The current detection circuit is sh

The current detection circuit is shown in Figure 3.3, which shows the current detection circuit of the system. The two-phase current of the motor stator is measured by the sensor, which is transformed into the corresponding information data through the signal processing. Since the stator current of synchronous motor is AC signal, the A / D conversion module in DSP needs a voltage signal with unipolarity of 0-3v. Therefore, vrefhi is a high-level input, 3V, and vreflo is grounded. The ratio of resistance determines the value of regulation amplitude. Resistance R3 = R4, resistance R5 and diodes D1 and D2 can be used to adjust the voltage amplitude properly. The function of resistor R2 and capacitor C is hardware filtering, and the filtering time constant T = r2c1, which should match the design of current loop. At the same time, the switching noise of power tube also needs to be filtered, and the landmark design value is 10 μ s-20 μ s.