Control method for electric transmission air pump

Abstract

An electric transmission air pump control method comprises the steps that according to a designed rotating speed-power curve of a generator and a pump motor, the matching balance relation between generated power and wind resistance loads brought by the rotating speed of the pump motor is reasonably distributed; in order to achieve the purpose that pump motors are always kept in operation during steady-state operation of a heat dissipation system and equipment overtemperature does not occur, speed regulation control over the heat dissipation air pumps is dynamically carried out in real time, and power generation operation of a power generator and speed regulation operation of a plurality of heat dissipation air pump motors can be controlled at the same time. Stable control over the electric transmission air pump is achieved without adding high-power energy storage equipment such as a super capacitor or a high-voltage power battery, the system cost is reduced, and the reliability is improved.

Description

Technical Field

[0001] The invention relates to the field of special vehicle electrical technology, and in particular to a method for controlling an electric transmission air pump. Background Art

[0002] In special vehicles, the power source of the power compartment cooling air pump is mainly provided by the engine through mechanical power take-off mechanisms such as belts and gears or hydraulic mechanisms. The speed of the air pump usually changes with the engine speed, and has problems such as low accuracy, slow response, and mismatched heat dissipation power; and due to the installation and layout restrictions of the power take-off mechanism, there is also the problem that the air pump is not arranged in the optimal position.

[0003] With the development of special vehicle electrical technology, electric air pumps based on new motor drive technology can accurately adjust the speed according to heat dissipation requirements, and the energy is transmitted through cables, so that the air pumps can be installed in a distributed manner in a position that is conducive to the design of the heat dissipation duct. The air pump control system can also be installed in a suitable position, freeing itself from the installation position restrictions of the power take-off mechanism.

[0004] However, as the engine power of vehicles becomes more and more abundant, the application of high-power diesel engines has brought about the demand for high-power heat dissipation, and the addition of new high-power power electronic equipment has also created new heat dissipation needs. The power of the electric transmission air pump itself determines the demand for high-power electric energy sources. The usual practice is to use a power take-off generator to convert the mechanical energy of the engine into electrical energy for the air pump. However, the simple power supply-load power transfer mode requires the power supply to have a high voltage stabilization quality in order to ensure the stability of the output voltage under the dynamic changes of the power load; at the same time, the speed of the power take-off generator itself usually changes dramatically with the engine speed, which makes the design of the power supply more difficult.

[0005] If the power system is designed according to this condition, it is necessary to add supercapacitors or high-voltage power batteries as high-power energy storage systems to smooth the peaks and fill the valleys of the dynamic changes in power generation and load. However, the addition of supercapacitors or high-voltage power battery packs will cause power waste in most working conditions, increase procurement and maintenance costs, increase system complexity, reduce reliability, and occupy vehicle installation space and weight distribution, which is an uneconomical approach. Summary of the invention

[0006] The present invention provides an electric transmission air pump control method, which integrates the power generation control module for controlling the generator with the control modules of various air pump motors, shares a high-voltage DC busbar, a charge discharge circuit, etc., can simultaneously control the power generation operation of the generator and the speed regulation operation of several heat dissipation air pump motors, and reasonably distributes the matching balance relationship between the power generation power and the wind resistance load brought by the speed of the pump motor according to the designed speed-power curve of the generator and the pump motor; with the purpose of always keeping the pump motor running in the steady-state operation of the heat dissipation system without overheating of the equipment, the speed regulation control of the heat dissipation air pump is performed dynamically and in real time, and the stable control of the electric transmission air pump without high-power energy storage equipment such as super capacitors or high-voltage power batteries is successfully realized, thereby reducing the system cost and improving the reliability.

[0007] The electric transmission air pump control method provided by the present disclosure mainly includes the following steps:

[0008] S1, when the engine is started for the first time, when the generator speed n is at the starting speed n0≤n≤generating speed n1, the generator works in the zero current condition, that is, the torque current is set to 0, and the power switch tube of the power generation 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 to run for the first time at the idling 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 water temperature TH at the engine water cooling radiator outlet and the water temperature TL at the electrical equipment water cooling radiator outlet; 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 conditions and shutdown conditions: in abnormal conditions, keep the motor in standby low-speed operation for as long as possible, waiting 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, the step S1 specifically includes:

[0012] Set the first power generation flag, the default setting is "0";

[0013] When the engine is started and the generator speed is n0≤n≤n1, the power generation control module works in the zero current control mode, that is, the power switch tube of the power generation control module is kept turned on with a very small duty cycle;

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

[0015] Furthermore, the step S2 specifically includes:

[0016] When the generator speed is within the range of [n1, n3], the electric transmission air pump simultaneously collects the water temperature TH at the outlet of the engine water cooling radiator and the water temperature TL at the outlet of the electrical equipment water cooling radiator;

[0017] When TH≤th1 and TL≤th2, the pump motor runs at 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 is accelerated from N1 to N2, and linearly adjusted in the speed range [N2, N3] with the change of water temperature TH or TL, wherein the pump motor speed N is prioritized with the one with higher speed regulation demand, that is, when N(TH)≥N(TL), N=N(TH); that is, when N(TH)≤N(TL), N=N(TL), N(TH) is the linear speed regulation value of the pump motor corresponding to the water temperature TH, and N(TL) is the linear speed regulation value of the pump motor corresponding to the 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] According to: the pump motor power and pump motor speed are approximately in a cubic relationship; the total power of the pump motor cannot exceed the maximum power generation power of the generator at the current speed; and when the generator speed n is in the constant torque area [n1, n2], the maximum power generation power that can be provided is approximately proportional to the speed, and when working in the constant power area [n2, n3], the maximum power generation power remains constant;

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

[0023] Furthermore, the step S3 specifically includes:

[0024] When the engine speed suddenly drops below the idle speed, causing the generator speed to drop below n1, the power generation control module exits the power generation condition and enters the zero current condition; at this time, the first power generation flag is still kept at "1" and the automatic power generation recovery strategy is executed:

[0025] If the generator speed recovers from the starting speed n0 to the generating speed n1, the power generation is resumed. When the bus voltage is greater than U1, the power generation is considered to be 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 working condition, completely blocks the generator output, and sets the first power generation flag position to "0", which is regarded as the engine being shut down;

[0027] When the generator exits the power generation condition but the first power generation flag is still "1", and the bus voltage can still be maintained above the safe voltage, the pump motor is driven to operate at an extremely low speed N0 to slowly consume the energy of the filter capacitor to maintain basic cooling air flow, waiting for the generator speed to rise with the engine speed to resume power generation;

[0028] When the generator exits the power generation condition but the first power generation flag has been set to "0", it is considered that the engine is shut down and the pump motor is driven to run at idle speed N1 to discharge the bus voltage below the safety 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 the present invention are as follows: (1) the system sets specific power generation and motor speed control strategies for different working stages by integrated control of the generator and pump motor operation, so as to ensure the balance of power flow distribution and the stability of bus voltage while completing the heat dissipation task; in extremely special power generation exit situations, the motor is kept running as much as possible, and when the conditions are met, the power generation and normal motor speed control actions are restored in an orderly manner;

[0031] (2) During the system startup phase, frequent entry / exit of power generation conditions is avoided, and bus voltage surges are prevented due to complete no-load when the generator speed fluctuates;

[0032] (3) Stable control of the electric air pump is achieved without high-power energy storage devices such as supercapacitors or high-voltage power batteries, reducing system costs and improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0034] Figure 1 This is the schematic diagram of the electric transmission air pump;

[0035] Figure 2 is a flow chart of a system initial startup strategy according to an exemplary embodiment;

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

[0037] Figure 4 is the motor speed limit curve obtained according to the generator speed;

[0038] Figure 5 Provide speed control operation strategy for air pumps;

[0039] Figure 6 To shut down and resume power generation and speed regulation strategies;

[0040] Figure 7 This is the overall control flow chart. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0042] The present disclosure provides a method for controlling an electric transmission air pump. In an exemplary embodiment, the structural relationship between the electric transmission air pump and the generator is as shown in the attached figure. Figure 1 As shown, the power generation control module and the pump motor control module are integrated, sharing the high-voltage DC busbar, filter capacitor, current sensor assembly, voltage sensor assembly, and charge discharge circuit, and can simultaneously control the power generation operation of the generator and the speed regulation operation of the three cooling air pump motors.

[0043] Specific control methods, such as Figure 7 As shown, the following steps are included:

[0044] (1) Start-up phase

[0045] Set the first power generation flag. When the engine is started for the first time, when the generator speed is n0≤n≤n1, the power generation control module works in the zero current control mode, that is, the given torque current is 0. At this time, due to the existence of the current sensor sampling noise, the feedback error amplitude will be equal to the sampling noise amplitude. The power switch tube 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 the current sampling noise to the sampling base value) to prepare for entering the voltage loop control mode, and also avoid the engine ignition failure and low-speed cranking, resulting in frequent entry / exit of the power generation condition, causing bus voltage spikes and triggering fault protection;

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

[0047] When the bus voltage U>U1, the three cooling air pumps are driven to run at the idle speed N1, with basic cooling capacity and a certain load to prevent the bus voltage from generating surge voltage due to complete no-load when the generator speed fluctuates. Figure 2 shown.

[0048] (2) Steady-state operation stage

[0049] The electric transmission air pump simultaneously collects the water temperature TH at the outlet of the engine water-cooled radiator and the water temperature TL at the outlet of the electrical equipment water-cooled radiator. When TH≤th1 and TL≤th2, the motor maintains the idle speed N1. When TH≥th2 or TL≥tl2, the motor maintains the high speed N3. To simplify the control, when th2>TH≥th1 or tl2>Tl≥tl1, the pump motor linearly adjusts the speed in the [N2, N3] speed range (th1 and tl1 both correspond to N2, th2 and tl2 both correspond to N3), and the motor speed N is prioritized with the higher speed regulation demand, that is, when N(TH)≥N(TL), N=N(TH); that is, when N(TH)≤N(TL), N=N(TL). The motor speed is adjusted according to the speed regulation curve of the two outlet water temperatures as shown in the attached figure. Figure 3 As shown, th1\th2\N1\N2\N3 are determined according to the actual requirements of the cooling 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 area [n1, n2], the maximum power generation can be provided is proportional to the speed; when working in the constant power area [n2, n3], the maximum power generation remains constant. The pump motor power is in a cubic relationship with the pump motor speed. Since the total power of the pump motor cannot exceed the maximum power generation at the current speed of the generator, the speed limit curves of the three pump motors N′=N′(n) at different speeds of the generator are obtained by transformation, that is, when the motor speed N> speed limit N′, N=N′.

[0052] The generator output power curve should be distinguished between working condition A and working condition B. Working condition A refers to the normal working condition, and working condition B refers to the severe environment condition for the engine (the speed limit curves under different working conditions are obtained by comparing the specific power curves of the generator and fan motor of the applicable system). The speed of the generator under different working conditions corresponds to different maximum power generation. An example of the motor speed limit curve obtained according to the generator speed is shown in the attached figure. Figure 4 As shown, compared with working condition B, working condition A consumes less power at the same speed, and the speed limit curve moves upward.

[0053] The air pump speed regulation operation strategy is obtained as shown in the attached Figure 5 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 the DC bus voltage is difficult to stabilize. At this time, the power generation control module exits the power generation condition and enters the 0 current condition, maintaining the switch tube to operate at a very small duty cycle. The 0 current condition can still replenish some energy to the bus through the controlled disconnection of the switch tube, but it is no longer controlled to maintain the bus voltage at a constant value to prevent the PI regulator from saturation. At this time, the first power generation flag is still kept at "1", which is regarded as the execution of the automatic power generation recovery strategy. If the generator speed returns from above the starting speed n0 to above the power generation speed n1, power generation is resumed. When the bus voltage is greater than U1, it is regarded as the power generation recovery 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 operating condition, completely blocks the generator output, and sets the first power generation mark position to 0, which is regarded as the engine being shut down.

[0057] When power generation is exited but the first power generation flag is still "1", when the bus voltage can still be maintained above the safe voltage, the pump motor is driven to operate at an extremely low speed N0 to slowly consume the energy of the filter capacitor in order to maintain the most basic cooling air flow and wait for the generator speed to resume power generation as the engine speed increases.

[0058] When the power generation is exited but the first power generation flag has been set to "0", it is regarded as the engine performing a shutdown operation, driving the pump motor to run at idle speed N1 to discharge the bus voltage to below the safe voltage, in order to use the pump motor to quickly discharge the bus high-voltage charge.

[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 shutdown and recovery power generation and speed regulation strategies are as follows Figure 6 shown.

[0061] The above technical scheme is only an exemplary embodiment of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the application methods and principles disclosed in the present invention, and it is not limited to the method described in the above specific embodiment of the present invention. Therefore, the method described above is only preferred and does not have a restrictive meaning.

Claims

1. A method for controlling an electric transmission air pump, comprising the following steps: S1, when the engine is started for the first time, when the generator speed n is at the starting speed n0≤n≤generating speed n1, the generator works in the zero current condition, that is, the torque current is set to 0, and the power switch tube of the power generation 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 to run for the first time at the idling 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 water temperature TH at the engine water cooling radiator outlet and the water temperature TL at the electrical equipment water cooling radiator outlet; 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 conditions and shutdown conditions: in abnormal conditions, keep the motor in standby low-speed operation for as long as possible, waiting for the generator speed to recover; in shutdown conditions, use the motor to quickly discharge the bus charge to below the safe voltage.

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

3. The method according to claim 2, characterized in that The step S2 specifically includes: When the generator speed is within the range of [n1, n3], the electric transmission air pump simultaneously collects the water temperature TH at the outlet of the engine water cooling radiator and the water temperature TL at the outlet of the electrical equipment water cooling radiator; When TH≤th1 and TL≤th2, the pump motor runs at 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 is accelerated from N1 to N2, and linearly adjusted in the speed range [N2, N3] with the change of water temperature TH or TL, wherein the pump motor speed N is prioritized with the one with higher speed regulation demand, that is, when N(TH)≥N(TL), N=N(TH); that is, when N(TH)≤N(TL), N=N(TL), N(TH) is the linear speed regulation value of the pump motor corresponding to the water temperature TH, and N(TL) is the linear speed regulation value of the pump motor corresponding to the water temperature TL.

4. The method according to claim 1 or 3, 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: According to: the pump motor power and pump motor speed are approximately in a cubic relationship; the total power of the pump motor cannot exceed the maximum power generation power of the generator at the current speed; and when the generator speed n is in the constant torque area [n1, n2], the maximum power generation power that can be provided is approximately proportional to the speed, and when working in the constant power area [n2, n3], the maximum power generation power remains constant; After transformation, the speed limit curves N′=N′(n) of each pump motor under different generator speeds n are obtained, that is, when the motor speed regulation speed N> speed limit N′, N=N′.

5. The method according to claim 2, characterized in that: The step S3 specifically includes: When the engine speed suddenly drops below the idle speed, causing the generator speed to drop below n1, the power generation control module exits the power generation condition and enters the zero current condition; at this time, the first power generation flag is still kept at "1" and the automatic power generation recovery strategy is executed: If the generator speed recovers from the starting speed n0 to the generating speed n1, the power generation is resumed. When the bus voltage is greater than U1, the power generation is considered to be 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 working condition, completely blocks the generator output, and sets the first power generation flag position to "0", which is regarded as the engine being shut down; When the generator exits the power generation condition but the first power generation flag is still "1", and the bus voltage can still be maintained above the safe voltage, the pump motor is driven to operate at an extremely low speed N0 to slowly consume the energy of the filter capacitor to maintain basic cooling air flow, waiting for the generator speed to rise with the engine speed to resume power generation; When the generator exits the power generation condition but the first power generation flag has been set to "0", it is considered that the engine has performed a flameout shutdown operation, and the pump motor is driven to run at idle speed N1 to discharge the bus voltage below the safety 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.

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