Electric car and control method and system of PTC electric heater for electric car

Abstract

The invention discloses an electric car and a control method and system of a PTC electric heater for the electric car. The control method comprises the following steps that the work current of the PTC electric heater is detected; the work current is sampled to acquire the sample values of the current, and the current sample value in each sampling period is subjected to integral computation to acquire the computed power of the PTC electric heater; within each switching period of a power switching tube, whether the computed power reaches the target power of the PTC electric heater or not is judged; if the computed power reaches the target power of the PTC electric heater, the PTC electric heater is controlled to stop heating by controlling the power switching tube so that the heating amount of the PTC electric heater within each switching period can be kept consistent with the heating amount corresponding to the target power. According to the method, the current integration algorithm is adopted for controlling the power switching tube, therefore, overall output heat equalization is achieved, comfort is greatly improved, and electromagnetic interference and switching losses can be reduced.

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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