An active discharge method for an exciting motor

Abstract

A method for active discharge of an excitation motor, comprising the steps of: Step S1: issue an active discharge command, parse it and transfer it, then go to Step S2; Step S2: determine whether the motor speed meets the active discharge condition. If it meets, go to Step S3; if it does not meet, Discharge_OutOfRange; Step S3: Discharge_Active; Step S4: determine whether the voltage value on the bus capacitor side meets the requirements. If it meets, the active discharge timer starts counting and go to Step S5; if it does not meet, go to Step S3; Step S5: Discharge_Done, go to Step S6; Step S6: exit the active discharge mode. In the said Step S3, when the motor speed meets the active discharge condition, by controlling the switching of the on and off states of the power tubes on the rotor side, not only fast discharge is achieved, but also the power tubes on the stator side are ensured to be idle.

Description

Technical Field

[0001] The present invention relates to the field of new energy motor control, and specifically to an active discharge method for an excitation motor. Background Art

[0002] With the development of hybrid vehicles or new energy vehicles, the requirements for their safety are getting higher and higher. When the vehicle fails under forced or non-forced conditions, it is particularly likely to endanger the safety of the vehicle and personnel. Therefore, people's requirements for the control of the electric drive system are getting higher and higher. Not only is it necessary to achieve high-precision control of the motor, but also to ensure the safety of the control, so that when a failure occurs, the safety of the product and personnel can be guaranteed. Therefore, the active discharge function is an indispensable functional requirement in hybrid vehicle or new energy motor control.

[0003] Currently, for both excitation motors and permanent magnet synchronous motors, for the active discharge method, the capacitor voltage on the motor controller bus is quickly reduced below the safe voltage by controlling the stator current or stator voltage.

[0004] However, for some special occasions, the existing general active discharge method cannot be satisfied. For example, when the power element on the stator side is damaged and cannot perform switching or closing actions, the active discharge action cannot be realized; or for the scenario of a collision (Crash), the vehicle controller often requires that when the motor controller performs active discharge, the stator side simultaneously performs active short-circuit protection (ASC), which makes the active discharge action unable to be carried out on the stator side at the same time. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide an active discharge method for an excitation motor, which performs an active discharge action through the rotor excitation coil, is realized by giving a fixed excitation current, and during the active discharge process, the power element on the stator side is in an idle state, and if there is a special request for the stator side switch tube to act, the stator side can still work normally. Thus, on the one hand, the problem that the power element on the stator side is damaged and cannot perform active discharge is solved, and at the same time, the requirements of performing active discharge while performing active short-circuit can be taken into account.

[0006] Technical Solution: The present invention provides an active discharge method for an excitation motor, including

[0007] Step S1: The Can communication receives the active discharge instruction sent by the vehicle, and after parsing, transfers the discharge mode request to the state machine module, and proceeds to step S2;

[0008] Step S2: Determine whether the motor speed meets the active discharge condition. If it is lower than the set speed value, the requirement is met, and proceed to Step S3; if it is higher than the set speed value, the requirement is not met, and the state machine module feeds back to the ECU that the active discharge mode does not meet the condition, i.e., Discharge_OutOfRange;

[0009] Step S3: The state machine module switches the control mode to the active discharge mode and feeds back to the ECU that the active discharge mode is in the active state, i.e., Discharge_Active, and proceed to Step S4;

[0010] Step S4: Determine whether the voltage value on the bus capacitor side meets the requirement. When the voltage value of the bus capacitor is less than the set voltage threshold, the active discharge timer starts counting, and proceed to Step S5; when the voltage value of the bus capacitor is not less than this voltage threshold, the timer does not start, and proceed to Step S3 to continue the discharge;

[0011] Step S5: When the count value of the active discharge timer in Step S4 is greater than the set parameter value, feed back to the ECU that the active discharge mode is in the completed state, i.e., Discharge_Done, and proceed to Step S6;

[0012] Step S6: The state machine module exits the active discharge mode, enters the normal control mode, and clears the excitation current;

[0013] Among them, in Step S3, when the motor speed meets the active discharge condition, by controlling the switching of the on and off states of the Mosfet power tube on the rotor side, rapid discharge is achieved. There is a Mosfet power tube on the rotor side of the excitation motor, and it is directly used for active discharge. This not only makes the discharge method simple and efficient, but also does not increase the hardware cost, saving costs.

[0014] Furthermore, in Step S3, when the motor speed meets the active discharge condition, the state of the Mosfet power tube on the stator side is the idle state. This not only avoids the occurrence of the situation where active discharge cannot be performed due to the damage of the original stator-side power components, but also when there is a special request for the stator-side switch tube to act, the stator side can still work normally, which can meet the requirement of entering the active short-circuit protection while performing active discharge, and has wide applicability.

[0015] Further, the rotational speed set value in step S2 is 100 rpm. Since the active discharge method is carried out by giving the excitation current, during the process of giving the excitation current, the back electromotive force will have a certain increase. If the rotational speed is too high, the superposition of the back electromotive force will bring certain risks. Therefore, active discharge is only allowed when the rotational speed is lower than the rotational speed set value of 100 rpm. If the rotational speed is higher than 100 rpm, it is fed back to the ECU that the discharge state does not meet the conditions, that is, the state of Discharge_OutOfRange.

[0016] Further, the voltage threshold in step S4 is 60V. When entering the active discharge state, when the voltage value on the bus capacitor side is less than the set voltage threshold of 60V, the active discharge timer starts to count and enters step S5. If the voltage value of the bus capacitor is not less than this voltage threshold of 60V, the timing does not start, and it turns to step S3 to continue the discharge until the voltage value on the bus capacitor side meets the conditions.

[0017] Further, the set parameter value in step S5 is 300ms. When the count value of the active discharge timer is greater than the set parameter value of 300ms, the active discharge is completed, that is, Discharge_Done.

[0018] From the above technical solutions, it can be seen that the present invention has the following beneficial effects: Using the idle power tube on the motor rotor side, adopting a given fixed excitation current, and carrying out active discharge through the rotor excitation coil, not only the method is simple and efficient, but also there is no increase in hardware cost; in addition, because the power tube on the rotor side is used for the active discharge action, during the entire active discharge process, the power components on the stator side are in an idle state, which not only avoids the occurrence of the situation where the power components on the stator side are damaged and active discharge cannot be carried out, but also when there is a special request for the action of the stator side switch tube, the stator side can still work normally, that is, it can meet the requirement of entering the active short-circuit protection while carrying out active discharge. Description of the Drawings

[0019] Figure 1 is the flow chart of the present invention;

[0020] Figure 2 is the schematic diagram of the motor electronic control structure of the excitation motor in the present invention;

[0021] Figure 3 is the control diagram of the rotor side in the present invention.

[0022] In the figure: None. Detailed Embodiment

[0023] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

[0025] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more, unless otherwise clearly defined.

[0026] In the present invention, unless otherwise clearly specified and defined, the terms such as "mounted", "connected", "connected to", "fixed" and the like should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over" and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0028] Embodiment 1

[0029] AsFigure 1 The flowchart of the present invention is shown, including

[0030] Step S1: The Can communication receives the active discharge command sent by the whole vehicle. After parsing, it transfers the discharge mode request to the state machine module and proceeds to step S2;

[0031] Step S2: Determine whether the motor speed meets the active discharge condition. If it is lower than the set speed value, the requirement is met and it proceeds to step S3; if it is higher than the set speed value, the requirement is not met, and the state machine module feeds back to the ECU that the active discharge mode does not meet the condition, that is, Discharge_OutOfRange;

[0032] Step S3: The state machine module switches the control mode to the active discharge mode and feeds back to the ECU that the active discharge mode is in the activated state, that is, Discharge_Active, and proceeds to step S4;

[0033] Step S4: Determine whether the voltage value on the bus capacitor side meets the requirement. When the voltage value of the bus capacitor is less than the set voltage threshold, the active discharge timer starts counting and proceeds to step S5; when the voltage value of the bus capacitor is not less than this voltage threshold, the timer does not start, and it proceeds to step S3 to continue the discharge;

[0034] Step S5: When the count value of the active discharge timer in step S4 is greater than the set parameter value, it feeds back to the ECU that the active discharge mode is in the completed state, that is, Discharge_Done, and proceeds to step S6;

[0035] Step S6: The state machine module exits the active discharge mode, enters the normal control mode, and clears the excitation current;

[0036] In step S3, when the motor speed meets the active discharge condition, by controlling the switching of the on and off states of the Mosfet power tube on the rotor side, rapid discharge is achieved.

[0037] In step S3, when the motor speed meets the active discharge condition, the state of the Mosfet power tube on the stator side is in the idle state.

[0038] The set speed value in step S2 is 100 rpm.

[0039] The voltage threshold in step S4 is 60V.

[0040] The set parameter value in step S5 is 300 ms.

[0041] As Figure 2The following is a schematic diagram of the motor electronic control structure of the excitation motor in this embodiment. The plus and minus signs at the upper and lower ends of Udc in the figure indicate the positive and negative poles of the motor controller; on the right side is the bus capacitor, and S1, S2, S3, S4, S5, and S6 are the 6 power components of the upper and lower bridge arms on the stator side, and the coil is the stator side winding; on the left side of Udc, G1, G2, H1, and H2 are the power components on the rotor side, and the coil is the rotor excitation coil.

[0042] As Figure 3 The following is a control diagram of the rotor side in this embodiment. By giving a fixed excitation current, a fixed excitation current Ifref is given. Through the rotor excitation current closed-loop module, an excitation voltage Uf is generated through a PI regulator, and the duty ratio for controlling the switching tubes of the H-bridge on the rotor side is calculated through a modulation module. When Uf is greater than or equal to 0, G2 and H1 are in the normally open state, H2 is in the normally closed state, and G1 adjusts the switching and closing time according to the duty ratio; on the contrary, when Uf is less than 0, G1 and H2 are in the normally open state, G2 is in the normally closed state, and H1 adjusts the switching and closing time according to the duty ratio.

[0043] It can be seen from this that when the motor speed meets the active discharge condition, in step S3, by controlling the switching of the on and off states of the power tubes on the rotor side, that is, when G1 and H2 are both in the closed state and G2 and H1 are both in the open state, or when G1 and H2 are both in the open state and G2 and H1 are both in the closed state, at this time, the H-bridge on the rotor side and the bus capacitor can form a closed loop, so as to quickly discharge the voltage of the bus capacitor and achieve rapid discharge.

[0044] At this time, the six power tubes S1, S2, S3, S4, S5, and S6 on the stator side are in the idle state. That is, during the active discharge process of the excitation motor, if there are special required operations, such as active short-circuit protection on the stator side, etc., it can still be achieved.

[0045] If a permanent magnet synchronous motor wants to discharge in this way, a discharge circuit similar to the rotor coil needs to be added.

[0046] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements can still be made, and these improvements should also be regarded as the protection scope of the present invention.

Claims

1. An active discharge method for an exciting motor, characterized in that: including Step S1: The Can communication receives the active discharge command sent by the whole vehicle. After parsing, it transfers the discharge mode request to the state machine module and proceeds to Step S2; Step S2: Determine whether the motor speed meets the active discharge condition. If it is lower than the set speed value, the requirement is met and it proceeds to Step S3; if it is higher than the set speed value, the requirement is not met, and the state machine module feeds back to the ECU that the active discharge mode does not meet the condition, i.e., Discharge_OutOfRange; Step S3: The state machine module switches the control mode to the active discharge mode and feeds back to the ECU that the active discharge mode is in the active state, i.e., Discharge_Active, and proceeds to Step S4; Step S4: Determine whether the voltage value on the bus capacitor side meets the requirement. When the voltage value of the bus capacitor is less than the set voltage threshold, the active discharge timer starts counting and proceeds to Step S5; when the voltage value of the bus capacitor is not less than this voltage threshold, the timer does not start, and it proceeds to Step S3 to continue the discharge; Step S5: When the count value of the active discharge timer in Step S4 is greater than the set parameter value, it feeds back to the ECU that the active discharge mode is in the completed state, i.e., Discharge_Done, and proceeds to Step S6; Step S6: The state machine module exits the active discharge mode, enters the normal control mode, and clears the excitation current; Among them, in Step S3, when the motor speed meets the active discharge condition, rapid discharge is achieved by controlling the switching of the on and off states of the Mosfet power tube on the rotor side.

2. The active discharge method of the excitation motor according to claim 1, characterized in that: In Step S3, when the motor speed meets the active discharge condition, the state of the Mosfet power tube on the stator side is the idle state.

3. The active discharge method of the exciting motor according to claim 1, characterized in that: The set speed value in Step S2 is 100 rpm.

4. The active discharge method of the excitation motor according to claim 1, characterized in that: The voltage threshold in Step S4 is 60V.

5. The active discharge method of the exciting motor according to claim 1, characterized in that: The set parameter value in Step S5 is 300 ms.

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