Control method and system of vehicle PTC heater
Technical Field
The invention relates to the technical field of vehicle heaters, in particular to a heating control method and system of a vehicle PTC heater.
Background
With the gradual popularization and spread of new energy automobiles, the PTC electric heater is applied more and more, and the automobile PTC heater is a device for assisting in heating a carriage by electric power. The PTC electric heater adopts a PTC thermistor element as a heating source, wherein the PTC thermistor is usually made of semiconductor materials, and the PTC thermistor element has the characteristic of changing along with the change of the ambient temperature, and the resistance value of the PTC thermistor element increases or decreases along with the change of the ambient temperature, so the PTC heater has the characteristics of energy conservation, constant temperature, safety, long service life and the like.
The existing PTC heater generally has the problems of low heating efficiency and inaccurate temperature control, and when part of heating pins of the PTC heater are in fault, the PTC heater can not flexibly take corresponding measures to start other normal heating pins for compensation heating.
For example, publication number "CN 102529641A" discloses a method and a device for controlling warm air of an automobile, which comprises the following steps: the control circuit loads weak current voltage; the PTC heater applies strong voltage; detecting the temperature of the PTC heater by using a control circuit, and comparing the detected temperature of the PTC heater with a target temperature value; the control circuit detects the voltage and the current of a strong current circuit of the PTC heater through a photoelectric coupling strong and weak current isolation circuit; the method is characterized in that: the driving circuit receives a duty ratio pulse width modulation signal output by the control circuit by using a gate bipolar transistor (IGBT) to enable a collector and an emitter to be switched on or switched off; a strong electric power is applied to the PTC heater through an Insulated Gate Bipolar Transistor (IGBT). The pulse width modulation control is adopted to output strong voltages with different frequencies by changing the duty ratio so as to obtain the linear control effect of the PTC heater. The advantage of this scheme is effectively avoiding PTC heater surface temperature too high, and the reliability is high. However, the scheme has the problems that when part of heating pins of the PTC heater are in fault, the PTC heater cannot monitor the heating pins and starts other normal heating pins for compensation; and the PTC heater has a low accuracy of the heating temperature range.
In view of the above-mentioned disadvantages of the conventional PTC heater, it is necessary to design a heating control method for a vehicle PTC heater, which can monitor the working state of the heating pin and make a corresponding coping strategy, and has accurate temperature control.
Disclosure of Invention
In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a heating control method and system for a vehicle PTC heater, which can monitor the working state of a heating pin and make a corresponding coping strategy, and can accurately control the temperature.
The technical scheme adopted for solving the technical problems is to provide a heating control method of a vehicle PTC heater, wherein the vehicle PTC heater comprises a plurality of heating pins; the heating control method includes the steps of:
s1, receiving heating control instructions and outputting opening instructions to the heating pins one by one;
s2, detecting whether the PTC heater for the vehicle reaches the preset maximum power, and if not, detecting whether the temperature reaches the preset temperature;
and S3, if the preset temperature is not reached, detecting the fault number of the heating pins and recombining the output states of the normal pins according to the fault number of the heating pins and the fault heating pins.
Further, the heating control command comprises an output power desired value; when the PTC heater for the vehicle reaches the preset maximum power in step S2, checking a preset control strategy table and outputting an actual driving value; when the detected temperature reaches the preset temperature in step S2, the driving value is output according to the preset percentage of the expected value of the output power and by referring to the preset control policy table.
Further, in the step S3, when all the heating pins are failed, the output is turned off; when only one normal pin exists, detecting the normal pin and controlling the output of the normal pin; when there are 2 or more normal pins, all the normal pins are detected, and the outputs of the normal pins are controlled according to a preset control strategy table.
Further, the preset control policy table includes: when a heating pin needing to be output fails, other normal heating pins are controlled to be started to replace the failed heating pin.
Further, the detecting whether the pin is normal includes the steps of:
detecting whether a driving signal exists on the pin, if not, detecting whether the current value is greater than a preset value, and if so, determining that the pin is in a short-circuit state;
if the driving signal exists, detecting whether the pin is opened, if so, detecting whether a short-circuit signal exists, and if so, determining that the pin is in an overcurrent state; if the short circuit signal does not exist, whether the current increase value reaches a preset value after the pin is opened is detected, if so, the pin is in a normal state, and if not, the pin is in an open circuit state.
The invention solves the technical problem and adopts the technical scheme that a heating control system of the PTC heater for the vehicle is also provided, which comprises the following components:
the control module is used for receiving the heating control instructions and outputting opening instructions to the heating pins one by one;
the detection module is in communication connection with the control module and is used for detecting whether the PTC heater for the vehicle reaches the preset maximum power or not, and if not, detecting whether the temperature reaches the preset temperature or not; if the temperature does not reach the preset temperature, detecting the fault number of the heating pins and the fault heating pins; the control module recombines the output states of the normal pins according to the detected heating pin fault number and the fault heating pins.
Further, the heating control command comprises an output power desired value; when the detection module detects that the vehicle PTC heater reaches the preset maximum power, the control module checks a preset control strategy table and outputs an actual driving value; when the detection module detects that the temperature reaches the preset temperature, the control module outputs a driving value according to the preset percentage of the output power expected value and checks the preset control strategy table.
Further, when the detection module detects that all the heating pins are in fault, the control module closes the output; when the detection module detects that only one normal pin exists, the normal pin is detected, and the control module controls the output of the normal pin; when the detection module detects that the number of the normal pins is 2 or more, all the normal pins are detected, and the control module controls the output of the normal pins according to a preset control strategy table.
Further, the preset control policy table includes: when a heating pin needing to be output fails, other normal heating pins are controlled to be started to replace the failed heating pin.
Further, the detection module is configured to detect whether the detection pin is normal:
when detecting whether the pin has a driving signal, if not, detecting whether the current value is greater than a preset value, and if so, determining that the pin is in a short-circuit state;
if the driving signal exists, detecting whether the pin is opened, if so, detecting whether a short-circuit signal exists, and if so, determining that the pin is in an overcurrent state; if the short circuit signal does not exist, whether the current increase value reaches a preset value after the pin is opened is detected, if so, the pin is in a normal state, and if not, the pin is in an open circuit state.
Compared with the prior art, the invention has at least the following beneficial effects:
in the invention, the control module outputs the opening instructions to all the heating pins one by one after receiving the heating control instructions, compared with the existing mode of opening all the heating pins together, the mode of opening all the heating pins one by one can effectively reduce the peak current of the PTC heater, improve the safety performance of the PTC heater, and is beneficial to the detection module to detect the state of each pin. Before the heating pin is opened and in the heating pin work, the operating condition of each heating pin is detected to detection module, not only can not reduce PTC heater's heating capacity, can also in time detect out whether each heating pin breaks down, and can judge out the specific trouble reason of the heating pin of trouble, for example: short circuit, open circuit, and over current. More importantly, when the detection module detects that two or more normal pins exist, the control module controls the output of the normal pins according to a preset control strategy table; when the detection module detects that a certain heating pin needing to work has a fault, the control module can check a preset control strategy table and search for an alternative scheme, and then opens the corresponding heating pin capable of working normally as compensation, so that the heating is efficient, the temperature control is accurate, and the influence on the PTC heater due to the fault of part of the heating pins is reduced.
Drawings
Fig. 1 is an overall schematic view of a heating control method of a PTC heater for a vehicle according to the present invention;
fig. 2 is a detailed control flow diagram of the PTC heater for vehicles according to the present invention;
FIG. 3 is a schematic diagram of a control method of the control module to output power desired value according to power and temperature of the PTC heater;
FIG. 4 is a schematic diagram of a method for detecting a heating pin by a detection module;
FIG. 5 is a schematic flow chart of detecting the working status of a pin;
FIG. 6 is a diagram of a first preset control policy table in the embodiment when the number of heating pins is 3;
FIG. 7 is a diagram of a second preset control policy table in the embodiment when the number of heating pins is 3;
Detailed Description
The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.
As shown in fig. 1-2, a heating control method of a PTC heater for a vehicle, the PTC heater for a vehicle includes a plurality of heating pins; the heating control method comprises the following steps:
s1, receiving heating control instructions and outputting opening instructions to the heating pins one by one;
s2, detecting whether the PTC heater for the vehicle reaches the preset maximum power, and if not, detecting whether the temperature reaches the preset temperature;
and S3, if the preset temperature is not reached, detecting the fault number of the heating pins and recombining the output states of the normal pins according to the fault number of the heating pins and the fault heating pins.
Compared with the unified mode of opening together in the prior art, in the scheme, after the heating control command is received, the heating pins are opened one by one, a time difference exists in the starting of each heating pin, the existence of the time difference can effectively reduce the peak current when the PTC heater is opened, and it needs to be explained that the peak current refers to the maximum load current of the electric equipment in a short time, and when the heating pins are opened simultaneously, the PTC heater can generate a very large peak current, the peak current is reduced in the mode of opening at intervals, and the safety performance and the service life of the PTC heater are further improved. And in step S3, the PTC heater recombines the normal pins to heat according to the number of failed heating pins and the failed heating pins, so that the output value of the heating pins is closer to the requested value, the influence of the partial pin failure on the heating effect of the PTC heater is reduced, and the function of each normal heating pin can be fully exerted.
As shown in fig. 3-4, the heating control command in step S1 includes a desired output power value, i.e., how much power the user wants to output. When the PTC heater for the vehicle reaches the preset maximum power at step S2, checking a preset control strategy table and outputting an actual driving value; when the detected temperature reaches the preset temperature in step S2, the driving value is output according to the preset percentage of the expected value of the output power and by checking the preset control strategy table, that is, when the temperature in the vehicle or the temperature of the PTC heater reaches the preset temperature, the value is reduced on the basis of the expected value of the output power, the heating rate is reduced, and unnecessary power waste can be reduced.
In step S3, when all the heating pins of the PTC heater fail, the output is turned off, and at this time, the PTC heater fails and cannot normally provide heat; after sending the opening instruction to each heating pin, the detection module of PTC heater can detect the state of each pin, according to the testing result of difference, formulates different outputs:
when 2 or more normal pins are provided, all the normal pins are detected, a preset control strategy table is checked, the output of the normal pins is controlled, the actual output value is close to the requested value to the maximum extent, and the number of the working pins at the moment can be one, two or more; when only one normal pin is detected, the normal pin is detected and output of the normal pin is controlled, and only one normal heating pin works at the moment; when all the heating pins of the PTC heater are in failure, the output is closed, and all the heating pins do not work. Specifically, the preset control policy table includes: when a heating pin needing to be output is failed, the scheme of replacing the failed heating pin by other normal heating pins is controlled to be started so as to enable the heating pin to be close to the actual requested value.
As shown in fig. 5, detecting whether the pin is normal includes the steps of:
detecting whether a driving signal exists on the pin, if not, detecting whether the current value is greater than a preset value, and if so, determining that the pin is in a short-circuit state;
if the pin is detected to have a driving signal, detecting whether the pin is opened, if so, detecting whether the pin has a short-circuit signal, and if so, determining that the pin is in an overcurrent state; if the short circuit signal does not exist, whether the current increase value reaches a preset value after the pin is opened is detected, if so, the pin is in a normal state, and if not, the pin is in an open circuit state. The current change of passing through of detection heating pin can judge the operating condition of heating pin, can judge which kind of form's of its concrete trouble that is, and then makes PTC heater make corresponding countermeasure.
Referring to fig. 6-7, in the embodiment when the number of the heating pins is 3, it should be noted that both the table one and the table two are included in the preset control policy table. In fig. 6, when there is no fault in any of the three heating pins of the PTC, the on-states of the three heating pins are controlled according to the magnitude of the requested power (i.e., the expected output power), as can be seen from table one, the powers of the heating pin 1, the heating pin 2 and the heating pin 3 are gradually increased, and when the requested power value is between 17% and 32%, the low-power heating pin 1 is turned on to perform heating; when the requested power value is between 33 and 49 percent, starting a heating pin 2 with power larger than that of the heating pin 1 for heating; when the requested power is between 50 and 66 percent, a high-power heating pin 3 is started for heating; when the requested power is 67-82%, starting the heating pin 1 and the heating pin 3 for heating; when the requested power is between 83-94%, the heating pins 2 and 3 are both started to heat; and when the requested power is 95-100%, the heating pin 1, the heating pin 2 and the heating pin 3 are all started to heat, so that the output power can be close to the requested power to the maximum extent. While some heating pins may be failed due to the increase of the usage time or the occurrence of an accident, in fig. 7, it can be summarized that when a pin which needs to operate originally but cannot operate normally due to the failure, the relevant alternative is looked up in the table two to make the actual output power close to the requested power. Taking the data of 83-94% as an example, when all the heating pins are normal, the heating pin 2 and the heating pin 3 should be both turned on for heating, and when the heating pin 1 fails, the heating pin 2 and the heating pin 3 work; when the heating pin 2 is in fault, the heating pin 3 is normally opened, and the heating pin 2 is closed, wherein the heating pin 1 and the heating pin 3 are opened to heat together; when the heating pin 3 is in fault, the heating pin 2 works normally, and the heating pin 3 is closed, and the alternative scheme is to open the heating pin 1 and heat the heating pin 2 together; the heating efficiency is high, and the temperature control is accurate.
This scheme still provides automobile-used PTC heater's heating control system, includes:
the control module is used for receiving the heating control instructions and outputting opening instructions to the heating pins one by one;
the detection module is in communication connection with the control module and is used for detecting whether the PTC heater for the vehicle reaches the preset maximum power or not, and if not, detecting whether the temperature reaches the preset temperature or not; if the temperature does not reach the preset temperature, detecting the fault number of the heating pins and the fault heating pins; the control module recombines the output states of the normal pins according to the detected heating pin fault number and the fault heating pins.
Wherein the heating control command comprises an output power desired value; when the detection module detects that the vehicle PTC heater reaches the preset maximum power, the control module checks a preset control strategy table and outputs an actual driving value; when the detection module detects that the temperature reaches the preset temperature, the control module outputs a driving value according to the preset percentage of the output power expected value and checks the preset control strategy table.
When the detection module detects all faults of the heating pins, the control module closes the output; when the detection module detects that only one normal pin exists, the normal pin is detected, and the control module controls the output of the normal pin; when the detection module detects that the number of the normal pins is 2 or more, all the normal pins are detected, and the control module controls the output of the normal pins according to a preset control strategy table. Specifically, the preset control policy table includes: when a heating pin needing to be output fails, other normal heating pins are controlled to be started to replace the failed heating pin.
Preferably, the detection module is configured to detect whether the detection pin is normal:
when detecting whether the pin has a driving signal, if not, detecting whether the current value is greater than a preset value, and if so, determining that the pin is in a short-circuit state;
if the driving signal exists, detecting whether the pin is opened, if so, detecting whether a short-circuit signal exists, and if so, determining that the pin is in an overcurrent state; if the short circuit signal does not exist, whether the current increase value reaches a preset value after the pin is opened is detected, if so, the pin is in a normal state, and if not, the pin is in an open circuit state.
If the driving signal exists, detecting whether the pin is opened, if so, detecting whether a short-circuit signal exists, and if so, determining that the pin is in an overcurrent state; if the short circuit signal does not exist, whether the current increase value reaches a preset value after the pin is opened is detected, if so, the pin is in a normal state, and if not, the pin is in an open circuit state.
The PTC heating method and the PTC heating system have the advantages of high safety performance, high heating efficiency and accurate temperature control, and can play the role of each heating pin to the greatest extent.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.