter adopts advanced magnetic flux algorithm and has the following characteristics:
1. The starting torque is 0.5Hz/150% (SVC)
2. Strong overload capacity 150% rated current 60S; 180% rated current 10S
3. Wide speed range 1:100
4. High speed stabilization accuracy ±0.5% maximum speed
5. Fast dynamic response <20mS
6. Excellent acceleration and deceleration characteristics 0.1S (the shortest)
The excellent acceleration and deceleration characteristics of ZVF300H VFD can cooperate with the load pump to achieve stable acceleration and deceleration in the shortest time; the fast dynamic response of ZVF300H can detect the regenerative power in time, realize the automatic acceleration and deceleration process without tripping, and can change the frequency conversion instantaneously with the change of the audio signal. The output frequency of the device is adjusted, thereby changing the waveform of the fountain water column, so that the water column waveform and the audio signal are synchronized without distortion.
1. Audio signal interference problem
From the working principle of the inverter, it is known that high-order harmonics will be generated on the input and output sides of the inverter when it is running, and this harmonic signal will interfere with other equipment through conduction, radiation, coupling, etc. Harmonic interference in the music fountain system will be amplified by the audio amplification system to form harsh noises and affect the playback of music.
Take the following measures when debugging this situation:
(1) Reduce the carrier frequency of the inverter;
(2) The inverter should be grounded reliably, the grounding wire should be thicker, and the distance between the grounding point and the inverter should be as short as possible;
(3) The input and output power lines of the inverter should be kept away from the audio signal line and control line as far as possible, and do not run the power line and the control line in the same slot;
(4) The power supply of the audio signal system should be isolated from the power supply of the inverter as much as possible.
2. The problem of inverter jump protection
The fountain pump adjusts the speed at any time with the strength of the audio signal, which requires the frequency converter to respond quickly. When adjusting the parameters of the inverter, the acceleration and deceleration time should be as short as possible, but if the acceleration and deceleration time is too short, overcurrent protection may occur. In order to reduce the interference of the audio frequency modulation signal, the analog AV1 needs to set the filter time appropriately. ZVF300H series inverter has the function of automatic fault reset. In order to avoid the fault of the inverter caused by the interference signal, this function can be turned on during debugging.