Boost power conversion circuit and control method

Abstract

A boost power conversion circuit and a control method. The circuit comprises: N first switch modules, N second switch modules, N-1 third switch modules, N-1 flying capacitors, and N-1 pre-charging units. The N second switch modules are connected in series to an inductor and to an input power supply to form a loop. The N first switch modules are connected in series to a load, to the inductor, and to the input power supply to form a loop. A flying capacitor and a third switch module are connected between a first common point between the first switch modules and a second common point between the second switch modules. Each flying capacitor is connected in parallel to a pre-charging unit. Each pre-charging unit is used for pre-charging, when a third switch module that is connected to the flying capacitor connected in parallel to the pre-charging unit is switched off and the voltage of the flying capacitor is less than a preset threshold, the flying capacitor. The boost power conversion circuit and the control method can ensure that the voltage of the flying capacitors does not drop to 0 V, thereby avoiding the problem of possible breakdown in a semiconductor device due to overvoltage when a boost power conversion circuit is used in a high voltage system.

Description

technical field [0001] Embodiments of the present invention relate to electronic circuit technologies, and in particular, to a boost power conversion circuit and a control method. Background technique [0002] Boost circuit does not specifically refer to a specific circuit, but generally refers to a boost circuit, that is, through the circuit to input a voltage, output a higher voltage, realize power conversion, and can input greater than or equal to three levels called It is a multi-level Boost circuit. [0003] Figure 1a It is a flying capacitor multi-level boost circuit, Figure 1b It is a schematic diagram of the control signal of a flying capacitor multi-level Boost circuit, such as Figure 1a , Figure 1b As shown, L is an inductor, D1, D2, D5, D6 are diodes, T1, T2 are semiconductor switches (can be insulated gate bipolar transistors (English: Insulated Gate Bipolar Transistor, referred to as: IGBT), metal-oxide layer Semiconductor field effect transistor (English...

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Problems solved by technology

[0004] However, according to the above analysis, it can be seen that Vout>Vin, all switching tubes can choose a withstand voltage of 0.5Vout; if there is no voltage on the flying capacitor, that is, Vc=0, and the capacitor voltage is 0, then the capacitor can be regarded as a short circuit, that is, the T1 tube Short-circuited by D1 and D5 in both directions, at this time T2 and D2 bear the input voltage Vin, and D6 bears the withstand voltage Vout-Vin; if Vin0.5Vout, if the withstand voltage exceeds D6, D6 will break down overvoltage; if Vin>0.5Vout, then T2 and D2 withstand the input voltage Vin, Vin>0.5Vout, if the withstand voltage of D2 and T2 exceeds 0.5Vout, D2 and T2 will break down due to overvoltage; D6 withstands the withstand voltage Vout-Vin, Vout-Vin<0.5Vout, not exceeding D6 Withstand voltage, D6 will not be overvoltage breakdown; from the above analysis, if the flying capacitor voltage Vc is zero, the semiconductors in the above scheme are at risk of overvoltage breakdown

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