Control method and system for electric vehicle and ptc electric heater used for electric vehicle

Abstract

A control method for a PTC electric heater of an electric vehicle, comprising the following steps: detecting working currents of a PTC electric heater; sampling the working currents to obtain current sampling values, and performing integral calculation on the current sampling value of each sampling period to obtain calculated power of the PTC electric heater; determining, within each switching period of a power switching transistor, whether the calculated power reaches target power of the PTC electric heater; if the calculated power reaches the target power of the PTC electric heater, controlling the PTC electric heater to stop heating by controlling the power switching transistor so that the heating amount of the PTC electric heater within each switching period keeps consistent with the heating amount corresponding to the target power. Also disclosed are a control system for a PTC electric heater of an electric vehicle, and an electric vehicle.

Description

technical field [0001] The invention relates to the technical field of electric vehicles, in particular to a control method for a PTC electric heater for an electric vehicle, a control system for a PTC electric heater for an electric vehicle and an electric vehicle. Background technique [0002] In the related art, common PTC electric heater products mostly adopt two control driving modes. One of them is switch control, the power switch tube or relay is kept closed or disconnected for a long time, and the power classification is realized by combining multiple power switch tubes or relays, such as figure 1 shown. However, in this control method, although the switching loss is small, the power level distribution is not fine enough, and the system cost is high. The other is PWM (Pulse Width Modulation, pulse width modulation) control, such as figure 2 As shown, the current is controlled by controlling the switching frequency of the power switching tube (such as IGBT) to adj...

AI Technical Summary

Problems solved by technology

However, this characteristic causes the heat output by the PTC electric heater to be unstable

Under the conditions of different heat dissipation conditions and different ambient temperatures, the output heat of the same PTC material after being energized is not the same, so there will be problems that the comfortable target power (heating capacity) cannot be adjusted.

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