CN114594300A - Current state judging method and circuit - Google Patents

Abstract

A current state judging method and a circuit thereof are provided, the current state judging method is used for judging the state of a current flowing through a coil of a motor and comprises the following steps: measuring a voltage of a node at which a high-side transistor and a low-side transistor are commonly coupled to the coil at a first time point when the high-side transistor and the low-side transistor are switched to an off state, and outputting a first voltage value; measuring the voltage of the node at a second time point when the high-side transistor and the low-side transistor are both kept in an off state, and outputting a second voltage value; comparing the first voltage value with the second voltage value to obtain a comparison result; and judging the state of the current according to the comparison result. The present disclosure also provides a current status determining circuit for performing the current status determining method. The current state judging circuit can avoid adding auxiliary circuit because it does not need to measure the voltage value higher than the system high voltage or lower than the system low voltage.

Description

Current state judging method and circuit

Technical Field

The present disclosure relates to a current state determining method and circuit, and more particularly, to a current state determining method and circuit for determining a state of a coil current.

Background

Taking a set of high-side transistors and low-side transistors in a driving circuit of a three-phase motor as an example, generally, the high-side transistors and the low-side transistors are turned on alternately to change the flow direction of the coil current, thereby driving the motor. When the motor is driven, there may be a period (hereinafter referred to as Dead Zone) when the high-side transistor and the low-side transistor are simultaneously in an off state. It is noted that the direction of the coil current in the dead time zone is most reflective of the instantaneous state of the motor in operation. In addition, the voltage value of a node where the high-side transistor, the low-side transistor and the motor coil are commonly coupled changes according to the flowing direction of the coil current in the dead zone. Therefore, conventionally, by comparing the voltage value of the node with the high voltage or the low voltage of the system, the flow direction of the coil current in the dead time can be determined, so as to obtain the real-time status information of the motor in operation.

However, the above-mentioned determination result is easily affected by the system noise, and since the voltage value higher than the system high voltage (or lower than the system low voltage) is measured, an auxiliary circuit (or other special measures) is often required, which further increases the cost. In addition, when the voltage value of the node is between the system high voltage and the system low voltage, the flow direction of the coil current cannot be judged.

Disclosure of Invention

Accordingly, the present disclosure provides a current status determining method. The current state judging method is used for judging the state of current flowing through a coil of a motor and comprises the following steps: measuring a voltage of a node at which a high-side transistor and a low-side transistor are commonly coupled to the coil at a first time point when the high-side transistor and the low-side transistor are switched to an off state, and outputting a first voltage value; measuring the voltage of the node at a second time point when the high-side transistor and the low-side transistor are both kept in an off state, and outputting a second voltage value; comparing the first voltage value with the second voltage value to obtain a comparison result; and judging the state of the current according to the comparison result.

In another embodiment, the step of determining the state of the current according to the comparison result includes: when the second voltage value is larger than the first voltage value, judging that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor; when the second voltage value is not larger than the first voltage value, the current is judged to pass through a second body diode of the low-side transistor and the node in sequence and flow into the coil.

In another embodiment, the step of determining the state of the current according to the comparison result includes: when the second voltage value is not less than the first voltage value, judging that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor; when the second voltage value is smaller than the first voltage value, the current is judged to sequentially pass through a second body diode of the low-side transistor and the node and flow into the coil.

Another aspect of the present disclosure is a current state determination method. The current state judging method is used for judging the state of current flowing through a coil of a motor and comprises the following steps: starting timing at a first time point when a high-side transistor and a low-side transistor are switched to an off state; measuring the voltage of a node at which the high-side transistor, the low-side transistor and the coil are commonly coupled at a second time point when the high-side transistor and the low-side transistor are kept in an off state, and outputting a voltage value; comparing the voltage value with a threshold value to obtain a comparison result; and judging the state of the current according to the comparison result.

In another embodiment, the step of determining the state of the current according to the comparison result includes: when the voltage value is larger than the threshold value, judging that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor; when the voltage value is smaller than the threshold value, the current is judged to sequentially pass through a second body diode of the low-side transistor and the node and flow into the coil.

Yet another aspect of the present disclosure is a current state determination circuit. The current state judging circuit is used for judging the state of a current flowing through a coil of a motor and comprises a voltage measuring unit and a processing unit. The voltage measuring unit is coupled to a node and is used for measuring the voltage of the node, wherein a high-side transistor, a low-side transistor and the coil are commonly coupled to the node. The processing unit is coupled to the voltage measuring unit and used for judging the current state when the high-side transistor and the low-side transistor are in an off state simultaneously according to the voltage change of the node.

In another embodiment, the voltage measurement unit outputs a first voltage value at a first time point when both the high-side transistor and the low-side transistor are switched to the off state; the voltage measuring unit outputs a second voltage value at a second time point when the high-side transistor and the low-side transistor are both kept in an off state; the processing unit compares the first voltage value with the second voltage value to obtain a comparison result, and judges the state of the current according to the comparison result.

In another embodiment, when the second voltage value is greater than the first voltage value, the processing unit determines that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor; when the second voltage value is not greater than the first voltage value, the processing unit determines that the current passes through a second body diode of the low-side transistor and the node in sequence and flows into the coil.

In another embodiment, when the second voltage value is not less than the first voltage value, the processing unit determines that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor; when the second voltage value is smaller than the first voltage value, the processing unit judges that the current sequentially passes through a second body diode of the low-side transistor and the node and flows into the coil.

In another embodiment, the processing unit starts timing at a first point in time when both the high-side transistor and the low-side transistor are switched to the off state; at a second time point when the high-side transistor and the low-side transistor are both kept in an off state, the voltage measuring unit outputs a voltage value, and the processing unit compares the voltage value with a threshold value; when the voltage value is larger than the threshold value, the processing unit judges that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor; when the voltage value is smaller than the threshold value, the processing unit judges that the current sequentially passes through a second body diode of the low-side transistor and the node and flows into the coil.

The current state determination circuit of the present disclosure may determine the state of the current in the coil in the dead zone according to the voltage change of the node. The current state judging circuit can judge the state of the current in the coil when the voltage of the node is between the high voltage of the system and the low voltage of the system without adding an auxiliary circuit because the voltage value higher than the high voltage of the system or lower than the low voltage of the system is not required to be measured. In addition, the phase information of the current acquired by the current state judging circuit is helpful for adjusting the phase relation between the current and the counter electromotive force of the motor, so that the motor can be operated at the optimal rotating speed value.

Drawings

FIG. 1 is a schematic diagram illustrating a current state determination circuit according to some embodiments of the present disclosure;

FIG. 2 is a schematic diagram illustrating a current state determination circuit in operation according to some embodiments of the present disclosure;

FIG. 3 is a schematic diagram illustrating a current state determination circuit in operation according to some embodiments of the present disclosure;

FIG. 4 is a schematic diagram illustrating a current state determination circuit in operation according to some embodiments of the present disclosure;

FIG. 5 is a schematic diagram illustrating a current state determination circuit in operation according to some embodiments of the present disclosure;

FIG. 6 is a flow chart illustrating a method for determining a current state according to some embodiments of the present disclosure;

FIG. 7A is a graph depicting a change in voltage at a node where a motor drive circuit is coupled to a coil, in accordance with some embodiments of the present disclosure;

FIG. 7B is a graph depicting a change in voltage at a node where a motor drive circuit is coupled to a coil, in accordance with some embodiments of the present disclosure;

FIG. 8 is a flow chart illustrating another method of determining a current state according to some embodiments of the present disclosure;

FIG. 9A is a graph depicting a change in voltage at a node where a motor drive circuit is coupled to a coil, in accordance with some embodiments of the present disclosure;

FIG. 9B is a graph illustrating voltage changes at a node where a motor driving circuit is coupled to a coil according to some embodiments of the present disclosure.

[ notation ] to show

10 coil

20 motor driving circuit

22 high side transistor

24 low side transistor

26 controller

100 current state judging circuit

102 voltage measuring unit

104 processing unit

200,300 method for determining current state

221 first body diode

241 second body diode

CS1 first control Signal

CS2 second control signal

VN voltage

VN1 first Voltage value

VN2 second Voltage value

Vcc, system high voltage

Vss System Low Voltage

Vth is threshold value

Vpd is voltage value

I1, I2, I3, I4 current

N is node

t1 first time point

t2 second time point

S201, S202, S203, S204, S205, S301, S302, S303, S304, S305

Detailed Description

The following embodiments are described in detail with reference to the accompanying drawings, but the embodiments are only for explaining the present invention and not for limiting the present invention, and the description of the structural operation is not for limiting the execution sequence thereof, and any structure obtained by recombining the elements and having an equivalent function is included in the scope of the present disclosure.

The term (terms) used throughout the specification and claims has the ordinary meaning as commonly understood in each art, in the disclosure herein and in the specific disclosure herein, unless otherwise indicated.

As used herein, the terms "first," "second," …, etc. do not denote any order or importance, nor do they denote any order or importance, but rather are used to distinguish one element from another element or operation described in such technical terms.

Further, as used herein, the term "couple" or "connect" refers to two or more elements being in direct physical or electrical contact with each other, or in indirect physical or electrical contact with each other, or to the mutual operation or action of two or more elements.

Referring to fig. 1, one embodiment of the present disclosure relates to a current state determining circuit 100. The current state determining circuit 100 is used for determining a state of a current (e.g., the current I2 in fig. 3 or the current I3 in fig. 4) passing through a coil 10 of a motor (not shown), and includes a voltage measuring unit 102 and a processing unit 104.

As shown in fig. 1, a motor driving circuit 20 is coupled to the coil 10 to drive the motor. The motor driving circuit 20 includes a high-side transistor 22, a low-side transistor 24 and a controller 26, wherein the high-side transistor 22, the low-side transistor 24 and the motor coil 10 are commonly coupled to a node N. In the present embodiment, the motor is a three-phase motor. It will be appreciated that the motor includes three coils (one of which is the coil 10 shown in figure 1). However, for the sake of simplicity of explanation, the other two coils and the two motor drive circuits corresponding to these coils are omitted in fig. 1. Structurally, the voltage measuring unit 102 is coupled to the node N, and the processing unit 104 is coupled to the voltage measuring unit 102 and the controller 26.

Specifically, the controller 26 is configured to generate a first control signal CS1 and a second control signal CS 2. The high-side transistor 22 is selectively turned on or off according to the voltage level of the first control signal CS1, and the low-side transistor 24 is selectively turned on or off according to the voltage level of the second control signal CS 2. The high-side transistor 22 includes a first terminal for receiving a system high voltage Vcc, a second terminal coupled to the node N, a first control terminal for receiving a first control signal CS1, a cathode terminal of the first body diode 221 coupled to the first terminal, and an anode terminal of the first body diode 221 coupled to the second terminal (or node N), and a first body diode 221 parasitic between the first terminal and the second terminal. The low-side transistor 24 includes a third terminal coupled to the node N, a fourth terminal for receiving a system low voltage Vss, a second control terminal for receiving a second control signal CS2, a cathode terminal of the second body diode 241 coupled to the third terminal (or node N), and an anode terminal of the second body diode 241 coupled to the fourth terminal, and a second body diode 241 parasitic between the third terminal and the fourth terminal.

In the present embodiment, the high-side transistor 22 is a pmos and the low-side transistor 24 is an nmos, however, the disclosure is not limited thereto. In some embodiments, the high-side transistor 22 may be implemented as nmos and the low-side transistor 24 may be implemented as pmos. Alternatively, in some embodiments, the high-side transistor 22 and the low-side transistor 24 may be implemented as bipolar transistors.

For a better understanding of the present disclosure, the operation of the current status determining circuit 100 will be described in the following paragraphs with reference to the drawings.

Referring to fig. 2 to 5, fig. 2 to 5 illustrate states of transistors in the motor driving circuit 20 when the motor is driven. Specifically, the controller 26 controls the voltage level of the first control signal CS1 and the voltage level of the second control signal CS2 to alternately turn on the high-side transistor 22 (shown in fig. 5) and the low-side transistor 24 (shown in fig. 2) to drive the motor. It is understood that there will be a period of time (hereinafter referred to as Dead Zone) when the motor is driven when the high-side transistor 22 and the low-side transistor 24 are simultaneously in the off state (as shown in fig. 3 and 4).

The voltage measuring unit 102 is used for measuring the voltage VN of the node N when the motor is driven, and the processing unit 104 is used for determining the state of the current in the coil 10 according to the change of the voltage VN of the node N when the high-side transistor 22 and the low-side transistor 24 are in the off state at the same time.

Referring to fig. 6, a flow chart of a current state determination method 200 according to an embodiment of the disclosure is shown. The current state determination circuit 100 shown in fig. 1 may perform a current state determination method 200 to determine the state of the current in the coil 10. The current state determination method 200 includes steps S201 to S205.

It is assumed that before the step S201 is entered, the controller 26 generates the first control signal CS1 with a high voltage level and the second control signal CS2 with a high voltage level respectively to turn off the high-side transistor 22 and turn on the low-side transistor 24 (in the embodiment, the high-side transistor 22 is a pmos, and the low-side transistor 24 is an nmos). Thus, as shown in fig. 2, a current I1 flows from the coil 10, sequentially through the node N and the low-side transistor 24, and flows to the system low voltage Vss to drive the motor. When the high-side transistor 22 is in the off state and the low-side transistor 24 is in the on state, the voltage measuring unit 102 continuously measures the voltage VN of the node N (at this time, the voltage VN is substantially the system low voltage Vss), and the processing unit 104 determines that the motor driving circuit 20 does not enter the dead zone according to the first control signal CS1 of the high voltage level and the second control signal CS2 of the high voltage level generated by the controller 26, and does not perform the processing.

The controller 26 then changes the second control signal CS2 from the high voltage level to the low voltage level to switch the low-side transistor 24 from the on state to the off state, so that the high-side transistor 22 and the low-side transistor 24 are simultaneously in the off state (as shown in fig. 3 and 4). In this way, the voltage VN at the node N is converted from the system low voltage Vss to the system high voltage Vcc (as shown in fig. 7A and 7B). During the transition of the voltage VN at the node N, the current state determination circuit 100 will execute the current state determination method 200.

It will be appreciated that transient currents (current I2 as shown in fig. 3 or current I3 as shown in fig. 4) are still present at the instant the low-side transistor 24 switches from an on-state to an off-state (while the high-side transistor 22 remains off). With the low-side transistor 24 completely turned off, the transient current will flow in the forward direction through the first body diode 221 or in the forward direction through the second body diode 241, so that the voltage VN at the node N is changed. For example, if the current I2 shown in fig. 3 (flows out of the coil 10 and sequentially passes through the node N and the first body diode 221) exists when the high-side transistor 22 and the low-side transistor 24 are both kept off, the voltage VN at the node N is increased upward (because the current I2 flows forward through the first body diode 221, so that the voltage VN at the node N is increased from the system low voltage Vss to a voltage higher than the system high voltage Vcc). On the contrary, if the current I3 (sequentially passes through the second body diode 241 and the node N and flows into the coil 10) as shown in fig. 4, the voltage VN at the node N is decreased downward (because the current I3 flows through the second body diode 241 in the forward direction, the voltage VN at the node N is decreased from the system low voltage Vss to a voltage value lower than the system low voltage Vss).

Accordingly, in step S201, at a first time point t1 (shown in fig. 7A and 7B) when both the high-side transistor 22 and the low-side transistor 24 are switched to the off state, the voltage measurement unit 102 measures the voltage VN at the node N and outputs a first voltage VN1 (e.g., the system low voltage Vss) to the processing unit 104.

In step S202, at a second time point t2 (shown in fig. 7A and 7B) when both the high-side transistor 22 and the low-side transistor 24 are turned off, the voltage measuring unit 102 measures the voltage VN at the node N again and outputs a second voltage VN2 to the processing unit 104. In the embodiment, the second time point t2 is later than the first time point t 1.

In step S203, the processing unit 104 receives the first voltage value VN1 and the second voltage value VN2, and compares the first voltage value VN1 with the second voltage value VN2 to obtain a comparison result.

Next, the processing unit 104 determines the state of the current in the coil 10 according to the comparison result. Specifically, when the voltage VN at the node N increases upward, the processing unit 104 obtains a result that the second voltage VN2 is greater than the first voltage VN1 in step S203 (as shown in fig. 7A), and proceeds to step S204. In step S204, the processing unit 104 determines that the current I2 (shown in fig. 3) flows out of the coil 10, sequentially passes through the node N and the first body diode 221, and flows into the system high voltage Vcc according to the result that the second voltage VN2 is greater than the first voltage VN 1. On the contrary, when the voltage VN at the node N decreases downward, the processing unit 104 obtains the result that the second voltage VN2 is not greater than the first voltage VN1 in step S203 (as shown in fig. 7B), and proceeds to step S205. In step S205, the processing unit 104 determines that the current I3 (shown in fig. 4) flows out of the system low voltage Vss, sequentially passes through the second body diode 241 and the node N, and flows into the coil 10 according to the result that the second voltage VN2 is not greater than the first voltage VN 1.

The voltage curve higher than the system high voltage Vcc and the voltage curve lower than the system low voltage Vss shown in fig. 7A and fig. 7B are only shown for convenience of illustration and understanding, and actually, the present disclosure does not measure the voltage values higher than the system high voltage Vcc and lower than the system low voltage Vss. Therefore, during the period when the voltage VN at the node N is changed from the system low voltage Vss to the system high voltage Vcc (as shown in fig. 7A and 7B), the processing unit 104 may obtain the result that the second voltage value VN2 "is not greater than the" first voltage value VN1 "instead of obtaining the result that the second voltage value VN 2" is less than the "first voltage value VN 1" in step S203.

Referring to fig. 5, the controller 26 then changes the first control signal CS1 from the high voltage level to the low voltage level to switch the high-side transistor 22 from the off state to the on state. Thus, as shown in fig. 5, a current I4 flows from the system high voltage Vcc, sequentially through the high-side transistor 22 and the node N, and flows into the coil 10 to drive the motor. When the high-side transistor 22 is turned on and the low-side transistor 24 is turned off, the voltage measuring unit 102 continuously measures the voltage VN at the node N (at this time, the voltage VN is substantially the system high voltage Vcc), and the processing unit 104 determines that the motor driving circuit 20 does not enter the dead zone according to the low-voltage level first control signal CS1 and the low-voltage level second control signal CS2 generated by the controller 26, and does not perform the processing.

The controller 26 then changes the first control signal CS1 from the low voltage level to the high voltage level to switch the high-side transistor 22 from the on state to the off state, so that the high-side transistor 22 and the low-side transistor 24 are turned off at the same time (as shown in fig. 3 and 4). In this way, the voltage VN of the node N is transformed from the system high voltage Vcc to the system low voltage Vss (not shown). During the transition of the voltage VN at the node N, the current state determination circuit 100 will again execute the current state determination method 200. Similar to the above description, when the voltage VN of the node N increases, the processing unit 104 obtains the result that the second voltage VN2 is not less than the first voltage VN1 (e.g., the system high voltage Vcc) in step S203 (because the present disclosure does not actually measure a voltage higher than the system high voltage Vcc), and then proceeds to step S204. In step S204, the processing unit 104 determines that the current I2 (shown in fig. 3) flows out of the coil 10, sequentially passes through the node N and the first body diode 221, and flows into the system high voltage Vcc according to the result that the second voltage value VN2 is not less than the first voltage value VN 1. On the contrary, when the voltage VN at the node N decreases downward, the processing unit 104 obtains a result that the second voltage VN2 is smaller than the first voltage VN1 in step S203, and proceeds to step S205. In step S205, the processing unit 104 determines that the current I3 (shown in fig. 4) flows out of the system low voltage Vss, sequentially passes through the second body diode 241 and the node N, and flows into the coil 10 according to the result that the second voltage value VN2 is smaller than the first voltage value VN 1.

Referring to fig. 8, a flow chart of a current state determination method 300 according to another embodiment of the disclosure is shown. The current state determination circuit 100 shown in fig. 1 may perform a current state determination method 300 to determine the state of the current in the coil 10. The current state determination method 300 includes steps S301 to S305. The current state determination method 300 is similar to the aforementioned description of the current state determination method 200, and is not repeated herein.

In the period of time (as shown in fig. 9A and 9B) during which the voltage VN of the node N is changed from the system low voltage Vss to the system high voltage Vcc, if the motor driving circuit 20 has the current I2 shown in fig. 3 when entering the dead zone, the voltage VN of the node N will increase to a voltage value higher than the system high voltage Vcc within a predetermined time (as shown in fig. 9A). On the contrary, if the current I3 shown in fig. 4 exists when the motor driving circuit 20 enters the dead zone, the voltage VN representing the node N does not increase to a voltage value higher than the system high voltage Vcc within the predetermined time (as shown in fig. 9B). Accordingly, the current state determination circuit 100 performs the current state determination method 300.

In step S301, at a first time point t1 (as shown in fig. 9A and 9B) when both the high-side transistor 22 and the low-side transistor 24 are switched to the off state, the processing unit 104 starts timing, wherein the processing unit 104 may include a timer (not shown) or the processing unit 104 itself has a timing function.

In step S302, at a second time point t2 (as shown in fig. 9A and 9B) when the high-side transistor 22 and the low-side transistor 24 are still turned off, the voltage measuring unit 102 measures the voltage VN at the node N and outputs a voltage value Vpd.

In step S303, the processing unit compares the voltage value Vpd with a threshold Vth (as shown in fig. 9A and 9B) to obtain a comparison result. Next, the processing unit 104 determines the state of the current in the coil 10 according to the comparison result. In the present embodiment, the threshold Vth is between the system high voltage Vcc and the system low voltage Vss.

Specifically, when the voltage VN at the node N increases to the voltage value higher than the system high voltage Vcc within the predetermined time, the processing unit 104 obtains the result that the voltage value Vpd is greater than the threshold value Vth in step S303 (as shown in fig. 9A), and proceeds to step S304. In step S304, the processing unit 104 determines that the current I2 (shown in fig. 3) flows out of the coil 10, sequentially passes through the node N and the first body diode 221, and flows into the system high voltage Vcc according to the result that the voltage value Vpd is greater than the threshold Vth. On the contrary, when the voltage VN at the node N does not increase to the voltage value higher than the system high voltage Vcc within the predetermined time, the processing unit 104 obtains the result that the voltage value Vpd is smaller than the threshold Vth in step S303 (as shown in fig. 9B), and proceeds to step S305. In step S305, the processing unit 104 determines that the current I3 (shown in fig. 4) flows out of the system low voltage Vss, sequentially passes through the second body diode 241 and the node N, and flows into the coil 10 according to the result that the voltage value Vpd is smaller than the threshold value Vth.

The voltage curve higher than the system high voltage Vcc and the voltage curve lower than the system low voltage Vss shown in fig. 9A and 9B are only shown for convenience of illustration and understanding, and actually, the present disclosure does not measure the voltage values higher than the system high voltage Vcc and lower than the system low voltage Vss.

In addition, in the period (not shown) during which the voltage VN of the node N is converted from the system high voltage Vcc to the system low voltage Vss, if the motor driving circuit 20 has the current I2 shown in fig. 3 when entering the dead zone, the voltage VN of the node N does not decrease downward to a voltage value (not shown) lower than the system low voltage Vss within the predetermined time. Accordingly, the processing unit 104 obtains the result that the voltage value Vpd is greater than the threshold Vth in step S303, and proceeds to step S304. On the contrary, if the current I3 shown in fig. 4 exists when the motor driving circuit 20 enters the dead zone, the voltage VN representing the node N decreases to a voltage value (not shown) lower than the system low voltage Vss within the predetermined time. Accordingly, the processing unit 104 obtains the result that the voltage value Vpd is smaller than the threshold Vth in step S303, and proceeds to step S305.

The current state determination circuit 100 of the present disclosure can determine the state of the current in the coil 10 in the dead zone according to the variation of the voltage VN at the node N. Since the voltage values higher than the system high voltage Vcc or lower than the system low voltage Vss are not required to be measured, the current state determining circuit 100 may determine the state of the current in the coil 10 without adding an auxiliary circuit when the voltage VN of the node N is between the system high voltage Vcc and the system low voltage Vss. In addition, the phase information of the current acquired by the current state judging circuit 100 is helpful for adjusting the phase relation between the current and the back electromotive force of the motor, so that the motor can be operated at the optimal rotating speed value.

Although the present disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the disclosure, and therefore, the scope of the disclosure should be determined by that defined in the appended claims.

Claims (10)

1. A current state determining method for determining a state of a current flowing through a coil of a motor, comprising:

measuring the voltage of a node at which a high-side transistor and a low-side transistor are commonly coupled with the coil at a first time point when the high-side transistor and the low-side transistor are switched to an off state, and outputting a first voltage value;

measuring the voltage of the node at a second time point when the high-side transistor and the low-side transistor are both kept in an off state, and outputting a second voltage value;

comparing the first voltage value with the second voltage value to obtain a comparison result; and

and judging the state of the current according to the comparison result.

2. The method of claim 1, wherein determining the current status according to the comparison comprises:

when the second voltage value is larger than the first voltage value, judging that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor;

when the second voltage value is not larger than the first voltage value, the current is judged to pass through a second body diode of the low-side transistor and the node in sequence and flow into the coil.

3. The method of claim 1, wherein determining the current status according to the comparison comprises:

when the second voltage value is not less than the first voltage value, judging that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor;

when the second voltage value is smaller than the first voltage value, the current is judged to sequentially pass through a second body diode of the low-side transistor and the node and flow into the coil.

4. A current state determining method for determining a state of a current flowing through a coil of a motor, comprising:

starting timing at a first time point when a high-side transistor and a low-side transistor are switched to an off state;

measuring the voltage of a node at which the high-side transistor, the low-side transistor and the coil are commonly coupled at a second time point when the high-side transistor and the low-side transistor are kept in an off state, and outputting a voltage value;

comparing the voltage value with a threshold value to obtain a comparison result; and

and judging the state of the current according to the comparison result.

5. The method of claim 4, wherein determining the current status according to the comparison comprises:

when the voltage value is larger than the threshold value, judging that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor;

when the voltage value is smaller than the threshold value, the current is judged to sequentially pass through a second body diode of the low-side transistor and the node and flow into the coil.

6. A current status determining circuit for determining a status of a current flowing through a coil of a motor, comprising:

a voltage measuring unit coupled to a node for measuring a voltage of the node, wherein a high-side transistor, a low-side transistor and the coil are coupled to the node; and

and the processing unit is coupled with the voltage measuring unit and used for judging the current state when the high-side transistor and the low-side transistor are in an off state simultaneously according to the voltage change of the node.

7. The current state determination circuit of claim 6, wherein the voltage measurement unit outputs a first voltage value at a first time point when both the high-side transistor and the low-side transistor are switched to the off state;

the voltage measuring unit outputs a second voltage value at a second time point when the high-side transistor and the low-side transistor are both kept in an off state;

the processing unit compares the first voltage value with the second voltage value to obtain a comparison result, and judges the state of the current according to the comparison result.

8. The circuit of claim 7, wherein when the second voltage value is greater than the first voltage value, the processing unit determines that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor;

when the second voltage value is not greater than the first voltage value, the processing unit determines that the current passes through a second body diode of the low-side transistor and the node in sequence and flows into the coil.

9. The circuit of claim 6, wherein when the second voltage value is not less than the first voltage value, the processing unit determines that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor;

when the second voltage value is smaller than the first voltage value, the processing unit judges that the current sequentially passes through a second body diode of the low-side transistor and the node and flows into the coil.

10. The circuit of claim 9, wherein the processing unit starts timing at a first time point when the high-side transistor and the low-side transistor are both switched to the off state;

at a second time point when the high-side transistor and the low-side transistor are both kept in an off state, the voltage measuring unit outputs a voltage value, and the processing unit compares the voltage value with a threshold value;

when the voltage value is larger than the threshold value, the processing unit judges that the current flows out of the coil and sequentially passes through the node and a first body diode of the high-side transistor;

when the voltage value is smaller than the threshold value, the processing unit judges that the current sequentially passes through a second body diode of the low-side transistor and the node and flows into the coil.

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