A method of controlling an electrically driven air pump

Abstract

A kind of electric transmission air pump control method, according to the rotational speed-power curve of generator, pump motor designed, reasonably distribute the matching balance relationship between power generation power and the wind resistance load brought by pump motor rotational speed;With the purpose that pump motor always runs without equipment over-temperature in the steady operation of heat dissipation system, dynamic real-time heat dissipation air pump speed control is carried out, this method can control generator power generation operation and the speed control operation of several heat dissipation air pump motors simultaneously, without adding super capacitor or high-voltage power battery and other high-power energy storage equipment to realize the stable control of electric transmission air pump, reduce system cost, improve reliability.

Description

Technical Field

[0001] This invention relates to the field of electrical technology for special vehicles, and in particular to a method for controlling an electric drive air pump. Background Technology

[0002] In special vehicles, the power source for the cooling air pump in the engine compartment is mainly provided by the engine through mechanical power take-off mechanisms such as belts and gears, or by hydraulic mechanisms. The air pump speed usually varies with the engine speed, resulting in problems such as low accuracy, slow response, and mismatch in cooling power; moreover, due to the limitations of the installation and layout of the power take-off mechanism, there is also the problem of the air pump not being placed in an optimal position.

[0003] With the development of electrical technology for special vehicles, electric air pumps based on new motor drive technology can be precisely speed-adjusted according to heat dissipation requirements, and energy transmission is carried out through cables, allowing air pumps to be distributed and installed in locations that are conducive to heat dissipation duct design. The control system of the air pump can also be installed in a suitable location, freeing it from the installation location restrictions of the power take-off mechanism.

[0004] However, with increasingly powerful vehicle engines, the application of high-power diesel engines has brought about a greater demand for heat dissipation, and the addition of new high-power power electronic devices has also created new heat dissipation requirements. The power of the electric air pump itself determines the demand for a high-power electrical energy source. The usual practice is to use a power take-off generator to convert the engine's mechanical energy into electrical energy to power the air pump. However, the simple power-load power transfer mode requires the power supply to have high voltage regulation quality to ensure stable output voltage under dynamic changes in the electrical load; at the same time, the speed of the power take-off generator itself usually varies drastically with the engine speed, which further increases the difficulty of power supply design.

[0005] If the power system is designed according to these conditions, it will inevitably require the addition of supercapacitors or high-voltage batteries as high-power energy storage systems to smooth out peak and valley load changes. However, the addition of supercapacitors or high-voltage battery packs will result in power waste in most operating conditions, increase procurement and maintenance costs, increase system complexity, reduce reliability, and occupy vehicle installation space and weight distribution, making it an uneconomical approach. Summary of the Invention

[0006] This disclosure provides a control method for an electric-driven air pump. It integrates the generator control module and the air pump motor control modules, sharing a high-voltage DC bus and charge discharge circuit. It can simultaneously control the generator's operation and the speed regulation of several cooling air pump motors. According to the designed speed-power curves of the generator and pump motors, it rationally allocates the matching balance between the generator power and the wind resistance load caused by the pump motor speed. With the aim of keeping the pump motor running without equipment overheating during the steady-state operation of the cooling system, it dynamically and in real-time controls the speed of the cooling air pumps. This successfully achieves stable control of electric-driven air pumps without high-power energy storage devices such as supercapacitors or high-voltage power batteries, reducing system costs and improving reliability.

[0007] The electrically driven air pump control method disclosed herein mainly includes the following steps:

[0008] S1, when starting the engine for the first time, when the generator speed n is at the starting speed n0≤n≤generating speed n1, the generator operates in 0 current condition, that is, the set torque current is 0, and the power switch of the generator control module is turned on with a very small duty cycle; when the speed n is greater than or equal to n1, the generator enters the generating condition, and when the bus voltage is greater than U1, the motor starts its first operation at the idle speed N1.

[0009] S2, when the generator speed fluctuates normally within the range of [n1, n3], the pump motor speed is linearly adjusted according to the outlet water temperature TH of the engine water-cooled radiator and the outlet water temperature TL of the electrical equipment water-cooled radiator; at the same time, the pump motor speed shall not exceed the speed limit value calculated according to the generator output power curve.

[0010] S3, when the generator speed drops below n1, distinguish between abnormal operating conditions and shutdown operating conditions: in abnormal operating conditions, maintain the motor in standby low-speed operation for as long as possible, and wait for the generator speed to recover; in shutdown conditions, use the motor to quickly discharge the bus charge to below the safe voltage.

[0011] Furthermore, step S1 specifically includes:

[0012] Set the initial power generation flag, which is set to "0" by default;

[0013] When the engine starts, if the generator speed n0≤n≤n1, the generator control module operates in 0 current control mode, that is, the power switch of the generator control module is kept on with a very small duty cycle.

[0014] When the generator speed n>n1, the generator control module enters the generator mode, sets the first generator flag to "1", and uses voltage loop control to control the generator voltage to rise at a given slope. When the bus voltage U>U1, each cooling air pump is driven to run at idle speed N1, which has basic heat dissipation capacity and generates a certain load.

[0015] Furthermore, step S2 specifically includes:

[0016] When the generator speed is within the range of [n1, n3], the electric drive air pump simultaneously collects the outlet water temperature TH of the engine water-cooled radiator and the outlet water temperature TL of the electrical equipment water-cooled radiator.

[0017] When TH≤th1 and TL≤tl1, the pump motor maintains the idle speed N1.

[0018] When TH≥th2 or TL≥tl2, the pump motor maintains high speed N3 operation;

[0019] When th2>TH≥th1 or tl2>TL≥tl1, the pump motor speed accelerates from N1 to N2, and linearly adjusts within the speed range [N2, N3] as the water temperature TH or TL changes. The pump motor speed N is prioritized based on the speed adjustment requirement, i.e., when N(TH)≥N(TL), N=N(TH); i.e., when N(TH)≤N(TL), N=N(TL). N(TH) is the linear speed adjustment value of the pump motor corresponding to water temperature TH, and N(TL) is the linear speed adjustment value of the pump motor corresponding to water temperature TL.

[0020] Furthermore, in step S2, when the generator speed n is within the range of [n1, n3], the pump motor speed N cannot exceed the maximum speed limit N′(n); wherein, the method for determining N′(n) specifically includes:

[0021] Based on the following: the power of the pump motor is approximately cubic to the pump motor speed; the total power of the pump motor cannot exceed the maximum power output of the generator at the current speed; and when the generator speed n is in the constant torque region [n1, n2], the maximum power output it can provide is approximately proportional to the speed, and when it is in the constant power region [n2, n3], the maximum power output remains constant.

[0022] After transformation, the speed limiting curves of each pump motor N′=N′(n) are obtained at different generator speeds n. That is, when the motor speed regulation speed N> the speed limit N′, N=N′.

[0023] Furthermore, step S3 specifically includes:

[0024] When the engine speed suddenly drops below idle speed, causing the generator speed to drop below n1, the generator control module exits the generator operation mode and enters the zero-current operation mode; at this time, the initial generator flag bit is still kept at "1", and the automatic generator recovery strategy is executed.

[0025] If the generator speed recovers from above the starting speed n0 to above the generating speed n1, then power generation is resumed. When the bus voltage is > U1, it is considered that the power generation has been restored and the motor resumes normal speed regulation operation.

[0026] When the generator speed is lower than the starting speed n0, the generator control module controls the generator to exit the 0 current condition, completely blocks the generator output, and sets the first power generation flag to "0", which is regarded as the engine has been shut down.

[0027] When the generator exits the power generation mode but the first power generation flag is still "1", and the bus voltage can still be maintained above the safe voltage, the drive pump motor runs at a very low speed N0 to slowly consume the energy of the filter capacitor in order to maintain basic cooling air flow, and wait for the generator speed to rise with the engine speed to resume power generation.

[0028] When the generator exits the power generation mode but the first power generation flag is already set to "0", it is considered that the engine has performed a shutdown operation, and the pump motor is driven to run at idle speed N1 to discharge the bus voltage to below the safe voltage.

[0029] When the bus voltage drops below the safe voltage, the motor control module also exits speed regulation, blocks the output, and all motors stop.

[0030] Compared with the prior art, the beneficial effects of this disclosure are: (1) The system sets specific power generation and motor speed regulation strategies for different working stages by integrating the operation of generator and pump motor, so as to ensure that the heat dissipation task is completed while maintaining the balance of power flow distribution and ensuring the stability of bus voltage; in extremely special cases of power generation shutdown, the motor is kept running as much as possible, and the power generation and motor normal speed regulation operation is restored in an orderly manner after the conditions are met.

[0031] (2) During the system startup phase, frequent entry / exit from the power generation mode is avoided, and the bus voltage is prevented from being surged due to complete no-load when the generator speed fluctuates.

[0032] (3) Stable control of electric air pumps without supercapacitors or high-voltage power batteries and other high-power energy storage devices has been achieved, reducing system costs and improving reliability. Attached Figure Description

[0033] The above and other objects, features and advantages of this disclosure will become more apparent from the more detailed description of exemplary embodiments of this disclosure taken in conjunction with the accompanying drawings, in which the same reference numerals generally represent the same components.

[0034] Figure 1 This is a schematic diagram of an electrically driven air pump.

[0035] Figure 2 This is a flowchart illustrating the system initial startup strategy according to an exemplary embodiment.

[0036] Figure 3 The motor speed control curve is based on the water temperature at two outlets.

[0037] Figure 4 This is the motor speed limiting curve obtained based on the generator speed;

[0038] Figure 5 For air pump speed regulation operation strategy;

[0039] Figure 6 For shutdown and power restoration, speed regulation strategies;

[0040] Figure 7 This is the overall control flow diagram. Detailed Implementation

[0041] Preferred embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0042] This disclosure provides a control method for an electrically driven air pump. In one exemplary embodiment, the structural relationship between the electrically driven air pump and the generator is shown in the attached figure. Figure 1 As shown, the power generation control module and the pump motor control module are integrated and share a high-voltage DC bus, filter capacitor, current sensor assembly, voltage sensor assembly, and charge discharge circuit. It can simultaneously control the generator to generate electricity and the speed regulation of three cooling air pump motors.

[0043] Specific control methods are as follows: Figure 7 As shown, it includes the following steps:

[0044] (1) Start-up phase

[0045] When the first power generation flag is set, and the generator speed n0≤n≤n1 is used for the first engine start, the power generation control module operates in 0 current control mode, that is, the given torque current is 0. At this time, due to the presence of sampling noise from the current sensor, the feedback error amplitude will be equal to the sampling noise amplitude. The power switch of the motor control module will still be turned on with a very small duty cycle (less than 1%, the duty cycle is the ratio of current sampling noise to sampling base value) to prepare for entering the voltage loop control mode. This also avoids the engine failing to start and turning at low speed, which would cause frequent entry / exit from the power generation mode, resulting in bus voltage spikes and triggering fault protection.

[0046] When the generator speed n>n1, the generator control module enters the generator mode, sets the first generator flag to 1, and uses voltage loop control to control the generator voltage to rise at a given slope.

[0047] When the bus voltage U > U1, all three cooling air pumps operate at idle speed N1, providing basic cooling capacity and generating a certain load to prevent surge voltage from occurring due to complete no-load operation when the generator speed fluctuates. (See attached...) Figure 2 As shown.

[0048] (2) Steady-state operation stage

[0049] The electric air pump simultaneously collects the outlet water temperature TH of the engine water-cooled radiator and the outlet water temperature TL of the electrical equipment water-cooled radiator. When TH≤th1 and TL≤tl1, the motor maintains an idle speed N1. When TH≥th2 or TL≥tl2, the motor maintains a high speed N3. To simplify control, when th2>TH≥th1 or tl2>Tl≥tl1, the pump motor linearly adjusts its speed within the [N2, N3] speed range (th1 and tl1 correspond to N2, th2 and tl2 correspond to N3). The motor speed N prioritizes the one with the higher speed requirement; that is, when N(TH)≥N(TL), N=N(TH); that is, when N(TH)≤N(TL), N=N(TL). The speed adjustment curves of the motor speed according to the two outlet water temperatures are attached. Figure 3 As shown, th1\th2\N1\N2\N3 are determined according to the actual requirements of the heat dissipation system, that is, according to the user's design input;

[0050] At the same time, the motor speed must not exceed the speed limit calculated according to the generator output power curve:

[0051] When the generator speed n is in the constant torque region [n1, n2], the maximum power output is proportional to the speed; when operating in the constant power region [n2, n3], the maximum power output remains constant. The pump motor power is cubically related to the pump motor speed. Since the total power of the pump motors cannot exceed the maximum power output of the generator at the current speed, the speed limiting curves N′=N′(n) for the three pump motors at different generator speeds are obtained after transformation. That is, when the motor speed regulation speed N> the speed limit N′, N=N′.

[0052] The generator output power curve needs to distinguish between operating conditions A and B. Operating condition A refers to normal operating conditions, while operating condition B refers to harsh environmental conditions for the engine (the speed limiting curves under different operating conditions are obtained by comparing them with the specific power curves of the generator and fan motor of the applicable system). Different generator speeds correspond to different maximum power outputs under different operating conditions. An example of a motor speed limiting curve obtained based on the generator speed is attached. Figure 4 As shown, in condition A, the power consumption is lower at the same speed compared to condition B, and the speed limit curve shifts upward.

[0053] The resulting air pump speed regulation operation strategy is as follows (see attached). Figure 5 As shown.

[0054] (3) When the engine speed suddenly drops below the idle speed, or even when the generator speed drops below n1,

[0055] Under this condition, the generator output capacity is insufficient, and DC bus voltage stabilization is difficult. At this time, the generator control module exits the generator mode and enters the zero-current mode, maintaining the switching transistors at a very small duty cycle. In the zero-current mode, some energy can still be supplied to the bus through the controlled switching of the switching transistors, but the control objective is no longer to maintain the bus voltage at a constant value to prevent PI regulator saturation. At this time, the initial generator flag bit is still kept at "1", which is considered as executing the automatic recovery generator strategy. If the generator speed recovers from above the starting speed n0 to above the generator speed n1, generator power generation is resumed. When the bus voltage is > U1, it is considered that the recovery generator power generation is completed, and the motor resumes normal speed regulation operation.

[0056] When the generator speed is lower than the starting speed n0, the generator control module controls the generator to exit the 0 current condition, completely blocks the generator output, and sets the first power generation flag to 0, which is regarded as the engine has been shut down.

[0057] When power generation is stopped but the initial power generation flag is still "1", the drive pump motor is driven at a very low speed (N0) to slowly consume the energy of the filter capacitor, while the bus voltage can still be maintained above the safe voltage. The purpose is to maintain the most basic cooling air flow and wait for the generator speed to rise with the engine speed to resume power generation.

[0058] When power generation is stopped but the initial power generation flag is already set to "0", it is considered that the engine has performed a shutdown operation. The pump motor is driven to run at idle speed N1 to discharge the bus voltage to below the safe voltage. The purpose is to use the pump motor to quickly discharge the high voltage charge on the bus.

[0059] When the bus voltage drops below the safe voltage, the motor control module also exits the speed regulation mode, blocks the output, and all motors stop.

[0060] The resulting shutdown and power restoration strategies, as well as speed regulation strategies, are as follows: Figure 6 As shown.

[0061] The above technical solutions are merely exemplary embodiments of the present invention. For those skilled in the art, based on the application methods and principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the methods described in the specific embodiments of the present invention. Therefore, the methods described above are merely preferred and not restrictive.

Claims

1. A method for controlling an electrically driven air pump, comprising the following steps: S1, When starting the engine for the first time, when the generator speed n is at the starting speed n0≤n≤generating speed n1, the generator operates in 0 current condition, that is, the set torque current is 0, and the power switch of the generator control module is turned on with a very small duty cycle; when the speed n is greater than or equal to n1, the generator enters the generating condition, and when the bus voltage is greater than U1, the motor starts its first operation at the idle speed N1. S2, when the generator speed fluctuates normally within the range of [n1, n3], the pump motor speed is linearly adjusted according to the outlet water temperature TH of the engine water-cooled radiator and the outlet water temperature TL of the electrical equipment water-cooled radiator; at the same time, the pump motor speed shall not exceed the speed limit value calculated according to the generator output power curve. S3, when the generator speed drops below n1, distinguish between abnormal operating conditions and shutdown operating conditions: in abnormal operating conditions, maintain the motor in standby low-speed operation for as long as possible and wait for the generator speed to recover; in shutdown conditions, use the motor to quickly discharge the bus charge to below the safe voltage. Step S2 specifically includes: When the generator speed is within the range of [n1, n3], the electric drive air pump simultaneously collects the outlet water temperature TH of the engine water-cooled radiator and the outlet water temperature TL of the electrical equipment water-cooled radiator. When TH≤th1 and TL≤tl1, the pump motor maintains the idle speed N1. When TH≥th2 or TL≥tl2, the pump motor maintains high speed N3 operation; When th2>TH≥th1 or tl2>TL≥tl1, the pump motor speed accelerates from N1 to N2, and linearly adjusts within the speed range [N2, N3] as the water temperature TH or TL changes. The pump motor speed N is prioritized based on the speed adjustment requirement, i.e., when N(TH)≥N(TL), N=N(TH); i.e., when N(TH)≤N(TL), N=N(TL). N(TH) is the linear speed adjustment value of the pump motor corresponding to water temperature TH, and N(TL) is the linear speed adjustment value of the pump motor corresponding to water temperature TL. Step S3 specifically includes: When the engine speed suddenly drops below idle speed, causing the generator speed to drop below n1, the generator control module exits the generator operation mode and enters the zero-current operation mode; at this time, the initial generator flag bit is still kept at "1", and the automatic generator recovery strategy is executed. If the generator speed recovers from above the starting speed n0 to above the generating speed n1, then power generation is resumed. When the bus voltage is > U1, it is considered that the power generation has been restored and the motor resumes normal speed regulation operation. When the generator speed is lower than the starting speed n0, the generator control module controls the generator to exit the 0 current condition, completely blocks the generator output, and sets the first power generation flag to "0", which is regarded as the engine has been shut down. When the generator exits the power generation mode but the first power generation flag is still "1", and the bus voltage can still be maintained above the safe voltage, the drive pump motor runs at a very low speed N0 to slowly consume the energy of the filter capacitor in order to maintain basic cooling air flow, and wait for the generator speed to rise with the engine speed to resume power generation. When the generator exits the power generation mode but the first power generation flag is already set to "0", it is considered that the engine has performed a shutdown operation, and the pump motor is driven to run at idle speed N1 to discharge the bus voltage to below the safe voltage. When the bus voltage drops below the safe voltage, the motor control module also exits speed regulation, blocks the output, and all motors stop.

2. The method according to claim 1, characterized in that, Step S1 specifically includes: Set the initial power generation flag, which is set to "0" by default; When the engine starts, if the generator speed n0≤n≤n1, the generator control module operates in 0 current control mode, that is, the power switch of the generator control module is kept on with a very small duty cycle. When the generator speed n>n1, the generator control module enters the generator mode, sets the first generator flag to "1", and uses voltage loop control to control the generator voltage to rise at a given slope. When the bus voltage U>U1, each cooling air pump is driven to run at idle speed N1, which has basic cooling capacity and generates a certain load.

3. The method according to claim 1, characterized in that, In step S2, when the generator speed n is within the range of [n1, n3], the pump motor speed N cannot exceed the maximum speed limit N′(n); wherein, the method for determining N′(n) specifically includes: Based on the following: the power of the pump motor is approximately cubic to the pump motor speed; the total power of the pump motor cannot exceed the maximum power output of the generator at the current speed; and when the generator speed n is in the constant torque region [n1, n2], the maximum power output it can provide is approximately proportional to the speed, and when it is in the constant power region [n2, n3], the maximum power output remains constant. After transformation, the speed limiting curves of each pump motor N′=N′(n) are obtained at different generator speeds n. That is, when the motor speed regulation speed N> the speed limit N′, N=N′.

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