Method for suppressing starting overvoltage and overcurrent of wireless power supply direct-driven direct current motor

Abstract

The invention discloses a method for suppressing the starting overvoltage and overcurrent of a wireless power supply direct-drive direct-current motor, and the method comprises a system for suppressing the starting overvoltage and overcurrent of the wireless power supply direct-drive direct-current motor. The system comprises a direct-current power supply, a high-frequency inverter, a transmitting coil module, a receiving coil module, a rectifying and filtering module, a voltage and current reduction module I, a voltage and current reduction module II, a voltage and current reduction module III, a motor load module, a current detection circuit module, a current comparison module and a timer module. According to the method, when mutual inductance is stable, current reference values of the step-down and current-reducing module I and the step-down and current-reducing module II are adjusted according to the change of the on-load condition of the direct-current motor to achieve effective suppression of overvoltage and overcurrent during starting, the implementation steps are simple, no complex hardware circuit is needed, the influence on the energy transmission efficiency of a wireless power supply system is small, and the method is suitable for popularization and application. And the direct current motor is not greatly damaged.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless power transmission, and specifically refers to a method for suppressing overvoltage and overcurrent at the start-up of a wirelessly powered direct-drive DC motor. Background Art

[0002] Wireless power technology uses spatial media, such as electric and magnetic fields, microwaves, and radiation, to transmit electrical energy from a power source to a device. Compared to traditional charging methods, wireless power technology offers advantages such as safety, reliability, and flexibility, making it particularly suitable for use in harsh electrical environments, such as coal mines and underwater environments. Furthermore, wireless power technology has widespread applications in consumer electronics, smart homes, industrial manufacturing, and healthcare.

[0003] The main difference between wireless power supply technology and wireless charging technology is that the load of wireless power supply technology is directly a motor or some devices that convert electrical energy into non-chemical energy, while the load end of wireless charging technology is often an energy storage device such as a battery, which then discharges through the energy storage device to power the load device.

[0004] During the starting process of a DC motor driven by a wireless power supply system, excessive starting voltage, excessive starting current, and excessive operating power often occur, which will destroy the circuit structure of the wireless power supply system and cause great harm to the DC motor. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for suppressing overvoltage and overcurrent during the startup of a wireless power supply direct-drive DC motor. The method can effectively suppress the overvoltage and overcurrent phenomena that occur during the startup of a DC motor driven by a wireless power supply system, and has little impact on the energy transmission efficiency of the wireless power supply system, and will not cause significant harm to the DC motor.

[0006] To achieve the above-mentioned object, the present invention provides a method for suppressing overvoltage and overcurrent at the startup of a wireless power supply direct-drive DC motor, including a system for suppressing overvoltage and overcurrent at the startup of a wireless power supply direct-drive DC motor, the system including a DC power supply, a high-frequency inverter, a transmitting coil module, a receiving coil module, a rectifier and filter module, a voltage reduction and current reduction module I, a voltage reduction and current reduction module II, a voltage reduction and current reduction module III, a motor load module, a current detection circuit module, a current comparison module, and a timer module, wherein: the DC power supply is connected to the input end of the high-frequency inverter, and the output end of the high-frequency inverter is connected to the input end of the transmitting coil module The output end of the transmitting coil module is arranged opposite to the input end of the receiving coil module, the output end of the receiving coil module is connected to the input end of the rectifier and filter module, the output end of the rectifier and filter module is sequentially connected to the voltage reduction and current reduction module I, the voltage reduction and current reduction module II, the voltage reduction and current reduction module III, and the motor load module. The voltage reduction and current reduction module I, the voltage reduction and current reduction module II, the voltage reduction and current reduction module III, and the motor load module are connected together in series. The current detection module is used to collect the instantaneous current of the motor load module and transmit the collected signal to the current comparison module for signal processing;

[0007] The voltage and current reduction module I includes a resistor R1, a capacitor C1, a switch tube S CR1 , resistor R1, capacitor C1, switch tube S CR1 Parallel connection; Buck and current reduction module II includes resistor R2, capacitor C2, switch tube S CR2 , resistor R2, capacitor C2, switch tube S CR2 Parallel connection; step-down and current reduction module III includes resistor R3, switch tube S R3 , resistor R3, switch tube S R3 Parallel connection;

[0008] The current comparison module includes current comparator I and current comparator II. The signal output by current comparator I is used to control the operation of buck-current reduction module I, and the signal output by current comparator II is used to control the operation of buck-current reduction module II. The timer is used to control the operation of buck-current reduction module III.

[0009] As a further solution of the present invention: an equivalent circuit is constructed to suppress overvoltage and overcurrent at the start of the wireless power supply direct drive DC motor, and a voltage reduction and current reduction module I, a voltage reduction and current reduction module II, and a voltage reduction and current reduction module III are connected in series at both ends of the motor load module; the voltage reduction and current reduction module I is composed of a switch tube S CR1 Control whether the resistor R1 and capacitor C1 are connected to the circuit, and the voltage and current reduction module II is composed of the switch tube S CR2 Control whether the resistor R2 and capacitor C2 are connected to the circuit, and the voltage and current reduction module III is composed of the switch tube S R3 Control resistor R3 to connect to the circuit; when switch S CR1When the switch is on, the resistor R1 and the capacitor C1 are short-circuited and not connected to the circuit. CR1 When the switch is not conducting, the resistor R1 and the capacitor C1 are connected to the circuit; when the switch S CR2 When the switch is on, the resistor R2 and the capacitor C2 are short-circuited and not connected to the circuit. CR2 When the switch is not conducting, the resistor R2 and the capacitor C2 are connected to the circuit; when the switch S R3 When the switch is on, the resistor R3 is short-circuited and not connected to the circuit. R3 When not conducting, resistor R3 is connected to the circuit; resistor R1, resistor R2, capacitor C1, and capacitor C2 satisfy the following conditions: R1C1≥1 / f1, R2C2≥1 / f2, where f1 and f2 are the switching transistors S, CR1 and switch tube S CR2 Maximum permissible operating frequency.

[0010] As a further solution of the present invention: the high-frequency inverter adopts a single-phase full-bridge inverter circuit, the output frequency of the high-frequency inverter is fixed, the output voltage is a square wave, and the output voltage satisfies the formula: U ab Represents the output voltage of the high-frequency inverter, V DC Indicates the voltage of the DC power supply.

[0011] As a further solution of the present invention: the compensation circuit of the transmitting coil module and the receiving coil module adopts an LCC-S type compensation circuit, the transmitting coil module adopts an LCC type coupling mode, and the transmitting coil module includes a primary measuring compensation coil inductance L r , primary side compensation capacitor C r , primary side coil inductance L p , primary side parallel compensation capacitor C p , first measure the compensation coil inductance L r The output end is divided into two paths, one of which is connected in series with the primary side parallel compensation capacitor C p , primary side coil inductance L p Then it is connected to the output of the high-frequency inverter, and the other one is connected in series with the primary side compensation capacitor C r Then connected to the output of the high-frequency inverter, and meet the following requirements: where ω T is the natural resonant frequency of the transmitting coil module;

[0012] The receiving coil module adopts an S-type coupling mode, and the receiving coil module includes a secondary side coil inductor L connected in series. S and secondary side compensation capacitor C S and the parasitic resistance R of the receiving coil s , and satisfy: Among them, ω SIndicates the natural resonant frequency of the receiving coil module.

[0013] As a further solution of the present invention: the current detection circuit detects the current at both ends of the motor load module and transmits the current signal to the current comparison module. When the current is greater than the threshold current set by the current comparator I, the current comparator I outputs a 0 signal, which turns the switch S CR1 The voltage and current reduction module I starts to work. When the current is less than the threshold current set by the current comparator I, the current comparator I outputs a signal of 1, which turns on the switch S. CR1 Short circuit, the step-down and current reduction module I stops working; when the current is greater than the threshold current set by the current comparator II, the current comparator II outputs a 0 signal, making the switch tube S CR2 The voltage and current reduction module II starts to work. When the current is less than the threshold current set by the current comparator II, the current comparator II outputs a signal of 1, which makes the switch S CR2 Short circuit, the voltage and current reduction module II stops working;

[0014] Switching tube S R3 Controlled by the timer module, when the start signal is detected, the timer module starts working. When the working time is less than the time set by the timer module, the timer module outputs a 0 signal and the voltage and current reduction module III starts working. When the working time is greater than or equal to the time set by the timer module, the voltage and current reduction module III stops working.

[0015] As a further solution of the present invention: the time reference value in the timer module is generally not more than 0.2s; the resistance values of the resistors R1, R2 and R3 in the step-down and current reducing module I, the step-down and current reducing module II and the step-down and current reducing module III are generally R a The current comparison reference threshold of the current comparator I in the current comparison module is usually The current comparison reference threshold of current comparator II is usually About, where U a is the equivalent output voltage of the rectifier and filter module, R a is the resistance of the armature winding, C e is the potential constant, n is the motor speed, is the stator flux.

[0016] As a further solution of the present invention: the driving angular frequency ω of the system d , the natural resonant frequency of the transmitting coil module ω T , the natural resonant frequency of the receiving coil module ω S Satisfy the formula: ω d =ω T =ω S .

[0017] As a further solution of the present invention: comprising the following steps:

[0018] Step 1: Set the parameters of the circuit components in the system voltage reduction and current reduction module I, voltage reduction and current reduction module II, and voltage reduction and current reduction module III according to the motor parameters and load conditions;

[0019] Step 2: setting the current comparison reference values of the current comparator I and the current comparator II in the current comparison module, and setting the time reference value in the timer module;

[0020] Step 3: After the system is started, the timer module starts timing, the current detection circuit module starts detecting the instantaneous current of the motor load module, and transmits the detected current signal to the current comparison module;

[0021] Step 4: Compare the timing signal of the timer module with the set time. When the working time is less than the time set by the timer module, the timer module outputs a 0 signal and the switch S R3 Disconnect, otherwise, the timer module outputs a 1 signal, the switch tube S R3 conduction;

[0022] Step 5: Compare the detected current signal with the threshold values set by current comparator I and current comparator II. When the current value is less than the threshold value set by current comparator I, current comparator I outputs a 1 signal, and the corresponding controlled switch tube is turned on. Otherwise, current comparator I outputs a 0 signal, and the corresponding controlled switch tube is turned off. Similarly, when the current value is less than the threshold value set by current comparator II, current comparator II outputs a 1 signal, and the corresponding controlled switch tube is turned on. Otherwise, current comparator II outputs a 0 signal, and the corresponding controlled switch tube is turned off.

[0023] Step 6: When all the switch tubes are turned on and can maintain the on state, the startup is completed when the voltage and current at both ends of the DC motor are stable.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] A method for suppressing overvoltage and overcurrent at startup of a direct-drive DC motor designed by the present invention adjusts the current reference values of the voltage-reduction and current-reduction module I and the voltage-reduction and current-reduction module II according to changes in the load condition of the DC motor when the mutual inductance is relatively stable, thereby effectively suppressing overvoltage and overcurrent at startup. The implementation steps are simple, no complex hardware circuits are required, and the energy transmission efficiency of the wireless power supply system is slightly affected, and no significant harm is caused to the DC motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the system for suppressing overvoltage and overcurrent at startup of a wireless powered direct-drive DC motor according to the present invention.

[0027] Figure 2 The present invention is a flow chart of a method for suppressing overvoltage and overcurrent at the start-up of a wireless powered direct-drive DC motor.

[0028] Figure 3 This is a current comparison diagram of the starting method in the method of the present invention and the direct starting method.

[0029] Figure 4 This is a voltage comparison diagram of the starting method in the method of the present invention and the direct starting method.

[0030] Figure 5 This is a power comparison diagram between the starting method in the method of the present invention and the direct starting method.

[0031] In the figure: 1. DC power supply, 2. high-frequency inverter, 3. transmitting coil module, 4. receiving coil module, 5. rectifier and filter module, 6. buck-current reduction module I, 7. buck-current reduction module II, 8. buck-current reduction module III, 9. motor load module, 10. current detection circuit module, 11. current comparison module, 12. timer module. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings.

[0033] A method for suppressing overvoltage and overcurrent at the start of a wireless powered direct-drive DC motor, such as Figure 1 As shown, a system for suppressing overvoltage and overcurrent at the start of a wireless power supply direct-drive DC motor is provided. The system includes a DC power supply 1, a high-frequency inverter 2, a transmitting coil module 3, a receiving coil module 4, a rectifier and filter module 5, a voltage reduction and current reduction module I6, a voltage reduction and current reduction module II7, a voltage reduction and current reduction module III8, a motor load module 9, a current detection circuit module 10, a current comparison module 11, and a timer module 12. The DC power supply 1 is connected to the input end of the high-frequency inverter 2, the output end of the high-frequency inverter 2 is connected to the input end of the transmitting coil module 3, and the output end of the transmitting coil module 3 is connected to the receiving coil. The input ends of the coil module 4 are relatively arranged, the output end of the receiving coil module 4 is connected to the input end of the rectifier and filter module 5, and the output end of the rectifier and filter module 5 is connected to the voltage reduction and current reduction module I6, the voltage reduction and current reduction module II7, the voltage reduction and current reduction module III8, and the motor load module 9 in sequence. The voltage reduction and current reduction module I6, the voltage reduction and current reduction module II7, the voltage reduction and current reduction module III8, and the motor load module 9 are connected together in series. The current detection module 10 is used to collect the instantaneous current of the motor load module 9 and transmit the collected signal to the current comparison module 11 for signal processing.

[0034] The voltage and current reduction module I6 includes a resistor R1, a capacitor C1, and a switch tube S CR1 , resistor R1, capacitor C1, switch tube S CR1Parallel connection; step-down and current reduction module II7 includes resistor R2, capacitor C2, switch tube S CR2 , resistor R2, capacitor C2, switch tube S CR2 Parallel connection; step-down and current reduction module III8 includes resistor R3, switch tube S R3 , resistor R3, switch tube S R3 Parallel connection;

[0035] The current comparison module 11 includes a current comparator I and a current comparator II. The signal output by the current comparator I is used to control the operation of the voltage reduction and current reduction module I6, and the signal output by the current comparator II is used to control the operation of the voltage reduction and current reduction module II7; the timer 12 is used to control the operation of the voltage reduction and current reduction module III8.

[0036] Build an equivalent circuit to suppress overvoltage and overcurrent at the start of wireless power supply direct drive DC motor, and connect voltage reduction and current reduction module I6, voltage reduction and current reduction module II7, and voltage reduction and current reduction module III8 in series at both ends of motor load module 9; voltage reduction and current reduction module I6 is composed of switch tube S CR1 Control whether the resistor R1 and capacitor C1 are connected to the circuit, and the voltage and current reduction module II7 is composed of the switch tube S CR2 Control whether the resistor R2 and capacitor C2 are connected to the circuit, and the voltage and current reduction module III8 is composed of the switch tube S R3 Control resistor R3 to connect to the circuit; when switch S CR1 When the switch is on, the resistor R1 and the capacitor C1 are short-circuited and not connected to the circuit. CR1 When the switch is not conducting, the resistor R1 and the capacitor C1 are connected to the circuit; when the switch S CR2 When the switch is on, the resistor R2 and the capacitor C2 are short-circuited and not connected to the circuit. CR2 When the switch is not conducting, the resistor R2 and the capacitor C2 are connected to the circuit; when the switch S R3 When the switch is on, the resistor R3 is short-circuited and not connected to the circuit. R3 When not conducting, resistor R3 is connected to the circuit.

[0037] The resistors R1, R2, and R3 are used to increase the equivalent resistance of the load end, reduce the current when the DC motor starts, and divide the voltage to reduce the damage caused by the excessive voltage at both ends of the DC motor when the DC motor starts. The capacitors C1 and C2 are used to reduce the voltage generated by the switch tube S. CR1 and S CR2 The voltage and current caused by the state change will fluctuate greatly. At the same time, the resistor R1, resistor R2, capacitor C1, and capacitor C2 should meet the following requirements: R1C1≥1 / f1, R2C2≥1 / f2, where f1 and f2 are the switching transistor S CR1 and switch tube S CR2 Maximum permissible operating frequency.

[0038] The high-frequency inverter 2 adopts a single-phase full-bridge inverter circuit. In the implementation process of the present invention, the output frequency of the high-frequency inverter 2 is fixed, the output voltage is a square wave, and the output voltage satisfies the formula: U ab Represents the output voltage of the high-frequency inverter, V DC Indicates the voltage of DC power supply 1.

[0039] The compensation circuit of the transmitting coil module 3 and the receiving coil module 4 adopts the LCC-S type compensation circuit. The transmitting coil module 3 adopts the LCC type coupling mode. The transmitting coil module 3 includes a primary compensation coil inductance L r , primary side compensation capacitor C r , primary side coil inductance L p , primary side parallel compensation capacitor C p , first measure the compensation coil inductance L r The output end is divided into two paths, one of which is connected in series with the primary side parallel compensation capacitor C p , primary side coil inductance L p Then it is connected to the output end of high frequency inverter 2, and the other one is connected in series with the primary side compensation capacitor C r Then connected to the output end of high frequency inverter 2, and meet the following requirements: where ω T is the natural resonant frequency of the transmitting coil module.

[0040] The receiving coil module 4 adopts an S-type coupling mode, and the receiving coil module 4 includes a secondary side coil inductor L connected in series. S and secondary side compensation capacitor C S and the parasitic resistance R of the receiving coil s , and satisfy: Among them, ω S Indicates the natural resonant frequency of the receiving coil module.

[0041] The current detection circuit 10 detects the current at both ends of the motor load module 9 and transmits the current signal to the current comparison module 11. When the current is greater than the threshold current set by the current comparator I, the current comparator I outputs a signal of 0, which turns the switch S CR1 The voltage and current reduction module I6 starts to work. When the current is less than the threshold current set by the current comparator I, the current comparator I outputs a signal of 1, which makes the switch S CR1 Short circuit, the step-down and current reduction module I6 stops working; when the current is greater than the threshold current set by the current comparator II, the current comparator II outputs a 0 signal, making the switch tube S CR2 The voltage and current reduction module II7 starts to work. When the current is less than the threshold current set by the current comparator II, the current comparator II outputs a signal of 1, which makes the switch SCR2 Short circuit, the voltage and current reduction module II7 stops working.

[0042] Switching tube S R3 Controlled by the timer module 12, when the start signal is detected, the timer module 12 starts working. When the working time is less than the time set by the timer module 12, the timer module 12 outputs a 0 signal, and the voltage reduction and current reduction module III8 works. When the working time is greater than or equal to the time set by the timer module 12, the voltage reduction and current reduction module III8 stops working.

[0043] The time reference value in the timer module 12 is generally not more than 0.2s; the resistance values of the resistors R1, R2, and R3 in the step-down and current reducing module I6, the step-down and current reducing module II7, and the step-down and current reducing module III8 are generally R a The current comparison reference threshold of the current comparator I in the current comparison module 11 is usually The current comparison reference threshold of current comparator II is usually About, where U a is the equivalent output voltage of the rectifier filter module 5, R a is the resistance of the armature winding, C e is the potential constant, n is the motor speed, is the stator flux.

[0044] The driving angular frequency ω of the system d , the natural resonant frequency of the transmitting coil module ω T , the natural resonant frequency of the receiving coil module ω S Satisfy the formula: ω d =ω T =ω S .

[0045] A method for suppressing overvoltage and overcurrent at the start of a wireless powered direct-drive DC motor, such as Figure 2 As shown, the following steps are included:

[0046] Step 1: Set the parameters of the circuit components in the system voltage reduction and current reduction module I6, voltage reduction and current reduction module II7, and voltage reduction and current reduction module III8 according to the motor parameters and load conditions;

[0047] Step 2: setting the current comparison reference values of the current comparator I and the current comparator II in the current comparison module 11, and setting the time reference value in the timer module 12;

[0048] Step 3: After the system is started, the timer module 12 starts timing, the current detection circuit module 10 starts detecting the instantaneous current of the motor load module 9, and transmits the detected current signal to the current comparison module 11;

[0049] Step 4: Compare the timing signal of the timer module 12 with the set time. When the working time is less than the time set by the timer module 12, the timer module 12 outputs a 0 signal, and the switch S R3 Disconnect, otherwise, the timer module 12 outputs a 1 signal, the switch tube S R3 conduction;

[0050] Step 5: Compare the detected current signal with the threshold value set by the current comparator. When the current value is less than the threshold value set by the current comparator, the current comparator outputs a 1 signal, and the corresponding controlled switch is turned on; otherwise, the timer module 12 outputs a 0 signal, and the corresponding controlled switch is turned off.

[0051] Step 6: When all the switch tubes are turned on and can maintain the on state, the startup is completed when the voltage and current at both ends of the DC motor are stable.

[0052] The following is a specific example of the present invention.

[0053] like Figure 1 The schematic diagram of the structure of the system for suppressing overvoltage and overcurrent at the start of wireless power supply direct drive DC motor is shown in the figure. The DC input voltage of the system is 100V, the operating frequency of the system is 85kHz, and the compensation coil L is measured once. r , primary side coil inductance L p , secondary side coil inductance L S All are wound with Litz wire, and the compensation coil L is measured once. r The inductance value is 11.98μH, and the primary side coil inductance L p , secondary side coil inductance L S The self-inductance value is 30μH, and the mutual inductance coefficient of the primary and secondary coils is M ps The primary side compensation capacitor C is 14μH. r The capacitance value is 292.62nF, and the primary side parallel compensation capacitor C p The capacitance value is 194.57nF, the secondary side compensation capacitor C S The capacitance value is 116.86nF. Under high frequency conditions, the resistance of the primary coil R p The resistance of the secondary coil is 0.2Ω. s The resistance is 0.2Ω, the filter capacitor C3 value is 100μF, the motor is a permanent magnet synchronous motor, and the load torque is 750N·m.

[0054] A method for suppressing overvoltage and overcurrent at the start-up of a wireless powered direct-drive DC motor comprises the following steps:

[0055] a. Set the capacitor and resistor parameters in the buck-current module I, buck-current module II, and buck-current module III. The resistance values of resistors R1, R2, and R3 are all 1.5Ω, and the capacitance values of capacitors C1 and C2 are both 470μF.

[0056] b. Set the switching time reference value of the timer module to 0.1s, set the current comparison reference value of current comparator 1 in the current comparison module to 35A, and set the current comparison reference value of current comparator 2 to 25A.

[0057] c. After the system is started, the timer module 12 starts timing, the current detection circuit module 10 starts detecting the instantaneous current of the DC motor module 9, and transmits the detected current signal to the current comparison module 11;

[0058] d. Compare the timing signal of the timer module 12 with the set time. When the working time is less than the time set by the timer module 12, the timer module 12 outputs a 0 signal, and the switch S R3 Disconnect, otherwise, the timer module 12 outputs a 1 signal, the switch tube S R3 conduction;

[0059] e. Compare the detected current signal with the thresholds set by current comparator I and current comparator II. When the current value is less than the threshold set by current comparator I, current comparator I outputs a 1 signal, and the corresponding controlled switch tube is turned on. Otherwise, current comparator I outputs a 0 signal, and the corresponding controlled switch tube is turned off. Similarly, when the current value is less than the threshold set by current comparator II, current comparator II outputs a 1 signal, and the corresponding controlled switch tube is turned on. Otherwise, current comparator II outputs a 0 signal, and the corresponding controlled switch tube is turned off.

[0060] f. When all the switch tubes are turned on and can maintain the on state, the startup is completed after the voltage and current at both ends of the DC motor are stable.

[0061] The working process of this case is that after the motor starts, when the working time is less than the time set by the timer module 12, 0.1s, the resistor R3 is connected to the circuit. At this time, the current in the circuit is greater than the switch tube S CR2 The comparative value current of the conduction is connected to the circuit and the capacitor C2 is charged. As the start time increases, when the working time is greater than the time set by the timer module 12, the switch tube S R3 The resistor R3 is short-circuited. At this time, since the voltage across capacitors C1 and C2 cannot change suddenly, and the resistor R3 is short-circuited, a large surge current will be generated in the circuit, and its value is greater than the comparison value of the current comparator I, causing the switch tube S to CR1Disconnected, resistor R1 is connected to the circuit, and capacitor C1 begins to charge. Simultaneously, due to the presence of the high-frequency switching tubes and current comparator, the loop current stabilizes near the comparison value of 35A on current comparator I. Similarly, when the loop current drops to the comparison value of 25A on current comparator II, the loop current also stabilizes near 25A, thereby reducing the starting current. Once all the switching tubes are turned on and remain on, the DC motor startup is complete once the voltage and current across the motor stabilize.

[0062] Depend on Figure 3 It can be seen that the starting current of this starting method is about 3 to 4 times the steady working current, which is much smaller than 10 to 12 times of direct starting. Figure 4 It can be seen that there is no overvoltage phenomenon when the motor starts. When the motor runs smoothly, the voltage drop caused by the switch tube is about 5V, which is within the acceptable range. Figure 5 It can be seen that when this starting method is used, there is no excessive power phenomenon at the starting moment similar to that produced by direct starting. At the same time, during stable operation, the efficiency of this starting method is only 2% lower than that of direct starting.

[0063] The method of the present invention has a strong inhibitory effect on the voltage and current at both ends of the DC motor when the motor starts, and after stable operation, the connected voltage and current reduction module has a small impact on the overall transmission efficiency and output power of the system. Therefore, this method does not require the addition of additional complex topology circuits, and at the same time effectively suppresses the phenomenon of overvoltage and overcurrent when the DC motor starts.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for suppressing overvoltage and overcurrent during startup of a wireless powered direct-drive DC motor, characterized in that: The invention relates to a system for suppressing overvoltage and overcurrent at the start of a wireless power supply direct drive DC motor. The system comprises a DC power supply (1), a high frequency inverter (2), a transmitting coil module (3), a receiving coil module (4), a rectifier filter module (5), a voltage reduction and current reduction module I (6), a voltage reduction and current reduction module II (7), a voltage reduction and current reduction module III (8), a motor load module (9), a current detection circuit module (10), a current comparison module (11), and a timer module (12). The DC power supply (1) is connected to the input end of the high frequency inverter (2), the output end of the high frequency inverter (2) is connected to the input end of the transmitting coil module (3), and the output end of the transmitting coil module (3) is connected to the receiving coil module (4). The input ends of the coil module (4) are arranged relative to each other, the output end of the receiving coil module (4) is connected to the input end of the rectifier filter module (5), the output end of the rectifier filter module (5) is sequentially connected to the voltage reduction and current reduction module I (6), the voltage reduction and current reduction module II (7), the voltage reduction and current reduction module III (8), and the motor load module (9), the voltage reduction and current reduction module I (6), the voltage reduction and current reduction module II (7), the voltage reduction and current reduction module III (8), and the motor load module (9) are connected together in series, and the current detection module (10) is used to collect the instantaneous current of the motor load module (9), and transmit the collected signal to the current comparison module (11) to process the signal; The voltage and current reduction module I (6) includes a resistor R1, a capacitor C1, a switch tube S CR1 , resistor R1, capacitor C1, switch tube S CR1 Parallel connection; Buck and current reduction module II (7) includes resistor R2, capacitor C2, switch tube S CR2 , resistor R2, capacitor C2, switch tube S CR2 Parallel connection; step-down and current reduction module III (8) includes resistor R3, switch tube S R3 , resistor R3, switch tube S R3 Parallel connection; The current comparison module (11) comprises a current comparator I and a current comparator II. The signal output by the current comparator I is used to control the operation of the voltage reduction and current reduction module I (6), and the signal output by the current comparator II is used to control the operation of the voltage reduction and current reduction module II (7). The timer (12) is used to control the operation of the voltage reduction and current reduction module III (8).

2. The method for suppressing overvoltage and overcurrent at startup of a wireless powered direct-drive DC motor according to claim 1, characterized in that: An equivalent circuit for suppressing overvoltage and overcurrent at the start of a wireless powered direct-drive DC motor is constructed, wherein a voltage reduction and current reduction module I (6), a voltage reduction and current reduction module II (7), and a voltage reduction and current reduction module III (8) are connected in series at both ends of a motor load module (9); the voltage reduction and current reduction module I (6) is composed of a switch tube S CR1 Control whether the resistor R1 and capacitor C1 are connected to the circuit, and the voltage and current reduction module II (7) is composed of the switch tube S CR2 Control whether the resistor R2 and capacitor C2 are connected to the circuit, and the voltage and current reduction module III (8) is composed of the switch tube S R3 Control resistor R3 to connect to the circuit; when switch S CR1 When the switch is on, the resistor R1 and the capacitor C1 are short-circuited and not connected to the circuit. CR1 When the switch is not conducting, the resistor R1 and the capacitor C1 are connected to the circuit; when the switch S CR2 When the switch is on, the resistor R2 and the capacitor C2 are short-circuited and not connected to the circuit. CR2 When the switch is not conducting, the resistor R2 and the capacitor C2 are connected to the circuit; when the switch S R3 When the switch is on, the resistor R3 is short-circuited and not connected to the circuit. R3 When not conducting, resistor R3 is connected to the circuit; resistor R1, resistor R2, capacitor C1, and capacitor C2 satisfy the following conditions: R1C1≥1 / f1, R2C2≥1 / f2, where f1 and f2 are the switching transistors S, CR1 and switch tube S CR2 Maximum permissible operating frequency.

3. The method for suppressing overvoltage and overcurrent at startup of a wireless powered direct-drive DC motor according to claim 1, characterized in that: The high-frequency inverter (2) adopts a single-phase full-bridge inverter circuit. The output frequency of the high-frequency inverter (2) is fixed and the output voltage is a square wave. The output voltage satisfies the formula: U ab Represents the output voltage of the high-frequency inverter, V DC Indicates the voltage of the DC power supply (1).

4. The method for suppressing overvoltage and overcurrent at startup of a wireless powered direct-drive DC motor according to claim 1, characterized in that: The compensation circuits of the transmitting coil module (3) and the receiving coil module (4) adopt an LCC-S type compensation circuit, the transmitting coil module (3) adopts an LCC type coupling mode, and the transmitting coil module (3) includes a primary compensation coil inductance L r , primary side compensation capacitor C r , primary side coil inductance L p , primary side parallel compensation capacitor C p , first measure the compensation coil inductance L r The output end is divided into two paths, one of which is connected in series with the primary side parallel compensation capacitor C p , primary side coil inductance L p Then it is connected to the output end of the high frequency inverter (2), and the other one is connected in series with the primary side compensation capacitor C r Then it is connected to the output end of the high frequency inverter (2) and satisfies: where ω T is the natural resonant frequency of the transmitting coil module; The receiving coil module (4) adopts an S-type coupling mode, and the receiving coil module (4) includes a secondary side coil inductor L connected in series. S and secondary side compensation capacitor C S , and satisfy: Among them, ω S Indicates the natural resonant frequency of the receiving coil module.

5. The method for suppressing overvoltage and overcurrent at startup of a wireless powered direct-drive DC motor according to claim 1, characterized in that: The current detection circuit (10) detects the current at both ends of the motor load module (9) and transmits the current signal to the current comparison module (11). When the current is greater than the threshold current set by the current comparator I, the current comparator I outputs a 0 signal, which makes the switch S CR1 The voltage and current reduction module I (6) starts to work. When the current is less than the threshold current set by the current comparator I, the current comparator I outputs a signal of 1, which makes the switch S CR1 Short circuit, the step-down and current reduction module I (6) stops working; when the current is greater than the threshold current set by the current comparator II, the current comparator II outputs a 0 signal, which makes the switch tube S CR2 The voltage and current reduction module II (7) starts to work. When the current is less than the threshold current set by the current comparator II, the current comparator II outputs a signal of 1, which makes the switch S CR2 Short circuit, the voltage and current reduction module II (7) stops working; Switch tube S R3 Controlled by a timer module (12), when a start signal is detected, the timer module (12) starts working; when the working time is less than the time set by the timer module (12), the timer module (12) outputs a 0 signal, and the voltage reduction and current reduction module III (8) works; when the working time is greater than or equal to the time set by the timer module (12), the voltage reduction and current reduction module III (8) stops working.

6. The method for suppressing overvoltage and overcurrent at startup of a wireless powered direct-drive DC motor according to claim 5, characterized in that: The time reference value in the timer module (12) does not exceed 0.2s; the resistance values of the resistors R1, R2, and R3 in the voltage-reducing and current-reducing module I (6), the voltage-reducing and current-reducing module II (7), and the voltage-reducing and current-reducing module III (8) are R a , the current comparison reference threshold of the current comparator I in the current comparison module (11) is The current comparison reference threshold of current comparator II is Among them U a is the equivalent output voltage of the rectifier filter module (5), R a is the resistance of the armature winding, C e is the potential constant, n is the motor speed, is the stator flux.

7. The method for suppressing overvoltage and overcurrent at startup of a wireless powered direct-drive DC motor according to claim 1, characterized in that: The driving angular frequency ω of the system d , the natural resonant frequency of the transmitting coil module ω T , the natural resonant frequency of the receiving coil module ω S Satisfy the formula: ω d =ω T =ω S .

8. The method for suppressing overvoltage and overcurrent at startup of a wireless powered direct-drive DC motor according to claim 1, characterized in that: The following steps are involved: Step 1: setting the parameters of the circuit components in the system voltage reduction and current reduction module I (6), voltage reduction and current reduction module II (7), and voltage reduction and current reduction module III (8) according to the motor parameters and the load condition; Step 2: setting the current comparison reference values of the current comparator I and the current comparator II in the current comparison module (11), and setting the time reference value in the timer module (12); Step 3: After the system is started, the timer module (12) starts timing, the current detection circuit module (10) starts detecting the instantaneous current of the motor load module (9), and transmits the detected current signal to the current comparison module (11); Step 4: Compare the timing signal of the timer module (12) with the set time. When the working time is less than the time set by the timer module (12), the timer module (12) outputs a 0 signal, and the switch S R3 On the contrary, the timer module (12) outputs a 1 signal, and the switch tube S R3 conduction; Step 5: Compare the detected current signal with the threshold values set by current comparator I and current comparator II. When the current value is less than the threshold value set by current comparator I, current comparator I outputs a 1 signal, and the corresponding controlled switch tube is turned on. Otherwise, current comparator I outputs a 0 signal, and the corresponding controlled switch tube is turned off. Similarly, when the current value is less than the threshold value set by current comparator II, current comparator II outputs a 1 signal, and the corresponding controlled switch tube is turned on. Otherwise, current comparator II outputs a 0 signal, and the corresponding controlled switch tube is turned off. Step 6: When all the switch tubes are turned on and can maintain the on state, the startup is completed when the voltage and current at both ends of the DC motor are stable.

Images