Active noise reduction control system of air heating PTC heater

Abstract

The invention discloses an active noise reduction control system for an air heating PTC heater, and relates to the field of air heating PTC heaters in a new energy automobile thermal management system, which comprises a first heating core body and a second heating core body which are symmetrically arranged, a first switch tube connected with the first heating core body in series, and a second switch tube connected with the second heating core body in series, and a control module. And the control module outputs two paths of driving signals to respectively control on and off of the first switching tube and the second switching tube. According to the active noise reduction control system of the air heating PTC heater, acoustic feedback and a self-adaptive control algorithm are combined, so that high-frequency noise generated by periodic on-off work of the PTC element can be effectively inhibited. According to the system, the driving phase is dynamically adjusted through noise signals collected in real time, so that out-of-phase sound waves generated by the two heating core bodies are offset in the propagation process, noise reduction is directly achieved from the noise source, and the acoustic comfort of a passenger compartment of the new energy automobile is improved.

Description

Technical Field

[0001] This invention relates to the field of air-heated PTC heaters in the thermal management system of new energy vehicles, specifically to an active noise reduction control system for air-heated PTC heaters. Background Technology

[0002] With the rapid development of new energy vehicles in my country, the requirements for overall vehicle comfort are increasing. Pure electric vehicles, by eliminating the traditional engine, significantly reduce cabin background noise, making the operating noise of previously masked components particularly prominent. The PTC heater for the passenger compartment, a crucial component for heating the passenger compartment, is typically installed below the dashboard. During operation, the piezoelectric effect of the PTC element generates a noticeable "ticking" noise. This noise intensifies with increasing modulation frequency and current through the heater core, severely impacting the comfort of passengers. Therefore, effectively suppressing the noise generated by the PTC heater during operation has become a pressing technical problem in the field of thermal management for new energy vehicles. Summary of the Invention

[0003] The purpose of this invention is to provide an active noise reduction control system for a wind-heated PTC heater to solve the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an active noise reduction control system for a wind-heated PTC heater, comprising a first heating core and a second heating core symmetrically arranged, a first switching transistor connected in series with the first heating core, a second switching transistor connected in series with the second heating core, and a control module; the control module outputs two drive signals to control the conduction and cutoff of the first switching transistor and the second switching transistor respectively; The system also includes acoustic sensors installed in the air duct; The control module includes a signal processing unit and a drive signal generation unit; The acoustic sensor is connected to the input terminal of the signal processing unit; The signal processing unit dynamically adjusts the phase difference between the two drive signals based on the sound pressure signal collected by the acoustic sensor.

[0005] Preferably, the signal processing unit includes an adaptive controller; the adaptive controller uses two driving signals as reference signals and the sound pressure signal as an error signal, calculates the phase adjustment amount through a minimum mean square algorithm and outputs it to the driving signal generation unit.

[0006] Preferably, the drive signal generation unit receives a phase adjustment amount and adjusts the phase difference between the two drive signals. The adjustment range of the phase difference is greater than zero and less than the pulse width of a single drive signal.

[0007] Preferably, it also includes a current detection circuit, which is connected to the power supply circuit of the first heating core and the second heating core; the control module controls the conduction sequence of the first switching transistor and the second switching transistor to avoid overlap according to the output signal of the current detection circuit.

[0008] Preferably, the control module is communicatively connected to the vehicle thermal management controller and receives a temperature setting signal; the control module synchronously corrects the duty cycle of the drive signal when adjusting the phase difference to maintain stable output thermal power.

[0009] Preferably, the acoustic sensor is a MEMS microphone, which is installed on the inner wall of the air outlet duct of the PTC heater.

[0010] Preferably, the first and second switching transistors are IGBT devices, and their gates are respectively connected to the two output terminals of the drive signal generation unit.

[0011] Preferably, the adaptive controller includes a digital signal processor, which stores an adaptive algorithm program.

[0012] Preferably, the first heating core and the second heating core are made of positive temperature coefficient ceramic material, and the difference in their resistance values ​​is less than five percent of the rated value.

[0013] A vehicle equipped with the aforementioned active noise reduction control system for a PTC heater.

[0014] This invention provides an active noise reduction control system for a PTC air-cooled heater. It has the following beneficial effects: This active noise reduction control system for the PTC heater effectively suppresses high-frequency noise generated by the periodic switching of the PTC element by combining acoustic feedback with an adaptive control algorithm. The system dynamically adjusts the drive phase using real-time acquired noise signals, causing the out-of-phase sound waves generated by the two heating elements to cancel each other out during propagation. This directly reduces noise at its source, improving the acoustic comfort of the passenger cabin in new energy vehicles.

[0015] This active noise reduction control system for the PTC air heater not only reduces noise but also ensures the operational safety of the power switching transistors and the stability of the heating output power by introducing a current safety closed-loop and thermal management collaborative control mechanism. The multi-loop control strategy ensures that the noise reduction process does not affect the system's heating performance and reliability, achieving multi-objective optimization of noise control, thermal comfort assurance, and safe system operation. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the module interaction of an active noise reduction control system for a PTC heater with air heating according to the present invention. Figure 2 This is a flowchart illustrating an active noise reduction control method for a PTC heater with air heating according to the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figure 1 and Figure 2 The present invention provides a technical solution: an active noise reduction control system for a wind-heated PTC heater, comprising a first heating core and a second heating core symmetrically arranged, a first switching tube connected in series with the first heating core, a second switching tube connected in series with the second heating core, and a control module; the control module outputs two drive signals to control the conduction and cutoff of the first switching tube and the second switching tube respectively; The system also includes acoustic sensors installed within the air duct; The control module includes a signal processing unit and a drive signal generation unit; The acoustic sensor is connected to the input terminal of the signal processing unit; The signal processing unit dynamically adjusts the phase difference between the two drive signals based on the sound pressure signal collected by the acoustic sensor.

[0019] It should be further explained that during system initialization, the control module outputs two drive signals with an initial phase difference to drive the first and second switching transistors respectively, causing the first and second heating cores to work alternately, thus avoiding the current superposition and increased noise caused by simultaneous conduction. During system operation, acoustic sensors arranged in the air duct collect the noise signals generated by the PTC in real time and transmit them to the signal processing unit in the control module.

[0020] The signal processing unit preprocesses and performs feature analysis on the sound pressure signal, identifying the main frequency components and amplitudes of the noise. Based on this sound pressure signal, the adaptive controller uses two drive signals as reference signals and the noise signal as an error signal. It performs real-time calculations using a filter-based least mean square algorithm to dynamically calculate the optimal phase offset that allows the noise to cancel each other out. This calculated offset is then output to the drive signal generation unit for fine-tuning the phase of the drive signal. This adjustment process continues to achieve active noise suppression.

[0021] Throughout the adjustment process, the control module monitors the current flowing through the heating core in real time to ensure that the conduction sequence of the two switching transistors does not overlap, thus avoiding the risk of short circuit. At the same time, it receives the temperature setting signal from the vehicle thermal management system and adjusts the duty cycle of the drive signal in coordination when adjusting the phase, so that the heating power output remains stable and maintains the thermal comfort of the ride.

[0022] This system achieves noise reduction while ensuring system safety and reliable heating performance through multi-layer closed-loop control that integrates acoustic feedback, current detection, and thermal management.

[0023] The signal processing unit includes an adaptive controller. The adaptive controller uses two drive signals as reference signals and the sound pressure signal as an error signal. It calculates the phase adjustment using a filter-based minimum mean square algorithm and outputs it to the drive signal generation unit. Further explanation is needed: in the specific implementation of the active noise reduction control system for the PTC heater, the adaptive controller in the signal processing unit operates as follows: the adaptive controller receives the real-time sound pressure signal from the acoustic sensor as the error signal, and simultaneously inputs the two generated drive signals as reference signals. The controller internally uses a filter-based minimum mean square algorithm for processing. This algorithm continuously adjusts its filter coefficients to calculate a phase adjustment that minimizes the energy of the error signal. This calculation process is continuous, enabling the system to automatically track changes in noise characteristics caused by variations in operating current, airflow fluctuations, or component aging, and to correct the phase difference of the drive signals in real time. During actual vehicle operation, if a change in the noise spectrum characteristics is detected, such as the appearance of new noise frequency components or an increase in the amplitude of existing noise, the algorithm will adjust the convergence step size and iteration weights accordingly to balance response speed and system stability, ensuring effective noise suppression under different operating conditions. The calculated phase adjustment is transmitted to the drive signal generation unit in real time to precisely control the relative delay of the leading or trailing edges of the two drive signals, thereby achieving a dynamic noise cancellation effect. This adaptive control mechanism does not require preset fixed delay parameters or manual intervention, forming a closed-loop active noise reduction capability and improving the system's intelligence and environmental adaptability.

[0024] The drive signal generation unit receives the phase adjustment amount and adjusts the phase difference between the two drive signals. The adjustment range of the phase difference is greater than zero and less than the pulse width of a single drive signal. It should be further explained that in the specific implementation, after receiving the phase adjustment amount from the adaptive controller, the drive signal generation unit dynamically adjusts the relative phase of the two drive signals. Internally, this unit implements phase control through a programmable timer or digital delay circuit. Its core mechanism is to precisely change the rising or falling edge delay time of one drive signal relative to the other signal based on the received digital or analog adjustment amount.

[0025] The adjustment range of the phase difference is strictly constrained to a range greater than zero and less than the pulse width of a single drive signal. This constraint is achieved through hardware comparison circuits or software limiting algorithms, ensuring that under any operating condition, the two drive signals will neither be completely synchronized, leading to current superposition, nor will the effective conduction time of a single heating element be excessively compressed due to an excessive phase difference, thereby guaranteeing the continuity and stability of the heating function.

[0026] When the theoretical adjustment calculated by the adaptive algorithm exceeds this preset range, the drive signal generation unit will automatically output the boundary value and record it in the internal flag for diagnosis or subsequent optimization by the upper-level control logic. Through this bounded dynamic phase adjustment, the system actively cancels noise while maintaining the heater's power output fluctuations within a narrow range, ensuring that the thermal comfort experience of passengers is not perceptibly disturbed by noise reduction control. This implementation method combines noise reduction algorithms with reliable engineering constraints, which is key to achieving a balance between vehicle-level NVH performance and thermal comfort.

[0027] It also includes a current detection circuit, which is connected to the power supply circuits of the first and second heating cores. The control module, based on the output signal of the current detection circuit, controls the conduction timing of the first and second switching transistors to avoid overlap. It should be further noted that, in specific implementation, the current detection circuit acquires the current signal in real time through a sampling resistor or Hall sensor connected in series in the power supply circuits of the first and second heating cores, and converts this signal into a voltage signal, which is then transmitted to the control module. The signal processing unit inside the control module performs analog-to-digital conversion and filtering on this voltage signal to obtain an accurate real-time current value.

[0028] The control module combines the predetermined phase difference between the two drive signals with the real-time current value for judgment. If the logic analysis indicates a risk of both switches conducting simultaneously under the current phase difference setting, the control module will prioritize the execution of a safety strategy. This strategy first suspends the adaptive controller's dynamic adjustment of the phase difference and immediately intervenes in the drive signal generation unit to forcibly fine-tune the phase of one of the drive signals. This ensures that at any given moment, the conduction intervals of the first and second switches are completely staggered in time, avoiding the formation of a low-impedance path.

[0029] This process involves rapid verification and intervention within each switching cycle. Its response speed is sufficient to complete logic judgment and signal correction before the power transistor's switching action is finished, thus fundamentally eliminating the risk of bridge arm shoot-through short circuits introduced by phase adjustment, ensuring the safety of power components and the reliability of the system. After executing the safety intervention, the system records the event and attempts to restore the adaptive noise reduction control function on a new, safe phase difference reference, thereby achieving a balance between safety and noise reduction performance.

[0030] The control module communicates with the vehicle's thermal management controller and receives the temperature setpoint signal. While adjusting the phase difference, the control module synchronously corrects the duty cycle of the drive signal to maintain stable output thermal power. It should be further noted that, in practice, the control module receives the target temperature signal or the current outlet air temperature signal from the vehicle's thermal management controller via the vehicle bus. While performing dynamic phase adjustment to suppress noise, the control module calculates in real time the potential fluctuations in heating power caused by changes in phase difference. Based on the thermal management target and the current operating conditions, the system establishes a mapping relationship between phase difference, duty cycle, and output thermal power.

[0031] When the phase difference adjustment action is executed, the control module synchronously starts the duty cycle compensation algorithm. Based on the pre-stored power model or real-time calculation, the algorithm reversely adjusts the pulse width of the two drive signals so that although the effective heating time of the two heating cores is offset, the product of their total conduction time and average current value in a complete modulation cycle can be maintained, thereby ensuring that the final output thermal power is consistent with the requirements of the vehicle thermal management system.

[0032] If the system detects that the outlet air temperature deviates from the target range due to phase adjustment, it will prioritize thermal comfort, appropriately widen the phase adjustment range or temporarily suspend the adjustment, and control the duty cycle with maintaining the set temperature as the primary objective. This coordinated control mechanism ensures that the noise reduction function does not negatively affect the heating effect of the passenger cabin, achieving a balance between noise control and thermal comfort management.

[0033] The acoustic sensor is a MEMS microphone, mounted on the inner wall of the PTC heater's outlet duct. It should be further noted that in the specific implementation, the acoustic sensor is a MEMS microphone, installed on the inner wall of the PTC heater assembly's outlet duct. This mounting point was carefully chosen to avoid areas with direct airflow and minimal turbulence; it is typically selected on the inner wall after abrupt changes in the duct cross-section or at bends. This ensures effective acquisition of noise generated by the PTC core vibration and propagated through the air, while minimizing interference from fan airflow noise and wind resistance noise. The MEMS microphone is connected to the duct wall via a dedicated mounting bracket. A high-temperature resistant rubber or silicone sealing ring is placed between the bracket and the duct wall to achieve mechanical decoupling and sealing, preventing vibration transmission and air leakage.

[0034] The sensor body is covered with metal foil or thermally conductive adhesive to achieve electromagnetic shielding and temperature uniformity protection. Its signal cable is a shielded twisted-pair cable that passes through a sealed connector on the duct wall and connects to the control module. This installation method ensures that the sensor can operate stably under harsh conditions of high temperature, high humidity, and vibration, and acquire raw sound pressure signals with a high signal-to-noise ratio. This provides accurate and reliable input for subsequent adaptive noise reduction algorithms, and is a prerequisite and foundation for the effective operation of the entire active noise reduction control system.

[0035] The first and second switching transistors are IGBT devices, with their gates connected to the two output terminals of the drive signal generation unit, respectively. It should be further noted that in the specific implementation, the first and second switching transistors are IGBT devices, with their collectors connected to the high-voltage terminals of the first and second heating cores, respectively, and their emitters connected to the current detection circuit. The two outputs of the drive signal generation unit are connected to the gates of the two IGBTs respectively through a dedicated gate driver chip. This gate driver chip provides the necessary voltage boost, current amplification, and isolation protection functions to ensure that the low-power logic signal output by the control module can reliably drive the IGBTs to turn on and off.

[0036] Each IGBT has a small gate resistor connected in series in its gate circuit to suppress signal ringing and control switching speed. At the same time, a Zener diode connected in reverse and a larger discharge resistor are connected in parallel between the gate and the emitter to form a gate overvoltage protection and charge discharge path.

[0037] The IGBT devices are mounted on a heatsink shared with the PTC heater assembly, but are electrically isolated from each other by an insulating thermal pad to ensure heat dissipation efficiency and meet safety requirements. This implementation method, which uses IGBTs in conjunction with specific drive and protection circuits, can meet the reliability requirements of automotive PTC heaters for high-voltage, high-current switching.

[0038] The adaptive controller includes a digital signal processor (DSP) that stores the adaptive algorithm program. Specifically, in implementation, the adaptive controller incorporates a DSP with integrated high-speed arithmetic logic unit (ALU) and a dedicated instruction set for digital signal processing. Upon system power-up, the adaptive algorithm program, stored in the processor's external non-volatile memory, is loaded into the internal RAM for execution. This program includes several functional modules: system initialization, interrupt service management, signal acquisition and preprocessing, adaptive filtering calculation, and drive signal parameter updates. During algorithm execution, the processor synchronously acquires the analog sound pressure signal output from the acoustic sensor via its multi-channel ADC interface and simultaneously reads the digital states of the two current drive signals as reference inputs.

[0039] Within each interrupt service cycle, the program calls the minimum mean square (LMS) filter function library to iteratively update the weight coefficients of the internal filter based on the latest reference and error signal sequences, and calculates the required phase adjustment. This calculation process fully considers the balance between processor accuracy and real-time performance, employing a combination of fixed-point arithmetic and lookup table methods to optimize execution speed, ensuring that complex adaptive calculations are completed with limited hardware resources. The calculated phase adjustment is sent to the drive signal generation unit via the processor's high-speed communication interface.

[0040] In addition, the program includes monitoring and diagnostic functions, continuously monitoring the algorithm's convergence status and the effectiveness of the input signals. When an anomaly is detected, it automatically switches to a preset safety mode to ensure the system's basic heating function remains unaffected. This software-based implementation using a digital signal processor provides a flexible and reliable operating platform for complex adaptive noise reduction algorithms, serving as the core of intelligent system control.

[0041] The first and second heating cores are made of positive temperature coefficient ceramic materials, with a resistance deviation of less than five percent of their rated values. It should be further noted that, in practice, both the first and second heating cores are made of ceramic materials with positive temperature coefficient characteristics, and their material formulations and sintering processes are consistent to ensure highly consistent resistance-temperature characteristic curves within the operating temperature range. During production, each pair of cores undergoes rigorous screening and matching tests. The core parameter is the actual resistance value measured under the same reference temperature and applied voltage conditions, and the resistance deviation between the two cores is controlled to be well within the product's rated nominal resistance tolerance.

[0042] This highly symmetrical resistive characteristic is the fundamental physical prerequisite for subsequent active noise cancellation control. It ensures that when the two drive signals are interleaved with a set phase difference, the current amplitude flowing through the two cores is basically the same, thus making the noise intensity generated by the vibration of the two sound sources, i.e. the cores, similar, creating the necessary conditions for subsequent sound wave cancellation through precise phase adjustment.

[0043] If the resistance characteristics of the two cores differ significantly, the resulting noise intensities will differ even under the same driving conditions, making it difficult to achieve the desired noise reduction effect through a single phase adjustment. Therefore, this implementation method, by strictly controlling the performance consistency of the core heat-generating components, lays the material foundation for the system's noise reduction capability from the source. It is an indispensable key link that is deeply coupled with subsequent circuits and control strategies.

[0044] A vehicle is equipped with an active noise reduction control system for a PTC heater. It should be further explained that, in practice, the active noise reduction control system for the PTC heater is integrated into the vehicle's passenger compartment thermal management system. This system assembly is typically installed below the dashboard or in a specific location between the front compartment and the passenger compartment, with its air duct outlet connected to the vehicle's air conditioning duct. The system's high-voltage power input is connected to the power battery via the vehicle's high-voltage junction box, receiving high-voltage DC power; its low-voltage power supply and communication interface are connected to the vehicle's domain controller or a separate thermal management controller via the vehicle wiring harness to obtain operating commands and target temperature signals.

[0045] When the vehicle starts and the driver or automatic air conditioning system requests heating, the vehicle controller or thermal management controller sends a start command and temperature setting parameters to the noise reduction control system. The system then begins to work according to the aforementioned control logic, that is, by using symmetrical core alternating operation, acoustic feedback adaptive phase adjustment, and current and thermal management coordinated control, it actively suppresses the noise generated by the PTC heater while providing the required heat.

[0046] Vehicle operating status information, such as vehicle speed, ambient temperature, and blower speed, can be transmitted to the control module via the vehicle bus. This information can serve as auxiliary input parameters for fine-tuning the aggressiveness or priority of the noise reduction algorithm, for example, appropriately prioritizing heating performance under extremely high load conditions. As a subsystem of the vehicle, the system's operating status and fault information can also be fed back to the vehicle's instrument panel or diagnostic system via the bus, enabling status visualization and fault warnings.

[0047] This implementation method clarifies the specific integration scheme, interaction interface and collaborative workflow for applying the noise reduction system to the whole vehicle environment, ensuring that the invention can ultimately achieve its expected noise reduction and heating effects in actual vehicle products.

[0048] It should be further explained that, in the specific implementation process, the system effectively suppresses the noise generated by the PTC element due to periodic current excitation through the coordinated cooperation of hardware topology and adaptive control algorithm. The hardware foundation of the system includes symmetrically placed first heating core (R1) and second heating core (R2). These two cores are made of ceramic materials with positive temperature coefficient characteristics and are precisely selected during the production process to ensure that their resistance values ​​are highly consistent under the same operating conditions. Each core is connected in series with a switching transistor (G1, G2), preferably an IGBT. The two IGBTs are independently controlled by two drive signals output from the control module to turn on and off.

[0049] The control module is the brain of the entire system, and its key feature is the introduction of an adaptive dynamic adjustment mechanism based on acoustic feedback. The implementation of this mechanism relies on an acoustic sensor, such as a MEMS microphone, installed on the inner wall of the PTC heater's outlet duct to collect operating noise in real time. The collected sound pressure signal is then fed into the digital signal processor (DSP) within the control module.

[0050] The adaptive noise reduction algorithm running in the DSP employs a minimum mean square filter algorithm. The purpose of this algorithm is to dynamically adjust the phase difference Δφ between the two drive signals, G1 and G2, so that the out-of-phase noise generated by the two cores acoustically cancels each other out.

[0051] The core calculation formula of the algorithm is as follows: The core of the minimum mean square algorithm for filtering x is to iteratively update the weight vector W(n) of a finite impulse response (FIR) filter. The output of this filter is the required phase adjustment. Its iterative formula is: W(n+1) = W(n) + μe(n)X'(n); Where: W(n) is the filter weight vector at the current time n, and W(n+1) is the updated weight vector at the next time step; μ is the convergence step size, a pre-set positive number used to control the convergence speed and stability of the algorithm; e(n) is the error signal, i.e., residual noise, collected by the acoustic sensor at the current time n; X'(n) is the signal after the reference signal X(n) is filtered by an estimation model Š(z) simulating the acoustic path transfer function. The reference signal X(n) is synchronized with the original drive signal.

[0052] The calculated phase adjustment is output to the drive signal generation unit, which precisely adjusts the phase of one of the drive signals using a programmable timer or digital delay line. The adjustment range of the phase difference is strictly constrained to a value greater than zero and less than the pulse width T of the single drive signal. pw Within the interval, i.e., 0 < Δφ <T pw This constraint ensures that: (a) the two drive signals never overlap, fundamentally avoiding the risk of a short circuit in the bridge arm; and (b) the effective conduction time of each heating core is not excessively compressed, thus guaranteeing the heating function.

[0053] To ensure system safety and reliability, multiple closed-loop monitoring systems were introduced, including the following two closed loops: Current safety closed-loop: The current detection circuit monitors the current flowing through the core in real time. The control module combines the phase difference setpoint with the real-time current value for judgment. The logical condition is: if |I R1 |>I threshold And|I R2 |>I threshold If the time intervals overlap, a short-circuit risk is identified (I). threshold(For a tiny current threshold close to zero). Once this condition is met, the control module will immediately pause adaptive adjustment, force intervention, and fine-tune the phase to ensure that the conduction intervals are completely offset.

[0054] Thermal Management Closed Loop: The control module receives the target temperature signal from the vehicle's thermal management system via the vehicle bus. When phase adjustment may cause fluctuations in thermal power, the system activates a duty cycle compensation algorithm. This algorithm is based on a pre-stored or real-time calculated lookup table that establishes a mapping relationship between phase difference, duty cycle, and output thermal power. The compensation logic is as follows: when an increase in phase difference Δφ causes an offset in the effective heating time, the system synchronously increases the duty cycle (D) of the drive signal according to the mapping relationship to maintain D(1|Δφ| / T). period The product stability of (T) period (to drive the signal cycle), thereby stabilizing the output thermal power and ensuring thermal comfort for passengers.

[0055] By employing a closed-loop technology of "acoustic feedback-adaptive phase modulation," supplemented by two auxiliary closed loops for current safety and thermal management, the contradiction between PTC heater noise, heating performance, and system safety is resolved. Furthermore, the algorithm formulas and logical judgment conditions provide a concrete and sufficient technical approach for implementing this technology.

[0056] An active noise reduction control method for a wind-heated PTC heater includes the following steps: Step S1: System initialization. The control module outputs two drive signals with an initial phase difference, which control the first switch and the second switch to conduct alternately, driving the first heating core and the second heating core to work in a time-sharing manner, so as to avoid the current superposition during the initial power-on. Step S2: The acoustic sensor collects the noise signal generated by the PTC heater in real time and transmits the sound pressure signal to the signal processing unit in the control module; Step S3: The signal processing unit preprocesses and extracts features from the sound pressure signal to identify the frequency and amplitude information of the noise; Step S4: The adaptive controller uses the two drive signals as reference signals and the sound pressure signal as the error signal to execute the minimum mean square filtering algorithm to calculate the optimal phase adjustment amount for noise cancellation in real time. Step S5: The drive signal generation unit dynamically adjusts the phase of one of the drive signals according to the phase adjustment amount, thereby changing the energizing sequence of the two heating cores; Step S6: The current detection circuit monitors the current flowing through the heating core in real time. If it is determined that there is a risk of simultaneous conduction of the two switching transistors, the control module will forcibly intervene to adjust the phase to ensure that the conduction intervals are completely staggered. Step S7: The control module receives the temperature signal from the vehicle's thermal management system. If the phase adjustment causes a change in heating power, the drive signal duty cycle is adjusted synchronously to maintain stable output thermal power. Step S8: The system continuously executes steps S2 to S7 in a loop to achieve multi-closed-loop active noise reduction control based on acoustic feedback, current safety and thermal management.

[0057] By combining acoustic feedback with adaptive control algorithms, high-frequency noise generated by the periodic switching of PTC elements can be effectively suppressed. This system dynamically adjusts the drive phase using real-time acquired noise signals, causing the out-of-phase sound waves generated by the two heating cores to cancel each other out during propagation. This directly reduces noise at its source, improving the acoustic comfort of the passenger cabin in new energy vehicles.

[0058] Furthermore, while achieving noise reduction, the system ensures the operational safety of the power switching transistors and the stability of the heating output power by introducing a current safety closed-loop and thermal management collaborative control mechanism. This multi-loop control strategy ensures that the noise reduction process does not affect the system's heating performance and reliability, achieving multi-objective optimization of noise control, thermal comfort assurance, and system safety operation, thus enhancing the product's overall competitiveness and practical value.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An active noise reduction control system for a PTC heater with air heating, comprising a first heating core and a second heating core symmetrically arranged, a first switching transistor connected in series with the first heating core, a second switching transistor connected in series with the second heating core, and a control module; the control module outputs two drive signals to control the on and off states of the first and second switching transistors respectively; characterized in that: The system also includes acoustic sensors installed in the air duct; The control module includes a signal processing unit and a drive signal generation unit; The acoustic sensor is connected to the input terminal of the signal processing unit; The signal processing unit dynamically adjusts the phase difference between the two drive signals based on the sound pressure signal collected by the acoustic sensor.

2. The active noise reduction control system for a PTC air heater according to claim 1, characterized in that: The signal processing unit includes an adaptive controller; the adaptive controller uses two driving signals as reference signals and the sound pressure signal as an error signal, calculates the phase adjustment amount through a minimum mean square algorithm and outputs it to the driving signal generation unit.

3. The active noise reduction control system for a PTC air heater according to claim 2, characterized in that: The drive signal generation unit receives the phase adjustment amount and adjusts the phase difference between the two drive signals. The adjustment range of the phase difference is greater than zero and less than the pulse width of a single drive signal.

4. The active noise reduction control system for a PTC air heater according to claim 1, characterized in that: It also includes a current detection circuit, which is connected to the power supply circuit of the first heating core and the second heating core; the control module controls the conduction sequence of the first switching transistor and the second switching transistor to avoid overlap based on the output signal of the current detection circuit.

5. The active noise reduction control system for a PTC heater according to claim 1, characterized in that: The control module is communicatively connected to the vehicle thermal management controller and receives temperature setting signals. When adjusting the phase difference, the control module synchronously corrects the duty cycle of the drive signal to maintain stable output thermal power.

6. The active noise reduction control system for a PTC air heater according to claim 1, characterized in that: The acoustic sensor is a MEMS microphone, which is installed on the inner wall of the air outlet duct of the PTC heater.

7. The active noise reduction control system for a PTC air heater according to claim 1, characterized in that: The first and second switching transistors are IGBT devices, and their gates are respectively connected to the two output terminals of the drive signal generation unit.

8. The active noise reduction control system for a PTC heater according to claim 2, characterized in that: The adaptive controller includes a digital signal processor, which stores an adaptive algorithm program.

9. The active noise reduction control system for a PTC air heater according to claim 1, characterized in that: The first heating core and the second heating core are made of positive temperature coefficient ceramic material, and the difference in their resistance values ​​is less than five percent of the rated value.

10. A vehicle, characterized in that: The air-heated PTC heater is equipped with an active noise reduction control system as described in any one of claims 1-9.

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