Design Of 500W Class D Audio Amplifier

The concept of class D audio amplifier has been proposed in 1958,and until the rise of power semiconductor,it makes the rapid occupation of the audio equipment market.The design technology of class D audio amplifier is continually improved,and its performance indicators are gradually rising.With the advantages of high efficiency,small size,energy saving and digital,class D audio amplifier continually replaces the traditional audio technology,and meets the needs of more people.In this paper,a 500 W class D audio amplifier is designed in detail from the aspects of auxiliary power supply,drive circuit,output circuit,protection circuit and filter circuit.The work includes the following aspects:1.The advantages and disadvantages of several kinds of traditional audio technology and class D power amplifier are compared,and the working principle of D audio amplifier is described in detail.Then the modulation of several class D amplifier and output stage circuit and filter circuit are described.On the basis of these theories,the system structure is confirmed.This paper explains the important role of delta sigma modulation technology in the class D audio amplifier.2.Design the core circuit and power supply auxiliary circuit of class D audio amplifier.The core circuit comprises an integrator,drive circuit,output circuit,filter circuit and protection circuit.On the one hand,select the appropriate control chip and power components,especially power components which use MOSFET designed by laboratory;on the other hand,we need design the parameters of the circuit in detail to make the circuit to achieve optimal performance.Auxiliary circuit uses switching power supply to provide the necessary power supply.3.Design PCB layout,set up the actual circuit and debug.With the help of laboratory equipment,the designed circuit is tested in the practical application environment.Including auxiliary power module,class D audio amplifier module and the overall performance.Adjust the parameters to optimize the test results.The test results show that the power of the class D audio amplifier,in the case of carrying 8?load is 556 W and 16 W with no load.When the input is a sinusoidal signal with a peak of 2V and frequency of 1.7KHz,the output is also a sinusoidal signal with a peak of 84.8V and frequency of 1.7KHz,the amplitude of signal is amplified to about 42.4 times,and almost no distortion occurs.The result basically meets the design requirements.In addition,the failure of power devices in circuit debugging is analyzed and discussed,and the corresponding solutions are given.