Voltage overload protection system and method for motor front drive

Abstract

This invention discloses a voltage overload protection system and method for a motor pre-driver. The overvoltage protection circuit compares a first reference voltage with the shared voltage of the input single-phase motor to output a first comparison signal. When the control circuit determines, based on the first comparison signal, that the shared voltage is greater than the first reference voltage, the control circuit closes the first and second upper bridge switches and opens the first and second lower bridge switches within one phase time of the commutation signal of the single-phase motor. After the phase time ends, the control circuit alternately opens the first and second lower bridge switches according to the level of the commutation signal.

Description

Technical Field

[0001] This invention relates to voltage overload protection systems, and more particularly to a voltage overload protection system and method for a motor pre-drive for protecting a bridge drive circuit of a single-phase motor. Background Technology

[0002] Electronic products generate heat during operation, especially in the enclosed enclosures of servers or other confined spaces. The heat produced by each circuit component circulates within the enclosure, heating other circuit components and potentially causing them to overheat and break down. Therefore, electronic products must be equipped with fans to cool the circuit components.

[0003] However, inside the fan, the control circuit controls the operation of multiple transistors in the motor drive circuit to drive the motor. During the process of driving the fan blades to rotate, a reverse current is generated to charge the shared voltage coupled to the single-phase motor, causing the shared voltage to be too high, which in turn leads to the damage of the transistors in the motor drive circuit. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a voltage overload protection system for a motor pre-drive, applicable to a bridge drive circuit for a single-phase motor, addressing the shortcomings of existing technologies. The bridge drive circuit includes multiple switching components. These components include a first upper bridge switch, a first lower bridge switch, a second upper bridge switch, and a second lower bridge switch. A first terminal of the first upper bridge switch and a first terminal of the second upper bridge switch are coupled to a shared voltage. A first node between the second terminal of the first upper bridge switch and the first terminal of the first lower bridge switch is connected to the first terminal of the single-phase motor. A second node between the second terminal of the second upper bridge switch and the first terminal of the second lower bridge switch is connected to the second terminal of the single-phase motor. The second terminals of the second upper bridge switch and the second lower bridge switch are grounded. The voltage overload protection system for the motor pre-drive includes an overvoltage protection circuit and a control circuit. The overvoltage protection circuit is located within the motor pre-drive and coupled to the shared voltage. The overvoltage protection circuit is configured to compare the shared voltage with a first reference voltage to output a first comparison signal. The control circuit is located within the motor pre-driver, connecting the control terminals of each switching component and the overvoltage protection circuit. It is configured to output multiple control signals to multiple switching components to turn them on or off. Specifically, when the control circuit determines, based on a first comparison signal, that the shared voltage is greater than a first reference voltage, it closes the first upper bridge switch and the second upper bridge switch and opens the first lower bridge switch and the second lower bridge switch within one phase of the commutation signal. After the same phase of the commutation signal ends, the first lower bridge switch and the second lower bridge switch are turned on alternately based on the level of the commutation signal of the single-phase motor.

[0005] In one implementation, when the commutation signal reaches the commutation time point from the first level to the second level, the control circuit closes the first lower bridge switch and opens the second lower bridge switch; when the commutation signal transitions from the second level to the first level, the control circuit closes the second lower bridge switch and opens the first lower bridge switch.

[0006] In one embodiment, the overvoltage protection circuit includes a first comparator. A first input and a second input of the first comparator are coupled to a shared voltage and a first reference voltage, respectively. The first comparator is configured to compare the shared voltage with the first reference voltage to output a first comparison signal.

[0007] In one embodiment, the overvoltage protection circuit compares the shared voltage with a second reference voltage to output a second comparison signal. Based on the second comparison signal, the control circuit determines that when the shared voltage is greater than the second reference voltage but not greater than the first reference voltage, it slightly opens the first upper bridge switch, which was originally in a closed state, keeps the first lower bridge switch and the second upper bridge switch fully open, and keeps the second lower bridge switch closed.

[0008] In one embodiment, the overvoltage protection circuit compares the shared voltage with the second reference voltage to output a second comparison signal. When the control circuit determines that the shared voltage is greater than the second reference voltage but not greater than the first reference voltage based on the second comparison signal, it slightly opens the second upper bridge switch, which was originally in the closed state, keeps the first upper bridge switch and the second lower bridge switch fully open, and keeps the first lower bridge switch closed.

[0009] In one embodiment, the overvoltage protection circuit further includes a second comparator. The first and second input terminals of the second comparator are respectively coupled to a shared voltage and a second reference voltage. The second comparator is configured to compare the shared voltage with the second reference voltage to output a second comparison signal.

[0010] Furthermore, this invention provides a voltage overload protection method for a motor pre-drive, applicable to a bridge drive circuit for a single-phase motor. The bridge drive circuit includes multiple switching components. These components include a first upper bridge switch, a first lower bridge switch, a second upper bridge switch, and a second lower bridge switch. A first terminal of the first upper bridge switch and a first terminal of the second upper bridge switch are coupled to a shared voltage. A first node between the second terminal of the first upper bridge switch and the first terminal of the first lower bridge switch is connected to the first terminal of the single-phase motor. A second node between the second terminal of the second upper bridge switch and the first terminal of the second lower bridge switch is connected to the second terminal of the single-phase motor. The second terminals of the second upper bridge switch and the second lower bridge switch are grounded. The voltage overload protection method for the motor pre-drive includes the following steps: comparing a shared voltage with a first reference voltage to generate a first comparison signal; determining whether the shared voltage has reached the first reference voltage based on the first comparison signal; if not, returning to the previous step; if yes, proceeding to the next step; closing the first upper bridge switch and the second upper bridge switch and opening the first lower bridge switch and the second lower bridge switch during one phase time of the commutation signal; and after the same phase time of the commutation signal ends, alternately opening the first lower bridge switch and the second lower bridge switch according to the level of the commutation signal of the single-phase motor.

[0011] In one embodiment, the voltage overload protection method for the motor pre-driver further includes the following steps: determining whether the commutation signal has reached the commutation time point from the first level to the second level; if yes, closing the first lower bridge switch and opening the second lower bridge switch, without proceeding to the next step; if no, proceeding to the next step; and determining whether the commutation signal has reached the commutation time point from the second level to the first level; if yes, closing the second lower bridge switch and opening the first lower bridge switch; if no, returning to the previous step.

[0012] In one embodiment, the voltage overload protection method for the motor pre-drive further includes the following steps: comparing a shared voltage with a second reference voltage to output a second comparison signal; and determining whether the shared voltage is greater than the second reference voltage but not greater than the first reference voltage. If not, return to the previous step; if yes, slightly open the first upper bridge switch, which was originally in the closed state, maintain the first lower bridge switch and the second upper bridge switch fully open, and maintain the second lower bridge switch closed.

[0013] In one embodiment, the voltage overload protection method for the motor pre-drive further includes the following steps: comparing a shared voltage with a second reference voltage to output a second comparison signal; and determining whether the shared voltage is greater than the second reference voltage but not greater than the first reference voltage. If not, return to the previous step; if yes, slightly open the second upper bridge switch, which was originally in the closed state, maintain the first upper bridge switch and the second lower bridge switch fully open, and maintain the first lower bridge switch closed.

[0014] As described above, the present invention provides a voltage overload protection system and method for a motor front driver, which has the following main features:

[0015] The shared voltage of the input single-phase motor is detected. When it is determined that the shared voltage is greater than the first reference voltage, the first stage is executed: the upper bridge switch is fully closed and the lower bridge switch is fully opened to achieve the reverse current stop recharging of the shared voltage.

[0016] When the commutation signal is reached, the second stage is executed: the upper bridge switch is completely turned off, and multiple lower bridge switches are turned on in turn according to the level of the commutation signal to cool down the bridge drive circuit.

[0017] If the shared voltage continues to rise, all bridge switches remain closed to prevent them from overheating and being damaged.

[0018] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the component configuration of the voltage overload protection system of the motor front driver, the single-phase motor, and the bridge drive circuit in the first to third embodiments of the present invention.

[0020] Figure 2 This is a schematic diagram of the internal components of the overvoltage protection circuit of the voltage overload protection system of the motor front driver according to the first embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the switching bridge drive circuit of the voltage overload protection system and method for the motor front driver according to the first embodiment of the present invention.

[0022] Figure 4 This is a flowchart illustrating the steps of a voltage overload protection method for a motor pre-driver according to a first embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of the switching bridge drive circuit of the voltage overload protection system and method for the motor front driver according to the second embodiment of the present invention.

[0024] Figure 6 This is a flowchart illustrating the steps of a voltage overload protection method for a motor front driver according to a second embodiment of the present invention.

[0025] Figure 7 This is a flowchart illustrating the steps of a voltage overload protection method for a motor front driver according to a third embodiment of the present invention.

[0026] Figure 8This is a schematic diagram of the internal components of the overvoltage protection circuit of the voltage overload protection system for the motor front driver according to the second and third embodiments of the present invention.

[0027] Figure 9 The above is a signal waveform diagram of the voltage overload protection system and method for the motor front driver according to the fourth embodiment of the present invention. Detailed Implementation

[0028] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. Furthermore, the accompanying drawings of the present invention are for simple illustrative purposes only and are not depictions of actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of protection of the present invention. In addition, the term "or" as used herein may, depending on the actual situation, include any combination of any one or more of the associated listed items.

[0029] [First Embodiment]

[0030] Please see Figures 1 to 4 ,in Figure 1 This is a schematic diagram of the component configuration of the voltage overload protection system of the motor pre-driver, the single-phase motor, and the bridge drive circuit in the first to third embodiments of the present invention. Figure 2 This is a schematic diagram of the internal components of the overvoltage protection circuit of the voltage overload protection system of the motor front driver according to the first embodiment of the present invention; Figure 3 This is a schematic diagram of the switching bridge drive circuit of the voltage overload protection system and method for the motor front driver according to the first embodiment of the present invention. Figure 4 This is a flowchart illustrating the steps of a voltage overload protection method for a motor pre-driver according to a first embodiment of the present invention.

[0031] The voltage overload protection method for the motor pre-drive in this embodiment may include, for example: Figure 4 Steps S101 to S123 shown can be performed by, for example Figure 1 The motor pre-driver 100 shown executes the bridge drive circuit HBDV of the single-phase motor MT in sequence.

[0032] like Figure 1As shown, the motor pre-driver 100 may include an overvoltage protection circuit 10 and a control circuit 20, which are disposed within the motor pre-driver 100. The control circuit 20 is connected to the overvoltage protection circuit 10 and the bridge drive circuit HBDV. The overvoltage protection circuit 10 is coupled to a shared voltage VCC. The single-phase motor MT is connected to the bridge drive circuit HBDV and coupled to the shared voltage VCC.

[0033] The bridge drive circuit HBDV includes multiple switching components, such as a first upper bridge switch H1, a first lower bridge switch L1, a second upper bridge switch H2, and a second lower bridge switch L2, which are configured as an H-bridge drive circuit. These switching components can be transistors of the same or different types, and the present invention is not limited thereto.

[0034] The first terminal of the first upper bridge switch H1 and the first terminal of the second upper bridge switch H2 are coupled to a shared voltage VCC. The first node OUT1 between the second terminal of the first upper bridge switch H1 and the first terminal of the first lower bridge switch L1 is connected to the first terminal of the single-phase motor MT, i.e., the first terminal of the inductor L of the single-phase motor MT. The second terminal of the inductor L of the single-phase motor MT is connected to the first terminal of the resistor R of the single-phase motor MT. The second node OUT2 between the second terminal of the second upper bridge switch H2 and the first terminal of the second lower bridge switch L2 is connected to the second terminal of the single-phase motor MT, i.e., the second terminal of the resistor R of the single-phase motor MT. The second terminals of the second upper bridge switch H2 and the second lower bridge switch L2 are grounded.

[0035] The bridge drive circuit HBDV is located outside the motor pre-driver 100 and cannot be cooled by the heat sink located on the motor pre-driver 100. Although adding a large capacitor to the circuit board of the bridge drive circuit HBDV can prevent damage to multiple switching components of the bridge drive circuit HBDV, when the fan is small, it can only accommodate the single-phase motor MT and the bridge drive circuit HBDV, and cannot accommodate the large capacitor that occupies space. Therefore, in this case, it is necessary to perform the following... Figure 4 Steps S101 to S123 are shown to prevent the bridge drive circuit HBDV from overheating and being damaged. The specific explanation is as follows.

[0036] In step S101, the control circuit 20 outputs multiple control signals M1P, M1N, M2P, and M2N to the control terminals of multiple switching components of the bridge drive circuit HBDV, respectively, to turn the switching components on or off, so as to control the bridge drive circuit HBDV to drive the single-phase motor MT to operate stably in normal mode.

[0037] For example, such as Figure 3As shown in the dashed box AH1, the control circuit 20 outputs a low-level control signal M1N to close the first lower bridge switch L1 and a high-level control signal M2P to close the second upper bridge switch H2. It also outputs a low-level control signal M1P to open the first upper bridge switch H1 and a high-level control signal M2N to open the second lower bridge switch L2. At this time, the bridge drive circuit HBDV drives the single-phase motor MT to operate stably, and the forward current IL11 flows sequentially from the first upper bridge switch H1 through the single-phase motor MT and the second lower bridge switch L2 to ground.

[0038] In this embodiment, when the commutation signal HLS is high, the current IL11 flows from the first node OUT1 of the single-phase motor MT to the second node OUT2 of the single-phase motor MT. However, this is only an example and is not intended to limit the invention. The commutation signal HLS indicates that the rotor (fan blades) is detected to rotate; a low or high level indicates the polarity direction. Therefore, the switching of the bridge drive circuit HBDV can be set according to actual needs at different levels of the commutation signal HLS, thereby determining the current flow direction. For example, when the commutation signal HLS is low, the current flows from the first node OUT1 to the second node OUT2.

[0039] In step S103, the control circuit 20 determines whether the current time has reached a commutation time point of the commutation signal HLS of the single-phase motor MT. If the current time has not yet reached the commutation time point of the commutation signal HLS, step S101 continues to be executed. Conversely, if the current time has reached the commutation time point of the commutation signal HLS, for example, but not limited to reaching... Figure 3 When the falling edge (which can actually be the rising edge) of a waveform of the commutation signal HLS is reached, step S105 is then executed.

[0040] In step S105, the control circuit 20 is used to switch the bridge drive circuit HBDV to switch some of the switching components from the on state to the off state, and other switching components from the off state to the on state.

[0041] For example, such as Figure 3 As shown in the dashed box AH2, the control circuit 20 closes the first upper bridge switch H1 and the second lower bridge switch L2, while opening the first lower bridge switch L1 and the second upper bridge switch H2. As a result, the reverse current IL12 flows from the first lower bridge switch L1 through the single-phase motor MT and the second upper bridge switch H2 to the shared voltage VCC, thus recharging the shared voltage VCC and causing an increase in VCC.

[0042] In this embodiment, for example, during the commutation process, the bridge drive circuit HBDV is driven from... Figure 3 The state shown in the dashed box AH1 in the image is switched to the state shown in the image. Figure 3The state shown in the dashed box AH2 is as indicated. It should be understood that during commutation, the bridge drive circuit HBDV may also switch from the state shown in the dashed box AH2 to the state shown in the dashed box AH1. Each time the bridge drive circuit HBDV is switched, especially when the first upper bridge switch H1 or the second upper bridge switch H2 is turned on, a reverse current will charge the shared voltage VCC.

[0043] In step S107, during the process of recharging the shared voltage VCC by the reverse current IL12, the shared voltage VCC is obtained by the overvoltage protection circuit 10. Then, the shared voltage VCC is compared with the first reference voltage VRF1 to output the first comparison signal CP1 to the control circuit 20.

[0044] For example, the overvoltage protection circuit 10 may include, for instance, the following: Figure 2 The first comparator CMP1 is shown. The first input terminal of the first comparator CMP1, for example, a non-inverting input terminal, is coupled to a shared voltage VCC, while the second input terminal of the first comparator CMP1, for example, an inverting input terminal, is coupled to a first reference voltage VRF1. The first comparator CMP1 is configured to compare the shared voltage VCC with the first reference voltage VRF1 to output a first comparison signal CP1 to the control circuit 20.

[0045] In step S109, the control circuit 20 uses the comparison signal CP1 to determine whether the shared voltage VCC is greater than the first reference voltage VRF1. If the first comparison signal CP1 outputs a low level, and the control circuit 20 determines that the shared voltage VCC is not greater than the first reference voltage VRF1 based on the low level comparison signal CP1, then it proceeds to step S111.

[0046] In step S111, the control circuit 20 is used to maintain the following... Figure 3 As shown in the dashed box AH2, the first upper bridge switch H1 and the second lower bridge switch L2 are closed, while the first lower bridge switch L1 and the second upper bridge switch H2 are opened to control the bridge drive circuit HBDV to drive the single-phase motor MT to operate stably. That is, the bridge drive circuit HBDV does not switch.

[0047] Conversely, if the first comparison signal CP1 outputs a high-level first comparison signal CP1, in step S109, when the control circuit 20 determines that the shared voltage VCC is greater than the first reference voltage VRF1 based on the high-level comparison signal CP1, it then executes steps S113 to S119.

[0048] In step S113, as Figure 3 As shown in the dashed box AH3, the control circuit 20 outputs a control signal M1P to the first upper bridge switch H1 to close the first upper bridge switch H1.

[0049] In step S115, as Figure 3 As shown in the dashed box AH3, the control circuit 20 outputs a control signal M2P to the second upper bridge switch H2 to close the second upper bridge switch H2.

[0050] In step S117, as Figure 3 As shown in the dashed box AH3, the control circuit 20 outputs a control signal M1N to the first lower bridge switch L1 to turn on the first lower bridge switch L1.

[0051] In step S119, as Figure 3 As shown in the dashed box AH3, the control circuit 20 outputs a control signal M2N to the second lower bridge switch L2 to turn on the second lower bridge switch L2.

[0052] After steps S113 to S119 are executed, since both the first upper bridge switch H1 and the second upper bridge switch H2 are closed, the fan blades will continue to rotate with the inertia of the single-phase motor MT, and the operating speed will gradually decrease. Meanwhile, the open first lower bridge switch L1 and the second lower bridge switch L2 form a closed path, allowing current IL13 to repeatedly flow through them without flowing to the shared voltage VCC, thus replacing the reverse current IL12 that previously charged the shared voltage VCC. Therefore, the shared voltage VCC will not rise further, thereby preventing excessively high shared voltage VCC from damaging the bridge drive circuit HBDV, especially the first upper bridge switch H1 and the second upper bridge switch H2.

[0053] In step S121, after the control circuit 20 closes the first upper bridge switch H1 and the second upper bridge switch H2 and opens the first lower bridge switch L1 and the second lower bridge switch L2, it waits for a period of time and then uses the control circuit 20 to determine whether the current time has reached the next commutation time point of the commutation signal HLS.

[0054] If the commutation signal HLS has not yet reached the next commutation time point, steps S113 to S119 continue to be executed. Conversely, if the commutation signal HLS has reached the subsequent commutation time point, the control circuit 20 will no longer simultaneously turn on the first lower bridge switch L1 and the second lower bridge switch L2 as in S113 to S119, but will instead execute step S123.

[0055] In step S123, the control circuit 20 uses the level of the commutation signal HLS to turn on the first lower bridge switch L1 and the second lower bridge switch L2 in turn.

[0056] For example, such as Figure 3As shown, when the control circuit 20 determines that the current time has reached the commutation point from low level to high level, the control circuit 20 switches the bridge drive circuit HBDV to... Figure 3 The state is shown in the dashed box AH4. That is, during the working cycle time t31 of the second waveform of the commutation signal HLS, the control circuit 20 keeps the first upper bridge switch H1 and the second upper bridge switch H2 closed, keeps the second lower bridge switch L2 open, but switches the first lower bridge switch L1 from the open state to the closed state.

[0057] Next, after the switching of the bridge drive circuit HBDV shown in the dashed box AH4 is completed, the next commutation time point of the commutation signal HLS is reached after a period of time, for example... Figure 3 When the commutation time point from high to low is reached, control circuit 20 switches the bridge drive circuit HBDV to... Figure 3 The state is shown in the dashed box AH5. That is, during the non-working cycle time t32 of the second waveform of the commutation signal HLS, the control circuit 20 keeps the first upper bridge switch H1 and the second upper bridge switch H2 closed, but changes the second lower bridge switch L2 from the open state to the closed state, and changes the first lower bridge switch L1 from the closed state to the open state.

[0058] Due to such Figure 3 The rising and falling edges of each waveform of the commutation signal HLS shown are used as commutation time points, and the first lower bridge switch L1 and the second lower bridge switch L2 will be turned on alternately.

[0059] In practice, if the bridge drive circuit HBDV is switched to such... Figure 3 After the state shown in the dashed box AH3, when the commutation time of the commutation signal HLS is the falling edge (instead of the rising edge mentioned above), then the bridge drive circuit HBDV is switched to the state shown in the dashed box AH3. Figure 3 The state is shown in the dashed box AH5. After a period of time, when the next commutation time point of the commutation signal HLS is at the rising edge, the bridge drive circuit HBDV is switched to the state shown in the dashed box AH5. Figure 3 The state is shown in the dashed box AH4.

[0060] [Second Embodiment]

[0061] Please see Figure 5 , Figure 6 and Figure 8 ,in Figure 5 This is a schematic diagram of the switching bridge drive circuit of the voltage overload protection system and method for the motor front driver according to the second embodiment of the present invention. Figure 6This is a flowchart illustrating the steps of the voltage overload protection method for the motor pre-driver according to the second embodiment of the present invention. Figure 8 This is a schematic diagram of the internal components of the overvoltage protection circuit of the voltage overload protection system for the motor front driver according to the second and third embodiments of the present invention.

[0062] The voltage overload protection method in this embodiment may further include, for example: Figure 6 Steps S201 to S213 shown can be performed by, for example Figure 1 The motor pre-driver 100 of the voltage overload protection system shown is activated.

[0063] In this embodiment, for example, in the aforementioned step S115, such as Figure 5 As shown in the dashed box AH1, the control circuit 20 fully opens the first upper bridge switch H1, fully closes the first lower bridge switch L1, fully closes the second upper bridge switch H2, and fully opens the second lower bridge switch L2 to drive the single-phase motor MT to operate stably as in step S101.

[0064] Therefore, when determining the commutation time point of the commutation signal HLS in step S113, step S115 is then executed, as follows. Figure 5 As shown in the dashed box AH2, the control circuit 20 fully closes the first upper bridge switch H1, fully opens the first lower bridge switch L1, fully opens the second upper bridge switch H2, and fully closes the second lower bridge switch L2 to drive the single-phase motor MT to operate stably.

[0065] It is worth noting that in the bridge drive circuit HBDV, from such Figure 5 The state transition shown in the dashed box AH1 is as follows: Figure 5 After the state shown in the dashed box AH2 is reached, the reverse current IL12 will flow through the fully open second upper bridge switch H2 to recharge the shared voltage VCC. During the process of the reverse current IL12 recharging the shared voltage VCC, step S201 can be executed.

[0066] In step S201, during the process of the reverse current IL12 recharging the shared voltage VCC, the shared voltage VCC will gradually rise. At this time, the overvoltage protection circuit 10 continuously detects the shared voltage VCC and compares the shared voltage VCC with the second reference voltage VRF2 to output the second comparison signal CP2.

[0067] For example, the overvoltage protection circuit 10 may include, in addition to, the features described above. Figure 2 In addition to the first comparator CMP1 shown, it may also include, as shown in the figure Figure 8The second comparator CMP2 is shown. The first input of the second comparator CMP2, for example, a non-inverting input, is coupled to a shared voltage VCC, while the second input of the second comparator CMP2, for example, an inverting input, is coupled to a second reference voltage VRF2. The second comparator CMP2 is configured to compare the shared voltage VCC with the second reference voltage VRF2 to output a second comparison signal CP2.

[0068] In step S203, the control circuit 20 uses the second comparison signal CP2 to determine whether the shared voltage VCC is greater than the second reference voltage VRF2 and less than the first reference voltage VRF1.

[0069] If the shared voltage VCC is not greater than the second reference voltage VRF2, step S205 is executed without switching the voltage protection, and the control circuit 20 continues to maintain the control bridge drive circuit HBDV at the specified value. Figure 5 The state is shown in the dashed box AH2. At this time, the reverse current IL12 continues to charge the shared voltage VCC, so step S201 continues to be executed, using the overvoltage protection circuit 10 to continuously detect the shared voltage VCC and compare it with the second reference voltage VRF2.

[0070] When the reverse current IL12 recharges the shared voltage VCC, causing the shared voltage VCC to increase to a level greater than the second reference voltage VRF2, steps S207 to S213 are then executed.

[0071] During steps S207 to S213, the control circuit 20 slightly opens the originally fully closed first upper bridge switch H1, while the other switching components of the bridge drive circuit HBDV remain unchanged. That is, the first lower bridge switch L1 and the second upper bridge switch H2 remain fully open, and the second lower bridge switch L2 remains closed. Figure 5 The portion enclosed by the dashed box AH22 is shown. After executing steps S207 to S213, steps S107 to S123 can be executed.

[0072] When the first upper bridge switch H1 is slightly open, a small current IL3 flows slowly from the shared voltage VCC through the first upper bridge switch H1, and then through the first lower bridge switch L1 to the ground terminal, thereby preventing the shared voltage VCC from being too high and causing damage to the bridge drive circuit HBDV.

[0073] In other words, when the shared voltage VCC increases to a level greater than the second reference voltage VRF2, but not greater than the first reference voltage VRF1, such as Figure 5 As shown in the dashed box AH22, first slightly open the first upper bridge switch H1.

[0074] [Third Embodiment]

[0075] Please see Figure 7 and Figure 8 ,in Figure 7 This is a flowchart illustrating the steps of a voltage overload protection method for a motor pre-driver according to a third embodiment of the present invention. Figure 8 This is a schematic diagram of the internal components of the overvoltage protection circuit of the voltage overload protection system for the motor front driver according to the second and third embodiments of the present invention.

[0076] The voltage overload protection method in this embodiment may further include, for example: Figure 7 Steps S301 to S313 shown can be performed by, for example Figure 1 The motor pre-driver 100 of the voltage overload protection system shown is activated.

[0077] In this embodiment, for example, in the aforementioned step S101, the control circuit 20 fully closes the first upper bridge switch H1, fully opens the first lower bridge switch L1, fully opens the second upper bridge switch H2, and fully closes the second lower bridge switch L2 to drive the single-phase motor MT to operate stably as in step S101. At this time, the current flows from the second upper bridge switch H2 through the second node OUT2 of the single-phase motor MT to the first node OUT1 of the single-phase motor MT, and then flows through the first lower bridge switch L1 to the ground terminal.

[0078] Next, when the commutation time of the commutation signal HLS is determined in step S103, step S115 is executed, using control circuit 20 to fully open the first upper bridge switch H1, fully close the first lower bridge switch L1, fully close the second upper bridge switch H2, and fully open the second lower bridge switch L2. At this time, the reverse current flows from the second node OUT2 of the single-phase motor MT to the first node OUT1 of the single-phase motor MT, and then flows back through the first upper bridge switch H1 to charge the shared voltage VCC. After executing step S115, step S301 is executed.

[0079] In step S301, during the reverse current recharge of the shared voltage VCC, the shared voltage VCC will gradually rise. At this time, the overvoltage protection circuit 10 continuously detects the shared voltage VCC and compares the shared voltage VCC with the second reference voltage VRF2 to output the second comparison signal CP2.

[0080] For example, such as Figure 8 As shown, the overvoltage protection circuit 10 of this embodiment includes a first comparator CMP1 and a second comparator CMP2. The first input terminal of the second comparator CMP2, for example, a non-inverting input terminal, is coupled to a shared voltage VCC, while the second input terminal of the second comparator CMP2, for example, an inverting input terminal, is coupled to a second reference voltage VRF2. The second comparator CMP2 is configured to compare the shared voltage VCC with the second reference voltage VRF2 to output a second comparison signal CP2.

[0081] In step S303, the control circuit 20 uses the second comparison signal CP2 to determine whether the shared voltage VCC is greater than the second reference voltage VRF2 and less than the first reference voltage VRF1.

[0082] If the control circuit 20 determines that the shared voltage VCC is not greater than the second reference voltage VRF2, it executes step S301 again to use the overvoltage protection circuit 10 to continuously detect the shared voltage VCC and compare the shared voltage VCC with the second reference voltage VRF2.

[0083] When the control circuit 20 determines that the reverse current recharges the shared voltage VCC, causing the shared voltage VCC to increase to a level greater than the second reference voltage VRF2, it then executes steps S307 to S313.

[0084] During steps S307 to S313, the control circuit 20 slightly opens the originally fully closed second upper bridge switch H2, but does not switch other switching components of the bridge drive circuit HBDV. That is, it keeps the first upper bridge switch H1 and the second lower bridge switch L2 fully open, and keeps the first lower bridge switch L1 fully closed. After steps S307 to S313 are executed, steps S107 to S123 can be executed.

[0085] When the second upper bridge switch H2 is slightly open, a small amount of current flows slowly from the shared voltage VCC through the second upper bridge switch H2, and then through the second lower bridge switch L2 to the ground terminal, thereby preventing the shared voltage VCC from being too high and causing damage to the bridge drive circuit HBDV.

[0086] [Fourth Embodiment]

[0087] Please see Figure 9 The above is a signal waveform diagram of the voltage overload protection system and method for the motor front driver according to the fourth embodiment of the present invention.

[0088] Within time t1, when the shared voltage VCC increases to a level greater than the second reference voltage VRF2 but not greater than the first reference voltage VRF1, the commutation signal HLS is high (in practice, it can also be as follows). Figure 5 (The level shown is replaced with a low level), and the control circuit 20 executes the first stage of the overvoltage protection program, controlling the originally fully closed first upper bridge switch H1 or the second upper bridge switch H2 to slightly open. As described above. Figure 3 In this embodiment, the micro-opening operation can be omitted as needed.

[0089] Next, as indicated by the high-level first-stage signal OVPV, within time t2, when the shared voltage VCC increases to a level greater than the first reference voltage VRF1, the commutation signal HLS is high (in practice, this can also be done as follows). Figure 5(The value shown is replaced with a low level), and the control circuit 20 executes the second stage of the overvoltage protection program, turning off the first upper bridge switch H1 and the second upper bridge switch H2, and turning on the first lower bridge switch L1 and the second lower bridge switch L2.

[0090] Next, as indicated by the high-level second-stage signal PVPP, the third stage of the overvoltage protection procedure is executed by the control circuit 20, which alternately opens the first lower bridge switch L1 and the second lower bridge switch L2 based on the level of the commutation signal HLS. For example, when the commutation signal HLS is high, as... Figure 5 In the embodiment shown, the second lower bridge switch L2 is turned on and the first lower bridge switch L1 is turned off, or in actual operation, the first lower bridge switch L1 is turned on and the second lower bridge switch L2 is turned off.

[0091] In this embodiment, as Figure 9 As shown, during the period when the second-stage signal PVPP is high, the first lower bridge switch L1 and the second lower bridge switch L2 are switched alternately three times. However, this is only an example, and the present invention is not limited to the example in this embodiment. In actual operation, the number of times the first lower bridge switch L1 and the second lower bridge switch L2 are switched alternately can be increased or decreased according to actual needs.

[0092] In summary, this invention provides a voltage overload protection system and method for a motor pre-drive, which has the following main features:

[0093] The shared voltage of the input single-phase motor is detected. When it is determined that the shared voltage is greater than the first reference voltage, the first stage is executed: the upper bridge switch is fully closed and the lower bridge switch is fully opened to achieve the reverse current stop recharging of the shared voltage.

[0094] When the commutation time of the commutation signal is reached, the second stage is executed: the upper bridge switch is completely turned off, and multiple lower bridge switches are turned on in turn according to the level of the commutation signal to cool down the bridge drive circuit.

[0095] If the shared voltage continues to rise, all bridge switches remain closed to prevent them from overheating and being damaged.

[0096] The above-disclosed content is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of the claims of the present invention. Therefore, all equivalent technical changes made based on the description and drawings of the present invention are included within the scope of the claims of the present invention.

Claims

1. A voltage overload protection system for a motor pre-drive, the voltage overload protection system being applicable to a bridge drive circuit of a single-phase motor, the bridge drive circuit comprising a plurality of switching components, the plurality of switching components including a first upper bridge switch, a first lower bridge switch, a second upper bridge switch, and a second lower bridge switch, a first terminal of the first upper bridge switch and a first terminal of the second upper bridge switch being coupled to a shared voltage, a first node between the second terminal of the first upper bridge switch and the first terminal of the first lower bridge switch being connected to the first terminal of the single-phase motor, a second node between the second terminal of the second upper bridge switch and the first terminal of the second lower bridge switch being connected to the second terminal of the single-phase motor, and the second terminals of the second upper bridge switch and the second lower bridge switch being grounded, characterized in that... The voltage overload protection system of the motor pre-driver includes: An overvoltage protection circuit is provided in the motor pre-driver. The overvoltage protection circuit is coupled to the shared voltage and is configured to compare the shared voltage with a first reference voltage to output a first comparison signal. as well as A control circuit is provided in the motor pre-driver. The control circuit is connected to the control terminal of each of the switching components and the overvoltage protection circuit. The control circuit is configured to output multiple control signals to the multiple switching components respectively to turn the multiple switching components on or off. When the control circuit determines that the shared voltage is greater than the first reference voltage based on the first comparison signal, it closes the first upper bridge switch and the second upper bridge switch and opens the first lower bridge switch and the second lower bridge switch within one phase time of a commutation signal. After the phase time ends, the first lower bridge switch and the second lower bridge switch are turned on alternately according to the level of the commutation signal of the single-phase motor.

2. The voltage overload protection system for the motor pre-driver according to claim 1, characterized in that, When the commutation signal reaches the commutation time point from the first level to the second level, the control circuit closes the first down-bridge switch and opens the second down-bridge switch. When the commutation signal transitions from the second level to the first level, the control circuit closes the second down-bridge switch and opens the first down-bridge switch.

3. The voltage overload protection system for the motor pre-driver according to claim 1, characterized in that, The overvoltage protection circuit includes a first comparator, the first input terminal and the second input terminal of the first comparator being coupled to the shared voltage and the first reference voltage, respectively. The first comparator is configured to compare the shared voltage with the first reference voltage to output the first comparison signal.

4. The voltage overload protection system for the motor pre-driver according to claim 1, characterized in that, The overvoltage protection circuit compares the shared voltage with the second reference voltage to output a second comparison signal. When the control circuit determines that the shared voltage is greater than the second reference voltage but not greater than the first reference voltage based on the second comparison signal, it slightly opens the first upper bridge switch, which was originally in the closed state, keeps the first lower bridge switch and the second upper bridge switch fully open, and keeps the second lower bridge switch closed.

5. The voltage overload protection system for the motor pre-driver according to claim 1, characterized in that, The overvoltage protection circuit compares the shared voltage with the second reference voltage to output a second comparison signal. When the control circuit determines that the shared voltage is greater than the second reference voltage but not greater than the first reference voltage based on the second comparison signal, it slightly opens the second upper bridge switch, which was originally in the closed state, keeps the first upper bridge switch and the second lower bridge switch fully open, and keeps the first lower bridge switch closed.

6. The voltage overload protection system for the motor pre-drive according to claim 4 or 5, characterized in that, The overvoltage protection circuit further includes a second comparator, the first input terminal and the second input terminal of the second comparator being coupled to the shared voltage and the second reference voltage, respectively. The second comparator is configured to compare the shared voltage with the second reference voltage to output the second comparison signal.

7. A voltage overload protection method for a motor pre-drive, the voltage overload protection method being applicable to a bridge drive circuit of a single-phase motor, the bridge drive circuit comprising a plurality of switching components, the plurality of switching components including a first upper bridge switch, a first lower bridge switch, a second upper bridge switch, and a second lower bridge switch, a first terminal of the first upper bridge switch and a first terminal of the second upper bridge switch being coupled to a shared voltage, a first node between the second terminal of the first upper bridge switch and the first terminal of the first lower bridge switch being connected to the first terminal of the single-phase motor, a second node between the second terminal of the second upper bridge switch and the first terminal of the second lower bridge switch being connected to the second terminal of the single-phase motor, and the second terminals of the second upper bridge switch and the second lower bridge switch being grounded, characterized in that... The voltage overload protection method for the motor front driver includes the following steps: (a) Compare the shared voltage with a first reference voltage to generate a first comparison signal; (b) Determine whether the shared voltage has reached the first reference voltage based on the first comparison signal. If not, return to step (a). If yes, proceed to step (c). (c) During one phase time of a commutation signal, the first upper bridge switch and the second upper bridge switch are turned off, and the first lower bridge switch and the second lower bridge switch are turned on; as well as (d) After the phase time ends, the first lower bridge switch and the second lower bridge switch are turned on alternately according to the level of the commutation signal of the single-phase motor.

8. The voltage overload protection method for the motor pre-driver according to claim 7, characterized in that, Step (d) of the voltage overload protection method for the motor front driver further includes the following steps: (e) Determine whether the commutation signal has reached the commutation time point from the first level to the second level. If yes, close the first down-bridge switch and open the second down-bridge switch, without executing step (f). If no, execute step (f); and (f). Determine whether the commutation signal has reached the commutation time point from the second level to the first level. If yes, turn off the second downbridge switch and turn on the first downbridge switch. If no, return to step (e).

9. The voltage overload protection method for the motor pre-driver according to claim 7, characterized in that, The voltage overload protection method for the motor front driver further includes the following steps performed prior to step (a): (g) Compare the shared voltage with the second reference voltage to output a second comparison signal; as well as (h) Determine whether the shared voltage is greater than the second reference voltage but not greater than the first reference voltage. If not, return to step (g). If yes, slightly open the first upper bridge switch which was originally in the closed state, keep the first lower bridge switch and the second upper bridge switch fully open, and keep the second lower bridge switch closed.

10. The voltage overload protection method for the motor pre-driver according to claim 7, characterized in that, The voltage overload protection method for the motor front driver further includes the following steps performed prior to step (a): (i) Compare the shared voltage with the second reference voltage to output a second comparison signal; as well as (j). Determine whether the shared voltage is greater than the second reference voltage but not greater than the first reference voltage. If not, return to step (i). If yes, slightly open the second upper bridge switch which was originally in the closed state, keep the first upper bridge switch and the second lower bridge switch fully open, and keep the first lower bridge switch closed.

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