Generator control device and generator starting method thereof

Abstract

A method for starting a generator of an integrated motor-generator by driving the motor-generator without position sensor to start an engine, the method comprising the following steps: (a) driving the motor-generator in reverse with a driving current having a frequency and an amplitude in a speed open-loop control mode, and obtaining load information according to the driving voltage and the driving current of the motor-generator; (b) determining whether the load information satisfies a heavy load condition; (c) stopping the motor-generator in reverse when it is determined that the load information satisfies the heavy load condition; and (d) driving the motor-generator in forward to start the engine. The application also relates to a generator control device suitable for starting an integrated motor-generator.

Description

Technical Field

[0001] This invention relates to a generator control device and a generator starting method suitable for starting an integrated motor generator, and particularly to a sensorless generator control device and a generator starting method. Background Technology

[0002] Traditional portable generator systems typically use a manual valve to start the engine. In recent years, portable generators with push-button start have gradually become the mainstream in the market, and DC brushed motors are commonly used as the power source for starting systems. However, due to the disadvantages of DC brushed motors, such as high noise, easy damage, and space occupation, portable generator system manufacturers are increasingly moving towards using integrated starter generator (ISG) systems. This means that the ISG acts as a motor to start the engine during startup and then functions as a generator after the engine is started, replacing the traditional DC motor starting system. However, how to effectively implement ISG and integrate it with the existing generator's electrical system has become the direction of technological competition among manufacturers.

[0003] like Figure 1 The diagram illustrates the cylinder pressure of an engine. As can be seen, when the engine piston P is at the compression top dead center (Cp), the cylinder pressure is extremely high, requiring a very large torque to rotate the engine. Typically, the engine must be started by the rotor of the generator rotating clockwise in a low-resistance region (Rl), utilizing the generator's rotational inertia to help overcome the compression top dead center. However, traditional starting methods involve: 1. Detecting the engine crankshaft position or the generator flywheel position; 2. Continuously rotating in a fixed arc; 3. Detecting if the generator speed decreases. Points 1 and 3 require position or speed sensors to determine the generator rotor position and speed, making them unsuitable for sensorless control systems. Point 2 is problematic because the rotor's starting position varies each time; continuously rotating a fixed arc before stopping would waste time and consume excessive power.

[0004] Therefore, how to design a generator control device and generator starting method suitable for starting an integrated motor generator, thereby reducing circuit costs and shortening engine starting time through a sensorless generator control device, is an important research topic of the inventors of this disclosure. Summary of the Invention

[0005] The purpose of this invention is to provide a generator starting method for an integrated motor-generator, thereby solving the problems of the prior art.

[0006] To achieve the foregoing object, the generator starting method of the present application drives the motor-generator without position sensor to start the engine, and comprises the following steps: (a) in the speed open-loop control mode, a first driving current with a first frequency and a first amplitude is applied to drive the motor-generator to reverse, and a first load information is obtained according to the driving voltage of the motor-generator and the first driving current; (b) it is determined whether the first load information satisfies a heavy load condition; (c) when it is determined that the first load information satisfies the heavy load condition, the reversing of the motor-generator is stopped; and (d) the motor-generator is driven to rotate forward to start the engine.

[0007] Still another object of the present application is to provide a generator control device suitable for starting a motor-generator, which solves the problems of the prior art.

[0008] To achieve the foregoing object, the generator control device of the present application is coupled to the motor-generator without position sensor, and the motor-generator drives the engine to start. The generator control device comprises an inverter and a control module. The inverter receives a DC voltage and is coupled to the motor-generator. The control module is coupled to the inverter and the motor-generator, and provides a pulse width modulation signal to the inverter, so that the inverter converts the DC voltage into a driving voltage and a driving current to drive the motor-generator. In the starting mode in which the motor-generator starts to drive the engine to operate, the control module adopts a speed open-loop control mode, i.e. the control module adjusts the pulse width modulation signal according to whether the driving voltage and the driving current correspondingly satisfy a heavy load condition, without referring to the rotating speed of the motor-generator, to control the motor-generator to rotate forward or reverse to start the engine.

[0009] The main object and technical effect of the present application is that, since the generator control device of the present application adopts the speed open-loop control mode in the starting mode of the motor-generator, i.e. provides the driving current with amplitude and frequency to control the motor-generator to rotate forward or reverse without referring to the rotating speed of the motor-generator, the load size of the motor-generator can be estimated in the reversing process of the motor-generator without position sensor or rotating speed information, which facilitates the subsequent control in the starting mode of the motor-generator. Compared with the method of using the rotating speed information to estimate the load size of the motor-generator in the prior art, the load estimation accuracy is better when the initial position of the rotor of the motor-generator is closer to the load dead point. Since the generator control device uses the first load information and the corresponding heavy load condition as the judgment basis for stopping the reversing, compared with the prior art in which the motor rotor is continuously rotated by a preset arc by using the position sensor, the time for starting the engine and the power consumption can be greatly reduced.

[0010] For further understanding of the technical means, methods and technical effects taken by the present application to achieve the predetermined purposes, please refer to the following detailed description and drawings of the present application. It is believed that the purposes, features and characteristics of the present application can be deeply and specifically understood from the description, and the drawings are provided for reference and illustration only, and are not used to limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 Engine cylinder pressure diagram

[0012] Figure 2 Generator control device circuit block diagram suitable for integrated motor generator of the present application

[0013] Figure 3A Motor generator single-phase equivalent circuit diagram of the present application

[0014] Figure 3B Vector diagram of the present application driving voltage and driving current projected onto dq axis coordinate first embodiment

[0015] Figure 3C Vector diagram of the present application driving voltage and driving current projected onto dq axis coordinate second embodiment

[0016] Figure 4 Generator starting method of the motor generator of the present application

[0017] Figure 5A Process diagram when starting the engine of the motor generator of the present application

[0018] Figure 5B First waveform diagram when starting the engine of the motor generator of the present application

[0019] Figure 5C Second waveform diagram when starting the engine of the motor generator of the present application; and

[0020] Figure 6 Waveform diagram in the starting mode of the present application

[0021] BRIEF DESCRIPTION OF DRAWINGS

[0022] P…engine piston

[0023] Cp…compression top dead center

[0024] 1…generator control device

[0025] 10…inverter

[0026] 12…control module

[0027] 122…pulse width modulation unit

[0028] 124 drive unit

[0029] 124A first conversion unit

[0030] 124B q-axis current controller

[0031] 124C d-axis current controller

[0032] 124D second conversion unit

[0033] 126 load detection unit

[0034] 128 loop control unit

[0035] 128A open loop control unit

[0036] 128B closed loop control unit

[0037] 130 control unit

[0038] 130A estimation unit

[0039] 130B switching unit

[0040] 140 low pass filter unit

[0041] 2 motor generator

[0042] 3 engine

[0043] Vdr, Vdr1 to Vdr3 drive voltage

[0044] Vdc direct current voltage

[0045] Idr, Idr1 to Idr3 drive current

[0046] PWM pulse width modulation signal

[0047] Sc1 to Sc3 control signal

[0048] Sl load signal

[0049] Sid d-axis current signal

[0050] Siq q-axis current signal

[0051] Svd d-axis voltage signal

[0052] Svq q-axis voltage signal

[0053] Vi1 first load information

[0054] Vi2 second load information

[0055] Vth first threshold value

[0056] Cc… control command

[0057] Cc1… first control command

[0058] Cc2… second control command

[0059] Cid, Ciq… current command

[0060] θr… angle command

[0061] Cs… start command

[0062] Cclose… close-loop control command

[0063] Ipeak… current peak value

[0064] f… frequency

[0065] Sp… rotation speed

[0066] ω… angular velocity

[0067] θe… electrical angle

[0068] Rs… equivalent resistance

[0069] Ls… equivalent inductance

[0070] Vrs, Vls… cross voltage

[0071] Vz… impedance voltage

[0072] Vemf… back electromotive force voltage

[0073] P1, P2, P3… point

[0074] (S100)~(S200), I~II… step

[0075] T1~T5… period DETAILED DESCRIPTION

[0076] The technical content and detailed description of the present application are described as follows in conjunction with the accompanying drawings.

[0077] Please refer to Figure 2A circuit block diagram of a generator control device for an integrated motor generator of the present application. The generator control device 1 is coupled to an integrated motor generator 2 (ISG, hereinafter referred to as motor generator) and the motor generator 2 drives an engine 3 to start. In a starting mode, the motor generator 2 operates in the form of a motor to start the engine 3; after the engine 3 is started, a generator mode is entered, and the motor generator 2 operates in the form of a generator to generate power driven by the engine 3. The generator control device 1 is powered by a direct current voltage Vdc to drive the motor generator 2 in the starting mode to start the engine 3. In the generator mode after the engine 3 is started, the engine 3 drives the motor generator 2 to provide the generator control device 1 with information of driving voltages Vdr1-Vdr3 (representing corresponding phases of the motor generator 2, respectively).

[0078] The generator control device 1 includes an inverter 10 and a control module 12. The inverter 10 receives a direct current voltage Vdc at one end and is coupled to the motor generator 2 at the other end. The control module 12 is coupled to the inverter 10 and, in the starting mode, provides a pulse width modulation signal PWM to control the inverter 10 to convert the direct current voltage Vdc into alternating driving voltages Vdr1-Vdr3 to provide the driving voltages Vdr1-Vdr3 and driving currents Idr1-Idr3 to drive the motor generator 2. The control module 12 includes a pulse width modulation unit 122, a driving unit 124, a load detection unit 126, and a loop control unit 128. The pulse width modulation unit 122 is coupled to the inverter 10 and is used to modulate the pulse width modulation signal PWM according to control signals Sc1-Sc3. The driving unit 124 is coupled to the pulse width modulation unit 122 and the motor generator 2 and, in the process of driving the motor generator from a standstill to reverse rotation, provides first load information Vii according to the driving voltages Vdr1-Vdr3 and the driving currents Idr1-Idr3 (representing corresponding phases of the motor generator 2, respectively).

[0079] The load detecting unit 126 is coupled to the driving unit 124, and judges whether the value of the first load information Vii satisfies a heavy load condition, and provides a load signal Sl according to the judgment result. In the embodiments of the present application, the heavy load condition can have the following four possible implementations, but is not limited to: the first load information Vii changes from greater than or equal to a first threshold value to less than the first threshold value; the first load information Vii continuously is less than the first threshold value for a preset time; the first load information Vii changes from less than or equal to a second threshold value to greater than the second threshold value; or, the first load information Vii continuously is greater than the second threshold value for a preset time. When the motor generator 2 is reversed during the starting mode, the load detecting unit 126 judges that the first load information Vii satisfies the above heavy load condition, and provides a load signal Sl representing stopping the reversal and starting the rotation of the rotor of the motor generator 2, otherwise, provides a load signal Sl representing the reversal of the rotor of the motor generator 2. The loop control unit 128 is coupled to the load detecting unit and the driving unit, and provides a control command Cc for driving the motor generator 2 to rotate or reverse according to the load signal Sl in the speed open loop control mode, and the control command Cc includes a current command Cid, Ciq for regulating the speed of the motor generator 2 and an angle command θr for regulating the angle of the motor generator 2. The driving unit 124 generates control signals Sc1-Sc3 (representing corresponding phases of the motor generator 2 respectively) according to the driving currents Idr1-Idr3 and the control command Cc, so that the pulse width modulation unit 122 correspondingly modulates the pulse width modulation signals PWM suitable for controlling the motor generator 2.

[0080] The drive unit 124 includes a first conversion unit 124A, a q-axis current controller 124B, a d-axis current controller 124C, and a second conversion unit 124D, and the first conversion unit 124A is coupled to the output of the inverter 10 and the loop control unit 128. The first conversion unit 124A receives information of the drive currents Idrl-Idr3and an angle command θr from the loop control unit 128, and provides a d-axis current signal Sid and a q-axis current signal Siq in the dq-axis according to the drive currents Idrl-Idr3and the angle command θr. The q-axis current controller 124B is coupled to the first conversion unit 124A, the second conversion unit 124D, and the loop control unit 128, and generates a q-axis voltage signal Svq according to the q-axis current signal Siq and a q-axis current command Ciq, the q-axis voltage signal Svq being a horizontal axis (q-axis) component of the sum of the drive voltages Vdr1-Vdr3vectors corresponding to the dq-axis coordinates. The d-axis current controller 124C is coupled to the first conversion unit 124A, the second conversion unit 124D, and the loop control unit 128, and generates a d-axis voltage signal Svd according to the d-axis current signal Sid and a d-axis current command Cid, the d-axis voltage signal Svd being a vertical axis (d-axis) component of the sum of the drive voltages Vdr1-Vdr3vectors corresponding to the dq-axis coordinates. The second conversion unit 124D is coupled to the pulse width modulation unit 122 and the loop control unit 128, and provides control signals Sc1-Sc3 to the pulse width modulation unit 122 according to the q-axis voltage signal Svq, the d-axis voltage signal Svd, and the angle command θr.

[0081] The load detection unit 126 is configured to determine whether the rotor of the motor generator 2 has been reversed to a position before the compression top dead center of the engine 3 according to the first load information Vii, which can be the q-axis voltage signal Svq (indicated by a dashed line) or the d-axis voltage signal Svd (indicated by a solid line), and to provide a load signal Sl to the loop control unit 128 accordingly. Specifically, the load will be heavier when the rotor is reversed closer to the compression top dead center. Therefore, the magnitude of the load can be used to determine whether the rotor of the motor generator 2 has been reversed to a proper position to ensure the longest starting stroke (with the largest moment of inertia to pass the compression top dead center) for each positive starting. Further, when the load is heavier, the proportion of real work in the mechanical power output by the motor generator will be higher, that is, the angle between the driving voltage projected on the dq axis and the horizontal q-axis will be smaller, relatively representing the d-axis voltage signal Svd of the load information Vii will be smaller, and the q-axis voltage signal Svq of the load information Vii will be larger. That is, the load detection unit 126 is configured to determine whether the value change of the first load information Vii satisfies the aforementioned heavy load condition, and when the value change of the first load information Vii satisfies the aforementioned heavy load condition, it represents that the rotor of the motor generator 2 has approached the compression top dead center of the engine and has been reversed to a proper starting position. In this way, the prior art can be avoided, which rotates the rotor of the motor generator by a fixed arc regardless of the initial position of the motor when the motor generator is in the starting mode, which can cause virtual energy consumption or noise problems, so as to reduce the power consumption during starting and reduce the hardware specifications; in addition, it is also not necessary to rely on the position sensor or the speed information to more accurately estimate the current load of the motor generator, and to automatically adjust the reversing time according to the load condition, saving the excess starting time.

[0082] The loop control unit 128 includes an open loop control unit 128A and a closed loop control unit 128B, and the open loop control unit 128A is coupled to the drive unit 124 and the load detection unit 126. In the start-up mode, the open loop control unit 128A does not refer to the estimated motor speed information, but provides the first control command Ccl and the second control command Cc2 for controlling the forward rotation or the reverse rotation of the motor generator 2 according to the load signal Sl, and the first control command Ccl and the second control command Cc2 also include the current command Cid, Ciq for driving the motor generator 2. In the start-up mode, when the open loop control unit 128A knows from the load signal Sl that the value of the first load information Vi1 does not satisfy the aforementioned heavy load condition, it means that the rotor has not been reversed to the appropriate start-up position, and the open loop control unit 128A provides the first control command Ccl for controlling the reverse rotation of the motor generator 2. The first control command Ccl causes the drive current Idrl-Idr3 provided by the control module 12 to be the first drive current with a first frequency and a first amplitude, and drives the motor generator 2 to reverse. The first frequency and the first amplitude of the first drive current gradually increase from 0 with a slope for a duration, and finally maintain a first fixed frequency and a first fixed amplitude which are substantially fixed values. For example, but not limited to, the first frequency and the first amplitude of the first drive current can be gradually increased from 0 with a slope for a duration in various ways. Since the first control command Ccl does not refer to the speed of the motor generator 2 as a control basis, this control method can be called a speed open loop control (I / F control) mode.

[0083] When the open loop control unit 128A knows from the load signal Sl that the value of the first load information Vi1 satisfies the aforementioned heavy load condition, it means that the rotor has been reversed to the appropriate start-up position. The open loop control unit 128A provides the second control command Cc2 for controlling the motor generator 2 to stop and start forward rotation. The second control command Cc2 causes the drive current Idrl-Idr3 provided by the control module 12 to be the second drive current with a second frequency and a second amplitude, and drives the motor generator 2 to forward rotate. Similar to the first drive current, the second frequency and the second amplitude of the second drive current will maintain a second fixed frequency and a second fixed amplitude which are substantially fixed values after a duration. And the second control command Cc2 is the same as the first control command Ccl, and does not refer to the speed of the motor generator 2 as a control basis, so it is also a speed open loop control (I / F control) mode. The first control command Ccl and the second control command Cc2 also include an angle command θr for regulating the angle of the motor generator 2, which is provided to the drive unit 124 to assist in controlling the angle of the motor generator 2 to forward rotate and reverse.

[0084] In an embodiment of the present application, the open-loop control unit 128A further provides a start command Cs to the driving unit 124 to excite and align the rotor of the motor generator 2. Specifically, before the generator control device 1 intends to start the motor generator 2 in the start mode, the rotor of the motor generator 2 can be first excited and aligned in direct current to facilitate the operation control of the rotor in the subsequent start mode. Therefore, the open-loop control unit 128A provides the start command Cs to the driving unit 124 so that the driving unit 124 can inject a current component of a predetermined angle to attract the rotor of the motor generator 2 to the predetermined angle.

[0085] In an embodiment of the present application, the control module 12 can further set a predetermined waiting time between the open-loop control unit 128A providing the first control command Ccl and providing the second control command Cc2. The purpose of setting the predetermined waiting time is to wait until the motor generator 2 is completely stationary before performing the forward rotation control, so as to make the process of starting the engine 3 driven by the motor generator 2 more stable and smooth, thereby improving the probability of successfully starting the engine 3.

[0086] The closed-loop control unit 128B is coupled to the driving unit 124 and the load detection unit 126, and performs forward rotation closed-loop control on the motor generator 2 according to whether the rotational speed of the motor generator 2 reaches a predetermined rotational speed. Specifically, after the open-loop control unit 128A provides the second control command Cc2 to drive the motor generator 2 to rotate forward, and the rotational speed of the motor generator 2 reaches the predetermined rotational speed, it indicates that the engine 3 has been successfully started. Thereafter, feedback control (such as but not limited to PI control) feedback driving current Idrl-Idr3 information and estimate rotational speed information as control basis, so as to make the motor generator 2 operate stably. Therefore, when the rotational speed of the motor generator reaches the predetermined rotational speed, the closed-loop control unit 128B provides a closed-loop control command Cclose to perform forward rotation closed-loop control on the motor generator 2. The closed-loop control command Cclose includes a current command Cid, Ciq for regulating the rotational speed of the motor generator 2, and an angle command θr for regulating the angle of the motor generator 2.

[0087] Further, since the generator control device 1 of the present application is a sensorless control device (without position), the motor generator 2's speed and rotor position need to be estimated when determining whether the motor forward rotation speed has reached a preset speed, when switching from the speed open loop control mode to the closed loop control mode, or in the closed loop control mode. Therefore, the control module 12 further comprises a control unit 130, and the control unit 130 is coupled to the drive unit 124 and the loop control unit 128. The control unit 130 comprises an estimation unit 130A and a switching unit 130B, the estimation unit 130A is coupled to the drive unit 124 and the switching unit 130B, and the switching unit 130B is coupled to the loop control unit 128. The estimation unit 130A estimates the motor generator 2's angular speed ω and electrical angle θe according to the d-axis current signal Sid, q-axis current signal Siq, d-axis voltage signal Svd and q-axis voltage signal Svq corresponding to the driving current Idr1-Idr3, and the angular speed ω can correspond to the motor generator 2's speed. The switching unit 130B receives the angular speed ω, and selectively switches the drive unit 124 to be coupled to the open loop control unit 128A or the closed loop control unit 128B according to the angular speed ω, so that the loop control unit 128 provides corresponding control commands Cc according to the motor generator 2's operating conditions. The electrical angle θe is provided to the loop control unit 128, so that the loop control unit 128 provides corresponding angle commands θr according to the electrical angle θe. Further, in an embodiment of the present application, in the starting mode, when the motor generator 2 is in the initial state of being stationary, the drive unit 124 is preset to be coupled to the open loop control unit 128A to perform the speed open loop reverse and forward rotation control of the motor generator 2; and when the aforementioned reverse and forward rotation speed open loop control process of the motor generator 2 is completed, and the motor generator 2's speed reaches the preset speed, the switching unit 130B only then switches the drive unit 124 to be coupled to the closed loop control unit 128B to perform the subsequent closed loop control of the motor generator 2. Since the generator control device 1 of the present application eliminates the circuit cost of a relatively expensive sensor (such as but not limited to a Hall sensor), the generator control device 1 of the present application can achieve the technical effect of reducing circuit cost.

[0088] Please refer to Figure 2In an embodiment of the present application, the control module 12 further comprises a low-pass filter unit 140. The low-pass filter unit 140 is coupled between the drive unit 124 and the load detection unit 126, and low-pass filters the second load information V12 (i.e. the q-axis voltage signal S vq or the d-axis voltage signal S vd) provided by the drive unit 124 to the first load information V11. Specifically, since the q-axis voltage signal S vq and the d-axis voltage signal S vd are DC signals with high frequency components, the high frequency components of the q-axis voltage signal S vq and the d-axis voltage signal S vd can cause interference to the load detection unit 126 and result in signal misjudgment. Therefore, the high frequency noise of the second load information V12 is filtered out by the low-pass filter unit 140 to improve the accuracy of the judgment of the load detection unit 126.

[0089] Please refer to Figure 3A for a schematic diagram of a single-phase equivalent circuit of the motor generator, Figure 3B for a vector diagram of the driving voltage and the driving current projected onto the dq-axis coordinate in the first embodiment of the present application, Figure 3C for a vector diagram of the driving voltage and the driving current projected onto the dq-axis coordinate in the second embodiment of the present application, please refer to Figure 2 , and refer to Figures 3A-3C In Figure 3A , Vdr1 is the single-phase voltage, Idr1 is the corresponding single-phase current, Vrs is the voltage across the equivalent resistance Rs of the corresponding phase in the motor generator 2, Vls is the voltage across the equivalent inductance Ls of the corresponding phase in the motor generator 2, Vemf is the counter electromotive force voltage of the corresponding phase, and Vz is the impedance voltage of the motor generator 2 (i.e. the vector sum of Vrs and Vls). The output mechanical power of the motor generator 2 is shown in the following formula 1:

[0090] Pm = ω x Te… (1)

[0091] wherein Pm is the mechanical output power of the motor generator 2, ω is the angular velocity, and Te is the output torque of the motor generator 2, which is determined by the load on the rotor shaft end of the motor generator 2 when the speed of the motor generator 2 is maintained. When the load on the shaft end of the motor generator 2 increases, the output torque Te of the motor generator 2 also increases to meet the requirement of maintaining the constant speed of the motor generator 2, so that the mechanical output power Pm of the motor generator 2 increases. In addition, the electrical input power of the motor generator 2 is shown in the following formula 2:

[0092]

[0093] wherein Pe is proportional to the mechanical output power of the rotor shaft of the motor generator 2, "3" is three phases (assuming that the driving voltage of each phase is equal to the driving current of each phase), Vemf is the back electromotive force voltage, θ1 is the angle between the driving voltage Vdr1 and the driving current Idr1, and θ2 is the angle between the back electromotive force voltage Vemf and the driving current Idr1. Also, the relationship between the mechanical output power and the electrical output power of the motor generator 2 is shown in the following equation 3:

[0094] Pm = Pe x η... (3)

[0095] wherein η is the efficiency of the motor generator 2. The single-phase equivalent voltage and current relationship of equation 2 is applied to the three-phase voltage and current of the motor generator 2 in the case of light load and heavy load, and the relative relationship of the voltage and current components can be represented by Figure 3B and 3C respectively. Figure 3B corresponding to the case where the load of the motor generator 2 is light, and Figure 3C corresponding to the case where the load of the motor generator 2 is heavy. When the driving current Idr (which is the vector sum of the driving currents Idr1 to Idr3 of each phase) having a first fixed frequency and a first fixed amplitude is input (I / F control), the vector size and phase of the driving voltage Vdr (which is the vector sum of the driving voltages Vdr1 to Vdr3 of each phase) provided by the inverter 10 will change with the increase of the load. Among them, in particular, the angle θ between the driving voltage Vdr and the driving current Idr clearly reflects the load characteristics, that is, when the mechanical power factor increases with the increase of the load, the load change characteristics can also be observed from the electrical power. For example, but not limited to, when the shaft end (d-axis) load increases, |Vil| = |Vdr x sin θ| will decrease (and vice versa). Therefore, by comparing Figure 3B and 3C it can be found that the first load information Vil is the d-axis voltage signal or the q-axis voltage signal of the motor generator 2, and the d-axis voltage signal is the perpendicular axis (d-axis) component (i.e. the component projected on the d-axis) of the driving voltage Vdr corresponding to an angle θ between the driving voltage Vdr and the driving current Idr, and the q-axis voltage signal is the horizontal axis (q-axis) component of the driving voltage Vdr. In Figure 3B , the perpendicular axis component of the driving voltage Vdr is larger than that in Figure 3C , so the load amount of Figure 3C is heavier (the horizontal axis component is just opposite) than that of Figure 3B .

[0096] Briefly, when the start-up mode is initiated, a driving current Idr of a fixed amplitude and a fixed frequency is first provided to drive the motor generator 2. Then, the load information Vi and the corresponding load amount of the motor generator 2 can be deduced from the mechanical output power of the motor generator 2. After the load information Vi and the corresponding load amount are obtained, the load detection unit 126 can compare the load information Vi and the corresponding load amount with the heavy load condition to determine whether the rotor of the motor generator 2 is approaching the compression top dead center Cp. The heavy load condition set by the load detection unit 126 represents a predetermined threshold value of the load amount approaching the compression top dead center Cp.

[0097] Further, the d-axis voltage signal Svd is the vertical axis component of the driving voltage Vdr corresponding to the vertical horizontal axis (i.e. the dq axis). When the load is heavier, the proportion of real work in the mechanical power output by the motor generator is higher, and the d-axis voltage signal Svd of the load information Vi1 is smaller. Therefore, when the d-axis voltage signal is used as the first load information Vi1, when the first load information Vi1 changes from being greater than or equal to a first threshold value to being less than the first threshold value, or when the first load information Vi1 is less than the first threshold value for a predetermined time, it represents that the heavy load condition is met (i.e. the rotor of the motor generator 2 is approaching the compression top dead center). Conversely, the q-axis voltage signal Svq is the horizontal axis component of the driving voltage Vdr corresponding to the vertical horizontal axis (i.e. the dq axis). When the load is heavier, the proportion of real work in the mechanical power output by the motor generator is higher, and the q-axis voltage signal Svq of the load information Vi1 is larger. Therefore, when the q-axis voltage signal is used as the first load information Vi1, when the first load information Vi1 changes from being less than or equal to a second threshold value to being greater than the second threshold value, or when the first load information Vi1 is greater than the second threshold value for a predetermined time, it represents that the heavy load condition is met (i.e. the rotor of the motor generator 2 is approaching the compression top dead center). The first threshold value and the second threshold value can be designed to be the same value or different values, which can be adjusted according to actual needs.

[0098] Please refer to Figure 4 For the motor generator start-up method of the motor generator, please also refer to Figures 2-3CThe motor generator 2 startup method first includes receiving a startup command (SI 00). The open-loop control unit 128A provides a startup command Cs to the drive unit 124 to magnetize and position the motor generator 2, enabling the drive unit 124 to inject a current component of a predetermined angle to attract the rotor of the motor generator 2 to the predetermined angle. Then, the open-loop control motor generator reverses (SI 20). The load detection unit 126 uses the first load information VI 1 to determine whether the rotor of the motor generator 2 has been reversed to a position before the compression top dead center of the engine 3, and provides a load signal Sl to the loop control unit 128 accordingly. The first load information VI 1 can be a q-axis voltage signal Svq or a d-axis voltage signal Svd. The open-loop control unit 128A provides a first control command Ccl to control the reversal of the motor generator 2. The first control command Ccl causes the control module 12 to provide a first drive current Idrl-Idr3 having a first frequency and a first amplitude that eventually become fixed values, to drive the motor generator 2 in a speed open-loop control (i.e., reverse I / F control) mode. The control module 12 can include a low-pass filter unit 140. The low-pass filter unit 140 low-pass filters the second load information VI 2 (i.e., the q-axis voltage signal Svq or the d-axis voltage signal Svd) provided by the drive unit 124 into the first load information VI 1, to improve the accuracy of the determination by the load detection unit 126.

[0099] Then, it is determined whether the first load information satisfies a heavy load condition (SI 40). When the open-loop control unit 128A determines from the load signal Sl that the value of the first load information VI 1 satisfies the heavy load condition, it means that the rotor has been reversed to the appropriate startup position. Otherwise, it means that the rotor has not been reversed to the appropriate startup position, and the process returns to step (SI 20). The difference in the heavy load condition depends on whether the first load information VI 1 uses the d-axis voltage signal Svd or the q-axis voltage signal Svq. When the rotor has been reversed to the appropriate startup position, the motor generator is waited to be stationary (SI 60). The control module 12 can set a predetermined waiting time between the provision of the first control command Ccl by the open-loop control unit 128A and the provision of a second control command Cc2, to wait for the motor generator 2 to be stationary before proceeding with the control of the forward rotation, to make the process of starting the engine 3 driven by the motor generator 2 more smooth. The way to make the motor generator 2 stationary can include forward rotation to be stationary or controlled braking.

[0100] Then, the open-loop control motor generator is started (S180). The open-loop control unit 128A provides a second control command Cc2 for controlling the motor generator 2 to start, and the second control command Cc2 drives the driving currents Idr1-Idr3 provided by the control module 12 to be second driving currents with a second frequency and a second amplitude that are eventually fixed values, so as to drive the motor generator 2 to start in a speed open-loop control (i.e., start I / F control) mode. Finally, when the rotation speed of the motor generator reaches a preset rotation speed, the closed-loop control of the motor generator is switched on (S200). After the open-loop control unit 128A provides the second control command Cc2, and when the rotation speed of the motor generator 2 reaches the preset rotation speed, it indicates that the engine 3 has been successfully started. After that, feedback control (for example, but not limited to, PI control) must be used to feedback the motor rotation speed or torque, so as to enable the motor generator 2 to operate stably. Therefore, when the rotation speed of the motor generator 2 reaches the preset rotation speed, the closed-loop control unit 128B provides a closed-loop control command Cclose, so as to control the motor generator 2 to start in a closed-loop control (i.e., speed closed-loop control) mode. The rotation speed of the motor generator 2 is obtained by estimating the angular speed ω and the electrical angle θe of the motor generator 2 through the d-axis current signal Sid, the q-axis current signal Siq, the d-axis voltage signal Svd, and the q-axis voltage signal Svq of the driving currents Idr1-Idr3 (at this time, the driving currents Idr1-Idr3 are the second driving currents).

[0101] Further, since the generator control device 1 of the present application uses the speed open-loop control mode to control the motor generator 2 to start and reverse with the amplitudes and frequencies that are eventually fixed values in the starting mode of the motor generator, the load of the motor generator 2 can be more accurately estimated and controlled in the subsequent starting mode without the position sensor or the rotation speed information. Moreover, since the generator control device 1 uses the first load information and the corresponding heavy load condition as the judgment for stopping the reverse, compared with the prior art, the rotor of the motor generator does not need to rotate a fixed arc, and the power consumption and the time for starting the engine 3 are greatly reduced.

[0102] Please refer to Figure 5A for the process schematic diagram of the motor generator of the present application for starting the engine, Figure 5B for the first waveform schematic diagram of the motor generator of the present application for starting the engine, Figure 5C for the second waveform schematic diagram of the motor generator of the present application for starting the engine, and Figures 2-4 for the third waveform schematic diagram of the motor generator of the present application for starting the engine, and Figure 5A , 5B , 5C. In Figure 5AIn the middle, the cylinder pressure is the largest compression top dead center Cp, compression top dead center Cp is usually also the most heavily loaded point. When the engine 3 has not started, the rotor of the motor generator 2 will usually stop at the valley position between the two compression top dead centers Cp (assuming stop at point P1 and P2). The control module 12 will first drive the motor generator 2 to reverse by controlling the inverter 10 (step I), and then judge whether the rotor of the motor generator 2 has reversed to the position before the compression top dead center of the engine 3 (point P3) by detecting the driving voltage Vdr1-Vdr3 and the driving current Idr1-Idr3 of the motor generator 2, which is detected by whether the first load information Vi1 meets the heavy load condition. When the control module 12 knows that the rotor of the motor generator 2 has reversed to the point P3, the control module 12 waits for the motor generator 2 to be stationary. After the motor generator 2 is stationary, the control module 12 drives the motor generator 2 to forward by controlling the inverter 10 (step II) to ensure that the forward starting has the longest starting stroke (i.e. has the largest moment of inertia to pass the compression top dead center Cp).

[0103] Figure 5B The waveform corresponding to the point P1 in Figure 5A has a longer reverse distance. Wherein the dashed line is the first load information Vi1, the solid line is the driving current Idr, and the horizontal line is the first threshold value Vth. At time T1, the generator control device 1 excites the motor generator 2 to position, so that the rotor of the motor generator 2 is positioned at point P1. At time T2, the generator control device 1 adopts the speed open-loop control mode, provides the first driving current with the first frequency and the first amplitude to the motor generator 2, and drives the motor generator 2 to reverse. From Figure 5BIt can be seen that the first frequency and the first amplitude of the first driving current will eventually maintain a first fixed frequency and a first fixed amplitude which are substantially fixed values after a short duration. At this time, the first load information Vii is increased from less than the first threshold value Vth to greater than or equal to the first threshold value Vth, and between the time periods T2 and T3, the first load information Vii is decreased from greater than or equal to the first threshold value Vth to less than the threshold value Vth, and the rotor of the motor generator 2 rotates to the point P3. At the time period T3, the generator control device 1 waits for a predetermined waiting time until the rotor of the motor generator 2 is stationary. At the time period T4, the generator control device 1 adopts the speed open-loop control mode, and provides a second driving current with a second frequency and a second amplitude to the motor generator 2 to drive the motor generator 2 to rotate forward. Similarly to the first driving current, the second frequency and the second amplitude of the second driving current will eventually maintain a second fixed frequency and a second fixed amplitude which are substantially fixed values after a short duration. Between the time periods T4 and T5, the rotational speed of the motor generator 2 has reached a preset rotational speed, and the motor generator 2 can be controlled to rotate forward in the closed-loop control mode. At the time period T5, the generator control device 1 controls the motor generator 2 to rotate forward in the closed-loop control mode to enter the power generation mode.

[0104] Further, the prior art position sensorless generator starting method usually uses the "motor rotational speed" to determine the current load, however, when the starting position of the motor is very close to the compression top dead center, the distance is not enough, and the rotational speed is not enough, resulting in a large error in the load determination of the prior art generator starting method. However, the present application discards the prior art "motor rotational speed" to determine the load at the time period T2, and instead uses the size of the real power or the reactive power in the mechanical power output by the motor generator (i.e. the horizontal axis component or the vertical axis component of the driving voltage Vdr) to determine the load size. Also because the frequency of the driving current is not controlled according to the rotational speed of the motor generator 2 at this time, it is called the speed open-loop control mode.

[0105] Figure 5C corresponds to the point P2 in Figure 5A which has a shorter reverse rotation distance. In Figure 5C , the width of the time period T2 is shorter than Figure 5B , the reason for which is that the point P2 is closer to the point P3, and the reverse rotation time of the motor generator 2 is relatively shorter. The remaining time periods are substantially the same as Figure 5BThe similarities are not elaborated here. It is worth mentioning that when the rotor starting point of motor-generator 2 is precisely at point P3, the first load information Vi1 will always be less than the first threshold value Vth during time period T2. Therefore, when the first load information Vi1 is already less than the first threshold value Vth at the beginning, and after the drive currents Idr1 to Idr3 have reached a first drive current with a first fixed frequency and a first fixed amplitude after a certain duration, if the first load information Vi1 is still less than the first threshold value Vth, then the reverse motor-generator 2 stops reversing and enters time period T3. Therefore, the preset time can be approximately equal to the duration. Please refer to [link to relevant documentation]. Figure 6 This is a waveform diagram in the startup mode of the present invention, for reference only. Figures 2-5C And consulted repeatedly Figures 5A-6 In this embodiment, the waveform diagram is based on... Figure 5B Taking the process of starting the engine with a motor-generator as an example, Figure 5C Or the rotor starting point of motor generator 2 happens to be at point P3, and the waveform can be determined accordingly. Figure 6 The waveforms are analogous and will not be elaborated further here. During time period T1, the generator control device 1 performs DC excitation alignment on the motor generator 2. Therefore, the current commands Cid and Ciq provided by the loop control unit 128 are DC current commands (frequency 0) to control the motor generator 2 to reverse excitation alignment. During time period T2, the current commands Cid and Ciq provided by the loop control unit 128 control the generator control device 1 to provide a first drive current with a first frequency and a first amplitude. Therefore, the peak current Ipeak (negative value) of the current commands Cid and Ciq decreases until it reaches a fixed value, and the frequency f increases until it reaches a fixed frequency. At this time, the speed Sp of the motor generator 2 is negative (reverse). The first load information Vi1 (in this embodiment, the vertical axis component Svd of the drive voltage is used as an example) increases from less than the threshold value Vth to greater than or equal to the first threshold value Vth.

[0106] In the period T2-T3, the first load information Vii decreases from being greater than or equal to the first threshold value Vth to being less than the first threshold value Vth, satisfying the heavy load condition, representing that the rotor of the motor generator 2 has approached the compression top dead center Cp. At the time period T3, the amplitudes and frequencies of the current commands Cid, Ciq provided by the loop control unit 128 are adjusted to 0, waiting for the rotor of the motor generator 2 to be stationary. At the time period T4, the current commands Cid, Ciq provided by the loop control unit 128 control the generator control device 1 to provide the second driving current with the second frequency and the second amplitude, so the current peak Ipeak (positive value) of the current commands Cid, Ciq increases until a fixed value, and the frequency f increases until a fixed frequency. At this time, the rotation speed Sp of the motor generator 2 is positive (forward rotation). At the time period T5, the rotation speed Sp of the motor generator 2 has reached the preset rotation speed, so the forward rotation closed loop control is performed on the motor generator 2.

[0107] It is worth mentioning that in an embodiment of the present application, Figures 5B-6 The waveform of the first load information Vii is shown in FIG. 5B-6 using the d-axis voltage signal Svd as the first load information Vii, which is compared with whether the first load information Vii is less than the first threshold value Vth. When the q-axis voltage signal Svq is used as the first load information Vii, the waveforms of FIG. 5B-6 and the threshold (second threshold) condition are just opposite, which will not be described and illustrated again here.

[0108] The above is only a detailed description of the preferred embodiments of the present application and the accompanying drawings, and the features of the present application are not limited thereto, and are not intended to limit the present application. The scope of the present application should be subject to the claims, and any embodiments that are consistent with the concept of the claims and similar changes thereof should be included in the scope of the present application. Any changes or modifications that can be easily thought of by those skilled in the art in the field of the present application can be covered by the claims of the present disclosure.

Claims

1. A generator starting method for an integrated motor-generator, comprising the following steps: (1) Starting an engine by driving a motor-generator without a position sensor. (a) In a speed open-loop control mode, a first drive current having a first frequency and a first amplitude is applied to drive the motor generator to reverse, and a first load information is obtained based on a drive voltage of the motor generator and the first drive current. (b) Confirm whether the first load information meets a heavy load condition; (c) When it is determined that the first load information meets the heavy load condition, stop reversing the motor generator; and (d) The motor generator rotates in the forward direction, thereby starting the engine.

2. The generator starting method as described in claim 1, wherein step (d) includes: (d1) A second driving current with a second frequency and a second amplitude is applied to drive the motor generator to rotate forward; (d2) Estimate a rotational speed of the motor-generator based on the driving voltage and the second driving current; and (d3) When the speed reaches a preset speed, the motor generator is controlled by a forward closed loop.

3. The generator starting method as described in claim 1, further comprising: (a0) The rotor of the motor generator is attracted to a predetermined angle by applying a current component of a given angle according to a start command.

4. The generator starting method as described in claim 1, wherein step (c) comprises: (c1) Provide a predetermined waiting time for the motor generator to come to a stop.

5. The generator starting method as described in claim 1, wherein step (a) comprises: (a1) Obtain a second load information based on the driving voltage and the first driving current; (a2) The first load information is obtained by performing a low-pass filter on the second load information.

6. The generator starting method as claimed in claim 1, wherein the first load information corresponds to a load amount of the motor generator, and the threshold value represents a predetermined threshold value of the load amount.

7. The generator starting method as claimed in claim 1, wherein the first load information is a d-axis voltage signal of the motor generator, and the d-axis voltage signal is a vertical axis component of the drive voltage corresponding to a vertical horizontal axis, and step (c) includes: (c2-1) When the first load information changes from greater than or equal to a first threshold value to less than the first threshold value, or when the first load information remains less than the first threshold value for a preset time, it means that the overload condition is met.

8. The generator starting method as claimed in claim 1, wherein the first load information is a q-axis voltage signal of the motor generator, and the q-axis voltage signal is a horizontal axis component of the drive voltage corresponding to a vertical horizontal axis, and step (c) includes: (c2-2) When the first load information changes from less than or equal to a second threshold value to greater than the second threshold value, or when the first load information continues to be greater than the second threshold value for a preset time, it means that the overload condition is met.

9. A generator control device for starting an integrated motor-generator, coupled to a motor-generator without a position sensor, wherein the motor-generator drives an engine to start, the generator control device comprising: An inverter receives a DC voltage and is coupled to the motor generator; and A control module is coupled to the inverter and the motor generator, and provides a pulse width modulation signal to the inverter so that the inverter converts the DC voltage into a drive voltage and a drive current to drive the motor generator. In a speed open-loop control mode, the control module adjusts the pulse width modulation signal according to whether the drive voltage and drive current meet a heavy load condition. First, it controls the motor generator to reverse. When the heavy load condition is met, it stops reversing the motor generator and controls the motor generator to rotate forward to start the engine.

10. The generator control device as claimed in claim 9, wherein the control module comprises: A pulse width modulation unit modulates the pulse width modulation signal according to a control signal; A drive unit is coupled to the pulse width modulation unit and the motor generator, and provides a first load information based on the drive voltage and the drive current; A load detection unit, coupled to the drive unit, determines whether the first load information meets the overload condition, and provides a load signal based on the determination result; and A primary loop control unit is coupled to the load detection unit and the drive unit, and provides a control command to the drive unit to drive the motor generator to rotate forward or reverse according to the load signal; The drive unit generates the control signal based on the drive current and the control command.

11. The generator control device of claim 10, wherein the circuit control unit comprises: An open-loop control unit provides a first control command for controlling the motor generator to reverse, thereby controlling the drive current to be a first drive current with a first frequency and a first amplitude, and provides a second control command for controlling the motor generator to rotate forward, thereby controlling the drive current to be a second drive current with a second frequency and a second amplitude. and A closed-loop control unit performs forward closed-loop control on the motor generator based on whether the generator's rotational speed has reached a preset speed.

12. The generator control device as claimed in claim 11, further comprising: A control unit, coupled to the drive unit and the loop control unit, and comprising: An estimation unit estimates the rotational speed based on a d-axis current signal, a q-axis current signal, a d-axis voltage signal, and a q-axis voltage signal corresponding to the driving current. A switching unit that switches the drive unit to be coupled to the open-loop control unit or the closed-loop control unit according to the rotational speed.

13. The generator control device of claim 11, wherein the open-loop control unit further provides a start command to attract a rotor of the motor generator to a predetermined angle.

14. The generator control device of claim 11, wherein the control module sets a predetermined waiting time between the provision of the first control command and the provision of the second control command by the open-loop control unit, the predetermined waiting time being used to wait for the motor generator to stop.

15. The generator control device as claimed in claim 10, further comprising: A low-pass filter unit is coupled to the drive unit and the load detection unit, and low-pass filters a second load information provided by the drive unit into the first load information.

16. The generator control device of claim 10, wherein the drive unit generates a d-axis voltage signal and a q-axis voltage signal according to the drive current and the control command, and converts the d-axis voltage signal and the q-axis voltage signal into the control signal.

17. The generator control device of claim 16, wherein the first load information is the d-axis voltage signal, and the d-axis voltage signal is a vertical axis component of the drive voltage corresponding to a vertical horizontal axis.

18. The generator control device of claim 17, wherein the heavy load condition is provided when the first load information changes from greater than or equal to a threshold value to less than the threshold value, or when the first load information remains less than the threshold value for a preset time.

19. The generator control device of claim 16, wherein the first load information is the q-axis voltage signal, and the q-axis voltage signal is a horizontal axis component of the drive voltage corresponding to a vertical horizontal axis.

20. The generator control device of claim 19, wherein the heavy load condition is that the first load information changes from less than or equal to a second threshold value to greater than the second threshold value, or when the first load information continues to be greater than the second threshold value for a preset time.

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