Elevator frequency converter IGBT over-temperature closed loop protection method based on switching frequency adjustment

Abstract

The invention discloses an elevator frequency converter IGBT over-temperature closed loop protection method based on switching frequency adjustment. The elevator frequency converter IGBT over-temperature closed loop protection method comprises the steps that firstly, IGBT junction resistance is detected; secondly, IGBT junction temperature is worked out; thirdly, switching frequency is adjusted. According to the elevator frequency converter IGBT over-temperature closed loop protection method, the IGBT junction resistance is directly detected, the junction temperature is accurately worked out for an NPC three-level frequency converter, and the IGBT internal temperature can be reflected more truly; a temperature closed loop is manufactured, through adjustment of the IGBT switching frequency, the IGBT temperature of a rectifier and the IGBT temperature of an inverter are adjusted independently and dynamically in real time so that the rectifier and the inverter can work in a safe temperature range, the frequency converter is controlled to enable the rotation speed of an elevator to be reduced and guarantee constant torque, and then a system is in a low-speed stable operation stage; the junction temperature is displayed visibly, so that operation personnel make judgments and execute corresponding operation conveniently; the real temperature of an IGBT chip can be accurately detected, and non-shutdown protection can also be conducted.

Description

technical field [0001] The invention relates to a hoist frequency converter IGBT over-temperature closed-loop protection method based on switching frequency adjustment, which belongs to the field of power electronics and power transmission. Background technique [0002] For the purpose of energy saving, frequency converters are used more and more in all walks of life, and their safety has gradually attracted people's attention. An important link that affects its safety is the IGBT overtemperature problem of the internal rectifier and inverter of the inverter, because IGBT overheating not only reduces the service life of power devices, but also seriously threatens the stability and safety of the inverter. In order to solve this problem some methods have been proposed and achieved certain results. [0003] The more common IGBT protection circuits include an over-temperature circuit designed based on the temperature of the IGBT case or the IGBT substrate temperature, and then ...

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Problems solved by technology

[0003] The more common IGBT protection circuits include an over-temperature circuit designed based on the temperature of the IGBT case or the IGBT substrate temperature, and then formulate a temperature warning for the case; there is an IGBT junction temperature detection device based on the detection of the IGBT switching frequency and the current when the IGBT is turned on and methods; some are based on automatic detection of IGBT temperature and implementation of segmental alarm and control; other methods either only detect IGBT junction temperature without protection, and need to detect IGBT switching frequency, which is troublesome to operate; or detect IGBT shell temperature, The accuracy is not enough; or only detect the IGBT temperature and alarm and control, no effective control method is given to reduce the IGBT temperature without stopping the machine, only a simple shutdown operation; there is no temperature closed-loop IGBT over-temperature protection for the hoist converter method

After searching, in the prior art: "A Thermal Overload Protection Method, Device and System for Power Electronic Equipment" (Application No.: 201310754113.6), this invention application also applies to thermal impedance detection, junction temperature calculation, etc., but its protection The measure is to stop sending IGBT pulses. This method has different junction temperature calculation methods, and has the disadvantage of shutting down during protection. It does not form a temperature closed loop, and it does not reduce the IGBT switching frequency under normal operating conditions to achieve dynamic adjustment of power device losses.

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