A start-up circuit of an ultra-wide voltage auxiliary power pwm chip

Abstract

The invention discloses a starting circuit of a PWM chip of an ultra-wide voltage auxiliary power supply, which comprises a voltage switch circuit, a voltage detection circuit and a charging circuit; the voltage switch circuit is composed of a MOS transistor Q1, a resistor R4 and a resistor R5; the voltage detection circuit consists of The MOS transistor Q2, the resistor R7 and the resistor R8 are composed; the charging circuit is composed of the resistor R1 and the resistor R2. The start-up circuit of the ultra-wide voltage auxiliary power supply PWM chip, no matter how the input voltage changes, the charging current of the PWM chip VCC is stable, and the relative change is small; when the power supply fails, the chip can restart and will not enter In the locked state, after troubleshooting, it can be restarted without power-off and restart, especially when working under ultra-high voltage, the circuit loss is much smaller than that of conventional circuits.

Description

technical field [0001] The invention relates to a power supply module and a switching power supply PWM auxiliary power starting circuit, in particular to a starting circuit of an ultra-wide voltage auxiliary power PWM chip; the input voltage can be as wide as 100-2000V. Background technique [0002] In photovoltaic inverters and ultra-high voltage direct current transmission systems, the voltage range is very wide, as low as 100 volts and as high as more than 4,000 volts, so it is difficult to design the auxiliary power supply of the system, especially the design of the high-voltage shoulder circuit Difficulties. On the one hand, it is necessary to find electronic components that can withstand high voltage. On the other hand, in terms of reliability, it is necessary to reduce the circuit loss of the shoulder part to prevent heat damage to key components. [0003] Currently commonly used switching power supply startup circuits (such as figure 1 As shown), since the resistor ...

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Problems solved by technology

[0003] Currently commonly used switching power supply startup circuits (such as figure 1 As shown), since the resistor R1 is always connected to the power supply input terminal VIN, the power consumption generated on it is P=(VIN-VCC)2 / R1. Obviously, if the switching power supply is working at a high voltage input, the power on the resistor R1 The power consumption will be very large, which will affect the power conversion efficiency, heat dissipation and reliability. At the same time, high-power resistors must be selected, which makes the switching power supply larger and more expensive.

[0004] The existing method to solve the problem of power consumption of the above-mentioned resistor R1 is as follows: figure 2 As shown, when the switching power supply works at high voltage input, the switching tube Q2 needs to withstand high voltage, and it is difficult to find a device that can withstand high voltage on the market. Even if a high-voltage IGBT tube is available, its cost is very high and it is rarely used There is a risk of stock outs

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